Important Plant Areas for algae - Natural History Museum

CONTENTS 

1.0 SUMMARY ........................................................................................................................................ 4 

2.0 IMPORTANT PLANT AREAS ....................................................................................................... 5 

Juliet Brodie and David M. John 

3.0 ALGAE ............................................................................................................................................... 5 


3.1 Introduction ........................................................................................................................... 5 

3.2 UK algal diversity ................................................................................................................. 7 

3.3 Algal habitats and their classification.................................................................................. 7 

3.4 Conservation legislation covering algae............................................................................... 8 

4.0 IMPORTANT PLANT AREAS FOR MARINE ALGAE............................................................. 8 

Juliet Brodie, Mary J. Holmes and Ian Tittley 

4.1 Introduction............................................................................................................................ 8 

4.11 Habitats and threats..................................................................................................... 9 

4.2 Methods for IPA selection..................................................................................................... 9 

4.21 Nomination and assessment of sites .......................................................................... 9 

4.22 Determining a list of ‘rare marine algae’................................................................... 11 

4.23 Consensus map .......................................................................................................... 11 

4.24 Selection of the first European IPAs to be proposed................................................. 11 

4.3 Results..................................................................................................................................... 11 

4.31 List of UK sites nominated as potential IPAs............................................................ 11 

4.32 Determining a list of ‘rare algae’............................................................................... 27 

4.33 Consensus map........................................................................................................... 41 

4.34 Selection of proposed European IPAs ..................................................................... 42 

4.4 Discussion................................................................................................................................ 43 

4.5 Recommendations.................................................................................................................. 46 

5.0 IMPORTANT PLANT AREAS FOR FRESHWATER ALGAE ................................................ 46 

David M. John and David B. Williamson 

5.1 Habitats and threats .............................................................................................................. 46 

5.2 Methods for IPA selection..................................................................................................... 47 

5.3 Sites and areas........................................................................................................................ 49 

5.4 Selection criteria .................................................................................................................... 49 

5.41 Criterion A - threatened species ................................................................................ 49 

5.42 Criterion B1 - species-richness.................................................................................. 50 

5.43 Criterion B2 - long history of study........................................................................... 50 

5.44 Criterion C - priority threatened habitats................................................................... 50 

5.45 Criterion D - important but ‘data deficient’ .............................................................. 50 

5.46 In summary ................................................................................................................ 51 

5.5 Results..................................................................................................................................... 51 

5.6 Discussion................................................................................................................................57 

5.7 Recommendations.................................................................................................................. 57 

6.0 ACKNOWLEDGEMENTS .............................................................................................................. 59

7.0 APPENDIX - MARINE ALGAE ..................................................................................................... 60 

7.1 Main references used for site descriptions .......................................................................... 60 

8.0 APPENDIX - FRESHWATER ALGAE.......................................................................................... 61 

8.1 Desmid IPAs and potential UK Red List species ................................................................ 61 

8.11 Introduction................................................................................................................ 61 

8.12 Selection of potential UK Red List desmids.............................................................. 61 

8.2 List of potential Red Data List desmids in the UK ............................................................. 62 

8.3 Details of IPAs for freshwater algae..................................................................................... 71 

LIST OF TABLES 

Table 4.1 Sites nominated as European IPAs for marine algae 13 

Table 4.2 Sites nominated as IPAs for marine algae in the UK. 14 

Table 4.3 Sites nominated as potential IPAs for marine algae in the UK, 

but for which more data are required (data deficient) 24 

Table 4.4 Provisional list of ‘rare’ marine red, brown and green seaweed 

species in the UK flora 27 

Table 4.5 Assessment of the proportion of the flora that are rare or data 

deficient 41 

Table 4.6 Proportion of seaweed samples from the UK held at the Natural History 

Museum herbarium collected from pre 1800 to present 45 

Table 5.1 Criteria adopted here for selecting potential desmid IPAs 49 

Table 5.2 EUNIS level 3 habitat types used for desmid IPA selection 49 

Table 5.3 EU Habitat Directive Annex 1 showing threatened and priority 

threatened habitats of special significance to UK desmids 51 

Table 5.4 Sites nominated as European/International IPAs for desmids in 

the UK 52 

Table 5.5 Sites nominated as UK IPAs for desmids 55 

Table 5.6 Potential UK IPAs (areas/sites19-45) for freshwater algae pending 

further investigation - ‘data deficient’ (often no modern data) 56 

Table 8.1 The number of desmid species recorded by David Williamson (DW) between about 1975 

and 2005 restricted to threatened/vulnerable oligotrophic, non-alkaline waters in the UK 62 

LIST OF FIGURES 

Figure 4.1 Map showing the approximate distribution of all IPAs and potential 

IPAs (‘data-deficient’) for freshwater algae/desmids and seaweeds in the UK 12 

Figure 4.2 Consensus map of all species for all sites based on 

Natural History Museum herbarium records 41 

LIST OF BOXES 

Box 1 Criteria for IPA identification 5 

Box 2 Classification of algae 6 

Box 3 Where algae occur 6 

Box 4 Species diversity in the UK 7 

Box 5 EUNIS Habitat Classification 8 

Box 6 Desmids (Order Zygnematales, Phylum Chlorophyta) 47 

2

LIST OF ABBREVIATIONS 

AONB Area of Outstanding Natural Beauty 

ASSI Area of Special Scientific Interest 

BAP Biodiversity Action Plan 

BM Herbarium abbreviation for the Natural History Museum, London 

BPS British Phycological Society 

dSAC Designated Special Area of Conservation 

DW David Williamson 

ESA Environmentally Sensitive Area 

EU European Union 

EUNIS European Union Nature Information 

IPA Important Plant Area 

IUCN International Union for the Conservation of Nature 

MCA Marine Conservation Area 

MNR Marine Nature Reserve 

MPA Marine Protected Area 

NNR National Nature Reserve 

NP National Park 

pSAC Possible Special Area of Conservation 

SAC Special Area of Conservation 

SPA Special Protected Area 

SSSI Site of Special Scientific Interest 

VMCA Voluntary Marine Conservation Area 

VMPA Voluntary Marine Protected Area 

VMR Voluntary Marine Reserve 

Citation 

Brodie, J., John, D. M., Tittley, I., Holmes, M.J. Williamson, D.B. (2007) Important Plant Areas for 

algae: a provisional review of sites and areas of importance for algae in the United Kingdom. Plantlife 

International, Salisbury, UK. 

3

1.0 SUMMARY 

For the first time, the Important Plant Area (IPA) concept, a mechanism for identifying the most 

important plant areas in the world, has been applied to the UK marine algae (seaweeds) and freshwater 

algae (excluding stoneworts) in order to determine which sites to propose as the first list of UK algal sites 

with IPA designation (‘European IPAs’). An initial list of 83 marine/brackish and 130 freshwater sites 

(‘UK IPAs’) were nominated by the membership of the British Phycological Society (BPS). The 

principal selection criteria used were the number of potential Red Data List algae (desmids only), 

presence and number of rare species, concentration of records (diversity ‘hotspots’), and a long history of 

recording. Some criteria were refined to take account of the special problems encountered when treating 

a data deficient group such as the algae. Also included are sites considered as potential IPAs but for 

which further information is required (‘data deficient’ IPAs). All sites were then assessed for their 

suitability to be nominated as potential European IPAs in the first round of assessment organised by 

Plantlife by applying the following criteria: A: the site holds significant populations of one or more 

species that are of global or European conservation concern, B: the site has an exceptionally rich flora in a 

European context in relation to its biogeographic zone; C: the site is an outstanding example of a habitat 

type of global or European plant conservation and botanical importance. 

For the seaweeds, criterion A was applied to an assessed list of ‘rare’ species, compiled using two sources 

of distribution maps (i) ‘Atlas’ of the seaweeds of Britain and Ireland and ii) those based on herbarium 

collections housed in the Natural History Museum (NHM) in London) and the list formed the basis of a 

potential Red Data List. Criterion A could be assigned to UK IPAs but not to the proposed European 

IPAs because no Red Data List exists for these marine algae. Criterion B was applied at both the UK and 

European level by undertaking consensus mapping of all the UK specimens in the NHM. Criterion C was 

only applied to sites where habitats listed in Annex 1 of the EU Habitats Directive were present. Of the 

83 UK IPAs, 9 sites (6 in England, 1 in Scotland, 1 in Wales, and 1 in Northern Ireland) were proposed as 

possible European IPAs. 

Of the freshwater algal IPA nominations received, almost two-thirds were for desmids, five for diatoms 

and the remainder based on a long history of study. Desmids and diatoms are the most species-rich and 

well-researched groups of freshwater algae in the UK. In the case of desmids (green algae), the majority 

of site-specific records date back more than 50 years and many sites have disappeared or changed 

significantly often due to nutrient enrichment. A UK site-specific desmid dataset compiled since 1975 by 

David Williamson was analysed to discover the most desmid-diverse sites and to prepare a potential Red 

Data List of UK desmids. Red Data List desmids were confined to habitats having nutrient-poor and nonalkaline 

waters; all are considered threatened or vulnerable. Desmids were placed into one of three IUCN 

categories: critically endangered, endangered and vulnerable. Rarity was estimated by determining the 

number of sites a desmid had been recorded from by David Williamson over the past 30 years. Only 

criterion B was applied to European IPAs (exceptionally rich desmid floras) and all or most criteria were 

used to define UK IPAs. Six European Desmid IPAs (5 in England, 1 in Wales) and 12 UK Desmid IPAs 

(9 in England, 2 in Scotland, 1 in Wales) are recognised under criteria A, B and C. A further 27 

sites/areas are recognised as potential UK IPAs for freshwater algae (19 in England, 5 in Scotland, 2 in 

Wales, 1 in Northern Ireland) but require further investigation. 

4

2.0 IMPORTANT PLANT AREAS 


The IPA concept was conceived in 1995 at the first Planta Europa conference held in Hyères, France. An 

IPA is defined as ‘a natural or semi-natural site exhibiting exceptional botanical richness and/or 

supporting an outstanding assemblage of rare, threatened and/or endemic plant species and/or 

vegetation of high botanic value’. Three criteria (Anderson, 2002; Box 1) have been used for recognising 

IPAs and a programme developed to identify and protect a network of the best sites/areas for plant 

conservation throughout Europe and in the rest of the world. 

The Global Strategy for Plant Conservation was adopted in 2002 by the parties to the Convention on 

Biological Diversity (Convention on Biological Diversity, 2002). The Strategy has 16 outcome-orientated 

targets with the fifth one calling for the protection of 50% of the most important areas for plant diversity 

by 2010. IPAs were considered to be the principle mechanism for identifying such areas or sites. The UK 

government’s first response to the Strategy document was published in 2002 Plant Diversity Challenge 

(Cheffings et al., 2004). 

Knowledge of the distribution patterns and conservation status of ‘lower plant’ groups lags well behind 

that for ‘higher’ plants. There is a need to use what information exists to recognise sites important for 

these groups and protect them before they disappear or become irreversibly changed. This report is the 

first attempt to recognise IPAs for freshwater algae and seaweeds. 

BOX 1 

Criteria for IPA identification 

Criterion A 

Site holds significant populations of one or more species that are of global or 

European conservation concern. 

Criterion B 

Site has an exceptionally rich flora in a European context in relation to its biogeographical zone. 

Criterion C 

Site is an outstanding example of a habitat type of global or European plant conservation and 

botanical importance. 

3.0 ALGAE 


3.1 INTRODUCTION 

The ‘algae’ are an artificial assemblage of organisms grouped together in large part on the basis of their 

ability to photosynthesise. Morphologically they are extremely diverse and range from single-celled 

microbes through to structurally complex multicellular forms up to several metres in length. The 

classification of the algae has undergone radical reorganisation in recent years and eukaryotic algae are 

now placed in most of the major lineages of life on earth (Box 2). Algae are worldwide in distribution and 

occupy an extremely wide range of habitats (Box 3). 

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BOX 2 

Classification of algae 

In some classifications, the prokaryotic blue-green algae or cyanobacteria are included. Current 

classifications 1 of the eukaryotic algae recognize four major groupings: Primiplantae: Rhodophytes 

(red algae) Charophytes (include stoneworts), Chlorophytes (green algae), Glaucophytes; 

Chromalveolates: Phaeophytes (brown algae), Chrysophytes (golden brown algae = Synurophyta, 

Dictyochophyta, Pedinellophyta), Eustigmatophyta, Raphidophyta, Bacillariophytes (diatoms), 

Haptophytes, Cryptophytes (cryptomonads), Dinophytes (dinoflagellates), Xanthophyta (=Tribophyta; 

‘Yellow-Green Algae’); Excavates: Euglenophytes (euglenoids); Rhizaria: Chlorarachniophytes. 

Most ‘seaweeds’ belong to the Chlorophytes, Phaeophytes and Rhodophytes. 

1 e.g. Keeling (2004). 

About 34,000 species are recognised today although it has been estimated that there could be in excess of 

350,000 algal species worldwide. Of this number about one-third are macroscopic of which seaweeds are 

important in the marine environment and stoneworts in freshwaters. 

BOX 3 

Where algae occur 

Algae are most abundant and diverse in seas, oceans, river systems and standing waters (from puddles 

through to lakes) where attached (benthic), free-floating (plankton) or loosely associated with hard 

surfaces and sediments. Some live in association with soil, soil-free surfaces (e.g., tree trunks, rocks, 

snow, ice) and in symbiotic partnership with a fungus to form a lichen; some also live within animals 

and plants. They are key primary producers, probably accounting for well over 50% of the global 

carbon budget and are at the base of most aquatic food chains. 

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3.2 UK ALGAL DIVERSITY 

Hardy & Guiry (2003) recorded 692 species in The Atlas of Marine Algae of Britain and Ireland (6 only 

known from Ireland), which represents approximately 14% of the world’s known marine algae. The 

number of species mentioned in The Freshwater Algal Flora of the British Isles (John et al., 2002) is 

about 5,000 and these are listed in A Coded List of British Freshwater Algae (Whitton et al., 2003). The 

number of seaweeds is almost certainly a more accurate figure since most microscopic algae are poorly 

known. A comparison of the number of species in the groups covered in this document is given in Box 

4. 

BOX 4 

Species Diversity in the UK 

Numbers for marine algae refer only to ‘seaweeds’ (benthic macroalgae) growing in brackish water 

and/or under fully marine conditions. These are compared to the numbers of freshwater species that 

occur in each of these phyla. For the species diversity of other freshwater phyla in the UK, see John et 

al. (2002). 

Freshwater 

Marine 

Rhodophyta (red algae) 22 339 

Phaeophyceae (brown algae) 2 185 

Chlorophyta (green algae) c. 1000* 100 

Xanthophyta/Tribophyta (Yellow-green algae) 73 16 

*includes 30 stoneworts and over 800 desmids 

3.3 ALGAL HABITATS AND THEIR CLASSIFICATION 

Algae occur not only in a wide range of aquatic habitats but are also common in terrestrial habitats 

including soil and soil-free surfaces. Little is known of the status of terrestrial algae or freshwater and 

marine algae in many of those habitats recognised in the European Union Nature Information System 

(EUNIS) classification of habitat types. (For the most important habitats for the algae under EUNIS, see 

Box 5.) 

7

BOX 5 

EUNIS Habitat Classification 

Habitats most important for algae. Asterisk denotes those habitats Stewart (2004) considered when 

selecting areas important for stoneworts. 

Level 1 

Marine Habitats (A); Coastal Habitats (B); Inland Surface Water Habitats (C); Mire, Bog & Fen (D) 

Level 2 

A1 Littoral rock and other hard substrata; A2 Littoral sediments; A3 Sublittoral rock and other hard 

substrata; A4 Sublittoral sediments; B1 Coastal dune and sand habitats (includes wet dune slacks and 

machair)*; B3 Rock cliffs, ledges and shores, including the supralittoral; C1 Surface standing water*; 

C2 Surface running waters*, C3 Littoral zone of inland surface waterbodies; D1 Raised and blanket 

bogs; D2 Valley mires, poor fens and transition mires; D4 Base-rich fens*; D5 Sedge and reed beds; 

D6 Inland saline and brackish marshes and reed beds. 

3.4 CONSERVATION LEGISLATION COVERING ALGAE 

Marine algae have been mentioned as an important feature in a range of site designations. These include 

Marine Nature Reserves (MNRs), Areas or Sites of Special Scientific Interest (ASSIs, SSSIs) or Special 

Areas of Conservation (SACs). The Skomer MNR was designated partly on the richness of the seaweed 

flora (Brodie & Watson, 1999). In contrast, algae other than stoneworts are rarely mentioned when 

designating freshwater sites or areas. 

Biodiversity Action Plans (BAPs) have been drawn up for only very few algae. Until now BAPs have 

only been prepared for 12 species of stonewort in freshwater/brackish habitats and two seaweeds: 

Anotrichium barbatum and Ascophyllum nodosum ecad mackayi in the marine environment 

(http://www.ukbap.org.uk/species.aspx). BAP listings are currently under review and 11 more species of 

marine algae have been put forward as possible candidates (Brodie, pers. comm.). The only seaweed 

listed in Appendix 1 of the Bern Convention that occurs in the UK is the kelp Laminaria ochroleuca. Any 

site containing a Bern Convention species is considered threatened and qualifies automatically for 

inclusion as a marine IPA; in the case of L. ochroleuca, this only applies to the species in the 

Mediterranean. Until now no freshwater algae in the UK have been listed as endangered or vulnerable 

with the exception of stoneworts. 

4.0. IMPORTANT PLANT AREAS FOR MARINE ALGAE 

Juliet Brodie, Mary Holmes and Ian Tittley 

4.1 INTRODUCTION 

Given that approximately 14% of the world’s known marine seaweeds have been recorded from the UK 

(see section 3.2), it is crucial that those sites of algal importance are identified and recognised. The aim 

of this work is to develop an inventory of sites considered to be important for the marine algae in a UK 

(national) context and to apply the IPA criteria in order to determine which should be proposed as 

possible European (international) IPAs. All UK sites included here are potentially of European 

importance but for now these are distinguished as UK IPAs which may eventually feed into the European 

8

inventory when more data become available. Those sites which were selected from the UK inventory to 

go forward as potential IPAs are referred to as European IPAs. 

4.11 Habitats and threats 

The varied geology and geomorphology of the UK is reflected in the coastline. The range of tidal height 

around the UK, which includes the second largest tidal range in the world at the Bristol Channel, means 

that extensive and geologically diverse seashores are a feature of the UK and they support a wide 

diversity of habitats from solid bedrock through boulders to sand and mud. A number of habitats are also 

created by the organisms themselves, e.g., maerl beds, which are areas of calcareous red algae that 

support a rich and unusual seaweed flora. Habitats that have already been identified as important and 

under potential threat for algae are i) chalk, ii) Zostera beds and iii) maerl 

(http://www.ukbap.org.uk/habitats.aspx). 

4.2 METHODS FOR IPA SELECTION 

4.21 Nomination and assessment of sites 

Site nomination 

In order to compile a list of the UK sites that could be potentially put forward as possible European IPAs 

for the marine algae, the members of the British Phycological Society were asked to nominate sites. The 

request by e-mail and in The Phycologist (Autumn, 2003, p. 3), asked for the following information: 1. 

Name and location of site, 2. Reason for proposing site (e.g., history of research, number of species, 

presence of rare species), 3. Would you be willing to be contacted to supply further information regarding 

the site? 

The result of this request was the nomination of 47 marine sites (Brodie & John, 2004a) followed by 

approximately 40 more sites, nominated by Ian Tittley (Brodie & John, 2004b). All sites were then 

assessed for their suitability to be nominated as potential IPAs in the first round of assessment organised 

by Plantlife. 

Site assessment 

A description of each site was constructed using data derived from a range of different sources including 

BPS field reports and survey reports (Appendix 7.1), Joint Nature Conservation Committee site 

(http://www.jncc.gov.uk/), Countryside Council for Wales (http://www.ccw.gov.uk/) and Scottish Natural 

Heritage (http://www.snh.org.uk/). The inclusion of type species recorded from some localities is only 

for red species at this stage; data for these are derived from The Seaweeds of the British Isles series 

(Dixon & Irvine, 1977; Irvine, 1983; Maggs & Hommersand, 1993; Irvine & Chamberlain, 1994; Brodie 

& Irvine, 2003). Where possible, the following information has been included: 

i) Site name and Vice-County. 

The name of the site was mainly as given by the nominator, although in a few cases where there were two 

or more sites in close proximity, these were amalgamated. A small number of sites were eliminated on the 

grounds that they did not fit with the criteria for marine sites. Vice Counties have been used, as these are 

not subject to council boundary changes. 

ii) Grid reference 

This varied from giving a grid reference to indicate a general area, to the central point of the site. For 

some sites, the two ends of a shore were given. 

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iii) Status 

In some cases the sites fell within SACs or SSSIs. Here the status is included but the IPA proposed may 

only be a part of the designated area. 

iv) Application of IPA criteria for UK IPAs 

At the UK level, the qualifying criteria applied were those stated in Box 1 plus an additional criterion D: 

Criterion A: Site holds significant populations of one or more species that are of global or European 

conservation concern. 

