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Turtle Nests at Risk from Rising Seas

Rising sea levels will impact on turtles well before the full effects of climate change are felt in most other places, according to a study of a Queensland turtle hatchery exposed to saltwater for different periods of time.

Turtles lay their eggs in places that remain high and dry so that the eggs can hatch, but rising sea levels and storm surges can overwash nests incubating on the beach.

The study, published in Royal Society Open Science, found that eggs that were inundated for 1–3 hours showed no significant level of mortality, but eggs that were underwater for 6 hours suffered a 40% increase in turtle embryo deaths.

Dr David Pike of James Cook University said that a big tide or storm surge overwashing buried turtle eggs for up to 6 hours is a realistic scenario. “In some places it only takes a small rise in sea levels, when combined with a storm or a king tide, to inundate what had previously been secure nesting sites.

“We were actually surprised at how resilient the eggs were,” he said. “We thought after 6 hours the mortality rate would be higher.”

Pike said that other factors could also contribute to mortality rates of green turtles, including high microbial levels and heavy metals in the soil.