Presentation is loading. Please wait.

Presentation is loading. Please wait.

Examining Population Structure of Two Species of Australian Freshwater Turtles: Wollumbinia latisternum and Elseya stirlingi Elliott Diggs 1, 2, Guilford.

Similar presentations


Presentation on theme: "Examining Population Structure of Two Species of Australian Freshwater Turtles: Wollumbinia latisternum and Elseya stirlingi Elliott Diggs 1, 2, Guilford."— Presentation transcript:

1 Examining Population Structure of Two Species of Australian Freshwater Turtles: Wollumbinia latisternum and Elseya stirlingi Elliott Diggs 1, 2, Guilford College 1, The School for Field Studies 2, Dr. Timothy Curran 2, Alastair Freeman 3, Queensland Parks and Wildlife Service 3 and Threatened Species Unit of the Environmental Protection Agency 3

2 What are they? Species of freshwater turtles of the family Cheluidae Species of freshwater turtles of the family Cheluidae Live in the North Johnstone River Catchment Live in the North Johnstone River Catchment Adult female E. stirlingi Adult male W. latisternum

3 E. stirlingi Largest of the study species and herbivorous Largest of the study species and herbivorous Adult females Adult females Mean SCL=17.01 cm Mean SCL=17.01 cm Mean weight=1998 g Mean weight=1998 g Juveniles Juveniles Mean SCL=11.30 cm Mean SCL=11.30 cm Mean weight=233 g Mean weight=233 g Adult males Adult males Mean SCL=17.01 cm Mean SCL=17.01 cm Mean weight=1771 g Mean weight=1771 g Restricted to the Johnstone and Barron Rivers of the Atherton Tablelands, Queensland Restricted to the Johnstone and Barron Rivers of the Atherton Tablelands, Queensland Presence in Wet Tropics recently documented in literature Presence in Wet Tropics recently documented in literature Adult female E. stirlingi

4 W. latisternum Smallest of the study species and omnivorous Smallest of the study species and omnivorous Adult females Adult females Mean SCL=17.01 cm Mean SCL=17.01 cm Mean weight=338 g Mean weight=338 g Juveniles Juveniles Mean SCL=10.36 cm Mean SCL=10.36 cm Mean weight=153 g Mean weight=153 g Adult males Adult males Mean SCL=17.01 cm Mean SCL=17.01 cm Mean weight=338 g Mean weight=338 g Common throughout eastern Australias tropical coastal regions Common throughout eastern Australias tropical coastal regions Juvenile W. latisternum

5 What is Population Structure? Age class ratios: comparing the number of juveniles and adults of both species Age class ratios: comparing the number of juveniles and adults of both species Sex ratios: comparing the number of males to females of both species specifically the adults of both species Sex ratios: comparing the number of males to females of both species specifically the adults of both species Juvenile and adult female E. stirlingi Adult male W. latisternum

6 Conflicting Views on Freshwater Turtle Population Structure Stable size distributions=larger number of adults specifically adult females than juveniles or hatchlings (Blamires et al. 2005) Focuses more with turtle longevity Focuses more with turtle longevity Favors breeding females Favors breeding females Documented for other species of Australian freshwater turtle e.g. Emydura macquarii (Spencer and Thompson, 2005) Documented for other species of Australian freshwater turtle e.g. Emydura macquarii (Spencer and Thompson, 2005)

7 Conflicting Views on Freshwater Turtle Population Structure Stable population structure=more juveniles and hatchlings (OMalley 2007) Favors future generations More juveniles=stable population structure More juveniles=stable population structure More juveniles=increases total number of breeding females More juveniles=increases total number of breeding females

8 Aims of Research Collect observational data on two poorly documented species of Australian freshwater turtles Collect observational data on two poorly documented species of Australian freshwater turtles Provide baseline data for future research Provide baseline data for future research Combine 2009 data with previous data to see if both species populations follow Blamires view Combine 2009 data with previous data to see if both species populations follow Blamires view

9 Hypothesis Majority of the populations for both species should skewed towards adult females Majority of the populations for both species should skewed towards adult females Adult female W. latisternum Adult female E. stirlingi

10 Study Sites

11

12 Allwood Allwood Mahar Hickey Fanning

13 Methods Turtles were captured by two experienced locals via snorkel Turtles were captured by two experienced locals via snorkel Fall 2009 I compared age class and sex of each turtle captured from Jan 2008-Nov 2009 Fall 2009 I compared age class and sex of each turtle captured from Jan 2008-Nov 2009 Used JMP version 7 to run Χ 2 tests Used JMP version 7 to run Χ 2 tests Sub-adult male W. latisternum