Criterion B: Site has an exceptionally rich flora in a European context in relation to its biogeographical 

zone. 

Criterion C: Site is an outstanding example of a habitat type of global or European plant conservation 

and botanical importance. 

Criterion D: A nominated site considered to be important but for which further information is required 

(‘data deficient’). 

At the UK level the criteria were applied as follows: 

Criterion A was assigned to a site if there was a species or species: 

i) confined to a specific habitat or habitats that are rare or absent elsewhere in Europe in the marine 

context, e.g., chalk cliffs, maerl beds; 

ii) nationally rare (Table 4.4), possibly declining and, if known, rare in a European context; 

iii) confined to only one known site in the UK; 

iv) nationally rare and a large proportion of the world’s known population (e.g., Schmitzia hiscockiana - 

about 98% of the world’s population occurs in the sea around the UK). 

Criterion B was assigned to a site if a large number of species had been recorded from it. If this 

information was not directly available, it was ascertained by consensus mapping (see 4.23) which was 

also used to confirm sites based on recorded numbers of species. Habitats and species composition 

(assemblages) were also taken into account. One site might not be diverse in terms of number of habitats 

present or have habitat types which typically have large numbers of species but might be rich in numbers 

of species or species assemblages for that particular habitat or geographical location. 

Criterion C was assigned to a site if it was an outstanding example for the algae of 

habitats which already have UK BAP conservation status: chalk, maerl and eel grass (Zostera), plus 

exceptional reef systems supporting rich algal communities, and saltmarsh and gravel sites to which some 

algae are confined and these are frequently neglected habitats. 

v) Number of species recorded 

For many sites it was not possible to provide this information. Where it has been possible, e.g. published 

species lists of good quality, an indication of diversity has been given based approximately on 200 = very high 

diversity. However, the habitat was also taken into account when assessing the richness of the site, given 

that some have inherently higher diversity than others. 

vi) Site description 

Site descriptions were compiled from a variety of sources including from the nominee, additional 

personal knowledge of the authors of this report, literature and web-based sources. Given the enormous 

range of sources and the difficulty of assessing the quality of some of these, a comprehensive literature 

search was not undertaken, but a list of the main references consulted are given in Appendix 7.1. 

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vii) Threatened or rare marine algae 

The concept of rare species was based primarily on a revised list of Brodie et al. (2005) (see 4.22 below). 

As with site descriptions, a variety of sources were used to obtain this information. 

4.22 Determining a list of ‘rare marine algae’ 

One of the goals of this work is to consider potential algal species for a UK Red Data List which will 

assist in the recognition of IPAs. In order to compile a list of species that could be assessed as potentially 

rare, mapping records were used. Those that occurred at ten sites or less have been included in the list. 

Two sources of maps were used: i) those in Hardy & Guiry (2003) and ii) those based on the collections 

in the herbarium at the Natural History Museum (BM). The initial list that resulted included 

approximately half the British flora. Each species on the list was given an initial category (Table 4.4) 

based on species information in Hardy & Guiry (2003) and personal knowledge. The list was then 

refined by removing species known to be common but under-recorded for one or other set of maps. The 

list was then circulated in The Phycologist (Brodie et al., 2005) and the BPS members asked to comment. 

Following that, the list was further refined by consulting individuals with particular expertise in different 

groups of algae (Table 4.4) and the category ‘data deficient’ added. It was then possible to use the 

information in relation to Criterion A. 

4.23 Consensus map 

A consensus map of the number of individuals recorded at each site around Britain was achieved by 

counting the number of specimens of each species. The map was created using DMAP for Windows 

(2005) using intervals of 30 species for each category. 

4.24 Selection of the first European IPAs to be proposed 

The philosophy behind IPAs is that once they have been selected, they should not be de-selected. The 

assessment of the sites that were nominated by the BPS membership (Tables 4.2 and 4.3) was based on a 

combination of well-documented data and anecdotal information. To select from that list the first 

potential European IPAs to be put forward for the algae (Table 4.1), sites were selected where there was 

well documented and verifiable data for the algae and where in the majority of cases the sites were 

already internationally recognised as important for a number of reasons which may include for the algae. 

The IPA Criteria A, B and C were then reapplied stringently in a European context, following strict 

guidelines. 

Criterion A could only be applied to sites where there were species which were known to be Ai) Globally 

threatened, Aii) European threatened, Aiii) on National Red List as Critical, Endangered or Vulnerable 

AND endemic, Aiv) National Red List as Critical, Endangered or Vulnerable AND near endemic (ie in 

just 2 or 3 countries in total). Therefore it was not possible to apply this with certainty to any of the 

European IPA proposed, given the data available, i.e. no Red Data Lists. 

Criterion C could only be applied to sites where habitats listed in Annex 1 of the EU Habitats Directive 

were present (mainly reefs in the context of the algae here, but for full list see: 

www.jncc.gov.uk/publications/jncc312/uk_habitat_list.asp). 

4.3 RESULTS 

4.31 List of UK sites nominated as potential IPAs 

A total of 83 sites were nominated for marine algae (Tables 4.2 and 4.3, and Fig. 4.1), including 39 in 

England, 14 in Wales, 25 from Scotland, 4 in Northern Ireland, plus 1 from the Isle of Man. 

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Figure 4.1 Map showing the approximate distribution of all IPAs and potential IPAs (‘data deficient’) 

for freshwater algae/desmids and seaweeds in the UK. 

Rockall is the only IPA not on the map. 

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Table 4.1 Sites nominated as European Important Plant Areas for marine algae 

Site number refers to the map in Figure 4.1. 

Site Grid ref. Status Qualifying 

criteria 

No. of 

species 

ENGLAND 

1 Berwick-upon- 

Tweed, 

Northumberland 

11 Whiteness Gap, 

Thanet, Kent 

21 Peveril Point to 

Durlston Head, 

Swanage, Dorset 

NU005540 

TR396710 

SZ780034 

SAC, 

AONB 

SSSI, 

SAC 

Durlston: 

VMCA 

Site description 

B High The site has many algal ‘diversity 

hotspots’ and includes nationally rare 

species. It has a long history of algal 

study and is the type locality for several 

species of algae. 

B Medium This site has unique assemblages 

associated with chalk platforms and 

caves and is the type locality for some 

chalk cliff algae. It has a long history of 

B 

Very 

high 

28 Plymouth, Devon SX485535 SAC B Very 

high 

29 Falmouth and 

Helford, Cornwall 

32 Lundy Island, 

Devon 

WALES 

41 Skomer Island, 

Pembrokeshire 

SCOTLAND 

53 Isle of Cumbrae, 

Argyll 

NORTHERN 

IRELAND 

82 Strangford Lough, 

Co. Down 

SW813321 SAC B, C Very 

high 

SS1345 

SM735095 

MNR, 

SAC, 

SSSI 

SAC 

MNR 

B, C Very 

high 

B 

Very 

high 

algal study. 

This site is a ‘diversity hotspot’ with 

many nationally rare species. It has a 

long history of algal study. 

This site has a very high algal diversity. 

It has a long history of algal study and it 

is the type locality for several species of 

algae. 

This area has sheltered intertidal 

mudflats and sandflats. It has a 

particularly diverse algal flora including 

a number of warm water species. It is 

the location of the largest and most 

southerly maerl bed in the UK. It has a 

long history of algal study. 

This site consists of granite and slate 

reef systems and a variety of habitats on 

the reefs. It is a ‘diversity hotspot’ for 

algae with over 300 species recorded. It 

has a long history of algal study. 

This site has a wide range of habitats, 

including excellent examples of algal 

communities on bedrock, boulders and 

cobble habitats. It has a very high 

diversity of algae, with over 240 species 

recorded. 

NS160540 B High This site has a high diversity of algae, a 

long history of study and is the type 

locality for species of algae. 

J589496 

SAC 

MNR 

B High The southern half of the site has high 

algal diversity for eastern Ireland, maerl 

beds and a long history of research. 

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Table 4.2 Sites nominated as IPAs for marine algae in the UK. 

Qualifying criteria: A = Site holds significant populations of one or more species that are of global or European conservation concern; B = Site has an 

exceptionally rich flora in a European context in relation to its biogeographical zone; C = Site is an outstanding example of a habitat type of global or 

European plant conservation and botanical importance. Site number refers to the map in Figure 4.1. 

Site Grid ref. Status Qualifying No. of Site description 

Threatened or rare species 

criteria species 

ENGLAND 

1 Berwick-upon- 

Tweed, 


4 

5 

NU005540 

Flamborough TA2570 

Head, West 

Riding, Yorkshire 

Scolt Head, 

Norfolk 

SAC; 

AONB 

SSSI; 

SAC; 

Heritage 

Coast 

B High Rocky shore including Bucket Rocks, Ladies Skerrs and Sharper's 

Head. The site has many algal ‘diversity hotspots’ and includes 

nationally rare species. It has a long history of algal study and is the 

type locality for several species of algae including, Acrochaetium 

battersianum G. Hamel, Phyllophora traillii Holmes ex Batters, 

Porphyrodiscus simulans Batters and Lithophyllum crouanii Foslie. 

C >100 Includes Flamborough Headland, Thornwick Bay, Chatterthrow Bay, 

North Landing, Selwick’s Bay, Cough Hole, Stack’s Pinnacle, South 

Landing area and Sewerby Rocks. Northern limit of chalk in UK. 

The best stretch of undisturbed chalk cliff coastline in the UK. 

Embayments, with chalk platforms and slabs, chalk boulders and 

cobbles with flint, shingle/gravel. Also caves, arches and pinnacles. 

This site has unique assemblages associated with calcareous 

platforms and caves. Southern limit for several algae, e.g. Ptilota 

gunneri P.C. Silva, Maggs & L.M. Irvine. Chrysophyte species 

include: Apistonema carterae Anand, Entodesmis maritima (Anand) 

Parke & Green and Thallochrysis litoralis Anand. Several recent 

surveys. 

TF802463 NNR C, D Low Offshore barrier island with some of the finest saltmarshes in UK. 

Algal diversity is low but site is an excellent example of saltmarsh 

14 

Callophyllis cristata 

Chlorochytrium dermatocolax 

Chroodactylon ornatum 

Kuetzingiella holmsii 

Myriactula haydenii 

Myrionema liechtensternii 

Pilinia rimosa 

Pseudendoclonium fucicola 

Sphacelaria caespitula 

Sphacelaria mirabilis 

Sphacelaria nana 

Sphacelaria racemosa 

Stragularia spongiocarpa 

Streblonema breve 

Streblonema fasciculatum 

Streblonema helophorum 

Symphyocarpus strangulans 

Acrochaete wittrockii 

Cruoria cruoriaeformis 

Pseudendoclonium submarinum 

Porphyrostromium ciliare 


Pneophyllum myriocarpum 

Rhodymenia delicatula 

Sphacelaria nana

7 Great Yarmouth, 

Norfolk 

9 Thames Estuary, 

Essex/Kent? 

habitat which is rarely considered for marine algae in the UK. The 

site has not been studied recently for the algae. There are collections 

at BM. It has classical saltmarsh communities with e.g., Bostrychia 

scorpioides (Hudson) Montagne. Notable algal communities occur 

in the tidal channels and macrophytes are found on consolidated 

cobble. 

TG527065 B, D The site includes Gorlestone and mouth of River Yar. A large Pilinia rimosa 

expanse of sand, consolidated gravel and shingle, with wooden 

groynes and piers; site much altered by human activity. It has a long 

history of algal study, including by Dawson Turner. It is an 

important locality in eastern England for type species, including: 

Naccaria wiggii (Turner) Endlicher, Bonnemaisonia asparagoides 

(Woodward) C. Agardh, possibly Halarachnion ligulatum 

(Woodward) Kützing, possibly Compsothamnion thuyoides (J.E. 

Smith) Nägeli, Plenosporium borreri (J.E. Smith) Nägeli, Halurus 

flosculosus (J. Ellis) Maggs & Hommersand, Apoglossum ruscifolium 

mid Thames c. 

Sheerness: 

TQ915754 

10 Thanet area, Kent TR348711 SSSI; 

SAC 

11 Whiteness Gap, 

Thanet, Kent 

14 Beachy Head, 

Eastbourne, 

Sussex 

TR396 710 

SSSI; 

SAC 

(Turner) J. Agardh and Chondria dasyphylla (Woodward) C. Agardh. 

B High Eocene clay and man-made structures. This site has a long history of 

study with records dating back to the 1600s. It is probably an area 

with a change in diversity with species lost and species gained due to 

dynamic changes in habitat and communities. There are seagrass 

beds and saltmarsh communities. Sheerness is the type location for 

Gloiosiphonia capillaris (Hudson) Carmichael, Ulva linza Linnaeus 

and Gracilariopsis longissima (S.G. Gmelin) M. Steentoft, L.M. 

Irvine & W.F. Farnham. 

C The Thanet Coast is the longest continuous stretch of coastal chalk in 

the UK. This site contains subtidal chalk reefs that extend into the 

intertidal zone forming chalk cliffs. These cliffs are the second most 

extensive representative of chalk caves in the UK. The caves support 

some specialised algal communities, for example, Pseudenoclonium 

submarinum Wille and Chrysonema litoralis P.L.Anand. Is the type 

locality for some chalk cliff algae (Anand, 1937). 

A 

Medium This site has unique algal assemblages associated with chalk 

platforms and caves and is the type locality for some chalk cliff 

algae. It has a long history of algal study. 

TV594955 C A site with chalk and upper greensand. Beachy Head is chalk. To 

the east, The Pound is a series of upper greensand reefs between 

which are shallow lagoons with diverse alga flora, and to the west 

towards Birling Gap there is chalk foreshore reef and associated algal 

15 


Apistonema carterae 

Scytosiphon dotyi 

Unique chrysophytes (Anand, 

1937) 

Dasya punicea (Zanardini) 

Meneghini ex Zanardini

communities. The range of geology is reflected in the algal 

communities, e.g. Pelvetia canaliculata and Ascophyllum nodosum 

occur on the reefs but not on chalk. The lagoons have a diverse algal 

flora. There are also cliff and cave algae. It is a site of historical 

importance. 

15 Brighton, Sussex TQ315037 B, C Chalk shore to east of Brighton. It has a long history of algal study 

(Merryfield collections in 19th century and earlier) and is the type 

locality for several species, including: Seirospora interrupta (J.E. 

Smith) F. Schmitz, Callithamnion corymbosum (J.E. Smith) 

Lyngbye, Anotrichium barbatum (C. Agardh) Nägeli, Monosporus 

pedicellatus (J.E. Smith) Solier and Polysiphonia fibrillosa (Dillwyn) 

Sprengel. The site is at the boundary of warm-water south-western 

species. Some historical interest. 

18 Bembridge, Isle 

of Wight 

19 South Wight, Isle 

of Wight 

20 Studland, Dorset SZ037825 Part of 

SAC 

21 Peveril Point to 

Durlston Head, 

Swanage, Dorset 

SZ650887 SAC A, D Unusual and diverse algal communities. The first record of 

Sargassum muticum in the UK was found from this site. Not a long 

history of study. Seagrass beds. 

SZ462771 SAC A?, B, C High This site has chalk platforms and caves with hard and soft chalk. 

There are unique algal assemblages associated with these platforms 

and caves, including possibly undescribed red crusts. Cave algal 

communities as described by Anand (1937). The algal communities 

vary depending on the substratum. It is designated an SAC because 

of the cliff and cave communities. It is also a biogeographical 

boundary; e.g., Cystoseira spp, Halopitys incurvatus and 

Himanthalia elongata are absent attached east of the Isle of Wight. 

There is a moderate history of algal recording with several recent 

studies and moderate collections. 

SZ780034 

Durlston 

VMCA 

Helminthocladia calvadosii 

Aglaothamnion bipinnatum 

Polysiphonia ceramiaeformis 

Rhodophysema georgei 


B Restricted area of chalk cliffs, reefs, platform and caves with a good Dasya corymbifera 

diversity of algae. The site has a long history of collecting with good Dasya punicea 

collections at the BM, but no recent collections. It is the type locality Polysiphonia furcellata 

for Apoglossocolax pusilla Maggs & Hommersand. 

Polysiphonia simulans 

B Very high This site is a ‘diversity hotspot’ with many nationally rare species. It 

has a long history of algal study. Swanage is the type locality for 

Acrochaetium trifilum (Buffham) Batters. 

16 

Atractophora hypnoides 

Bornetia secundiflora 

Dasya corymbifera 

Erythrotrichia welwitschii 

Laurencia pyramidalis 


Polysiphonia subulifera 


Stragularia spongiocarpa

22 Kimmeridge 

Ledges 

23 Weymouth, 

Dorset 

SY9177 VMR A, D Jurassic limestone ledges. Unusual algal assemblages. Only known site for Ceramium 

circinatum 

SY683781 B, D High It has a long history of study and is the type locality for several Atractophora hypnoides 

species of algae including: Callocolax neglectus F. Schmitz ex Dasya corymbifera 

Batters, Nitophyllum punctatum (Stackhouse) Greville and Chondria Helminthocladia calvadosii 

capillaris (Hudson) M.J. Wynne. Good historical records and good Lophosiphonia reptabunda 

collections at the BM. 




24 The Fleet, Dorset SY6081 Part of 

SAC 

(Chesil 

and 

Fleet) 

A, C The Fleet is the largest example of a lagoon in England and has 

features of both lagoonal inlets and percolation lagoons. It has fully 

saline to reduced salinity regions. It supports extensive populations 

of Zostera spp. 

25 Sidmouth, Devon SY1287 B High This site has a wide range of habitats including sand interspersed 

with boulder and bedrock, worm reefs and granite boulder sea 

defences. It has a long history of algal study and is the type locality 

for several species of algae including: Porphyra linearis Greville, P. 

dioica Brodie & L. Irvine, Cordylecladia erecta (Greville) J. Agardh, 

Polysiphonia devoniensis Maggs & Hommersand, P. elongella 

Harvey, Gelidium pusillum (Stackhouse) Le Jolis and Gymnogongrus 

griffithsiae (Turner) C.F.P. Martius. 

26 Torquay, Devon SX930640 B, D High This site has a long history of algal study. It has a high diversity of 

species and is the type locality for several species of algae including 

Kallymenia microphylla J. Agardh, Compsothamnion gracillimum 

De Toni, Ceramium echinotum J. Agardh, C. pallidum (Nägeli ex 

Kützing) Maggs & Hommersand, C. siliquosum (Kützing) Maggs & 

Hommersand and Sphondylothamnion multifidum (Hudson) Nägeli. 

27 Wembury, Devon SX5147 VMCA B, D High A moderately exposed shore with varied intertidal rocky 

communities. This site has a long history of study and is a diversity 

hotspot. 

28 Plymouth, Devon SX485535 SAC B Very high This site has a very high algal diversity. It has a long history of algal 

study and it is the type locality for several species of algae including 

Acrochaetium brebneri (Batters) G. Hamel, Colaconema 

endophyticum (Batters) J.T. Harper & G.W. Saunders, C. 

bonnemaisoniae Batters and Polysiphonia foetidissima Cocks ex 

Bornet. Laminaria ochroleuca is recorded from this site. 

17 

Titanoderma laminariae 

Lamprothamnion papulosum 

(nationally rare charophyte). 

Zostera spp 

Grateloupia turuturu 

Sarcodiotheca gaudichaudii 

Solieria chordalis 

Lophosiphonia reptabunda 

Gelidium corneum 

Polysiphonia furcellata 





Bornetia secundifora 

Helminthocladia calvadosii 

Gigartina pistillata 


Rhodophysema georgei

29 Falmouth and 

Helford, Cornwall 

SW813321 SAC A, B, C Very high This area has sheltered intertidal mudflats and sandflats. It has a 

particularly diverse algal flora including a number of warm water 

species. It is the location of the largest and most southerly maerl bed 

in the UK. It has a long history of algal study. Type species include 

30 Lizard, Cornwall SW690174 

(SAC grid 

red) 

31 Scilly Isles, 

Cornwall 

32 Lundy Island, 

Devon 

SV912111 

SS1345 

NNR; 

SAC 

SSSI; 

SAC; 

SPA; 

AONB; 

Ramsar; 

MPA; 

ATBI 

MNR; 

SAC; 

SSSI 

Phymatolithon calcareum (Pallas) Adey & D.L. McKibbin. There are 

extensive populations of Zostera. 

Schmitzia hiscokiana 

Schmitzia neapolitana 

Acrothrix gracilis 



Grateloupia dichotoma 

Halymenia latifolia 

Itonoa marginifera 

Lithothamnion corallioides 


Schmitzia hiscockiana 

A, B High Historical site with high diversity. Audouinella lorrain-smithiae 


Codium adhaerens 

Dasya ocellata 

Desmarestia dresnayi 



Grateloupia dichotoma 

Microcaldia glandulosa 

Pterosiphonia pennata 

Pringsheimiella scutata 

Sphacelaria tribuloides 

A, B High An archipelago of granite islands off southwest of England with a 

high diversity of marine habitats and communities in a range of 

A, B, C 

exposure conditions. It is the type locality for several species of algae 

including: Rhodophysema georgei Batters and Erythrotrichia 

bertholdii Batters. There are extensive seagrass beds of Zostera 

marina. There is a high diversity of algae. There are historical 

studies. It is designated a European ATBI site. 

