Hydrobiologia (2006) 568(S):51–55 G. Coulter, O. Timoshkin, L. Timoshkina & K. Martens (eds), Species and Speciation in Ancient Lakes DOI 10.1007/s10750-006-0334-6 Ó Springer 2006 The formation of a fouling community on artificial substrate in Lake Baikal L.S. Kravtsova*, I.V. Weinberg, I.V. Khanaev, D.Yu. Sherbakov, S.V. Semovsky, F.V. Adov, N.A. Rozhkova, G.V. Pomazkina, N.G. Shevelyova & I.A. Kaygorodova Limnological Institute, Siberian Branch of the Russian Academy of Sciences, Irkutsk, 664033, Russia (*Author for correspondence: E-mail: lk@sherb.lin.irk.ru) Key words: artificial substrate, fouling community, Lake Baikal Abstract The development of a fouling community at the surface of an artificial substrate in the littoral zone of Lake Baikal was studied. This epibenthic community was composed of 23 diatom species and 57 invertebrate species. The core community consisted of molluscs and caddisflies feeding mostly on diatoms. In Lake Baikal a fouling community develops in a sequence similar to marine environments. Introduction Lake Baikal has a complicated geomorphological structure and distribution of bottom sediments is heterogeneous. Active lythodynamic processes and the influx of terrigenous material from numerous rivers, shore erosion and from human activity result in continuously changing biotopes. The composition and distribution of bottom sediments influences the development of bottom biocenoses. Rates of biotope development and species succession in Lake Baikal are not well studied, and as an experimental contribution in this regard we describe the development of a fouling community on an artificial substrate in Bolshye Koty Bay. titative samples were thus obtained. While sampling, water transparency and temperature were measured. Species identifications were performed by the following scientists: diatoms (Pomazkina), lower crustaceans (Sheveleva), leaches and oligochaets (Kaygorodova), amphipods (Weinberg), molluscs (Adov), caddisflies (Rozhkova) and chironomids (Kravtsova). Species diversity was estimated by the Shannon index. Averaged species abundance was used in calculations. Faunistic resemblance was estimated using the Sorensen index (Odum, 1986). Samples were clustered based on their resemblance, and resemblance matrices derived from the Sorensen index. Subsequent clusterisation estimates were obtained by UPGMA algorithm (PHYLIP ver 3.7 package). Materials and methods The study site was at 2–3 m depth, 18 km NorthWest of the lake outlet at the Angara River. Ordinary building bricks (30) were arranged along the bottom in March 2000. The area of one substrate = 306 cm2. Samples were taken by divers, who put the bricks into diving sacks raised to the surface. Epibenthic organisms were removed by lancet and brush, rinsed with small amounts of water and fixed in 70% ethanol. In total 22 quan- Results Eighty three taxa were found on the artificial substrate: 23 diatom spp. and 57 invertebrate spp., as follows: Cyclopoidae – 3, Rotatoria – 1, Harpacticoidae – 2, Turbellaria – 1, Hirudinea – 4, Oligochaeta – 4, Isopoda – 1, Amphipoda – 24, Trichoptera – 4, Chironomidae – 7, Mollusca – 6 (Table 1). Species diversity as estimated by the 52 Table 1. Species composition of a fouling community at the surface of an artificial substrate in Bolshye Koty Bay Algae Echiuropus sp. Amphora ovalis (Kutz.) Kutz. Eulimnogammarus bifasciatus (Dyb.) Cocconeis placentula var. lineata (Ehr.) Cl. Eulimnogammarus cruentus (Dor.) Cyclotella minuta (Skv.) Antip. Cymbella helvetica Kutz. Eulimnogammarus cyaneus (Dyb.) Eulimnogammarus grandimanus Baz. Cymbella stuxbergii var. intermedia Wisl. Eulimnogammarus lividus (Dyb.) Cymbella turgida (Greg.) Cl. Eulimnogammarus maacki (Gerstfeldt.) Cymbella ventricosa Kutz. Eulimnogammarus marituji Baz. Didymosphenia geminata (Lyngb.) M. Schmidt Eulimnogammarus sp. Fragilaria capucina Desm. Eulimnogammarus verrucosus (Gerstfeldt.) Fragilaria crotonensis Kitt. Eulimnogammarus viridis (Dyb.) Fragilaria pinnata Ehr. Fragilaria spinosa Skv. Micruropus