Warming oceans are likely to threaten sea turtles’ survival, even as the animals lay eggs during cooler seasons to adapt to climate change, new research suggests.
Modeling by Australian scientists
at Deakin University has found that sea turtles are unlikely to be able to
alter their nesting behavior enough to mitigate the effects of higher sea
surface temperatures. The researchers analyzed 58 nest sites worldwide covering
all seven sea turtle species and suggest that if the reptiles laid their eggs
earlier to avoid hotter beaches, each shift mitigates at best 55% of a 1.5C
rise in sea temperature would.
The sex ratio of turtle
hatchlings is closely determined by the temperature of the nest in which the
eggs are hatched, with warmer nests producing more females. Higher temperatures
have also been associated with lower hatching success rates.
In a ‘doomsday scenario’,
according to study co-author Prof Graeme Hays, ‘only females may be produced
from certain populations, which would then obviously lead to population
extinction’.
A 2018 study found that 99.1% of
juvenile turtles obtained from breeding beaches north of the reef are female. Hays
stressed that the new research isn’t “all doom and gloom,” but stressed the
potential need for conservation strategies to cool temperatures on the breeding
beaches.
“There is a lot of good news
around the world with sea turtles,” he said. “Populations are increasing at a
number of locations around the world; Nature conservation works really
successfully. “With the feminization of global warming [research]what we are
trying to do now is to get the information so we can avoid problems later… [so]
If turtles need help along the way, we won’t be caught off guard.”
Christine Madden Hof, global
director for sea turtle conservation at the World Wide Fund for Nature (WWF),
said: “We need more data to understand how different species of sea turtles
will fare in different places around the world of climate change. WWF is
involved in trials where seawater and freshwater have been successfully used to
artificially cool turtle nests.
Increasing shade coverage on
beaches by tenting or planting vegetation has also been suggested as an
approach to improve sex ratios. It would take care to ensure nesting habitats
are not disturbed, Hays said.
WWF is also currently
investigating the minimum number of male turtles needed to sustain populations.
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