Very high This site consists of granite and slate reef systems and a variety of 

habitats on the reefs. It is a ‘diversity hotspot’ for algae with over 

300 species recorded. It is the most northerly site recorded 

Laminaria ochroleuca. It has a long history of algal study. 

18 




Halymenia latifolia 




Pterosiphonia pennata 

Schmitzia hiscokiana 


Codium vermilara 

Colacodictyon reticulatum 

Itonoa marginifera 

Kuetzingiella battersii 

Microcladia glandulosa 

Myriactula stellulata


33 Ilfracombe, 

Devon 

36 Bees Head, 

Cumbria, 

Cumberland 

WALES 

SS500476 B, D This is a site with good diversity and historical records. It is the type 

locality for Calliblepharis jubata (Goodenough & Woodward) 

Kützing. 

NX940146 A Medium An isolated outcrop of red sandstone - effectively an island - in an 

area with few rocky sites in north-west England. A good range of 

algal communities in the intertidal site. Zostera angustifolia. 



37 The 

Gower/Swansea, 

Glamorgan 

38 Milford Haven 

Waterway, 

Pembrokeshire 

39 West Angle Bay, 

Pembrokeshire 

40 St. Anne's Head, 

Pembrokeshire 

41 Skomer Island, 

Pembrokeshire 

42 Cymyran Strait, 

Anglesey 

SS875385 to 

SS871635 

SM8604 (site 

of maerl bed 

within the 

SAC) 

SM849032 

SM810029 

SM735095 

AONB; 

NNR; 

SSSI 

SAC; 

part NP; 

part 

SSSI; 

part ESA 

SSSI; 

SAC; 

NP 

SSSI; 

SAC; 

NP 

SAC 

MNR 

B, D High This includes Worms Head, Port Eynon, Oxwich and Mumbles 

Head. It was the first SSSI in Britain. It is an area of high algal 

diversity. 

A?, C, D? High A ria with a wide range of environmental conditions, including 

seabed substrates, tidal streams and salinity gradients. There is a 

high diversity of species and extensive beds of Zostera. 

B High West Angle Bay is a small, westfacing rocky bay at the southern 

edge of Milford Haven Waterway and is a mixture of moderately 

exposed rocky cliffs, platforms, rockpools and overhangs with some 

sand on the mid and upper shore in the centre of the bay. This site is 

one of the richest sites for marine flora and fauna in South and West 

Wales. The shore platforms at West Angle Bay are of considerable 

importance, for the algal communities within rockpools. 

A?, D? An exposed rocky headland on the northern side of the entrance to 

Milford Haven Waterway. Large rockpools in midshore support 

Cystoseira baccata a south-western and western species of limited 

distribution. 

B, C Very high This site has a wide range of habitats, including excellent examples 

of algal communities on bedrock, boulders and cobble habitats. It 

has a very high diversity of algae, with over 240 species recorded. 

SH290770 SSSI A Sheltered sand and mud strait between the Inland Sea and the west 

coast of Anglesey. The strait drains to a channel at low water with 

sand along the shore and mud, saltmarsh and bedrock along the mud 

and uppershore. The site supports an unusual form of Ascophyllum 

nodosum ecad scorpioides and Zostera spp. 

Maerl and associated species: 


Gelidiella calcicola 

Petrosiphonia pennata 


Mesogloia lanosa 

Sphacelaria mirabilis 

Hydrolithon cruciatum 

Hinksia ovata 






19

43 Enlli and Pen SH1324 and 

Llŷn, Caernarvon around 

44 Oyster Bank, 

Tremadog Bay, 

Caernarvon 

46 The Sarnau, 

Caernarvon 

48 Porth Cwyfan, 

Caernarvon 

49 Rhosneigr Reef, 

Anglesey 

50 Wear Point, 

Caernarvon 

SCOTLAND 

SH3530 

Various (as 

stated by 

CCW) 

SAC; 

NNR 

MNR; 

SAC 

A, B Very high Bedrock, cliffs, caves and gullies on wave and tide exposed shores. 

Bedrock cliffs, boulders, caves and gullies in the subtidal with 

generally clear water all result in a large infralittoral zone. The site 

was proposed because of Schmitzia hiscockiana and the diversity of 

intertidal and subtidal algal assemblages; the number of species is 

very high (207) in a relatively small area. 

A, C The Oyster Bank at Pwllheli is a sheltered area of mud and sand 

bottom with stabilised pebbles and shells including small cobbles and 

pebbles in a muddy matrix. The site lies at a depth of 8 m within 

Tremadog Bay which is in the Pen Llŷn Sarnau marine SAC. It is 

the only known site in the UK for Anotrichium barbatum. 

Dermocorynus montagnei is a truly rare species confined to gravel. 

SAC A?, B, D? High? The Sarnau is comprised of three unusual shallow subtidal reefs 

(Sarn Badrig, Sarn-y-Bwch and Sarn Cynfelyn) which extend southwest 

into Cardigan Bay. The largest of the reefs, Sarn Badrig, 

extends about 24 km offshore. The Sarnau are thought to be the 

remains of glacial moraines formed during the last glaciation, and are 

considered to be unique sublittoral reef features in the British Isles 

(Coastal Geomorphology Partnership) and are composed entirely of 

boulders, cobbles and pebbles with various grades of sediments 

mixed in. The communities of the Sarnau are typically composed of 

ephemeral seaweed species that grow rapidly during the summer or 

are very robust species that resist scour by sand mobilised by winter 

storms. 

SH335684 SSSI B?, D Two small bays and an island (with causeway) on the west coast of 

Anglesey. The shore is made up of complex rugged platforms which 

support a wide range of habitats including rockpools, overhangs and 

boulders. The platforms are covered with a dense canopy of fucoids, 

kelps and red algae. The site was nominated because of its diverse 

algal community and for Cystoseira. 

SH3172 

SM94119429 

/ SM939044 

SSSI; 

AONB 

B A series of reefs and pools on the west coast of Anglesey at 

Rhosneigr. It was designated as an SSSI in 1980 for its rich algal 

assemblage. This site under threat from non-native species e.g., 

Sargassum muticum. 


Anotrichium barbatum 

Dermocorynus montagnei 

Polysiphonia furcellata 

Osmunda truncata 


Ceramium cimbricum 

Compsothamnion gracillimum 

Gloiosiphonia capillaris 

Polysiphonia devoniensis 


Osmundea truncata 

SAC A? Low shore muddy shingle spit. Chondracanthus teedei 

20

52 Lamlash Bay, 

Arran, Argyll 

NS030315 MPA A, B Some of the seabed of Lamlash Bay consists of soft substrata 

including patches of seagrass. There are also the remains of a deep 

maerl bed, which although has been extensively damaged by scallop 

dredging since the 1970s, still has significant area of maerl. More 

recently, previously undiscovered patches of maerl were found in 

excellent condition. There are also Zostera spp. 

53 Isle of Cumbrae NS160540 B High This site has a high diversity of algae and a long and extensive 

history of study, especially since the mid 19th C. There are large 

collections in the BM. Maerl has been found between the Cumbrae 

Islands. It is the type locality for species of algae including 

Petrocelis hennedyi (Harvey) Batters. 


54 Loch Sween, NR720820 MCA A This site has diverse and unusual algal assemblages. Phymatolithon calcareum 

Argyll 

55 Tiree, Argyll NM980450 B This site is a diversity hotspot and is the northernmost limit for some 

algal species. 

56 Sound of Islay, NR435700 C Site has maerl beds. 

Inner Hebrides 

58 Sound of Arisaig, NM650800 SAC; 

Ascophyllum nodosum ecad 

Inner Hebrides 

SSSI 

59 Barra/Eriskay 

Sound, Outer 

Hebrides 

60 Loch Maddy 

complex, north 

Uist, Outer 

Hebrides 

(including Loch 

Eport, North Uist, 

Outer Hebrides) 

62 Sound of Harris, 

Outer Hebrides 

67 Loch Duich Head, 

Ross and 

Cromerty 

A, C The site is of sublittoral sandbanks on the west coast of Scotland with 

some of the most extensive beds of maerl in the UK. There are rich 

communities associated with the maerl, including several rare and 

scarce species, such as the alga Gloiosiphonia capillaris. Zostera 

marina is found on shallow sand in outer Loch Ailort. The site is an 

important part of the transition from southern to northern 

communities that occurs along the coast of the UK. 

NF760080 dSAC B, C This site is a diversity hotspot and supports maerl beds. 

NF930680/ 

NF880645 

SAC A, C This site is representative of fjardic sea lochs on the coast of northwest 

Scotland. There are numerous rocks and islands. There are 

dense beds of knotted wrack Ascophyllum nodosum ecad mackayi 

and a variety of kelp forest types that illustrate the wave exposure 

gradient in the loch. There are also maerl communities. 

NF970810 B, D This site is a possible diversity hotspot. 

NG930190 

SAC; 

SSSI 

mackayi 


Ascophyllum nodosum ecad 

mackayi 

Callophyllis cristata 

C The reef system at this site is considered to be one of the best areas in Ascophyllum nodosum ecad 

the UK. There is maerl. 

mackayi 


21

68 Loch Eriboll, 

Sutherland 

71 Sullom 

Voe/Lerwick, 

Shetland 

NC430590 A? C This site is a diversity hotspot for uncommon sublittoral algae. 

Maerl. 

Sullom Voe: 

HU380757 

SAC A High Sullom Voe is the only Scottish example of a ria. The flora is borealarctic 

(northern) and species-rich. There is a good recent history of 

study over the past 30-40 years. There are detached Phyllophora 

communities and unusual forms of Saccharina latissima. There is 

maerl at the mouth of the voe. There is a good check list for the area 

and the exceptionally long list of rare or threatened species reflects 

the intensity of study by algal experts at the site. Fucus distichus (as 

evanescens) occurs in the harbour. 

75 St. Andrews, Fife NO5318 B, C This site has a long history of collecting, is a diversity hotspot and 

has a unique rockpool flora. 

77 Pettico Wick, 

Scottish Borders 

NT9069 B, D Mixture of sand, shingle, boulders and bedrock. This site has a long 

history of study of sublittoral algae and is a diversity hotspot. 

78 St. Abbs Head, 

Scottish Borders 

NT9169 

NORTHERN 

IRELAND 

NNR; 

MNR; 

VMR; 

SAC 

B, C Rocky coastline with exposed shores. Sublittoral habitats include 

bedrock, boulders, caves, reefs, gravel and sand further offshore. 

This site is a diversity hotspot especially for sublittoral algae. 

Generally recognised as a site for marine biological studies. 

Acrochaetium nemalii 

Acrothrix gracilis 

Antithamnionella floccosa 

Blastophysa rhizopus 

Botrytella micromora 

Capsosiphon fulvescens 

Colacodictyon reticulatum 

Dictyosiphon chordaria 

Ulva ralfsii 

Epicladia perforans 


Hincksia ovata 

Leptonella fasciculata 

Mesogloia lanosa 

Myrionema papillosum 

Phaeostroma pustulosum 

Phycocelis crouaniorum 


Psuedendoclonium fucicola 


Scageliothamnion pusillum 

Stictyosiphon soriferus 

Streblonema fasciculatum 

Streblonema infestans 

Streblonema parasiticum 

Titanoderma laminariae 

22

82 Strangford J589496 

Lough, Co. Down 

ISLE OF MAN 

MNR; 

SAC 

A, B High The southern half of the site has high algal diversity for eastern 

Ireland, maerl beds and a long history of research. All Zostera 

species present. 

Aglaothamnion tripinnatum 


Feldmannia paradoxa 


Rhodochorton concrescens 


Ulva ralfsii 

83 Isle of Man SC360854 

(centre of Isle 

of Man) 

B High Notably Port Erin and Port St Mary. There is a diverse range of 

habitats from sheltered to exposed. There is a continuous history 

from 19 th C with collections at the BM. Odonthalia dentata and 

Porphyra amplissima are at their southern limits. It is the type 

locality for Lithophyllum nitorum W.H. Adey & P.J. Adey. 



23

Table 4.3 Sites nominated as potential IPAs for marine algae in the UK, but for which more data are required (data deficient). 

Site number refers to the map in Figure 4.1. 

Site Grid ref. Status Qualifying No. of Site description 

criteria species 

ENGLAND 

2 Low Newton-bythe-Sea, 

NU2424 D Also known as St Mary’s, Newton Haven. Bedrock, boulders and sand. 

This site has a long history of study. 


3 St. Mary's Island, NZ3575 D Also known as Bait Island. Rocky shore. This site has a long history of 

North Tyneside, 

study and is a diversity hot spot. It is the type locality and only known site 

Durham 

6 Sheringham, 

Runton and 

Cromer, Norfolk 

TG145435 to 

TG225 425. 

2-3 km 

centred on 

West Runton: 

TG185435 

for Acrochaetium sanctae-mariae (Darbishire) G. Hamel. 

D Includes Robin Friend, West Runton, East Runton and Cromer. Rock 

outcrops with sand, consolidated gravel and shingle. It is a significant 

eastern site because it is an isolated area of 2-3 km of chalk on an 

otherwise soft coastline. It has a long history of algal study with very old 

historical collections including by Dawson Turner (1775-1858) and has 

been a focus for algal growth studies, including by I. Tittley, 1980s-1990s. 

8 Harwich, Essex TM262320 D An isolated outcrop of cement stone, which was formerly widespread but 

apparently decreasing; a comparable habitat in Felixstowe has been 

destroyed. The site has a long history of study including by Samuel Dale 

Padina (1700s). There are some unusual species, including Cutleria 

multifida and its other life history phase, Aglaozonia. It is the type locality 

for Osmundea pinnatifida (Hudson) Stackhouse. 

12 Folkstone/East 

Wear Bay/Dover 

D A site of diverse geology, including hard rocky substrata, in south east 

England, including lower greens and, gault and chalk with very diverse 

microhabitats and exposures. This is reflected in the algae. There are 

good communities of species which are uncommon in south east England, 

including a natural zonation of brown algae (Pelvetia canaliculata - only 

place in south east England, Ascophyllum nodosum, fucoids and kelps) and 

a good diversity of species (Choriocolax polysiphoniae (very rare at the 

site), Chorda filum, Scinaia forcellata, Mastocarpus stellatus). 

13 Hastings, Sussex TQ813092 D Medium A site with unusual geology of Wealden series of rocks. Algal 

communities, patchy and restricted in this part of Sussex, are present on 

intertidal reefs. There is a good historical record. It is the type locality for 

Rhodymenia holmesii Ardissone. 

16 Mixon Hole, 

Sussex 

SZ865902 

Marine 

SNCI 

D 

44 species 

listed 

Limestone capping a clay bed exposed as a clay cliff face off the coast of 

Chichester and Selsey Bill. It has been referred to in diving reports. There 

are unusual marine communities including algae. There is no historical 

record. 

24 

Threatened or rare species 

Acrochaetium sanctae-mariae 

Helminthocladia calvadosii – 

an early record from 

Sheringham, 1797.

17 Hayling Island/ 

Solent/ 

Portsmouth, 

Hampshire 

34 Lilstock, 

Somerset 

35 Walney Island, 

South Cumbria, 

Cumberland 

(might be 

deleted) 

WALES 

45 The Inland Sea, 

Caernarvon 

47 Pennar Gut, 

Caernarvon 

SCOTLAND 

51 Loch Ryan/ 

Stranraer, 

Wigtown 

57 Coll, Inner 

Hebrides 

61 Rockall, Outer 

Hebrides 

63 St. Kilda, Outer 

Hebrides 

SU683017 

(centre of 

Langstone 

Harbour) 

Part of 

SAC 

D An area of consolidated boulder gravel, saltmarshes, seagrass and manmade 

habitats including a large marina. The site is potentially threatened 

by introduced species. An unusual diversity of algae occurs in the various 

harbours. Algal epiphytes in the marina. Alien algae were first recorded 

in the Solent area: Sargassum muticum, Undaria pinnatifida, Grateloupia 

turuturu, Solieria chordalis, Sarcodiotheca gaudichaudii. 

ST1644 SSSI D A series of Jurassic limestone ledges. Reasonably diverse flora given 

location up the Bristol Channel. Site of recent research into green 

endophytes of Chondrus crispus (Bown et al., 2003). 

SD184665 

(centre of 

Walney 

Island) 

SSSI D A large rock in vast area of mud. There are historical records. It is the 

type locality for Dictyota dichotoma (Hudson) J.V. Lamouroux. There are 

Zostera communities on one side and Sabellaria communities on other 

side. There are very rich algal communities on scars nearby, e.g. Roa 

Island. 

SH275795 SSSI D The Inland Sea is a permanent water body between Anglesey and Holy 

Island. It has two restricted man-made in and out flow points and never 

dries to a channel at low water. The shores of the Inland Sea are a mixture 

of sheltered bedrock, mud and saltmarsh. It appears to be a site with 

southern species, e.g. Griffithsia devoniensis, Gracilaria bursa-pastoris 

(the most northern record for this species). 

SM943030 SAC D Exceptionally rare habitats supporting particularly unusual biotope 

combinations and/or species assemblages; where the actual biotopes or 

assemblages may not in themselves be of the overriding importance, but 

the physical condition which they represent is the primary importance. 

NX056662 

NX06-61 

NM200570 

D? A site with a long history of study and unusual assemblages. It is reported 

to be the most northerly record for Spyridia filamentosa in the UK. 

57°35’48’’N, SSSI D? Isolated granite rock in sea. There are few collections although some at 

13°41’19’’W 

BM. Alaria esculenta has been reported from 33 m depth. 

NF090990 SAC, D An isolated site with a good range of habitats from sheltered to exposed. It 

World 

is reported to be the most northern limit of Carpomitra costata. The site 

Heritage 

appears to be understudied for the algae. 

Site 

Chondria coerulescens 

64 Dunvegan, Skye NG255468 SAC D Lithothamnion corallioides 

(qv note in Irvine & 

25

65 Loch na h'Airde, NG393163 D This site has unusual algal assemblages. 

Skye 

66 Ord, Skye NG616132 D This site has unusual algal assemblages. 

69 Stenness/Skaill, 

Kirkwall, Orkney 

SAC This area has a good diversity of habitats, communities and species. Loch 

Stenness is an inland tidal, saline lake with unusual algal communities. 

Skaill has a long history of study with good historical collections to early 

19th C. There are collections from Kirkwall, but the site has changed and 

some habitats are lost. Fucus distichus is around the southern end of its 

range here. 

70 Otterswick, HY690428 D The site has unusual algal assemblage. There are old collections in BM. 

Sanday, Orkney 

72 Aberdeen NJ7964- 

NJ7262 

73 Elie to 

Anstruther, Fife 

Coast between 

NO491001- 

NO564036 

D This area has not been localised to any particular site. It covers 

Gardenstown in the north to the tidal limit of the North Esk estuary in the 

south. There are historical records (see Wilkinson, 1979). 

D An area of rocky reef, pool and lagoons. There are very good historical 

collections in mid to late 19 th C. Comparisons of recent and old studies 

suggest that the flora is stable and that the diversity of species is similar to 

those that were found in Edinburgh in the past but are now lost. 

74 Isle of May, Fife NT655994 SAC D High A site with a good diversity of habitats. 

76 Lamberton 

Beach, Scottish 

Borders 

NT9758 D Rocky shore site with a long history of study. 

NORTHERN 

IRELAND 

79 Rathlin Island, 

Co. Antrim 

80 Barr Hall Bay, 

Co. Down 

81 Kearney Point, 

Co. Down 

SAC = 

D133518 

J6146 

J6451 

SAC; 

SSSI/ 

ASSI; 

NNR 

High 

An area of intertidal and subtidal rock, including rocky reefs with caves. 

There is Zostera marina. 

Chamberlain, 1994) 

Antithamnionella floccosa 

Prasiola furfuracea 







26

4.32 Determining a list of ‘rare algae’ 

Table 4.4 is a provisional list of ‘rare’ species with the initial category based on species information in 

Hardy & Guiry (2003) and personal knowledge, and the result after assessment by experts in the different 

algal groups. Prior to the assessment of all the species on the list, almost half of the British flora was 

listed (Table 4.5). After assessment, this was down to 19%. For the brown algae, 35% of species were 

assessed as rare but none of the species was data deficient, whereas overall 10% of the flora was deemed 

data deficient. 

Table 4.4 Provisional list of ‘rare’ marine red, brown and green seaweed species in the UK flora. 

Rarity status before and after assessment by experts is shown. 

Assessors: Juliet Brodie, Christian Boedeker, Yvonne Chamberlain, Robert Fletcher, Linda Irvine, 

Frederik Leliaert, Christine A. Maggs, Fabio Rindi, Barbara Rinkel. 

R = rare; U = under-recorded; I = identification problems; T = taxonomic problem; L = localized; N = 

northern; S = southern; A = alien; dd = data deficient; C = common; BAP = Biodiversity Action Plan 

species; Ab = abundant; LC = locally common. 

