A turtle’s tail; helping a living fossil in Lawn Hill Gorge

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1 A turtle’s tail; helping a living fossil in Lawn Hill Gorge
The Gulf snapping turtle (Elseya lavarackorum) Alastair Freeman Threatened Species Unit EHP Atherton Amanda Freeman P.O. Box 1536 Atherton Lea Ezzy Queensland Parks and Wildlife Service DNPSR Townsville

2 Is moderately large species of freshwater turtle originally described from fossil material fossil material indicated tup to 50cm in size modern maximum 35cm Currently listed as Vulnerable under the Queensland Nature Conservation Act (NCA) Listed as Endangered under the federal Environmental and Biodiversity Conservation Act (EPBC) Identified as a high priority under the internal prioritization process “Back on Track

3 Restricted distribution four population nodes over Nicholson and Calvert catchments in NW Qld and adjacent NT. Not known further east in Leichardt (unsuitable habitat) may occur further west in upper reaches of neighboring Robinson Catchment but no further west (different species E dentata in McArthur river catchment). Habitat in Settlement Creek catchment thought to be unsuitable.

4 In 2010 Threatened Species Unit staff and volunteers carried out surveys in and around Boodjamulla National Park Timed snorkel surveys indicated that highest densities recorded in the Middle Gorge area of Boodjamulla NP

5 Habitat features likely to drive distribution and density:
The density of Pandanus aquaticus (Pandanus) at water level The number of fruit-bearing Ficus racemosa (cluster fig)

6 Provides shore side habitat complexity above and below the water
Pandanus aquaticus Provides shore side habitat complexity above and below the water Protection from predators (including ghosts of predators past?) Turtles consume leaves and fruit and graze algae on the leaves and branches Predators such as human hunters maybe even ghosts of predators past such as the large freshwater crocodile that is thought to have inhabited this system as recently as years Palimarchus sp

7 Fruit important in diet Can fruit year round, at times prolifically
Ficus racemosa Fruit important in diet Can fruit year round, at times prolifically Turtles congregate below fruiting trees and display antagonistic behaviour over floating fruit Observations have been made of this aquatic turtle traveling on dry land (>3m)to feed on fig fruit Fig was the most common fruiting species identified in Elav scats

8 Riparian ecosystem This riparian vegetation, Regional Ecosystem 1.3.9a, has been identified as a regional ecosystem that is rare with a Vegetation Management and Biodiversity conservation Status “Of Concern” This riparian (RE1.3.9) vegetation has been identified as a regional ecosystem that is rare with a Vegetation Management and Biodiversity Status “Of Concern” The subclass 1.3.9a: “Aquatic ecosystems poorly known but threatened by grazing and increasing human use. Other threatening processes include weed infestation and disturbance by feral pigs”

9 Methodology 10 timed snorkel transects in Middle Gorge area; along each transect turtles were identified, and classified according to age and sex - conducted between 2010 and 2014 Transects classified on riparian vegetation condition (% density of P. aquaticus and number of F. racemosa) Mean number of turtles per snorkeler per 30 minutes of search effort and per metre of transect were calculated and correlated with mean % Pandanus aquaticus cover at water level and number of fruit bearing sized Ficus racemosa for each transect Pearsons Correlation

10 Results : Pandanus cover
Turtles/30 mins P= 0.05 Turtles/m P= 0.02

11 Results – Ficus racemosa
Turtles/30 mins P= 0.02 Turtles/m P= 0.03

12 2010 - QPWS rangers started targeted weed control in this area
Introduced vines stinking passionfruit (Passiflora foetida ) and butterfly pea ( Clitoria ternatea) smother riparian vegetation in parts of Middle Gorge QPWS rangers started targeted weed control in this area As far as we are aware the most significant area of this habitat is contained in Boodjamulla NP in the Lawn Hill Creek where it is subject to ongoing threats (degradation) from weed invasion 2010 2014

13 Mean turtles/30 min18.35 (n=6) (Pandanus coverage peaked at 85%) 2010 Pre weed control turtles /30 min 7.78 (Pandanus coverage 65%)

14 Summary Elseya lavarackorum numbers highest where Pandanus coverage highest and cluster figs of fruiting size most numerous This riparian vegetation type is rare and impacted by degradation caused by weed invasion

15 The good news Feasible to manage the weed threat to this key habitat
The most significant habitat is protected in Lawn Hill gorge, Boodjamulla NP Feasible to manage the weed threat to this key habitat Managing this habitat for turtles also helps other threatened species, protects a rare Regional Ecosystem and maintains scenic amenity in a high use recreational area 15

16 Acknowledgements This work would not be happened without the support of the Federal Australian Government, the Threatened Species Unit, Queensland (Dept. Environment and Heritage) and Queensland Parks and Wildlife Service as well as a small group of fantastic volunteers who perform above and beyond the call of duty.