eugenii Baz. Micruropus sp. Gomphonema quadripunctata (Ostrup) Wislouch Micruropus littoralis crassipes Sow. Gomphonema ventricosum Greg. Micruropus littoralis littoralis (Dyb.) Gomphonema olivaceoides Hust. Micruropus macroconus macroconus Baz. Navicula cryptocephala var. intermedia Grun. Micruropus minutus (Sow.) Navicula lacus baicali Skv. and Meyer. Micruropus vortex vortex (Dyb.) Navicula radiosa Kutz. Pallasea cancellus (Pall.) Navicula menisculus Schum. Navicula tripunctata (O. F. Muller) Bory. Poekilogammarus erinaceus Tacht. Poekilogammarus sp. Nitzschia dissipata (Kutz.) Grun. Trichoptera Nitzschia linearis W. Smith. Baicalina bellicosa Mart. Rhoicosphenia curvata (Kutz.) Grun. Baicalodes ovalis Mart. Cyclopoida Thamastes dipterus Hag. Acanthocyclops jasnitskii Maz. Chironomidae Acanthocyclops konstantinovi Maz. Cricotopus pulchripes Verral. Rotatoria Dicranophorus sp. Cricotopus sp.1 Cricotopus sp.2 Harpacticoida Neozavrelia minuta Linev. Harpacticella inopinata Sars. Orthocladius gr. olivaceus Harpacticella sp. Orthocladius gr. thienemanni Hirudinea Paratanytarsus baicalensis (Tshern.) Baicalobdella torquata (Grube) Mollusca Codonobdella truncata Grube Choanomphalus amauronius Burg. Piscicola sp. Oligochaeta Choanomphalus gerstfeldtianus Ldgh. Choanomphalus maacki maacki Gerstf. Nais bekmanae Sok. Maackia bythiniopsis Ldh. Nais sp.1 Maackia herderiana Ldh. Nais sp.2 Megalovalvata baicalense Gerstf. Isopoda Baicalasellus angarensis Dyb. Amphipoda Baicalogammarus pullus (Dyb.) Brandtia latissima lata (Dyb.) Echiuropus macronychus sempercarinatus (Baz.) 3 2,5 2 1,5 1 0,5 0 number, ind. Shannon index, bit. 53 V VI VII VIII IX XII IV VIII month V VI VII VIII IX XII IV VIII month Figure 1. Species diversity at the surface of an artificial substrate in Bolshye Koty Bay, Lake Baikal (2000–2001). Shannon index varied from 2.1 to 2.7 bit (Fig. 1). Total density of organisms was 300–900 specimens per substrate square (Fig. 2). Of the meio (<2 mm)-benthic organisms the most numerous were Harpacticoidae, and of macroorganisms molluscs, amphipods, caddisflies and chironomids (Fig. 3). Discussion Benthic organisms that occur in Bolshye Koty Bay are diverse: 250 species of diatoms (Pomazkina, 2000), 41 of meio- and macro-phytes (Izhboldina, 1974) and 244 of macroinvertebrates (Kravtsova et al., 2003). It is likely the diversity and density of invertebrates naturally present in the stony littoral of Lake Baikal accelerated intense and rapid colonization of the artificial substrate. Biofouling resembled in general the process which takes place in marine conditions (Scheer, 1945; Khalaman, 2001). At first, a brownish-green film of periphyton appeared on the substrate surface, consisting mostly of diatoms dominated by Gomphonema ventricosum, Navicula cryptocephala var. intermedia and Cocconeis placentula var. lineate. Then number, ind 600 500 400 300 200 100 0 Amphipoda Chironomidae Mollusca Trichoptera Figure 3. Dynamics of the abundance of the major groups of invertebrates at the surface of an artificial substrate in Bolshye Koty Bay, Lake Baikal (2000–2001). macrophytes of the genus Draparnaldioides, followed by Tetraspora and Stratonostoc appeared. Colonization by invertebrates continued in parallel. After 2 months, the crustacean Harpacticella inopinata and mollusc Maackia herderiana were abundant, with smaller quantities of Choanomphalus maacki maacki (Mollusca), Brandtia latissima lata and juvenile Eulimnogammarus, Micruropus (Amphipoda) and the caddisfly Thamastes dipterus. Eggs of caddisflies and molluscs also appeared. The species complex present during early colonisation differed from those at later stages (Fig. 4). During summer diatom diversity increased, mostly due to seasonal fluctuations of species of the genera Fragilaria, Navicula and Gomphonema. In the substrate, as distinct from the artificial surfaces, annually abundant diatoms dominating in December 2000 and April 2001 were Cocconeis placentula var. lineata, Cymbella ventricosa and Navicula cryptocephala var. intermedia. Species composition also changed through fluctuations in secondary species of invertebrates, while the 900 800 700 600 500 400 300 200 100 0 V VI VII VIII IX XII IV VIII month Figure 2. Dynamics of total abundance of invertebrates at the surface of an artificial substrate in Bolshye Koty Bay, Lake Baikal (2000–2001). Figure 4. Cluster analysis of the species complexes developing on the artificial substrate in different months (Bolshye Koty Bay of Lake Baikal, 2000–2001). 