SPECIES 

35 

Initial 

category 

After 

assessment 

RED ALGAE 

Acrochaetium battersianum G. Hamel R dd 

Acrochaetium minutum (Suhr) G. Hamel U dd 

Acr n Acrochaetium nemalii (De Notaris ex L. Dufour) Bornet R R 

Agardhiella subulata (C. Agardh) Kraft & M.J. Wynne A A 

Aglaothamnion bipinnatum (P.L. Crouan & H.M. Crouan) Feldmann-Mazoyer U, L R but not 

threatened 

Aglaothamnion diaphanum L’Hardy Halos & Maggs R U 

Aglaothamnion feldmanniae Halos S Possible A 

Aglaothamnion gallicum (Nägeli) Halos ex Ardré U, S C 

Aglaothamnion priceanum Maggs, Guiry & Rueness R U 

Aglaothamnion pseudobyssoides (P.L. Crouan & H.M. Crouan) Halos R, S, U R 

Aglaothamnion tripinnatum (C. Agardh) Feldmann-Mazoyer S Fairly R 

Anotrichium barbatum (C. Agardh) Nägeli R, S BAP species 

Anotrichium furcellatum (J. Agardh) Baldock R, I, S, A A 

Antithamnion villosum (Kützing) Athanasiadis in Maggs & Hommersand S C 

Antithamnionella floccosa (O.F. Müller) Whittick R, N R 

Antithamnionella spirographidis (Schiffner) Wollaston I, A A 

Antithamnionella ternifolia (J.D. Hooker & Harvey) Lyle I, A A 

Apoglossocolax pusilla Maggs & Hommersand R R 

Asterocolax erythroglossi J. Feldmann & G. Feldmann R C 

Atractophora hypnoides P.L. Crouan & H.M. Crouan R R 

Bornetia secundiflora (J. Agardh) Thuret S R 

Callophyllis cristata (C. Agardh) Kützing U, N R 

Calosiphonia vermicularis (J. Agardh) F. Schmitz S R 

Ceramium cimbricum H.E. Peterson R, U, T R 

Ceramium circinatum (Kützing) J. Agardh R, I, S extremely R, 

declined, 

Kimmeridge 

only 

Ceramium flaccidum (Kützing) Ardissone U Not C 

Ceramium pallidum (Nägeli ex Kützing) Maggs & Hommersand U Extremely C 

Ceratocolax hartzii Rosenvinge N U

Chondracanthus teedei (Mertens ex Roth) Kützing S S 

Chondria coerulescens (J. Agardh) Falkenberg S S 

Choreonema thuretii (Bornet) F. Schmitz U dd 

Chroodactylon ornatum (C. Agardh) Basson R, U dd 

Colacodictyon reticulatum (Batters) Feldmann R, U dd 

Colaconema caespitosum (J. Agardh) Jackleman, Stegenga & J.J. Bolton U dd 

Colaconema endophyticum (Batters) J.T. Harper & G.W. Saunders U dd 

Compsothamnion decompositum (J. Agardh) Maggs & L'Hardy-Halos Not recorded 

from Britain 

Not recorded 

from Britain 

Compsothamnion gracillimum De Toni R, U, I Not C 

Compsothamnion thuyoides (J.E. Smith) Nägeli U C - Ab 

Corallina elongata J. Ellis & Solander U, S, I Not C 

Crouania attenuata (C. Agardh) J. Agardh R, S S 

Cruoria cruoriaeformis (P.L. Crouan & H.M. Crouan) Denizot L On maerl, BAP 

Cryptonemia seminervis (C. Agardh) J. Agardh R, S R 

Dasya corymbifera J. Agardh R, I, S Has declined 

Dasya ocellata (Grateloup) Harvey R., S Relatively C 

Dasya punicea (Zanardini) Meneghini ex Zanardini R, I, S Very R 

Dermocorynus montagnei P.L. Crouan & H.M. Crouan R, U Truly R - gravel 

Drachiella minuta (Kylin) Maggs & Hommersand R, U S, truly R 

Erythrocladia irregularis Rosenvinge U C 

Erythrotrichia bertholdii Batters R, U dd 

Erythrotrichia investiens (Zanardini) Bornet R, U, T dd 

Erythrotrichia reflexa (P.L. Crouan & H.M. Crouan) Thuret ex De Toni R, U, S dd 

Erythrotrichia welwitschii (Ruprecht) Batters U dd 

Erythropeltis discigera v. flustrae Batters R, U, I, S dd 

Exilicrusta parva Y.M. Chamberlain R, I, S dd 

Gastroclonium reflexum (Chauvin) Kützing R, S C 

Gelidiella calcicola Maggs & Guiry U On maerl 

Gelidium corneum (Hudson) J.V. Lamouroux R, S T, dd 

Gelidium maggsiae Rico & Guiry 

Not recorded Milford Haven 

from Britain 

Gigartina pistillata (S.G. Gmelin) Stackhouse S R 

Gonimophyllum buffhamii Batters U C 

Gracilaria bursa-pastoris (S.G. Gmelin) P. C. Silva S S 

Gracilaria multipartita (Clemente) Harvey S S 

Gracilariopsis longissima (S.G. Gmelin) Steentoft, L.M. Irvine & Farnham U, I Ab 

Grateloupia dichotoma J. Agardh S R 

Grateloupia luxurians (A. Gepp & E.S. Gepp) de Clerk et al. R, A A 

Grateloupia turuturu Yamada R, A A 

Haemescharia hennedyi (Harvey) K.L. Vinogradova & T. Yacovleva R, U U 

Halosacciocolax kjellmanii S. Lund R, U C 

Halymenia latifolia P.L. Crouan & H.M. Crouan ex Kützing L R? On maerl 

Helminthocladia calvadosii (J.V. Lamouroux ex Duby) Setchell R R 

Holmsella pachyderma (Reinsch) Sturch R, U C 

Hydrolithon boreale (Foslie) Y.M. Chamberlain U dd 

Hydrolithon cruciatum (Bressan) Y.M. Chamberlain R dd 

Hydrolithon samoense (Foslie) Keats & Y.M. Chamberlain R, T dd 

Hydrolithon sargassi (Foslie) Y.M. Chamberlain T, S dd 

Itonoa marginifera Masuda & Guiry R R, S 

Laurencia pyramidalis Bory de Saint-Vincent ex Kützing R, S R, declined 

Leptophytum bornetii (Foslie) Adey R dd 

Leptophytum elatum Y.M. Chamberlain R dd 

Leptophytum leave (Strömfelt) Adey N dd; C in N; deep 

water species 

Lithophyllum duckerae Woelkerling 

36 

Only one 

subfossil 

Only one 

subfossil

specimen in specimen in BM 

BM 

Lithophyllum fasciculatum (Lamarck) Foslie R dd; no recent 

material or 

records 

confirmed 

Lithophyllum hibernicum Foslie 

Not recorded 

from Britain 

Not recorded 

from Britain 

Lithophyllum nitorum W.H. Adey & P.J. Adey R dd 

Lithothamnion lemoineae Adey R, N dd 

Lophosiphonia reptabunda (Suhr) Kylin R, S R? Threatened, 

declined 

Meiodiscus spetsbergensis Saunders & McLachlan R, T, N dd 

Microcladia glandulosa (Solander ex Turner) Greville R, S R, no decline 

Neevea repens Batters R, U dd 

Osmundea osmunda (S.G. Gmelin) K.W. Nam & Maggs U C 

Osmundea ramossisima (Oeder) Athanasiadis R, I C 

Osmundea truncata (Kützing) K.W. Nam & Maggs R R (2 sites) 

Peyssonnelia armorica (P.L. Crouan & H.M. Crouan) Weber-van Bosse R, S Very R 

Peyssonnelia atropurpurea P.L. Crouan & H.M. Crouan S S 

Peyssonnelia immersa Maggs & L.M. Irvine U U 

Phymatolithon brunneum Y.M. Chamberlain R, S dd; West Angle 

Bay, Wales 

Pikea californica Harvey S, A A 

Plagiospora gracilis Kuckuck U U 

Pneophyllum confervicola (Kützing) Y.M. Chamberlain U dd 

Pneophyllum coronatum (Rosanoff) Penrose U dd 

Pneophyllum limitatum (Foslie) Y.M. Chamberlain U dd 

Pneophyllum lobescens Y.M. Chamberlain U dd 

Pneophyllum myriocarpum (P.L. Crouan & H.M. Crouan) Y.M. Chamberlain U dd 

Polysiphonia ceramiaeformis P.L. Crouan & H.M. Crouan R R 

Polysiphonia denudata (Dillwyn) Greville ex Harvey R, S S 

Polysiphonia devoniensis Maggs & Hommersand R, S S 

Polysiphonia foetidissima Cocks ex Bornet R Declined; found 

once in Wales 

Polysiphonia furcellata (C. Agardh) Harvey R R 

Polysiphonia harveyi J. Bailey U, A A 

Polysiphonia opaca (C. Agardh) Moris & De Notarius R, S R; declined, 

Jersey 

Polysiphonia simulans Harvey R, S Uncommon 

Polysiphonia subulifera (C. Agardh) Harvey R, L R, except in 

Ireland; maerl 

Porphyra drachii J. Feldmann U, A dd 

Porphyridium purpureum (Bory de Saint-Vincent) K. Drew & Ross U dd 

Porphyrostromium boryanum (Montagne) P.C. Silva R, U dd 

Porphyrostromium ciliare (Carmichael) M.J. Wynne U dd 

Pterosiphonia ardreana Maggs & Hommersand R R, S 

Pterosiphonia pennata (C. Agardh) Sauvageau R, S R, S 

Pterosiphonia pinnulata (Kützing) Maggs & Hommersand R R, A? 

Pterothamnion crispum (Ducluzeau) Nägeli R, I, S Fairly C 

Pterothamnion polyacanthum (Kützing) Nägeli R Not recorded 

from Britain 

Ptilothamnion sphaericum (P.L. Crouan & H.M. Crouan ex J. Agardh) Maggs R 

R 

& Hommersand 

Rhodella maculata Evans R dd 

Rhodochorton concrescens K.M. Drew R, U dd 

Rhodophysema feldmannii Cabioch Not recorded Not recorded 

37

from Britain from Britain 

Rhodophysema georgei Batters R R; on Zostera 

Rhodymenia delicatula P. Dangeard R R 

Sahlingia subintegra (Rosenvinge) Kornmann U C 

Sarcodiotheca gaudichaudii (Montagne) Gabrielson R, A A 

Scagelothamnion pusillum (Ruprecht) Athanasiadis R, I R, N 

Schmitzia hiscockiana Maggs & Guiry R R 

Schmitzia neapolitana (Berthold) Lagerheim ex P.C. Silva R R 

Solieria chordalis (C. Agardh) J. Agardh R, A A 

Spermothamnion strictum (C. Agardh) Ardissone R R 

Stylonema alsidii (Zanardini) K. Drew U C 

Titanoderma corallinae (P.L. Crouan & H.M. Crouan) Woelkerling, Y.M. U 

Quite C 

Chamberlain & P. C. Silva 

Titanoderma laminariae (P.L. Crouan & H.M. Crouan) Y.M. Chamberlain R R 

Tsengia bairdii (Farlow) K.C. Fan & Y.P. Fan R R; occurs 

intermittantly 

BROWN ALGAE 

Acrothrix gracilis Kylin R R 

Asperococcus ensiformis (Delle Chiaje) M.J. Wynne R R 

Asperococcus scaber Kuckuck R, U R 

Botrytella micromora Bory de Saint-Vincent R R 

Botrytella reinboldii (Reinke) Kornmann & Sahling R R 

Buffhamia speciosa Batters R R 

Chilionema hispanicum (Sauvageau) R.L. Fletcher R, U R 

Chilionema ocellatum (Kützing) Kornmann U U 

Choristocarpus tenellus Zanardini R R; on gravel 

Cladosiphon contortus (Thuret) Kylin R R 

Compsonema microspongium (Batters) Kornmann R R 

Compsonema minutum (C. Agardh) Kornmann R, U R 

Compsonema saxicolum (Kuckuck) Kornmann R, U U 

Corynophloea crispa (Harvey) Kuckuck U? U 

Cylindrocarpus microscopicus P.L.Crouan & H.M. Crouan R R 

Cystoseira humilis v. myriophylloides (Sauvageau) J.H. Price & D.M. John R, S R 

Desmarestia dresnayi J.V. Lamouroux ex Leman U RR 

Dichosporangium chordariae Wollney R, N R 

Dictyosiphon ekmanii Areschoug N N, R 

Dictyota spiralis Montagne U, I, S U, I, S 

Elachista stellaris Areshoug R, S R, S 

Felmannia irregularis (Kützing) G. Hamel U U 

Feldmannia lebelii (Areschoug ex P.L. Crouan & H.M. Crouan) G. Hamel R R 

Feldmannia paradoxa (Montagne) G. Hamel R, U R 

Fucus cottonii M.J. Wynne & Magne L C in W. 

Scotland 

Fucus distichus Linnaeus N N Scotland 

Fucus evanescens C. Agardh R, N Not in UK; 

nomenclatural 

problem 

Giraudia sphacelarioides Derbès & Solier R R 

Halothrix lumbricalis (Kützing) Reinke R, U R 

Haplospora globosa Kjellman R R 

Herponema solitarium (Sauvageau) G. Hamel 

Not recorded 

in Britain 

Hinksia fenestrata (Harevey ex Berkeley) P.C. Silva R, N R 

Hincksia mitchelliae (Harvey) P.C. Silva U U 

Hincksia ovata (Kjellman) P.C. Silva R R, U 

Hincksia sandriana (Zanardini) P.C. Silva U U 

38 

Not recorded in 

Britain

Hincksia secunda (Kützing) P.C. Silva U U 

Kuetzingiella battersii (Bornet & Sauvageau) Kornmann R R 

Kuetzingiella holmesii (Batters) Kornmann R R 

Laminaria ochroleuca Bachelot de la Pylaie S LC, SW 

Laminariocolax aecidioides (Rosenvinge) Burkhardt & Peters U U 

Leblondiella densa (Batters) G. Hamel R R 

Leptonematella fasciculata (Rienke) P.C. Silva R R 

Mesogloia lanosa P.L. Crouan & H.M. Crouan R R 

Microcoryne ocellata Strömfelt R R 

Microspongium globosum Reinke R R 

Microspongium immersum (Levring) P.M. Pedersen R R 

Mikrosyphar polysiphoniae Kuckuck U U 

Mikrosyphar porphyrae Kuckuck U U 

Myriactula areschougii (P.L. Crouan & H.M. Crouan) G. Hamel U U 

Myriactula chordae (J.E. Areschoug) Levring U U 

Myriactula clandestina (P.L. Crouan & H.M. Crouan) Feldmann U U 

Myriactula haydenii (Gatty) Levring R, U R, U 

Myriactula stellulata (Harvey) Levring R R, U 

Myriocladia lovenii J. Agardh R R 

Myriocladia tomentosa P.L. Crouan & H.M. Crouan R R 

Myrionema corunnae Sauvageau U U 

Myrionema liechtensternii Hauck U R, U 

Myrionema magnusii (Sauvageau) Loiseaux R U 

Myrionema papillosum Sauvageau R, I R, I 

Padina pavonica (Linnaeus) Thivy S S 

Petalonia filiformis (Batters) Kuntze U U 

Petroderma maculiforme (Wollny) Kuckuck U U 

Phaeostroma pustulosum Kuckuck R, U R, U? 

Phycocelis crouaniorum Athanasiadis R, U R, U? 

Phycocelis foecunda Strömfelt R, U U 

Pilinia rimosa Kützing R R, U 

Pleurocladia lacustris A. Braun R R 

Pogotrichum filiforme Rienke U U 

Protectocarpus speciosus (Børgesen) Kuckuck ex Kornmann U U 

Pseudolithoderma roscoffense Loiseaux R, I, S S, U, I 

Punctaria crispata (Kützing) Batters R, S R, S 

Punctaria tenuissima (C. Agarh) Greville U U 

Scytosiphon dotyi M.J. Wynne R, U R, U 

Sorapion kjellmanii (Wille) Rosenvinge R, I R, I 

Sorapion simulans Kuckuck R, U R 

Sphacelaria caespitula Lyngbye R, N R, N 

Sphacelaria mirabilis (Reinke ex Batters) Prud’homme van Reine R R, N 

Sphacelaria nana Nägeli ex Kützing R R 

Sphacelaria racemosa Greville R R 

Sphacelaria rigidula Kützing U U 

Sphacelaria tribuloides Meneghini R R 

Sphaerotrichia divaricata (C. Agardh) Kylin R R 

Stictyosiphon soriferus (Reinke) Rosenvinge R, N R, not north 

Stilopsis lejolisii (Thuret) Kuckuck & Nienburg ex G. Hamel R R 

Stragularia spongiocarpa (Batters) G. Hamel R R 

Streblonema breve (Sauvageau) De Toni R R 

Streblonema fasciculatum Thuret R R 

Streblonema helophorum (Rosenvinge) Batters R R 

Streblonema infestans (H. Gran) Batters U R 

Streblonema intestinum (Reinsch) Batters R R 

Streblonema myriocladiae (P.L. Crouan & H.M. Crouan) G.R. South & Tittley R R 

Streblonema parasiticum (Sauvageau) Levring R, U R 

39

Streblonema stilophorae (P.L. Crouan & H.M. Crouan) Kylin R, S R 

Strepsithalia buffhamiana (Batters) Batters R R 

Symphyocarpus strangulans Rosenvinge R R 

Zanardinia typus (Nardo) G. Furnari S Declined 

GREEN ALGAE 

Acrochaete heteroclada Correa & Nielsen U, T U 

Acrochaete leptochaete (Huber) R. Nielsen R R, U 

Acrochaete operculata Correa & Nielsen U, T dd 

Acrochaete repens Pringsheim U, T C, T 

Acrochaete wittrockii (Wille) Nielsen U dd 

Blastophysa rhizopus Reinke R, T dd 

Bolbocoleon piliferum Pringsheim U U 

Capsosiphon fulvescens (C. Agardh) Setchell & N.L. Gardner U, I dd 

Chaetomorpha aerea (Dillwyn) Kützing U, I dd 

Chaetomorpha crassa (C. Agardh) Kützing I, T dd 

Characium marinum Kjellman R, U dd 

Chlorochytrium cohnii E.P. Wright U dd 

Chlorochytrium dermatocolax Reinke R, U, N dd 

Chlorochytrium facciolae (Borzi) Bristol R, U dd 

Cladophora aegagropila (Linnaeus) Trevisan U brackish 

Cladophora battersii Hoek R R, L 

Cladophora coelothrix Kützing R R, L 

Cladophora dalmatica Kützing R, U, I I, U? 

Cladophora flexuosa (O.F. Müller) Kützing R, U, I I, U? 

Cladophora prolifera (Roth) Kützing R, U, I R, L 

Cladophora retroflexa (Bonnemaison ex P.L. Crouan & H.M. Crouan) Hoek R, U R. L 

Cladophora vagabunda (Linnaeus) Hoek R, U, I C? 

Codium adhaerens C. Agardh R R; declined 

Codium bursa (Linneaus) C. Agardh R R; declined 

Codium vermilara (Olivi) Delle Chiaje R, U, S R; declined 

Derbesia marina (Lyngbye) Solier U, I dd 

Derbesia tenuissima (Moris & De Notaris) P.L. Crouan & H.M. Crouan R, I R? dd 

Epicladia perforans (Huber) R. Nielsen I dd 

Ochlochaete hystrix Thwaites ex Harvey U dd 

Ostreobium queketii Bornet & Flahault U C 

Phaeophila dendroides (P.L. Crouan & H.M. Crouan) Batters U, T dd 

Pilinia rimosa Kützing T dd 

Prasiola calophylla (Carmichael ex Greville) Kützing 

R 

Prasiola crispa (Lightfoot) Kützing U LC 

Prasiola furfuracea (Mertens ex Hornemann) Kützing U, I, N R 

Pringsheimiella scutata (Reinke) Höhnel ex Marchewianka R, U, I dd 

Protomonostroma undulatum (Wittrock) K.L. Vinogradova R dd 

Psuedendoclonium fucicola (Rosenvinge) R. Nielsen U, T dd 

Pseudendoclonium submarinum Wille U, T dd 

Pseudopringsheimia confluens (Rosenvinge) Wille R, U, I dd 

Rosenvingiella polyrhiza (Rosenvinge) P.C. Silva U LC, N 

Sykidion dyeri E.P. Wright R, U, I Dd 

Tellamia contorta Batters (incl intricata) U C 

Ulothrix implexa (Kützing) Kützing U C 

Ulva ralfsii (Harvey) Le Jolis R, U, T R? 

Ulva rigida C. Agardh U, I C 

Ulvella lens P.L. Crouan & H.M. Crouan U Dd 

Umbraulva olivascens (P.L.J. Dangeard) E.H. Bae & I.K. Lee U, I, S A? 

Urospora neglecta (Kornmann) Lokhorst & Trask R Dd 

Urospora wormskioldii (Mertens ex Hornemann) Rosenvinge U C 

40

Table 4.5 Assessment of the proportion of the flora that are rare or data deficient. 