14 Results Both Species Adult Sex Ratios Contingency Table Species by Sex Species FemaleMaleTotal E. stirlingi465096 W. latisternum 121830 Total5868126 Contingency Graph Species by Sex Species Sample percentage for each sex W. latisternumE. stirlingi Male Female 1.00 0.75 0.50 0.25 0.00

15 Adult E. stirlingi Sex Ratios Across Pool Contingency Table Pool by Sex Contingency Graph Pool by Sex PoolFemaleMaleTotal Allwood9817 Fanning182240 Hickey8715 Mahar111324 Total465096 Sample percentage for each sex Pool AllwoodFanningHickeyMahar Female Male 1.00 0.75 0.50 0.25 0.00

16 Adult W. latisternum Sex Ratios Across Pools Contingency Table Pool by Sex Contingency Graph Pool by Sex PoolFemaleMaleTotal Allwood71522 Hickey415 Mahar123 Total121830 20% of cells had expected counts <5 AllwoodHickeyMahar Male Female 0.00 0.25 0.50 0.75 1.00

17 Both Species Age Class Ratios Across Pools Contingency Table Pool by Age PoolAdultJuvenileTotal Allwood393776 Fanning401555 Hickey203555 Mahar272653 Total126113239 Contingency Graph Pool by Age p-value=0.0016 1.00 0.75 0.50 0.25 0.00

18 W. latisternum Age Class Ratios Across Pools Contingency Table Pool by Age PoolAdultJuvenileTotal Allwood221133 Fanning055 Hickey51419 Mahar3710 Total303767 Contingency Table Pool by Age p-value=0.0011 20% of the cells had expected values <5

19 E. Stirlingi Age Class Ratios Across Pools Contingency Table Pool by Age PoolAdultJuvenileTotal Allwood172643 Fanning401050 Hickey152136 Mahar241943 Total9676172 Contingency Graph Pool by Age p-value=0.0001

20 Conclusions Hypothesis being skewed towards adult females for both species was not supported Exceptions The overall trend for both species favors adults but not adult females The overall trend for both species favors adults but not adult females Hickey Pool shows signs of stability for both species according to Blamires Hickey Pool shows signs of stability for both species according to Blamires Allwood and Fanning show signs of stability for E. stirlingi Allwood and Fanning show signs of stability for E. stirlingi 2008 SFS observations reported more adult E. stirlingi than juveniles when compared cumulatively Dethier (2008) and DeBree (2008) 2008 SFS observations reported more adult E. stirlingi than juveniles when compared cumulatively Dethier (2008) and DeBree (2008)

21 Implications Each pool has juveniles of both species, which suggests that both species are breeding at each pool Each pool has juveniles of both species, which suggests that both species are breeding at each pool Juveniles might be migrating between pools within the entire catchment Juveniles might be migrating between pools within the entire catchment Habitat alteration might explain age class ratio data for Fanning Pool Habitat alteration might explain age class ratio data for Fanning Pool My results have and will continue aiding in the long term conservation and provide more knowledge of two poorly documented species of Australian freshwater turtles My results have and will continue aiding in the long term conservation and provide more knowledge of two poorly documented species of Australian freshwater turtles Beef Cattle at Fanning Pool Adult E. stirlingi females Damaged shell Normal Shell

22 Future Research Compare the number of adult females to other members of the population Compare the number of adult females to other members of the population Longer study period Longer study period Conduct study during both species breeding seasons Conduct study during both species breeding seasons

23 Acknowledgements Alastair Freeman for his Ethics permit EPA/N/07/04, Dr. Timothy Curran, Maggie Chan, and Margaret Hodgekiss-Lilly for assistance in the field Alastair Freeman for his Ethics permit EPA/N/07/04, Dr. Timothy Curran, Maggie Chan, and Margaret Hodgekiss-Lilly for assistance in the field Heather and Dennis Allwood, Peter and Carmeal Hickey, Peter and Barbara Mahar, and Kate and David Fanning for allowing this study to be conducted on their individual properties Heather and Dennis Allwood, Peter and Carmeal Hickey, Peter and Barbara Mahar, and Kate and David Fanning for allowing this study to be conducted on their individual properties

24 Questions? Adult female E. stirlingi


Download ppt "Examining Population Structure of Two Species of Australian Freshwater Turtles: Wollumbinia latisternum and Elseya stirlingi Elliott Diggs 1, 2, Guilford."

Similar presentations


Ads by Google