54 Figure 5. Structure of a fouling community on the artificial substrate in Lake Baikal. Ratios (%) of dominating species abundance to total numbers of benthic invertebrates from May 2000 to August 2001. (1 – Choanomphalus maacki maacki, 2 – Maackia herderiana, 3 – Thamastes dipterus, 4 – benthic invertebrates). dominating species did not change. During the period of study the substrate community was dominated by Maackia herderiana, Choanomphalus maacki maacki and Thamastes dipterus. Their frequency of appearance was up to 91–95% of the community and their areal density highest except for the last species (Fig. 5). It is interesting, that the first to appear on the newly available artificial habitats were species probably under most competition pressure in the adjacent areas from species with similar life-cycle strategies. As examples, in Lake Baikal where Choanomphalus amauronius was most numerous, the numbers of Choanophalus maacki maacki was lower, and in biotopes dominated by caddisflies Baicalina bellicosa, larvae of Thamastes dipterus were rare (Kravtsova et al., 2003). These species evidently compete not only for space but also for feeding resources because all consume the same diatoms (Sitnikova et al., 2001). It is very likely that the set of algal species in the artificial habitat changes due to predation to some extent. The nucleus of the community during the colonization consists of the most phylogenetically distant species where they belong to the same species flock. This supports the principle of competitive exclusion (Odum, 1986). Species diversity on the artificial substrate was lower than on similar surfaces of rough boulders around the adjacent area (3.2–4.5 bit), and sharp seasonal fluctuations of species numbers not occurred. Only a small increase of juveniles (of caddisflies) in September was found. Similar changes were described previously on the stony substrates of Lake Baikal shallow zone (Kaplina, 1974). Thus quantitative changes in the artificial and in natural substrates around them appeared synchronous. Conclusions In general, epibenthic community formation on new experimental biotopes placed in Lake Baikal followed a sequence observed in marine environments, in that the fouling community colonised first by microperiphyton followed by macrophytes along with invertebrates. The community consisted chiefly of molluscs and caddisflies, the main foods of which are diatom algae. No colonizing sponges and almost no polychaetes were observed. Acknowledgements The authors are grateful to the Director of the Limnological Institute Prof M.A. Grachev for the organization of under-water studies led by I.V. Khanaev, and to divers: I.Yu. Parfeevets, A.B. Kupchinsky and A.L. Novitsky for their enthusiasm during sampling; also to M.N. Murashko and A.V. Natyaganova for technical support in the 55 processing of samples. Special thanks are due to Dr Y. Masuda and E.V. Weinberg for sponsoring fieldwork in 2000. References Izhboldina, L. A., 1974. Macrophytes of Southern Baikal and productivity of some species dominating the littoral in the region of Bolshye Koty. Productivity of Baikal and anthropogenic changes in its nature. Irkutsk, (in Russian) 111–116. Kaplina, G. S., 1974. Macrozoobenthos of the stony littoral grounds of Lake Baikal and its seasonal dynamics [data of 1963–1968, region of Bolshye Koty], Productivity of Baikal and anthropogenic changes in its nature. Irkutsk, (in Russian) 126–127. Khalaman, V. V., 2001. 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