Algal 

group 

Number 

of species 

Proportion of the flora 

assessed as rare before 


assessed as rare after 

in the UK assessment (%) assessment (%) 

Red 339 41 12.5 11 

Brown 185 53.5 35 0 

Green 100 52 10 26 

Total 624 47 19 10 


assessed as data deficient 

after assessment (%) 

4.33 Consensus map 

The consensus map is shown in Fig. 4.2. The majority of sites with a high diversity are scattered along 

the south-west and southern coasts of England, although several northern sites, notably Berwick upon 

Tweed and the Clyde (Millport) also have large numbers of species recorded from them. 

Figure 4.2 Consensus map of all species for all sites based on Natural History Museum herbarium 

records. 

Diversity 

1 - 30 

31 - 60 

61 - 90 

91 - 120 

121 - 150 

151 - 180 

181 - 210 

211 - 240 

241 - 270 

All Species 

41

4.34 Selection of proposed European IPAs 

The first 9 IPAs submitted are listed in Table 4.1. There were 6 sites from England, 1 from Scotland, 1 

from Wales and 1 from Northern Ireland. With the exception of two sites (Peveril Point to Durlson, and 

the Isle of Cumbrae), all sites selected are within an area that has a European conservation designation. 

Qualifying for criterion A 

At present no species qualify under Criterion A but this may change in the future as the preliminary 

assessment of species status is refined. 

Qualifying for criterion B 

Sites were selected because of their high or very high diversity, and/or as outstanding examples of 

habitats considered to be of algal importance e.g. maerl beds and/or because of their unique assemblages 

of algae. 

Qualifying for criterion C 

Two of the sites, Lundy and Falmouth & Helford, have outstanding habitats that are listed in Annex 1 of 

the EU Habitats Directive. 

Some sites such as Lundy, Falmouth & Helford and Skomer are already well established as important 

sites for marine algae. Other sites in this list will almost certainly qualify under other criteria but more 

data are required to verify this. 

42

4.4 DISCUSSION 

This is the first time that an attempt has been made to apply the IPA criteria to the marine algae in the UK 

and elsewhere in Europe. The large number of sites nominated and their extensive coverage of the 

coastline around the UK reflects two main things: i) the richness and diversity of algal sites around the 

UK and ii) the immense wealth of knowledge amongst the phycological community. It appears that a 

number of sites have been nominated based on the intuition (‘gut feeling’) of these people, or the studies 

that they have undertaken at these sites. This also resulted in it being difficult to gain an indication of the 

actual boundaries of a site hence difficult to assign grid references to each site. Furthermore, some of 

these sites were SACs or within SACs, which also made it difficult to supply grid references that reflected 

the algal sites. As a consequence, many of these grid references need to be re-evaluated and the 

boundaries of each site to be determined. 

Also problematic has been the assessment of the sites, and the search for information is by no means 

exhaustive. Tracking down the grey literature, particularly before widespread use of electronic publishing, 

is problematic, and one of the recommendations from this work is that that the many reports that do exist 

should be fully documented and widely accessible. 

The ability to apply the IPA criteria also varied from site to site depending on the data available. While 

the application of IPA criterion C of outstanding example of habitat type was relatively straightforward, 

although unsatisfactory, for UK sites, given that most of the relevant habitats already had UK 

conservation legislation (chalk, maerl, Zostera beds), it was much more restrictive for European sites. 

Sites of international importance for particular habitats important for marine algae, but which are not 

Annex 1 habitats, have not yet been included. Future work should ensure omissions of, for example, 

Zostera beds, would be addressed. The application of criteria A and B was less straightforward. This often 

reflected the lack of verifiable data so the novel approach of utilising specimens from the algal herbarium 

and distribution maps was devised. 

It is possible to be critical of the way that criterion A has been applied. Some UK sites that have qualified 

under this criterion have done so because they contain species that have been determined as rare based on 

their presence at 10 sites or less in Britain and Ireland. In many cases, however, little or nothing is known 

about the status of the populations of these species. For criterion B, the use of consensus mapping to 

determine the very rich sites was valuable to provide confirmation for sites that were already considered 

or documented to be rich and to provide information for other sites where these data were lacking. A 

potential difficulty here is defining what is meant by rich, given that number of species alone is not 

necessarily an indication of the diversity of a site and to overcome this, the habitat type has also been 

taken into account. The use of criterion D was deemed necessary for sites where other data were lacking 

but the site was considered worth nominating. 

The data reveal that further assessment of many of the UK sites will be necessary before they can be 

nominated as European IPAs. There are relatively little data available for site assessment that is recent. 

Many of the collections that were used as data in this work were made over 50 years ago. An analysis of 

the proportion of seaweed samples collected over 50 years intervals since 1800 (Table 4.6) indicates that 

almost 60% of the collections were made before 1900 with a peak in the second half of the 19 th C, and 

about 75% before 1950. These collections provide an excellent comparative perspective for assessing the 

status of sites today but the lack of comparative modern collections should be addressed to maintain the 

ability to make such comparisons. There was a drive for marine surveys in the 1980s with the 

consideration of sites for conservation status (e.g., MNRs). There has been comparatively little recent 

acquisition of data for the marine algae. The approach that we have taken also reflects the lack of 

comparative data for marine algae for the rest of Europe (or indeed other parts of the world), although we 

recommend that in the absence of direct data a similar method could be adopted where there are other 

well-developed herbarium collections. 

44

Table 4.6 Proportion of seaweed samples from the UK held at the Natural History Museum herbarium 

collected from pre 1800 to present. 

Time period Proportion of specimens collected (%) 

Pre 1800 1 

1800-1849 14 

1850-1899 44.5 

1900-1949 16 

1950-1999 24 

2000- 0.5 

Determining the number of species recorded at each site was not always possible, although for the nine 

sites that were put forward as potential European IPAs, good information was available. The consensus 

map based on herbarium data was valuable in confirming these sites in terms of diversity. Obviously 

such maps reflect where the collectors have been and this often reflects the transport system of the time or 

favourite coastal resorts. However, this hapazardness coupled with the large sampling effort, has left an 

important legacy – a reference point for the marine algae of the UK from about 100-150 years ago. 

Furthermore, the collections as a whole are a verifiable record of an alga’s existence in space and time. 

The value of diversity also needs to be considered carefully: sites which are clearly extremely diverse in 

terms of numbers of species are almost certainly important, but other sites, such as saltmarsh sites may 

not have a high diversity of species but are nevertheless important as habitats for algae in their own right. 

However, up to date check-lists for sites are valuable, especially if comparisons can be made with earlier 

lists. 

The threatened or rare species listed for sites were derived from the assessed list of rare species (Table 

4.4) in conjunction with species lists from the various sources we used. The finding that approximately 

19% of the flora is rare, with the largest proportion being brown algae, is of note. It is possible that a 

number of the species are under-recorded, given that many of them are small and filamentous and some 

endophytic or endozoic (i.e. living within another alga or animal), and not necessarily easily seen or 

identified. The finding that approximately 10% of the flora is data deficient in terms of knowing whether 

a species is rare or not indicates that much greater input is needed to really determine the extent of species 

distribution. As discussed in relation to site assessment, much of the information is from sources that are 

quite old, so the exact nature of the flora today for many areas requires reassessment. It is therefore our 

opinion that virtually all of these species require re-evaluation at all the sites that they have been recorded 

from as well as at other sites around the UK. We need to be able to assess whether species are genuinely 

rare or under-recorded. The species on this list also need assessment to determine their status and whether 

they have declined in order to see if they have potential for Red Data List inclusion. 

The IPA process has been criticised because it is a selection of sites and what is not selected is therefore 

potentially neglected. Some would argue that the whole of the coastline of the UK should be made an 

IPA for the marine algae and no doubt this should be aspired to. However, counter to that, some sites are 

better than no sites; many of the sites are already in areas designated for their conservation importance for 

a whole range of reasons, e.g., plants, geology, invertebrates. Although IPAs have no legal status, 

nevertheless they are a means of raising awareness among the general public and represent a potentially 

useful tool in that aim. 

45

4.5 RECOMMENDATIONS 

• A number of findings have resulted as a consequence of this work and these are summarised in the 

following recommendations: 

• A comprehensive collection of literature relating to site assessment should be brought together and 

be available electronically and physically. 

• An up to date assessment should be made of sites proposed as IPAs, including good checklists of 

the flora. 

• Species listed as rare or data deficient need reassessment. 

• Up to date collections of marine algae should be made from around the UK. 

• The approach adopted for the development of IPAs as put forward in this document should be 

discussed and applied elsewhere. 

5.0 IMPORTANT PLANT AREAS FOR FRESHWATER ALGAE 

David M. John and David B. Williamson 

5.1 HABITATS AND THREATS 

The Atlantic climate together with differences in geology and geomorphology account for the extremely 

varied landscape of the UK and abundance of rivers, streams, lakes, ponds and boggy or fenland pools. 

Distribution of these aquatic habitats relate to differences in geology, rainfall patterns and human activity. 

As a consequence, the UK can be divided roughly into (a) a more northerly and westerly part dominated 

by hard, igneous or metamorphic Palaeozoic rocks where the climate is cooler, rainier and more oceanic, 

and (b) a lowland part where the geology is more varied and the climate warmer and drier. The total area 

of standing inland water is significantly greater in Scotland (about 1604 km²) compared to Wales (125 

km²) and England (675 km²). In the Scotland there are over 30,000 lochs and lochans together with over 

10,000 burns and rivers. High rainfall areas are often in mountainous uplands where the rocks are 

generally resistant to weathering and the waters are naturally nutrient-poor and of low fertility. By way of 

contrast, many lowland areas have softer, fine grain, sedimentary rocks and glacially deposited clays and 

silts. In such lowland and populous areas most waters are shallow, nutrient-rich and ponds and lakes are 

frequently artificially enriched (‘eutrophicated’) by plant nutrients. 

Many waters in the UK have irreversibly changed or disappeared through neglect, mismanagement, water 

abstraction, land reclamation, dam construction, peat extraction, acidification and nutrient enrichment. In 

nutrient-poor water with an acid pH, the desmids are the most common and abundant algae. These green 

algae are gradually replaced by a succession of other algae if these waters become enriched by nutrients 

above natural background levels, a process known as ‘eutrophication’ (see Duckworth et al., 2002). 

Inevitably the threats to the conservation status of freshwaters are significantly greater in the more 

populous and agriculturally important lowlands compared to the wetter and more mountainous areas. 

Scotland has the greatest area (c.1364 km²) of still relatively nutrient-poor water (‘oligotrophic’) in the 

UK although even once ‘pristine’ lochs have undergone phosphorus enrichment over the past century 

(Fozzard et al., 1999). Desmid diversity and abundance is exceptionally high in oligotrophic waters, 

especially in such lentic habitats as moorland pools, ponds and shallow lakes. All these threatened or 

vulnerable freshwater habitats are most abundant in north-west Scotland, North Wales and the English 

Lake District. Organisms largely restricted to such soft ‘acid’waters are therefore also vulnerable and 

46

threatened hence our focus on desmids. Upland blanket bogs, raised lowland bogs and associated lakes 

are listed as threatened habitats in Annex 1 of the EU Habitat Directive (see Table 5.3). 

5.2 METHODS FOR IPA SELECTION 

The British Phycological Society membership was asked by Brodie & John (2004a) to nominate the most 

important UK areas/sites for freshwater and marine algae. Over 140 nominations were received for 

freshwater algal IPAs of which 80 were important for desmids (Box 6) (about two-thirds of sites), 5 for 

diatoms and the rest for other algal groups or because they have a long history of study. Only in the case 

of desmids were nominations supported by site-specific records although most modern lists are 

unpublished. The majority of the most comprehensive desmid lists were published at least a century ago 

but often fail to mention specific localities. There is no doubt that many sites/areas have undergone 

considerable change since they were originally sampled. 

BOX 6 

Desmids (Order Zygnematales, Phylum Chlorophyta) 

Desmids are a very distinctive microbial group of green algae that are commonly very beautiful and 

remarkably elaborate. They are single-celled or filamentous and usually recognized by having a 

noticeable central constriction to the cell or bilaterally symmetrical cell contents. Desmid growth is 

linked to bicarbonate whose concentration is linked to pH, carbonic acid and carbon dioxide. They 

are most common in soft and generally ‘acid’ waters where they make use of the higher 

concentration of carbon dioxide and carbonic acid. It seems they have intrinsically slow growth 

rates thus allowing them to cope with low nutrient levels (principally nitrogen and phosphorus). 

Potential IPAs for desmids were selected using site-specific records compiled over the past 30 years by 

one of us (DW). These IPAs are all believed to have not undergone significant change over this period 

and still remain relatively nutrient-poor aquatic habitats with an acid pH (‘non-alkaline’). These sites are 

all EUNIS habitat types that are regarded as threatened (see Table 5.2). The number of records of a 

desmid species at such threatened sites was used to give an indication of its conservation status and to 

assist in deciding to which of the following IUCN Red List categories to assign it: critically endangered, 

endangered or vulnerable. Potential UK Red Data List desmid taxa recognised here are listed in Appendix 

8.2. The presence and number of potential Red Data List species is a criterion used for designating 

desmid IPAs. 

We have focused on desmid species although a large numbers of infraspecific taxa are recognised often 

based on subtle differences in morphology. Doubt attaches to the status of many forms and varieties 

although others are distinctive and can be more commonly encountered than the type or ‘nominal’ form. 

Infraspecific forms are only mentioned if very common and distinctive (see Appendix 8.2). 

The following is a summary of the sources of information consulted in drawing up a potential list of UK 

and European IPAs: 

Site-specific data on desmids compiled by one of us (DW); stored as a card index and with many records 

supported by line drawings. 

Site-specific records extracted from literature sources. 

Information on IPAs nominated by members of the British Phycological Society. 

Advice sought by contacting experts and other competent persons on key groups. 

Unpublished records compiled by the authors and taken from published sources of information including 

the desmid Red Data Lists published for Austria (Lenzenweger, 1999), Germany (Gutowski & 

Mollenhauer, 1996) and the Netherlands (Coesel, 1998). 

47

Information from report on UK stoneworts IPAs (Stewart, 2004). 

Information on the type locality of species known only from UK or rarely reported 

outside. 

48

5.3 SITES AND AREAS 

Many larger water bodies (e.g., reservoirs or lakes) represent a single ‘site’ or unit. Sometimes also 

treated as single units are clusters of similar pieces of water lying in close geographical proximity or 

within a well-defined area (e.g., pools/ponds in a particular Sphagnum bog). 

Flowing waters are more unstable compared to standing water and for this reason are excluded unless 

having a long history of study. Over time ponds and lakes undergo change, but generally this takes place 

over decades unlike streams and rivers where changes can be dramatic even over a season. If the only 

available records date back more than 50 years then uncertainty surrounds the present status of a site or 

area. If there is doubt concerning the present status of a site then it might be designated as a ‘data 

deficient’ IPA. 

5.4 SELECTION CRITERIA 

Anderson (2002) identified three criteria for selecting European IPAs and these were adapted and further developed by Stewart 

(2004) when selecting Important Stonewort Areas (ISAs). A similar exercise has been carried out when considering IPAs in 

the context of desmids (Table 5.1). 

Table 5.1 Criteria adopted here for selecting potential desmid IPAs. 

The IUCN categories are critically endangered (category 1), endangered (category 2) and vulnerable 

(category 3). 

Criterion European IPA UK IPA 

A Site/area containing 

potential UK Red Data List 

desmid species 

B1 Site/area having an 

exceptionally rich algal flora 

B2 Long history of algal 

recording 

C Site of a priority threatened 

habitat of major significance to 

desmids/algae in Annex I of the 

EU Habitat Directive 

D Site referred to as ‘data 

deficient’ 

- Contains 5 or more desmid species in 

potential UK Red Data List categories 1 

or 2 

Site/area has an exceptionally rich 

algal flora (over 70 desmid species) 

or 500 species of freshwater algae 

Site has an exceptionally rich desmid 

flora (over 50 desmid species) 

- Site has a long history of desmid records 

Site is a priority threatened habitat 

of major significance to 

desmids/algae and is in Annex I of 

the EU Habitat Directive 

Site is a priority threatened habitat of 

major significance to desmids/algae and is 

in Annex I of the EU Habitat Directive 

- Site considered important for algae but for 

which further information is needed, 

sometimes known historically to be an 

algal biodiversity ‘hotspot’ but not 

studied since about 1950 or information 

otherwise incomplete 

Table 5.2 EUNIS level 3 habitat types used for desmid IPA selection. 

Almost two-thirds of the more than 800 species of desmid known from the UK are restricted to these 

habitat types. 

Code and habitat description 

C1 Surface standing water 

C1.1 - Permanent oligotrophic lakes, ponds and pools 

C1.4 - Permanent dystrophic lakes, ponds and pools 

D1 Raised and blanket bogs 

D1.1 - Raised bogs 

49

5.41 Criterion A – threatened species 

As mentioned above, IUCN criteria have been adopted when assessing potential UK Red Data List 

desmids (see Appendix 8.1). One of the criteria used for selecting an important site/site complex (area) is 

the number of potential UK Red Data List desmid species present. 

We defined the ‘best’ UK desmid sites as those containing ‘at least 5 desmids belonging to the potential 

Red Data List falling into the IUCN categories of critically endangered (Category 1) and endangered 

(Category 2)’. 

The extinct category has not been used although a significant number of desmid taxa have not been 

recorded for at least 50 years. Very probably these desmids are very rare and might simply have been 

‘missed’ by DW. Any desmid not recorded over the past 50 years is regarded here as ‘Data Deficient’ 

rather than extinct. Some of these ‘missing’ desmids are endemics with the majority known only from 

endangered or vulnerable habitat types mentioned in the EUNIS list. 

5.42 Criterion B1 – species-richness 

UK and European IPAs: UK IPAs for desmids are defined here as ‘those in vulnerable or threatened 

habitats containing at least 40 desmid species. Some sites/areas with lower diversities are only included 

if containing at least 5 potential UK Red List species’; European IPAs for desmids are defined as ‘those 

in vulnerable or threatened habitats containing at least 70 desmid species’. 

5.43 Criterion B2 - long history of study 

The provisional assessment of the best UK fungi sites (Evans et al., 2001) uses criteria in addition to 

those recommended by Anderson (2002). The potential fungal sites include those having long lists of 

species, assemblages of rare and indicative species, new records of UK species, a long history of 

recording and sites ‘outstanding’ for fungi. 

The criterion of ‘long history of study’ is used for considering important sites/areas for freshwater algae 

in the UK. It can be applied to permanent standing bodies of water for which records sometimes go back 

over several decades (e.g., Windermere, Priest Pot, Lough Neagh, Loch Leven). Sometimes these sites 

may be representative of a particular habitat type (e.g., nutrient-enriched lakes). All these sites or areas 

are also considered ‘data deficient’ since uncertainty surrounds their current status. 

5.44 Criterion C - priority threatened habitats 

According to Anderson (2002), the criteria for selecting IPAs allow for ‘the five ‘best’ sites, of priority 

threatened habitat of major significance on Annex 1 of the EU Habitats Directive’, or ‘up to 5 ‘best’ sites 

of other threatened (but non-priority) habitats listed on the annex’. Threatened and priority threatened 

habitats mentioned in Annex 1 that are of special significance to desmids are listed in Table 5.3. It is not 

possible to readily select the ‘best’ 5 sites since the data are too incomplete. A possible approach might be 

to choose those containg at least 5 potential UK Red List species. For now all desmid sites that conform 

to the criteria selected here are listed with the most species-rich ones considered of European importance. 

50

Table 5.3 EU Habitat Directive Annex 1 showing threatened and priority threatened habitats of special 

significance to UK desmids. 

Code and Habitat Directive Descriptive 

3. Freshwater Habitats 

31. Standing Water 

3110/3110 Oligotrophic waters containing very few minerals 

3160 Natural dystrophic lakes and ponds 

7. Raised Bogs and Mires and Fens 

71. Sphagnum Acid Bogs 

71.10 Active raised bogs 

71.20 Degraded raised bogs still capable of natural regeneration 

71.30 Blanket Bogs 

5.45 Criterion D – important but ‘data deficient’ 

Many aquatic habitats disappear over time or become dramatically altered due to changes in water 

chemistry and/or other factors. For this reason, sites/areas recognised as ‘hotspots’ of algal diversity are 

‘data deficient’ if their current/recent status is unknown. This is also the case for many historically 

important water bodies. 

Data deficient sites/areas are believed to be important but require confirmation through further study. The 

sites or areas identified here under criterion D are potential IPAs for freshwater algae in the UK but 

require further work. Sites of similar status were recognized when designating fungal IPAs (Evans et al., 

2001) and Stewart (2004) who listed them as ‘Locally Important Stonewort Sites’. 

5.46 In summary 

The best sites/areas are judged on the number of potential UK Red Data List desmids (Criterion A), 

diversity of desmids and/or other algal groups (Criterion B1), long history of recording (Category B2) and 

whether confined to endangered, threatened or vulnerable (C) habitats recognised by EUNIS (see Table 

5.2). To qualify for IPA status a site/area must meet at least two of these criteria. 

