Sickness previously believed to occur only in humans and some whale and dolphin species.
Already at risk from oil spills, hunting and habitat destruction, sea turtles have another obstacle to contend with: decompression sickness, also known as the bends. Scientists claim the sickness has been diagnosed for the first time in loggerhead sea turtles, with individuals accidentally caught in fishing nets most likely to suffer.
The bends is caused by the formation of nitrogen bubbles in the blood and tissues following a sudden drop in surrounding pressure, such as when a diver ascends rapidly from a deep dive, or if a turtle is pulled quickly from the depths. In humans, symptoms range from joint pain to paralysis and death, but what animals feel is unknown.
A team of international scientists, including experts from the Zoological Society of London (ZSL), diagnosed the sickness, which was previously thought to only occur in humans and some whale and dolphin species. The study, published in the journal Diseases of Aquatic Organisms, suggests that some live turtles, while appearing initially active, possibly have the bends and may die following release.
Caught in nets
In the study, 29 sea turtles accidentally caught in commercial fishing nets off the coast of Spain were found to suffer from the bends. “This is the first time that the bends has been confirmed in a marine reptile,” said Dr Paul Jepson, co-author of the study and marine vet at ZSL.“It also shows that endangered sea turtles accidentally caught in fishing nets are at risk of dying, even if they initially appear to be still alive when brought up to the sea surface. Ideally we want to avoid sea turtles being caught in commercial fishing activities but, if they are, I hope that this research will make fisheries more vigilant about unintentionally catching sea turtles and the risks of decompression sickness from rapid ascent,” he added.
Two of the creatures were treated with human recompression protocols carried out at Oceanographic in Valencia, and responded well. They were subsequently released back into the Mediterranean Sea. The findings have direct implications for sea turtle conservation, as many more may die as a result of commercial fishing activities than previously thought. Marine turtle populations are declining in the Mediterranean Sea, with six out of seven species endangered worldwide.