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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