5.5 RESULTS 

A total of 45 sites/areas are recognised. Of these, six are IPAs for desmids, considered to be of 

European/International importance (5 English, 1 Scottish) and 12 are IPAs of UK importance (9 English, 

2 Scottish, 1 Welsh) for desmids. The remaining 27 are potential UK IPAs (areas/sites) for freshwater 

algae (19 English, 5 Scottish, 2 Welsh, 1 Northern Irish) pending further investigation. One of these is 

possibly a potential European/International IPA: Snowdonia area: Capel Curig/Cader Idris. The proposed 

UK and European/International IPAs for freshwater algae are based on species diversity and/or long 

history of study (Tables 5.4, 5.5, 5.6; see details in Appendix 8.3) although potential Red Data List 

desmids are also taken into account. The six European/International IPAs for desmids form part of the 

UK IPA inventory comprising sites of European importance for vascular plants, bryophytes, lichens and 

marine algae. The distribution of all UK IPAs and the 27 potential IPAs for freshwater algae are shown in 

the map (Fig. 4.1). 

51

Table 5.4 Sites nominated as European/International IPAs for desmids in the UK. 

Nomination based on the following qualifying criteria: A, B1, B2, C. 

No. Site name 

Grid 

Desmid No. of potential Red No. of European Red 

reference diversity Data List desmids Data List desmids * 

Qualifying criteria Nominator 

1 Loughrigg Fell NY 364040 70+ 6 11 A; B1, B2; C David Williamson 

2 Kelly Hall Tarn SD288933 70+ 9 9 A; B1, B2; C David Williamson 

3 Three Dubs Tarn SD378974 70+ 11 8 A; B1, B2; C David Williamson 

4 Lochan Feoir NC227250 70+ 6 8 A, A2; B1, B2; C David Williamson 

5 Long Moss Tarn SD291936 70+ 5 11 A; B1, B2; C David Williamson 

6 Lower Bostraze (St. Just area) SW392321 100 2 1 B1, B2; C David Williamson 

* Austria, Germany, Netherlands 

54

Table 5.5 Sites nominated as UK IPAs for desmids. 

Nomination based on the following qualifying criteria: A, B1, B2, C. 

No. Site name Grid reference 

Desmid No. of potential Red No. of European Red 

diversity Data List desmids Data List desmids* 

Qualifying criteria Nominator 

7 Torver Tarn SD281926 50+ 10 6 A; B1, B2; C David Williamson 

8 Dock Tarn NY274144 50+ 13 7 A; B1, B2; C David Williamson 

9 Barngate Tarn (‘Drunken NY351011 40+ 4 2 A; B2; C David Williamson 

Duck’ Tarn) 

10 Silver Howe Fell NY325065 50+ 2 5 A; B1, B2; C David Williamson 

11 Goosey Foot Tarn SD338970 50+ 2 8 A; B1, B2; C David Williamson 

12 Culag Wood Bog NC093214 50+ 4 10 A; B1, B2; C David Williamson 

13 Podnet Moss NY405925 50+ 7 8 A, B1, B2; C David Williamson 

14 Gurnals Dub Tarn SD503992 50+ 5 4 B1, B2; C David Williamson 

15 Wrynose Pass, pools on NY2702 50+ 6 3 A; B1, B2; C David Williamson 

summit 

16 Thursley Common SU9040 50+ 2 4 B1, B2; C David Williamson 

17 Pant y Llyn (near Builth SO048468 50+ 3 0 B1, B2; C David Williamson 

Wells) 

18 Loch Bad an Og NC116312 50+ 5 7 A; B1, B2; C David Williamson 

* Austria, Germany, Netherlands 

55

Table 5.6 Potential UK IPAs (areas/sites19-45) for freshwater algae pending further investigation - ‘data deficient’ (often no modern data). 

No. Site name Grid reference Desmid diversity 

No. of potential Red Qualifying 

Data List desmids criteria 

Nominator 

19 Cwm Bochlwd SH657597 C; D David John 

20 Claise Fearna SE 1 NC206466 20 3 C; D Alan Joyce 

21 Loch an Eilean NG472306 incomplete list 3 C; D David Williamson 

22 Cader Idris/Capel Curig area SH7013/SH7258 600+ B1, B2; C; D David John & David 

Williamson 

23 Malham Tarn area SD8966 600+ B2; D Alan Brook 

24 The Serpentine, Eaton Park SJ416600 B2; D David John 

25 Priest Pot SD357978 140+ B2; D Hilary Belcher & Erica Swale 

26 Hells Kettles (near Darlington) NZ280140 B2; D Brian Whitton 

27 Rostherne Mere SJ732819 B2; D Brian Moss 

28 Crose Mere SJ4330 B2; D Brian Moss 

29 White Mere SJ 414330 B2; D Brian Moss 

30 Oakmere SJ576676 B2; D Brian Moss 

31 Little Sea, Studland SZ035835 B2; D D.C. Stevens 

32 Martham Broad TG 4520 B2; D Brian Moss 

33 River Wear NZ1134 NZ24, 

B2; D Brian Whitton 

NZ28, NY94 

34 River Bure TG2521 B2; D Keith Clarke 

35 Abbot’s Pond (near Bristol) ST536732 B2; D David Mann 

36 Lake Windermere SD3995 SD4197 140+ B2; D John Lund 

(West-mid) SD38 

and NY38 

37 River Coquet NU212036 B2; D Martyn Kelly 

38 Stream Weston Combe (near SY1688 B2; D David John 

Branscombe) 

39 Wicken Fen TL 5570 B2; D Hilary Belcher & Erica Swale 

40 River Thames SU761003 (near 

B2; D David John 

mid-point) 

41 River Wye SO597168 (near 

B2; D David John 

mid-point) 

42 Loch Leven NO150015 B2; D Brian Whitton 

43 Blackford Pond NT 253709 B2; D David Mann 

44 Isle of Mull NM7236 600+ B2; D David John 

45 Lough Neagh, Traad Beach H955870 (Irish Grid) B2; D David Jewson 

56

5.6 DISCUSSION 

Considerable progress has been made designating IPAs for other data deficient cryptogam groupings 

including fungi, lichens and bryophytes. For the most part, these groups are macroscopic and there is a 

large following of competent amateurs. As a consequence considerably more is known of their 

distribution, ecology and abundance compared to microscopic algae. The lack of comprehensive sitespecific 

floristic data collected over the last 50 years is one of several reasons why the task of selecting 

IPAs for freshwater microalgae has been so daunting. Other reasons include the absence of persons 

competent to identify microalgae, identification is time consuming and requires a compound light 

microscope, complex sample preparation is sometimes required, key microhabitats are not sampled, 

flawed sampling methods (e.g., incorrect mesh size of plankton nets) and a lack until recently of a 

comprehensive identification guide to UK freshwater algae. 

A factor that must be taken into account is the quality of the information. Sometimes records are suspect 

and acceptance often depends on a judgement made on the competence of the person identifying the 

material. As in other cryptogamic groups, there are very many species recorded on just a few occasions 

and these therefore fall into the IUCN Red List Category of ‘data deficient’. All too often surveys fail to 

take any or adequate account of algae and sampling tends to focus on just a few of the more obvious 

microhabitats. Even when sampling is comprehensive there is a tendency to record only the more 

conspicuous and better known algal groups or phyla with the result that the rest are ignored or receive 

only cursory consideration. Despite all these problems it has been possible to recognise a number of 

provisional IPAs for microalgae. Such a defensible list of IPAs for algae is important since it draws 

attention to the need to ensure that (a) lesser known groups are considered when a site or area is 

designated for its conservation importance, and (b) account is taken of algae in the management planning. 

Some of the provisional IPAs recognised are already given some form of protection. 

5.7 RECOMMENDATIONS 

Literature relating to each proposed freshwater IPA should be compiled and made readily available. 

New and comprehensive surveys of the freshwater algae need to be undertaken at all of the IPAs 

proposed. 

Further assessment of the status of the potential Red List desmids is required through literature searches 

and new data before a desmid Red List can be produced. 

Published and unpublished data sets for other groups of freshwater algae (e.g., diatoms, red algae) should 

be examined to determine whether provisional IPAs can be recognised for them. 

New surveys are required at sites/areas considered to be important for freshwater algae but that are ‘data 

deficient’. 

58

6.0 ACKNOWLEDGEMENTS 

We wish to express our thanks to all those who nominated IPAs and apologise if your nomination was not 

one of those chosen. We also acknowledge the support of CCW, notably Paul Brazier, who supplied us 

with considerable information. We are also grateful to the Friends of the Earth volunteers who undertook 

the bulk of the census work in the herbarium at The Natural History Museum. We are also grateful to all 

the experts who helped to assess the rare species list (their names are listed in Table 4.4). Special thanks 

to Chris Maggs who has provided tremendous input at various stages, Alan Brook and Alan Joyce who 

provided us with unpublished site data on desmids, and Jim Chimonides for preparing maps showing the 

distribution of the IPAs. We acknowledge the support of the British Phycological Society for a grant to 

enable aspects of this work to be undertaken. Thanks also to Plantlife who gave us the original 

inspiration for this work at a workshop in November 2003 and who encouraged us to continue with what 

seemed at times to be an impossible task. Special thanks go to Jenny Duckworth who gave us much 

valuable advice especially in the final stages. We also thank Deborah Long and Jill Williams at Plantlife 

for their assistance in the final production of this document. 

59

7.0 APPENDIX - MARINE ALGAE 

7.1. MAIN REFERENCES USED FOR SITE DESCRIPTIONS 

Bates, C.R., Moore, C.G., Malthus, T., Harries, D.B., Austin, W., Mair, J.M. & Karpouzli, E. 2004. 

Broad scale mapping of sublittoral habitats in The Sound of Barra, Scotland. Scottish Natural 

Heritage Commissioned Report No. 005 (ROAME No. F01AA401B). 

Brodie, J. & Jones, E. 1993. BPS field meeting, Anglesey, 17-19 July 1992. The Phycologist 34: 5-8. 

Brodie, J. & Watson, D. 1999. Marine community and species monitoring: algal communities – advice 

on development of conservation objectives. CCW Contract number 334. 104 pp plus appendices. 

Hardy, F.G. 1985. The marine fauna of the Cullercoats District 17. Flora: Seaweeds. Report of the 

Dove Marine Laboratory Third Series, No. 30. 

Hardy, G. & Scott, G. 1994. Seaweeds of the Yorkshire Coast. The Phycologist 38: 22-25. 

Hiscock, S. 1984. Marine algal communities of the St Abbs area; Southeast Scotland. Nature 

Conservancy Council/Marine Conservation Society. 

Irvine, D.E.G., Smith, R.M., Tittley, I., Fletcher, R.L. & Farnham, W.F. 1972. A survey of the marine 

algae of Lundy. British Phycological Journal 7: 119-135. 

Irving, R. 2006. Inventory of the littoral caves of the South Wight Maritine SAC. Report submitted to 

English Nature by Sea Scope - Marine Environmental Consultants. 

Norton, T.A. 1976. The marine algae of the eastern border counties of Scotland. British Phycological 

Journal 11: 19-27. 

Powell, H.T. 1956. Lists of marine algae collected at St Bees Head, Cumberland by members of the 

British Phycological Society 12 th September, 1955. British Phycological Bulletin 4: 18-25. 

Price, J., Hepton, C.E.L. & Honey, S.I. 1980. The marine flora of the Lizard - I. Cornish Studies 7 

(1979): 7-37. 

Price, J.A., Hepton, C.E.L. & Honey, S.I. 1981. Marine flora of the Lizard – II. Cornish Studies 8: 5-36. 

Wilkinson, M. 1975. The marine algae of Orkney. British Phycological Journal 10: 387-397. 

Wilkinson, M. 1979. Marine algae of the Grampian region of Scotland. British Phycological Journal 14: 

33-41. 

Wilkinson, M. 1980. The marine algae of Galloway. British Phycological Journal 15: 265-273. 

Wilkinson, M. 1982. Marine algae from Glamorgan. British Phycological Journal 17: 101-106. 

Wood, C. 1984. Sussex sublittoral survey. Selsey Bill to Beachy Head. Marine Conservation Society: 

South Sea Branch for Nature Conservancy Council. 

60

8.0 APPENDIX - FRESHWATER ALGAE 

8.1 DESMID IPAS AND POTENTIAL UK RED LIST SPECIES 

8.11 Introduction 

The IUCN has developed criteria for determining the conservation status of individual species. Those taxa 

demonstrated to be endangered, vulnerable or critically endangered are published in Red Data Lists. One 

of the principal criteria for selection is a population decline over time. Often such a change in aquatic 

organisms is the result of habitat loss or changes in water chemistry resulting in an increase in some 

species/species-groups and a decline in others. In largely microscopic groups any increase or decrease in 

abundance is difficult if not impossible to quantify and therefore has often had to be inferred from habitat 

changes. Many freshwater species/ species groups in European Red Data Lists are restricted mostly to 

endangered or threatened habitat. Some of the most threatened aquatic habitats are often those whose 

water is typically poor in nutrients (‘oligotrophic’) and has a low pH (‘acid’ pH) (Table 5.3). Not only are 

these habitats commonly threatened by nutrient enrichment (‘eutrophication’), but are also becoming lost 

or depleted due to several factors that include drainage, afforestation and peat removal. Small-scale peat 

digging or ‘turf cutting’ is not in itself disadvantageous since the new areas of open water often in time 

become Sphagnum-filled pools. 

8.12 Selection of potential UK Red List desmids 

The selection of a desmid as endangered or vulnerable is based upon our knowledge of their ecology in 

the UK. All desmids largely confined to nutrient-poor and non-alkaline waters (occasionally 

circumneutral) are regarded as threatened. The ecological information is taken from a variety of sources 

including the desmid chapters in The Freshwater Algal Flora of the British Isles (see Brook, 2002), a 

review by Lenzenweger (2003) and our own unpublished data. 

A special difficulty has been deciding to which of the three IUCN Red List categories to place a desmid 

since it is necessary to know how rare or common is the taxon. The solution to this problem was to use 

site-specific records compiled by one of us (DBW) to discover how many sites/areas a particular desmid 

taxon had been recorded over the past 30 years. It follows that the rarest and most endangered desmids 

are those recorded on the fewest number of occasions. All these desmid taxa were placed in one of the 

three IUCN categories depending on the number of sites/areas from whence they had been recorded. 

The following numbers of desmid records were used to define each category: 

Category 1 - critically endangered: not recorded by DW. 

Category 2 - endangered: recorded by DW at 1 to 10 sites. 

Category 3 - vulnerable: recorded by DW at 11 or more sites 

Our approach has been to regard as threatened, those desmids that are almost wholly confined to nutrientpoor 

and non-alkaline waters. All species in the UK falling into these categories are listed in Table 8.1 

(Appendix 8.2). 

All these potential UK Red Data List Desmids in the UK are confined to nutrient poor lakes as well as 

ponds and pools associated with blanket bog and raised bog areas that are very common in the north and 

west of the British Isles. These habitats are very extensive in Scotland and are probably less impacted by 

human activity than many areas in Europe as suggested by the larger numbers of critically endangered 

desmids listed for Germany, Austria and the Netherlands. A possible way to select Red Data List 

Desimids in the UK is to consider the status in the UK of those in European Red Data Lists. Any 

61

conclusions drawn would need to be treated with caution since there are very few European Red Data 

Lists. Also the Red Data List of desmids for the Netherlands (Coesel, 1998) was not based on IUCN 

criteria although many of the same taxa are also in lists for Germany (Gutowski & Mollenhauer, 1996) 

and Austria (Lenzenweger, 1999). The Scottish Highlands and the English Lake District are ‘hotspots’ of 

desmid diversity in the UK (John et al., 2006). Only a few UK important desmid areas have been 

recognised elsewhere and all are relatively limited in extent (e.g., Thursley Common in Surrey; Bostraze 

in Cornwall). 

Comprehensive data on distribution and ecology are lacking for desmids. Until more information is 

forthcoming it is impossible to further assess the conservation status of desmids and meaningfully 

comment on the most important centres of desmid diversity. 

8.2 LIST OF POTENTIAL RED DATA LIST DESMIDS IN THE UK 

Table 8.1. The number of desmid species recorded by David Williamson (DW) between 1975 and 2005 

restricted to threatened/vulnerable oligotrophic, non-alkaline waters in the UK. 

Red Data List categories recognised by the IUCN (1994) are as follows: 1 Critical - threatened with 

extinction since very rare and habitat endangered (not recorded by DW, very rare and habitat 

endangered); 2. Endangered - rare and habitat endangered (1-10 records by DW); 3. Vulnerable - 

common but confined to threatened/vulnerable habitats (11+ records by DW). All species are represented 

by the type/nominal variety and other varieties are simply listed, 'only' is used in cases where the type 

variety has not been recorded. 

