Thursday, 5 October 2017

Climate change study of leatherback sea turtle hatchlings decline fails to provide answers


October 4, 2017 by Bob Yirka

(Phys.org)—A team of researchers with Monash University in Australia and the West Indies Marine Animal Research and Conservation Service has found that changes in temperature and rainfall in the West Indies is not a factor in the declining rate of survival of leatherback sea turtle hatchlings in the U.S. Virgin Islands. In their paper published in the journal Royal Society Open Science, the team details their study, noting that more research is required to find the true cause of the declining survival rate of the hatchlings.

Leatherback sea turtles are truly unique. Not only are they the only species of turtle without a hard shell (they have thick leathery skin on their backs instead), but they are the largest species of turtle. Because they lay their eggs in the sand, prior research has shown that the hatchlings that emerge are likely to be particularly vulnerable to climate change. In this new effort, the researchers looked at 20 years of data for the turtles that hatch at the Sandy Point National Wildlife Refuge to gain some insight into the impact climate change might be having on the local population.

The researchers report that hatchling survival rates over the years 1990 to 2010 dropped from 74 percent to 55 percent—an amount that is likely to have a serious impact on population growth over the next few decades—the turtles are long lived, though no one has been able to prove how long. Estimates range from 30 to 50 or even 100 years. Prior studies have also found that the survival rates for the hatchlings has declined, and the assumption is that changes to the environment are the cause. To find out if that was the case, the researchers compared hatchling survival rates for each year over the two-decade span with temperature and rainfall that occurred during nesting season in the area. They report that they were unable to find any correlating factors. They also report that there were occasional changes that caused problems for the hatchlings, but they are not trends. They further note that their findings are particularly confusing in light of the fact that turtle population counts in the park have been rising over the past several years.


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