Freshwater turtles of the Kimberley
By Nancy Fitzsimmons and Tony Tucker
The Kimberley Plateau is an ancient landscape, formed around 250 million years ago. Its physical characteristics have been determined by periods of uplift and erosion, creating magnificent gorges and cliff formations. The most recent uplift occurred 20 million years ago with rivers cutting down through uplifted sandstone resulting in the present river systems, throughout the landscape.
Over the past 15 million years the area has undergone a gradual increase in aridity and a shift from tropical and temperate rainforests to savannah. The landscape varies from steep escarpments along the northern border characterised by beautiful waterfalls, to large areas of erosion plains with woodlands, sandstone gorges and savannah rainforests. There are large networks of river drainages and the plateau experiences extensive flooding during the summer wet season.
Many consider the area pristine due to its isolation, yet its land management needs are pressing. It has been subject to intensive cattle and sheep grazing over the past 100 years resulting in areas of high bank erosion and disruption of riparian vegetation. In the eastern Kimberley region the Ord River supports an important agricultural economy and there are plans for its expansion. Although various plans to dam the Fitzroy River in the western Kimberley have been overturned, the idea continues to be revisited.
In the Kimberley, most of what we know of freshwater species in the river systems comes from survey data rather than in-depth ecological studies. This has been true of the freshwater turtles inhabiting the region. At present, there are three genera of freshwater turtles recognised in the Kimberley, a long-necked species (Chelodina sp.), a red or yellow-faced short neck (Emydura sp.) and a snapping turtle (Elseya sp), but the exact species designations remain unclear.
Our work in the Kimberley to date has focused on establishing sites for long-term ecological studies and for collecting tissue samples for genetic studies. Two major study sites have been established, one in the western Kimberley at Bell Creek, Silent Grove and the other in the eastern Kimberley at Drysdale River, Drysdale Station. Other minor sites include King Edward River and Mitchell River, both in the Mitchell Plateau area.
Ecological studies of the turtles in these areas will provide insights into how these ecosystems are functioning and to the threats facing these species and their habitats. This, combined with the genetic studies, will provide information on the patterns of biodiversity across this freshwater landscape. A major goal of our combined ecological and genetic research is to contribute towards assessing the conservation needs and priorities of the Kimberley and to provide information to land managers.
Some of the questions we will be focussing on, with the help of Earthwatch volunteers, include:
- What species are present in the Kimberley and how are they related to other freshwater turtles?
- What are the size and composition of Kimberley turtle populations?
- How are turtle populations changing over time?
- What are turtles feeding on?
- How are turtles using the habitat?
- What is the reproductive condition of the population through time?
- How serious are any threats to the turtle populations?
The volunteers will snorkel through the rivers, locating and catching turtles which they will mark, measure, weigh and then release. Some turtles will have time-depth recorders attached and these will be radio tracked by volunteers. Volunteers will also help with assessments of habitat quality and collection of tissue samples for genetic analysis as part of the study.
We look forward to working with our first teams of volunteers this July-August. With their assistance, we will be able to proceed with this research which we hope will have long term effects on the conservation of this magnificent and little known region of Australia.
Dr Nancy FitzSimmons is based at the Applied Ecology Research Group in the University of Canberra. Dr Tony Tucker is based at the Sea Turtle Ecology Group, Mote Marine Laboratory, Florida. Both Dr FitzSimmons and Dr Tucker are experienced Earthwatch team leaders, having been involved previously on projects in Puerto Rica, the US and Malaysia.
Why Study Freshwater Turtles?
The Kimberley turtles are:
- important components of freshwater biodiversity
- key species in the area’s food webs
- indicator species of ecosystem health
- an important food source and cultural icon for aboriginal communities
- like all turtles, part of mythology that has been shared by many cultures
- simply, great little animals that are wonderful to see in their natural habitat!
Your opportunity to be involved.
Each team is approx 2 weeks and teams either start in Kununurra and end in Broome or start in Broome and end in Kununurra.
For more information and team dates, look at the Discovery Expeditions on the Expedition Search or contact Earthwatch Australia on +61 (0) 3 9682 6828 or email email@example.com
Since 1999 preliminary studies have:
- Marked and measured - 790 Emydura sp.,
- 121 Chelodina sp.,
- 9 Elseya dentata
- Taken nearly 500 genetic samples
- Undertaken dietary studies on 24 turtles