Categories 

No 

DW 

record 

Genus Species Includes following varieties/forms s 1 2 3 

Actinotaenium capax minus 0 + 

Actinotaenium crassiusculum 0 + 

Actinotaenium lagenarioides 0 + 

Actinotaenium minutissimum 0 + 

Actinotaenium mooreanum 0 + 

Actinotaenium phymatosporum 0 + 

Actinotaenium spinospermum 0 + 

Actinotaenium truncatum 0 + 

Actinotaenium wollei 0 + 

Closterium decorum 0 + 

Closterium delpontei 0 + 

Closterium exile 0 + 

Closterium subjuncidiforme 0 + 

Closterium variabile 0 + 

Cosmarium asphaerosporum strigosum 0 + 

Cosmarium broomei 0 + 

Cosmarium canaliculatum 0 + 

Cosmarium clepsydra 0 + 

Cosmarium fastidiosum 0 + 

Cosmarium garrolense 0 + 

Cosmarium geminatum 0 + 

Cosmarium geometricum 0 + 

Cosmarium jenisejense 0 + 

Cosmarium kjellmanii grande, ornatum 0 + 

Cosmarium latifrons 0 + 

62

Cosmarium logiense 0 + 

Cosmarium nitidulum 0 + 

Cosmarium obsoletum 0 + 

Cosmarium ocellatum incrassatum 0 + 

Cosmarium prominulum subundulatum 0 + 

Cosmarium protuberans padulosa 0 + 

Cosmarium pseudobiremum 0 + 

Cosmarium pulcherrimum 0 + 

Cosmarium pusillum 0 + 

Cosmarium quadrangulatum 0 + 

Cosmarium quasillus 0 + 

Cosmarium retusiforme 0 + 

Cosmarium retusum angustatum 0 + 

Cosmarium sinostegos obtusius 0 + 

Cosmarium speciosissimum 0 + 

Cosmarium subbroomei 0 + 

Cosmarium subquadratum 0 + 

Cosmarium taxichondriforme 0 + 

Cosmarium taxichondrum 0 + 

Cosmarium tetragonum lundellii, elegans, heterocrenatum, 0 + 

Cosmarium trachydermum 0 + 

Cosmarium tumidum 0 + 

Cosmarium ungerianum subtriplicatum 0 + 

Cosmarium wittrockii 0 + 

Cosmocladium constrictum 0 + 

Cosmocladium perissum 0 + 

Cylindrocystis gracilis 0 + 

Euastrum crassicolle 0 + 

Euastrum intermedium 0 + 

Gonatozygon pilosum 0 + 

Penium didymocarpum 0 + 

Penium polymorphum 0 + 

Pleurotaenium eugeneum 0 + 

Sphaerozosma vertebratum latius, punctulatum 0 + 

Spondylosium ellipticum 0 + 

Spondylosium pygmaeum compressum 0 + 

Spondylosium secedens 0 + 

Staurastrum arnellii inornatum, spiniferum 0 + 

Staurastrum conspicuum 0 + 

Staurastrum eboracense 0 + 

Staurastrum echinodermum 0 + 

Staurastrum heimerlianum spinulosum 0 + 

Staurastrum kaiseri 0 + 

Staurastrum pachyrhynchum 0 + 

Staurastrum pseudosebaldi simplicius 0 + 

Staurastrum pseudotetracerum 0 + 

Staurastrum pungens 0 + 

Staurastrum quadrispinatum 0 + 

Staurastrum rugulosum 0 + 

Staurastrum spiniferum 0 + 

Staurastrum striatum 0 + 

Staurastrum subpygmaeum subangulatum 0 + 

Staurodesmus quadratus 0 + 

Staurodesmus pterosporum 0 + 

63

Xanthidium tenuissimum 0 + 

Actinotaenium adelochondrum 1 + 

Actinotaenium clevei 1 + 

Actinotaenium colpopelta 1 + 

Actinotaenium cruciferum 1 + 

Actinotaenium curtum 10 + 

Actinotaenium gelidum 2 + 

Actinotaenium inconspicuum 1 + 

Actinotaenium obcuneatum 7 + 

Actinotaenium perminutum 2 + 

Actinotaenium rufescens 5 + 

Actinotaenium subtile 4 + 

Actinotaenium turgidum 9 + 

Closterium anguineum 1 + 

Closterium archerianum pseudocynthia 8 + 

Closterium calosporum brasiliense 10 + 

Closterium limneticum 3 + 

Closterium nematodes proboscideum 1 + 

Closterium nylandicum 4 + 

Closterium pygmaeum 4 + 

Closterium sublaterale 3 + 

Closterium subscoticum 2 + 

Closterium subulatum 1 + 

Closterium toxon 8 + 

Closterium variabile 1 + 

Cosmarium alpestre 2 + 

Cosmarium bioculatum depressum 9 + 

Cosmarium capitulum groenlandicum 2 + 

Cosmarium commissurale acutum, crassum 6 + 

Cosmarium cyclicum arcticum, nordstedtianum 7 + 

Cosmarium cymatopleurum 2 + 

Cosmarium dentiferum 2 + 

Cosmarium dybowskii 1 + 

Cosmarium eductum 1 + 

Cosmarium eichlerianum 2 + 

Cosmarium entochondrum 1 + 

Cosmarium fictopraemorsum 1 + 

Cosmarium fontigenum 6 + 

Cosmarium hammeri homalodermum, protuberans 3 + 

Cosmarium isthmium hibernicum, horizontale 9 + 

Cosmarium isthmochondrum decussiferum, pergranulatum 4 + 

Cosmarium carinthiacum 9 + 

Cosmarium lundellii corruptum, ellipticum 2 + 

Cosmarium luxuriosum 2 + 

Cosmarium microsphinctum maius, parvula 1 + 

Cosmarium nasutum asperum, granulatumonly 1 + 

Cosmarium norimbergense depressum 3 + 

Cosmarium novae-semliae granulatum, sibiricum 4 + 

Cosmarium obliquum ovale, tatricum, trigonum, 4 + 

Cosmarium ordinatum schulzii 4 + 

Cosmarium pachydermum aethiopicum 1 + 

Cosmarium paragranatoides 3 + 

Cosmarium perforatum 1 + 

Cosmarium pericymatium corrugatum, eboracense 8 + 

64

Cosmarium phaseolus elevatum, minus, skujae 9 + 

Cosmarium plicatum 4 + 

Cosmarium pokornyanum taylorii 4 + 

Cosmarium polygonum 1 + 

Cosmarium praegrande 4 + 

Cosmarium pseudamoenum basilare 5 + 

Cosmarium pseudobroomei convexum 1 + 

Cosmarium pseudocommissurale 1 + 

Cosmarium pseudoexiguum 2 + 

Cosmarium pseudonitidulum validum 4 + 

Cosmarium pseudoornatum 4 + 

Cosmarium pseudoprotuberans alpinum, kossinskajae 1 + 

Cosmarium pygmaeum 8 + 

Cosmarium quadratulum 3 + 

Cosmarium rectangulare cambrense, hexagonum 3 + 

Cosmarium repandum minus, papillatum 1 + 

Cosmarium simplicius 2 + 

Cosmarium sphagnicolum 1 + 

Cosmarium sphalerostichum 4 + 

Cosmarium subalatum 1 + 

Cosmarium subarctoum punctatum 2 + 

Cosmarium subimpressulum 2 + 

Cosmarium subspeciosum validius 4 + 

Cosmarium tatricum novizelandicum, sphaeruliferum 2 + 

Cosmarium tenue 1 + 

Cosmarium tetrachondrum 2 + 

Cosmarium thwaitesii penioides 1 + 

Cosmarium trachypleurum minus 1 + 

Cosmarium truncatellum 1 + 

Cosmarium tumidum subrectangulare 6 + 

Cosmarium tyrolicum beanlandii 5 + 

Cosmarium umbilicatum 3 + 

Cosmarium undulatum minutum, wollei 10 + 

Cosmarium vexatum lacustre 8 + 

Cosmarium vogesiacum 1 + 

Cosmarium woloszynskae 2 + 

Cosmarium binum 6 + 

Cosmocladium pulchellum 1 + 

Cosmocladium saxonicum 2 + 

Cosmocladium tuberculatum 2 + 

Cosmocladium tumidum 1 + 

Desmidium aptogonum ehrenbergii, acutius 6 + 

Desmidium pseudostreptonema 5 + 

Docidium undulatum perundulatum 2 + 

Euastrum aboense 1 + 

Euastrum boldtii 2 + 

Euastrum cornubiense 1 + 

Euastrum divaricatum 1 + 

anglicanum, cambrense, ornatum, 

snowdoniense 1 + 

Euastrum dubium 

Euastrum erosum granulosum 1 + 

Euastrum gayanum 6 + 

Euastrum gemmatum 9 + 

Euastrum inerme 3 + 

65

Euastrum jenneri 5 + 

Euastrum montanum 1 + 

Euastrum sinuosum 1 + 

Euastrum sublobatum dissimile 1 + 

Euastrum turneri 4 + 

Euastrum ventricosum 8 + 

Genicularia elegans 4 + 

Genicularia spirotaenia 1 + 

Gonatozygon kinahanii 3 + 

Groenbladia neglecta 2 + 

Groenbladia undulata kriegeri, perundulata 3 + 

Mesotaenium macrococcum minus 3 + 

Micrasterias brachyptera 2 + 

Micrasterias conferta hamata 7 + 

Micrasterias furcata dichotoma, pseudocrux 5 + 

Micrasterias mahabuleshwarensis dichotoma, europaea, wallichii 1 + 

Micrasterias verrucosa 3 + 

Pleurotaenium maximum 3 + 

Pleurotaenium nodosum 7 + 

Pleurotaenium nodulosum 6 + 

rectum (=Haplotaenium 

Pleurotaenium rectum) 7 + 

Pleurotaenium tridentulum capitatum 9 + 

Pleurotaenium truncatum crassum, farquharsonii 5 + 

Roya cambrica 1 + 

Roya obtusa montana 2 + 

Spondylosium papillosum 9 + 

Spondylosium planum 10 + 

Spondylosium pulchellum pyramidatum 10 + 

Staurastrum arcuatum 1 + 

Staurastrum asperum 5 + 

Staurastrum bicorne 0 + 

Staurastrum bifidum 0 + 

Staurastrum bloklandii 0 + 

Staurastrum boreale 4 + 

Staurastrum borgeanum 1 + 

Staurastrum brachycerum 1 + 

Staurastrum brasiliense lundelli 6 + 

Staurastrum brebissonii brevispinum 9 + 

Staurastrum capitulum spetsbergense 7 + 

Staurastrum cerastes triradiatum 3 + 

Staurastrum chavesii 2 + 

Staurastrum circulare americanum only 1 + 

Staurastrum clepsydra sibiricum only 3 + 

Staurastrum coarctatum subcurtum 2 + 

Staurastrum cosmarioides 1 + 

Staurastrum cosmospinosum 1 + 

Staurastrum cristatum 3 + 

Staurastrum cyathipes 2 + 

Staurastrum denticulatum 2 + 

Staurastrum dispar 4 + 

Staurastrum disputatum 2 + 

Staurastrum donardense 2 + 

Staurastrum duacense 1 + 

66

Staurastrum elongatum 4 + 

Staurastrum erasum 5 + 

Staurastrum forficulatum 2 + 

Staurastrum furcatum aciculiferum, subsenarium 8 + 

Staurastrum gladiosum delicatulum 3 + 

Staurastrum gracile 3 + 

Staurastrum hexacerum 3 + 

Staurastrum hystrix 7 + 

Staurastrum iotanum 1 + 

kouwetsii (=S. 

subbrebissonii) 4 + 

Staurastrum 

Staurastrum laeve 2 + 

Staurastrum laevispinum 1 + 

Staurastrum longispinum bidentatum 6 + 

Staurastrum manfeldtii annulatum, splendidum 6 + 

Staurastrum meriani minutum 6 + 

Staurastrum micron perpendiculatum 1 + 

Staurastrum monticulosum bifarium, groenlandicum 1 + 

Staurastrum muticum depressum 5 + 

Staurastrum natator 1 + 

Staurastrum neglectum 2 + 

Staurastrum nodosum 0 + 

Staurastrum oligacanthum incisum 4 + 

Staurastrum oxyacanthum polyacanthum 6 + 

Staurastrum paradoxum 7 + 

Staurastrum pileolatum cristatum 4 + 

Staurastrum pilosum 3 + 

Staurastrum polymorphum munitum, pusillum, simplex 3 + 

Staurastrum proboscideum 3 + 

Staurastrum pyramidatum 7 + 

Staurastrum quadrangulare 2 + 

Staurastrum scabrum 7 + 

Staurastrum sebaldi ornatum, productum 9 + 

Staurastrum senarium 4 + 

Staurastrum setigerum 1 + 

Staurastrum sexangulare 7 + 

Staurastrum striolatum 5 + 

subarcuatum (= S. avicula 

var. subarcuatum) 5 + 

Staurastrum 

Staurastrum subavicula 4 + 

Staurastrum subcruciatum 6 + 

Staurastrum subnudibrachiatum 3 + 

Staurastrum subpygmaeum 3 + 

Staurastrum subscabrum 3 + 

Staurastrum tohopekaligense trifurcatum 2 + 

Staurastrum trapezicum 2 + 

Staurastrum turgescens arcticum 1 + 

Staurastrum uhtuense 1 + 

Staurastrum verticillatum 5 + 

Staurastrum bulbosum 1 + 

Staurastrum echinatum 2 + 

Staurodesmus aristiferus protuberans 2 + 

Staurodesmus aversus 2 + 

Staurodesmus bulnheimii subincus 8 + 

67

Staurodesmus connatus 3 + 

Staurodesmus controversus 2 + 

Staurodesmus corniculatus 2 + 

Staurodesmus grandis parvus 3 + 

Staurodesmus incus ralfsii 6 + 

Staurodesmus lanceolatus compressus 2 + 

Staurodesmus megacanthus orientalis, subcurvatus 1 + 

Staurodesmus mucronatus subtriangularis 4 + 

Staurodesmus omearae minutus 4 + 

Staurodesmus patens 1 + 

Staurodesmus phimus occidentalis 1 + 

Staurodesmus sellatus 1 + 

Staurodesmus spencerianus 4 + 

Staurodesmus subtriangularis 2 + 

Staurodesmus validus 8 + 

Teilingia excavata subquadrata 4 + 

Tortitaenia alpina 3? + 

Tortitaenia luetkemuelleri 2 + 

Xanthidium basidentatum 2 + 

Xanthidium bifidum 4 + 

Xanthidium brebissonii varians 6 + 

Xanthidium concinnum boldtianum 4 + 

Xanthidium fasciculatum oronense 7 + 

Xanthidium impar 2 + 

Xanthidium variabile 6 + 

Actinotaenium cucurbita 50 + 

Actinotaenium cucurbitinum 50 + 

Actinotaenium diplosporum 17 + 

Actinotaenium silvae-nigrae 12 + 

Bambusina brebissonii 72 + 

Closterium abruptum maius, nilssonii 39 + 

Closterium angustatum gracilius, sculptum 57 + 

Closterium attenuatum 64 + 

Closterium baillyanum alpinum 111 + 

Closterium closterioides varieties 101 + 

Closterium cornu varieties 34 + 

Closterium costatum westii 88 + 

Closterium didymotocum crassum 30 + 

Closterium directum oligocampylum 94 + 

Closterium idiosporum 28 + 

Closterium intermedium hibernicum 75 + 

Closterium jenneri 19 + 

Closterium juncidum varieties 65 + 

Closterium lineatum varieties 39 + 

Closterium lunula varieties 73 + 

Closterium navicula 37 + 

Closterium pritchardianum angustum 25 + 

Closterium ralfsii hybridum 30 + 

Closterium rostratum brevirostratum 47 + 

Closterium setaceum elongatum 48 + 

Closterium striolatum rectum, subtruncatum 105+ + 

Closterium turgidum 30 + 

Closterium dianae varieties 141 + 

Cosmarium amoenum mediolaeve 93 + 

68

Cosmarium boeckii 36 + 

Cosmarium brebissonii 82 + 

Cosmarium connatum 38 + 

Cosmarium crenulatum 13 + 

Cosmarium cucumis magnum 25 + 

Cosmarium difficile sublaeve 135 + 

Cosmarium excavatum duplo-maius 13 + 

Cosmarium galeritum 24 + 

Cosmarium margaritatum 45 + 

Cosmarium margaritiferum subrotundatum 168 + 

Cosmarium monomazum polymazum 25 + 

Cosmarium nymannianum 23 + 

Cosmarium ochthodes amoebum 13 + 

Cosmarium ornatum 136 + 

Cosmarium orthostichum compactum, pumilum 21 + 

Cosmarium ovale subglabrum 33 + 

Cosmarium pseudoconnatum ellipsoideum 21 + 

Cosmarium pseudopyramidatum carniolicum, lentiferum, maximum 32 + 

Cosmarium quadratum angustatum, willei 118 + 

Cosmarium quadrifarium polyticha, hexastichum, octastichum 22 + 

Cosmarium quadrum 20 + 

Cosmarium quinarium 18 + 

Cosmarium ralfsii montanum, rotundatum 53 + 

Cosmarium regnellii minimum, pseudoregnellii 11 + 

Cosmarium regnesii montanum, tritum 12 + 

Cosmarium speciosum biforme, rostafinskii, simplex 22 + 

Cosmarium sphaeroideum 11 + 

Cosmarium sportella subnudum 11 + 

Cosmarium subcostatum beckii 12 + 

Cosmarium subcrenatum divaricatum 34 + 

Cosmarium subcucumis 12 + 

Cosmarium subundulatum 31 + 

Cosmarium tetraophthalmum 112 + 

Cosmarium turpinii eximium, podolicum 13 + 

Cosmarium variolatum cataractarum, rotundatum, skujae 36 + 

Cosmarium venustum excavatum, hypohexagonum, minus 13 + 

Cosmarium conspersum latum, rotundatum, subrotundatum 14 + 

Cylindrocystis brebissonii minor, turgida 36 + 

Desmidium grevillei (=cylindricum) 12 + 

Desmidium swartzii amblyodon 51 + 

Docidium baculum 28 + 

Euastrum ampullaceum 71 + 

Euastrum bidentatum oculatum 75 + 

Euastrum binale gutwinskii, hians,, minus, retusum 29 + 

Euastrum crassum microcephalum 76 + 

Euastrum cuneatum 43 + 

Euastrum denticulatum 54 + 

Euastrum didelta 38 + 

ornatum, novae semliae, ornithocephalum, 

pseudelegans, spinosum 142 + 

Euastrum elegans 

Euastrum humerosum affine 39 + 

Euastrum insigne 33 + 

Euastrum pectinatum brachylobum 150 + 

Euastrum pinnatum 21 + 

69

Euastrum pulchellum 15 + 

Euastrum verrucosum alatum, coarctatum, planctonicum 108 + 

Gonatozygon aculeatum groenbladii 18 + 

Gonatozygon brebissonii kjellmanii, laeve, minutum, vulgare 83 + 

Gonatozygon monotaenium pilosellum 83 + 

Micrasterias americana boldtii, lewisiana 31 + 

Micrasterias apiculata 29 + 

Micrasterias crux-melitensis 16 + 

Micrasterias denticulata angulosa 95 + 

Micrasterias fimbriata spinosa 34 + 

Micrasterias jenneri 36 + 

Micrasterias oscitans mucronata 37 + 

Micrasterias papillifera includes pseudomurrayi 68 + 

Micrasterias pinnatifida pseudoscitans 44 + 

Micrasterias radiosa elegantior, ornata, murrayi 26 + 

Micrasterias rotata 43 + 

Micrasterias thomasiana notata, pucherrima 51 + 

Micrasterias truncata bahusiensis , semiradiata 50+? + 

curtum, latum, lamellosum, naegeli, parvum, 

rhomboideum 100+ + 

Netrium digitus 

Netrium interruptum minor, sectum 51 + 

Netrium oblongum cylindricum 50 + 

Penium cylindrus cuticulare 32 + 

Penium exiguum 31 + 

Penium margaritaceum 20 + 

Penium spirostriolatum amplificatum 71 + 

Pleurotaenium coronatum fluctuatum, robustum 44 + 

minutum(=Haplotaenium 

Pleurotaenium minutum) crassum 70 + 

Roya anglica 16 + 

filiformis (=Onchyonema 

filiforme) 12 + 

Sphaerozosma 

Sphaerozosma vertebratum 29 + 

Staurastrum alternans basichondrum 20 + 

Staurastrum arachne arachnoides, basiornatum, curvatum 17 + 

Staurastrum arctiscon 20 + 

Staurastrum brachiatum 28 + 

Staurastrum cyrtocerum compactum 12 + 

Staurastrum dilatatum hibernicum 25 + 

Staurastrum furcigerum armigerum, reductum 44 + 

Staurastrum hirsutum muricatum 47 + 

Staurastrum inconspicuum crassum, planctonicum 25 + 

Staurastrum inflexum 19 + 

Staurastrum johnsonii 11 + 

Staurastrum lapponicum 19 + 

Staurastrum maamense 12 + 

Staurastrum margaritaceum 

coronulatum, hirtum, robustum, 

subcontortum 67 + 

Staurastrum ophiura cambricum 14 + 

Staurastrum polytrichum 15 + 

coronatum, kjellmani, pygmaeum, 

subproductum 51 + 

Staurastrum punctulatum 

Staurastrum sexcostatum productum 15 + 

Staurastrum simonyi 12 + 

70

Staurastrum spongiosum perbifidum 14 + 

Staurastrum teliferum 126 + 

Staurodesmus brevispina altus, boldtii, obversus 19 + 

Staurodesmus convergens laportei, pumilus, ralfsii 49 + 

Staurodesmus dickiei circularis, rhomboideus 14 + 

Staurodesmus extensus joshuae, longispinus, vulgaris 25 + 

Staurodesmus glaber debaryanus 12 + 

Staurodesmus indentatus 27 + 

Staurodesmus mamillatus maximus 17 + 

Staurodesmus triangularis americanus, limneticus 13 + 

Staurodesmus tumidus (=Staurastrum tumidum) 25 + 

Tetmemorus brebissonii minor 95 + 

Tetmemorus granulatus 200+ + 

Tetmemorus laevis minutus 21 + 

Xanthidium aculeatum 12 + 

depauperatum, hebridarum, laeve, 

polymazum, oligocanthum, planum, 

triquetrum 158 + 

Xanthidium antilopaeum 

Xanthidium armatum cervicorne, fissum, irregularis 83 + 

Xanthidium controversum planctonicum 12 + 

Xanthidium cristatum angulatum, delpontii, leiodermum, uncinatum 18 + 

Xanthidium octocorne 59 + 

Xanthidium robinsonianum 11 + 

Xanthidium smithii collum, maius 17 + 

78 236 153 

8.3 DETAILS OF IPAS FOR FRESHWATER ALGAE 

European IPA for Desmids 

1. Loughrigg Fell, Cumbria 

Grid ref: 

NY364040 

Status: 

SSSI 

Ownership: 

unknown 

Qualifying criteria: 

A; B1, B2; C 

No. of species recorded: 

70 plus 

No. of potential UK Red List desmids 6 

Survey period 

July 1979 - May 1993 (13 visits) 

Records contact: 

David Williamson 

Site 

description 

The fell lies to the north-east of Windermere, its summit (235 m) being approximately 3 km west of 

Ambleside. The fell lies along the north eastern side of Loughrigg Tarn but is at a higher level. Besides 

many flushes there are many soft water pools and ponds with an acid pH. There is a pond sufficiently 

large to be considered a tarn, Lily Tarn, whose algal flora is dominated by the desmid genus Staurastrum. 

It is significant that this is one of the most frequently sampled areas. 

Potential UK Red Data List desmids 

Cosmarium variolatum, Hyalotheca mucosa, Staurastrum oxycanthum, S. margaritaceum, S. scabrum, S. 

senarium. 

71


2. Kelly Hall Tarn, Cumbria 

Grid ref: 

SD288933 

Status: 

unknown 

Ownership: 

National Trust 


A; B1, B2; C 


70 plus 


Survey period 

May 1981 – June 2000 (8 visits by DW and Alan Brook) 




Small shallow lake (about 1.5 m deep) although a dam has been added to increase depth and volume. A 

reservoir with a sign saying the water is used for drinking water and so no swimming allowed. 


Cosmarium pseudoconnatum, C. retusiforme var. incrassatum, Desmidium aptogonum, Sphaerozosma 

vertebratum, Staurastrum laeve, S. manfeldtii, S. quadrangulare, S. spongiosum, S. striolatum. 


3. Three Dubs Tarn, Cumbria 

Grid ref: 

SD378974 

Status: 

unknown 

Ownership: 

unknown 


A, A2, B1, B2, C 


70 plus 


Survey period 

June 1980 – April 1990 (4 visits) 




Small shallow lake. 


Actinotaenium obcuneatum, Closterium toxon, Cosmarium entochondrum, C. excavatum var. duplomaius, 

C. pseudoconnatum, C. pyramidatum, Groenbladia undulata var. perundulata, Hyalotheca 

mucosa, Staurastrum brasiliense var. lundellii, S. longispinum, Staurodesmus validus. 


4. Lochan Feoir, Highlands (Sutherland) 

Grid ref: 

NC227250 

Status: 

Unknown 

Ownership: 

Unknown 


A; B1, B2; C 

No. of species recorded: 70 


Survey period 

Sept 1993 - Sept 1994 (2 visits) 

72


David Williamson; Desmidium records from Alan Joyce 


Small loch (area 2.6 ha) and oligotrophic. 


