European pond turtle could return to British rivers and lakes
The European pond turtle could be swimming in British rivers and lakes again thanks to a new crowdfunded campaign as conservation scientists seek sites for an experimental reintroduction.
Global heating is believed to be making Britain increasingly suitable for the enigmatic species, which may have vanished because of global cooling thousands of years ago but is now threatened by droughts in southern Europe.
Conservation scientists behind the plan say that the turtle, Emys orbicularis, fulfils a valuable ecological role now missing in Britain – there are no longer any carrion-feeding aquatic animals that hoover up dead fish that can pollute waterways during heatwaves.
But there is still debate over whether the European pond turtle was a native species in recent history, with museum authorities refusing scientists permission to carbon date the only surviving fossils, found in East Wretham, Norfolk, in 1836.
The fossils, which are held by the University of Cambridge’s Museum of Zoology, are deemed too precious to be tested using carbon dating, which destroys small fragments.
Scientists now hope that innovative analysis of sedimentary DNA – which has discovered the turtle was present on Doggerland before it was inundated by the rising North Sea around 8,000 years ago – can be used to definitively prove that it was a post-Ice Age resident of Britain.
Bill Sutherland, professor of conservation biology at the University of Cambridge, said it “would be really interesting to know” the exact date of the turtle fossils and said the reintroduction could contribute to restoring the ancient biodiverse wetlands of the East Anglia Fens.
“It’s an exciting, visionary project to look at the potential to re-establish this long-lost species,” he said.
The European pond turtle reintroduction working group is led by Harvey Tweats of Celtic Reptile& Amphibian Ltd, a conservation company he founded as a teenager with fellow conservationist Tom Whitehurst.
Tweats said returning the species to Britain would improve the holistic functioning of wrecked wetland ecosystems and also inspire people.
“When the turtles pull themselves out of the water and are hit by the sun they look like they’ve been coated in golden dust – they are absolutely beautiful,” he said. “It is about engaging people in conservation and it is about joy. Who doesn’t love a turtle?”
Senior conservation scientists on the reintroduction working group said the turtle posed no apparent threat to fish species and was mostly a scavenger, performing valuable ecosystem services particularly when overheated rivers cause mass fish kills.
Justin Gerlach, an ecologist at the University of Cambridge with a special interest in turtles, said: “It seems that the European pond turtle is not a significant fish predator so they shouldn’t be a problem for the angling community. They are not going to damage river banks, they are not going to be attacking birds. There seem to be no downsides to doing this.
“In hot summers, oxygen levels in river water drops and you’re going to get a lot of dead fish. If you haven’t got scavengers other than invertebrates – as in Britain – then dead fish pollute the water and smell. A pond turtle will eat these dead fish and also catch and eat diseased fish so you would have a lower incidence of disease in fish populations. Both of these things would keep the rivers in a healthier state.”
Gerlach, the scientific lead for the European pond turtle reintroduction group, said that he believed that the turtle was probably wiped out by humans after a cooling climate left it on the brink of extinction several thousand years ago.
But he said that this was simply a theory at this stage and before an experimental release could occur he would want to definitively prove that the turtle was once resident in Britain.
The surviving fossils found at East Wretham were given an approximate age of 5,000-8,000 years old based on pollen records discovered in moss associated with the specimens. Unfortunately the moss, which could be tested using more reliable modern methods, has since disappeared.
The working group is seeking funding for fencing and monitoring alongside a site in the Breckland region where the turtles were probably last resident. The area has a multitude of ancient “pingos” or glacial ponds as well as the last naturally-occurring inland sand dunes where the turtles like to lay their eggs.
Some conservation scientists on the working group say that the turtles should be introduced whether its status as a former native species is proven or not, because it will be a valuable trial of “assisted colonisation”, whereby species are given a helping hand by humans to move to regions better suited to their survival in an era of rapid climate warming.
Dr Sarah Dalrymple, reader in conservation ecology at Liverpool John Moores University and a member of an International Union for Conservation of Nature group looking at translocations, said: “A few decades ago we would never have thought that the European pond turtle might survive here but there’s anecdotal evidence that it can and the projections suggest that the climate will become more suitable for this species.
“Assisted colonisation is being a bit brave and trying some species out. This is a really good candidate. We can have a very controlled and well-monitored release into the wild in an enclosure. It’s a fantastic opportunity to tease out what works and what we should be doing in a relatively low-risk project.”