Cosmarium excavatum var. duplo-maius, Desmidium graciliceps, D. occidentale, Micrasterias conferta, 

Sphaerozosma vertebratum, Staurastrum sexangulare. 


5. Long Moss Tarn, Cumbria 

Grid ref: 

SD291936 

Status: 

unknown 

Ownership: 



A; B1, B2; C 


70 plus 


Survey 

May 1981-Oct 1999 (6 visits) 




The lake lies in a narrow, linear hollow scoured out by ice flowing south-southwest and parallel to 

Coniston water (see Haworth et al., 2003). It is a small (area 5.75 km²), shallow (


Cosmarium phaseolus, Euastrum gayanum 

UK IPA for Desmids 

7. Torver Tarn, Cumbria 

Grid ref: 

SD281926 

Status: 

SSSI 

Ownership: 



A; B1, B2; C 


50 plus 


Survey period 

May 1981 – July 1990 (6 visits) 




A small tarn just 1.5 m in maximum depth and slightly alkaline with a comparatively high in calcium 

(Haworth et al., 2003). The shallow extremities and the inflow on the north side are surrounded by 

Sphagnum peat. Its small catchment is mainly rock, bracken and peat. 


Actinotaenium inconspicuum, Cosmarium regnesii, C. sportella, Groenbladia undulata var. perundulata, 

Hyalotheca mucosa, Staurastrum incus, S. glaber, S. laeve, S. longispinum, Sphaerozosma vertebratum. 


8. Dock Tarn, Cumbria 

Grid ref: 

NY274144 

Status: 

SSSI 

Ownership: 

unknown 


A; B1, B2; C 


50 plus 


Survey period 

Sept 1981 – May 1988 (5 visits) 




One of the largest of the Cumbrian tarns (over 34 km²) lying in a moorland hollow on the upland between 

lower Eskdale and Dunnerdale. Its water has a low to circumneutral pH and is nutrient-poor 

(oligotrophic). The small catchment is of rough grassland, heather moor, rock outcrops and wet peat. 


Actinotaenium capax, Cosmarium galeritum, C. regnellii, C. undulatum, C. excavatum, C. 

pseudonitidulum, Gonatozygon monotaenium, Hyalotheca mucosa, Staurastrum brasilense, S. 

longispinum, S. sebaldi, S. senarium, S. sexangulare. 


9. Barngate Tarn ('Drunken Duck' tarn), Cumbria 

74

Grid ref: 

NY351011 

Status: 

unknown 

Ownership: 

unknown 


A; B2; C 



Survey period 

July 1979 – March 1986 (5 visits) 




Small lake. 


Cosmarium phaseolus, C. sportella, C. subtumidum, Hyalotheca mucosa. 


10. Silver Howe Fell, Cumbria 

Grid ref: 

NY325065 

Status: 

Unknown 

Ownership: 

Unknown 


A; B1, B2; C 



Survey period 

August 1982 – May 1993 (4 visits); 2 records for 

August 1973 by Edna Lind. 




The moss has many soft water and acid pH bog pools and small tarns. 


Cosmarium undulatum, Euastrum humerosum. 


11. Goosey Foot Tarn, Cumbria 

Grid ref: 

SD338970 

Status: 

unknown 

Ownership: 



A; B1, B2; C 



Survey period 

June 1981- June 2003 (6 visits) 




Artificial impoundment with a low dam at either end and was formerly the reservoir for the village of 

Hawkshead. Its water is oligo- to mesotrophic, covers an area of about 1.5 ha and is about 2.5 m deep. 

75


Roya cambrica var. limnetica, Euastrum humerosum var. affine. 

UK IPAs for Desmids 

12. Culag Wood Bog, Assynt (Sutherland) 

Grid ref: 

NC093214 

Status: 

unknown 

Ownership: 

Assynt Estates 


A; B1, B2; C 



Survey period 

March 1994 – Oct 2003 (8 visits) 




Wood covers 36 hectares and contains many boggy pools. Sampled by David Williamson, I. Evans, Peter 

York and David John. 


Cosmarium variolatum, C. praegrande, Pleurotaenium rectum, Closterium toxon. 


13. Podnet Moss, Cumbria 

Grid ref: 

NY405925 

Status: 

unknown 

Ownership: 

unknown 


A, B1, B2; C 


50 plus 





Many soft, acid water bog pools. David Williamson and Edna Lind sampled these pools between 1979 

and 1996. 


Cosmarium perforatum, Euastrum dubium, Staurodesmus incus, S. spencerianus, Staurastrum 

oxyacanthum, S. quadrangulare, S. subcruciatum. 


14. Gurnal Dubs Tarn, Cumbria 

Grid ref: 

Status: 

Ownership: 



SD503992 

unknown 

unknown 

B1, B2; C 

50 plus 

76


Survey period 

July 1979 – April 1983 (4 visits) 




Shallow lake. 


Cosmarium regnesii, Sphaerozosma vertebratum, Staurastrum hystrix, S. longispinum, S. teliferum. 


15. Wrynose Pass, pools on summit, Cumbria 

Grid ref: 

NY2702 

Status: 

Unknown 

Ownership: 

Unknown 


A; B1, B2; C 


50 plus 





Bog pools at the summit have been sampled by David Williamson between 1979 and 2000. 


Actinotaenium obcuneatum, Cosmarium conspersum, C. variolatum, Euastrum ventricosum, 

Staurodesmus glaber, S. incus. 


16. Thursley Common, Surrey 

Grid ref: 

SU9040 

Status: 

SSSI, cSAC, RAMSAR Site 

Ownership: 

unknown 


B1, B2; C 


50 plus 


Survey period March 1981 - June 1984 




Thursley Common in north-west Surrey represents an area of northern Atlantic wet heath and consists of 

woodland, heath and bog in north-west Surrey. There are several ponds as well as Sphagnum-filled peaty 

pools whose water is soft with an acid pH. A causeway dam and weirs maintain the water level high and 

the ponds are actively managed. Historically known to be a desmid-rich area and probably the most 

important desmid area in south-east of England. 


Cosmarium ornatum, Closterium pritchardianum, C. ralfsii var. hybridum. 

77


17. Pant y Llyn (near Builth Wells), Powys 

Grid ref: 

SO048468 

Status: 

Unknown 

Ownership: 

Unknown 


B1, B2 ; C 


50 





The lake has been artificially deepened by two dams and drains water running off the blanket bog on Pant 

y Llyn Hill. The blanket bog and Llyn should be considered as a unit. 


Cosmarium pygmaeum, C. paragranatoides, Euastrum gayanum. 


18. Loch Bad an Og, Highlands (Sutherland) 

Grid ref: 

NC116312 

Status: 

Unknown 

Ownership: 

Unknown 


A; B1, B2; C 






David Williamson has sampled this small loch in September 1994 and June 1995. 


Cosmarium cyclicum, C. variolatum, C. venustum, Staurastrum striolatum, Staurodesmus corniculatus. 

Potential IPAs (areas/sites19-45) pending further investigation - ‘data deficient’ (often no modern data) 

Potential Desmid IPAs (19-21) 

19. Cwm Bochlwyd, Snowdonia 

Grid ref: 

Status: 

Ownership: 



SH657597 

Snowdonia National Park 

Unknown 

B2; D 

150 spp. 


The last comprehensive study was in 1956 and focused on the desmids. No complete list of desmids 

78

published (Duthie, 1965) hence its ‘data deficient’ status. 

20. Claise Fearna SE 1, Scourie South 

Grid ref: 

NC206466 

Status: 

Unknown 

Ownership: 

Unknown 


C; D 


Unknown 



Alan Joyce 


Small lake. 


Desmidium pseudostreptonema, D. occidentale, D. graciliceps. 

21. Loch an Eilean, South Sky 

Grid ref: 

NG472306 

Status: 

Unknown 

Ownership: 

Unknown 


C; D 


Unknown 



Alan Joyce 


Small lake. 


Desmidium pseudostreptonema, D. occidentale, D. graciliceps. 

Potential Freshwater Algal IPAs (22-45) 

It is possible that areas 22 and 23 might prove to be sites also of European importance. 


There are well over a hundred lakes more than an acre in size in Snowdonia, from Llyn Ogwen in the 

north to Tal y Llyn in the south. Many were studied by George and William West in the early years of the 

20 th century who considered the area around Capel Curig as ‘record-breaking’ in terms of desmid 

diversity. Further surveys of many lakes, ponds and pools carried in the 1950’s and 60’s (Duthie, 1965; 

Woodhead & Tweed, 1954-55) confirm the area to be one of the most algal diverse areas in the UK and 

possibly Europe. They report finding at least 1500 algal species and over 500 subspecies in 

Caernarvonshire and Anglesey in the 1950s. Unfortunately there are no modern data. 

22. Cader Idris and Capel Curig area 

Grid ref: 

79 

SH7013/SH7258

Status: 

Ownership: 




SSSIs, cSAC 

B1, B2; C; D 

1500 plus 


Areas of lakes, ponds and bogs are especially rich in desmids. Long history of study, unusual 

assemblages of algae associated with lime-rich waters. 

23. Malham Tarn Area, Yorkshire 

Grid ref: 

Status: 

Ownership: 



SD8966 

SSSI, cSAC 

Unknown 

B2; D 

600 plus 


One of the areas in the United Kingdom known to have an exceptionally diverse an algal flora (over 600 

species) that includes several endemics and notable rarities (see Pentecost, 2004). The area includes 

Malham Tarn (2 ha. in area) as well as patches of calcareous mire and fen, and numerous permanent and 

ephemeral streams and springs (mostly neutral or alkaline). The tarn is one of the few UK sites where 

Cladophora balls are recorded. According to Stewart (2004), a site of national importance for stoneworts. 

Nationally rare green algae include endolithic Oocardium calcareum. Very comprehensive investigations 

of the algal flora of the Malhal Tarn area were carried out in the 1950’s by Lund (1961) and, more 

recently, by Pentecost (2004). 

24. The Serpentine, Eaton Park, Cheshire 

Grid ref: 

SJ416600 

Status: 

unknown 

Ownership: 

unknown 


B2; D 


unknown 

Survey period 1932-1965 


One of the few small lakes in the UK whose algal flora has been studied over an extended period. 

Seasonality was studied by E.G. Williams over a 20-year period (1932-1965) and he discovered a number 

of algae rarely reported in the UK (e.g., Chrysolykos planctonicus, Chrysophyta). There have been no 

modern studies on the lake and therefore it is not known whether it has changed over the past 40 years 

(see Williams, 1965). 

25. Priest Pot, Cumbria 

Grid ref: 

SD357978 

Status: 

SSSI 

Ownership: 

Unknown 

Qualifying criteria: B2; D? 


Over 140 spp. 

Survey period 

1965-1991 (main period) 

80


A small freshwater lake (1 hectare) lying within a hollow in a wooded fen at the northern end of 

Esthwaite Water. Relatively undisturbed since its isolation from Esthwaite Water about 400 years ago. It 

has been the subject of intensive study with Findlay & Maberley (2000) remarking that ‘more is already 

known about the natural history of Priest Pot than any other water body of similar size’. For a summary of 

information on the pond, see Findlay & Maberley (2000). 

26. Hells Kettles (near Darlington), Durham 

Grid ref: 

Status: 

Ownership: 



Survey period 

NZ280140 

Unknown 

Unknown 

B2; D 

Unknown 


The ‘kettles’ consist of two small ponds formed by subsidence of the underlying Magnesian limestone. 

All submerged surfaces are usually marl-encrusted but management changes in the past few years have 

resulted in nutrient enrichment resulting in dramatic changes in its algal flora (including stoneworts). 

Until recently the Kettles contained an assemblage of attached algae characteristic of hard, alkaline water. 

One of the few UK sites from which the very rare brown alga Pleurocladia lacustris has been recorded, a 

possible potential Red List species. Several detailed ecological studies have been carried out in the 

Kettles including an inventory of the algae (see Hudson et al., 1971). The most recent changes in its 

ecology are believed to be a consequence of the raising of the water level causing wash-in of nutrient 

from the surrounding grazing land. An Important Stonewort Area of local importance. 

27. Rostherne Mere, Cheshire 

Grid ref: 

Status: 

Ownership: 



SJ732819 

SSSI, RAMSAR 

Unknown 

B2; D 

Unknown 


A large (48.7 ha) and deep (27 m) lake receiving water from a stream derived ultimately from Little Mere 

and Mere Mere, as well as streams and ground water. Blue-green algal blooms have probably occurred in 

this nutrient-rich lake for several thousand years. One of the few lakes where nutrient enrichment is 

caused from secondarily treated sewage. The phytoplankton have been monitored over a long period (see 

Belcher & Storey, 1968). 

28. Crose Mere, Shropshire 

Grid ref: SJ 430305 

Status: 

Unknown 

Ownership: 

Unknown 


B2; D 


Unknown 

81


Moderately large (15.2 ha) lake occupying the southern part of a complex peat- and water-filled basin 

lying between hummocks of morainic sands and gravels. Principally fed by relatively nutrient rich ground 

water. Seasonal changes in the phytoplankton were studied between January 1966 and December 1971 by 

Reynolds & Allen (1968) and Reynolds (1973). 

29. White Mere, Shropshire 

Grid ref: SJ 414330 

Status: 

SSSI, RAMSAR 

Ownership: 

unknown 


B2; D 


unknown 


The lake is a large and isolated basin about 25 ha in area and has no apparent permanent surface inflow 

other than a small inlet flowing in from Lee Wood. Largely fed by ground water and is a perched water 

body surrounded by sand and gravel as well as clay deposits. It is believed to be a natural nutrient-rich 

lake that has had blue-green algal blooms probably for several thousand years. The mere became an SSSI 

in 1986 and is part of the West Midland Meres and Mosses RAMSAR site. Agricultural activities 

probably account for the recent phase of eutrophication. 

30. Oakmere, Cheshire 

Grid ref: 

Status: 

Ownership: 



SJ576676 

unknown 

unknown 

B2; D 

unknown 


The algae have been studied on several occasions between about 1944 and 1968 (see Lind 1944). 

31. Little Sea, Studland, Dorset 

Grid ref: 

Status: 

Ownership: 




SY035835 

Reserve, managed by the National Trust 

unknown 

B2; D 

Unknown 

D.C. Stevens 


Cut-off from the sea around 1890 by the accumulation of sand dunes. Originally brackish-water but now 

an oligotrophic lake. A UK site of local importance for stoneworts. Information on this lake is to be 

found in unpublished reports by D.C. Stevens (voluntary warden, National Trust) who began monitoring 

it in 1991. 

32. Martham Broad (north and south), Norfolk 

Grid ref: 

TG4520 

82

Status: 

Ownership: 



SSSI, cSAC, All Ramsar 

Unknown 

B2; D 

Unknown 


The two broads largely escaped the enrichment pollution that resulted in the loss of the rooted vegetation 

(including stoneworts) from most in the 1970s. There are records of algae (other than stoneworts) 

extending back well before the main phase of pollution in the area. It is of regional importance for algae 

on two accounts: (a) existence of a reasonably comprehensive baseline of information on its algal flora, 

and (b) being one of the few broads not impacted by nutrient enrichment. Stewart (2004) considers it to 

be a site of European importance for stoneworts since 10 species belonging to this group have been 

recorded from it. 

33. River Wear, Durham 

Grid ref: 

Status: 

Ownership: 



NZ1134 NZ24, NZ28, NY94 

Unknown 

Unknown 

B2; D 

Unknown 


Long history of study (see Whitton & Buckmaster, 1970; Whitton et al., 1998). 

34. River Bure, Norfolk 

Grid ref: 

Status: 

Ownership: 



TG2521 

Unknown 

Unknown 

B2; D 

Unknown 


Most of the River Bure valley lying above the junction of the River Thurne. The Broadland part of the 

valley is an area of marshland, woodland and scattered broads. Considerable baseline and long-term 

information on the phytoplankton in the slow-flowing Bure River (e.g., Moss et al., 1984,1988), 

including in some cases its floodplain lake and broads. 

35. Abbot's Pond (near Bristol), Somerset 

Grid ref: 

Status: 

Ownership: 



ST536732 

Unknown 

Unknown 

B2; D 

Unknown 


One of the most researched small ponds in the UK (see Moss, 1969a, 1969b; Round & Eaton, 1966, 

Round & Happy, 1965). No recent investigations so unknown whether conditions today are similar to 

when intensively investigated in the 1960s. 

83

36. Lake Windermere, Cumbria 

Grid ref: 

Status: 

Ownership: 



SD3995, SD4197 (West-mid) SD38 & NY38 

Unknown 

Unknown 

B2; D 

150 plus spp. 


Windermere is not only the largest (ca. 14.8 km²) but the most thoroughly researched natural lake in 

England. This glacial ribbon lake is divided into a deeper north basin and a shallower more productive 

south basin. Data sets extend back more than 50 years and cover the period in the 1960s when its algal 

flora changed in response to the discharge into the lake of mineralised, secondary-treated sewage. Almost 

150 species of algae have been recorded in the phytoplankton of the lake. For a list of the planktonic 

algae recorded from Windermere and a summary of earlier research, see Reynolds & Irish (2000). 

37. River Coquet, Northumberland 

Grid ref: 

Status: 

Ownership: 




NU212036 

SSSI 

Unknown 

B2; D 

Unknown 

Martin Kelly 


Drains the southern flanks of the Cheviot Hills in Northumberland. Diatom sites in Coquetdale sampled 

from the middle part of the 20 th century (Donkin, 1869). Notable for the unusual abundance of the diatom 

Didymosphenia geminata in the UK. 

38. Stream, Weston Combe (near Branscombe), Devon 

Grid ref: 

Status: 

Ownership: 



SY1688 

Unknown 

Unknown 

B2; D 

Unknown 


A stream running through a small coastal valley running lying between Sidmouth and Branscombe on the 

south Devon coast. The small catchment is of woodland and pasture with the water alkaline and many 

surfaces marl-encrusted. What proved to be a new species of algae was collected by a Mr Scourfield in 

1917 as small, green, lime-encrusted cushion-like growths on and within the splash and spray of a small 

waterfall about 10 m from where the stream runs onto the shore (West, 1918; Johnson & John, 1992). 

This is the type locality of Gongrosira scourfieldii G.S. West, a green alga still unrecorded from 

elsewhere. Observed growing its type locality (June 2004) around the waterfall close to the beach and 

along much of the course of the stream. 

84

39. Wicken Fen, Cambrideshire 

Grid ref: TL 5570 

Status: 

SSSI, cSAC, RAMSAR 

Ownership: 



B2; D 



Much of the fen (247 hectares) is a nature reserve owned by the National Trust. It comprises a mixture of 

sedge fen, carr scrub and includes various aquatic habitats such as ditches. The fen is is one of the only 

areas of undrained peat fen for which there is a long history of algal study. For a summary of information 

on the fen and its aquatic algae, see Friday & Harley (2000). Designated a stonewort site of European 

importance by Stewart (2004), partly on account of stonewort diversity (12 spp). 

40. River Thames, Southern England 

Grid ref: 

Status: 

Ownership: 



SU761003 (near mid-point of course) 

unknown 

Various 

B2; D 

unknown 


Various early studies of the plankton and more recently (mostly 1980s) of the benthic algae. 

41. River Wye, England/Wales 

Grid ref: 

Status: 

Ownership: 



SO597168 (near mid-point of course) 

SSSI (in part) 

Various 

B2; D 

unknown 


Several studies of the benthic and planktonic algae (including unpublished reports) with some focusing on 

the diatoms. 

42. Loch Leven, Perth & Kindross 

Grid ref: 

Status: 

Ownership: 



NO150015 

unknown 

unknown 

B2; D 

unknown 


Large, mostly fairly shallow lake that has become increasingly eutrophicated. For summary of long-term 

studies on this lake, see Bailey-Watts (1974, 1978). 

85

43. Blackford Pond, Edinburgh 

Grid ref: 

Status: 

Ownership: 




NT253709 

unknown 

unknown 

B2; D 

unknown 

David Mann 


Various studies but all focusing on diatoms. 

44. Isle of Mull, Argyll & Bute 

Grid ref: 

Status: 

Ownership: 



NM7236 

Unknown 

Various 

B2; D 

600 spp. Plus 


Mull Survey carried out by staff of the Natural History Museum, London between 1965-1970. Wide 

range of habitats including lochs, small pools, etc. (see Jermy & Crabbe, 1978). 

45. Lough Neagh, Traad Beach, Northern Ireland 

Grid ref: 

Status: 

Ownership: 



H955870 (Irish Grid) 

unknown 

various 

B2; D 

unknown 


This large mesotrophic lake has a long history of study (see Gibson, 1993), especially Traad beach (see 

Jewson et al., 2006). 

86

9. REFERENCES 

Anand, P.L. 1937. A taxonomic study of the algae of the British chalk-cliffs. Journal of Botany, London 

75, Supplement II b: 1-51. 

Anderson, S. 2002. Identifying Important Plant Areas. Plantlife International, London. 

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