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Sea turtles and climate change

March 24, 2025 By EarthWise Leave a Comment

Life is a struggle for survival from the moment a sea turtle hatches. In fact, only one sea turtle out of every 1,000 typically reaches adulthood as a result of natural predators and other challenges. Those fortunate enough to make it to adulthood face serious threats from humans. For example, sea turtles are hunted for their meat, eggs, and shells in some regions. Their beach habitats get developed. Harmful marine debris and oil spills pollute their waters and beaches.

Now, climate change is exposing sea turtles to even greater threats. Rising sea levels and stronger storms threaten to erode and destroy their nesting beaches. Warming oceans disrupt currents, potentially exposing sea turtles to new predators, and damaging the coral reefs that some depend on to survive.

As these environmental challenges intensify, sea turtles are beginning to adapt in surprising ways. According to a new study by researchers from the University of Exeter in England and the Society for the Protection of Turtles in Cyprus, sea turtles are responding to climate change by nesting earlier. Researchers monitoring nesting green and loggerhead turtles in Cyprus have discovered they are returning to their regular nesting spots earlier each year to compensate for rising temperatures.

Temperature plays a crucial role in determining the biological sex of sea turtles. Warmer nest temperatures produce more female hatchlings than males.

But at least for now, sea turtles seem to be doing enough to ensure their eggs continue to hatch by nesting earlier in more ideal temperatures. While this is good news, there’s no guarantee that it will continue.

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Turtles change nesting patterns in response to climate change

Photo, posted December 20, 2021, courtesy of Cape Hatteras National Seashore via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rainfall and sea turtles

October 4, 2024 By EarthWise Leave a Comment

There are seven species of sea turtles that inhabit the world’s oceans. Six of the seven sea turtle species – all of them except the flatback – are present in U.S. waters, and are listed as threatened or endangered under the Endangered Species Act.

Sea turtles, which have been around for more than 100 million years, spend the majority of their lives in the ocean, but they do periodically come ashore to nest. Female sea turtles lay their eggs in the sand and then return to the ocean. Survival odds for sea turtle hatchlings are quite bleak. In fact, only one out of every 1,000 makes it to adulthood.

Research shows that both air and sand temperatures are critical for sea turtle hatchling development. Cooler temperatures produce larger, heavier hatchlings with more males. Hatchling size matters because larger hatchlings, which can move faster, are more likely to survive because they spend less time on risky beaches. But rising temperatures might shorten incubation periods, and erratic rainfall can disrupt growth, potentially affecting survival.

A new international study by researchers from Florida Atlantic University and the University of Tübingen in Germany found that fluctuating rainfall patterns have a greater impact than changes in air temperature on sea turtle hatchling development.

The results, which were recently published in the journal BMC Ecology and Evolution, reveal that the impact of rainfall varies between species. As climate change shifts rainfall patterns, the impact on sea turtle nesting sites suggests that global conservation strategies for some species – like loggerhead and green sea turtles – likely need to be updated.

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Rain or Shine? How Rainfall Impacts Size of Sea Turtle Hatchlings

Sea Turtle

Photo, posted August 27, 2015, courtesy of USFWS/Orsulak via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Not All Eggs In One Basket | Earth Wise

March 2, 2021 By EarthWise Leave a Comment

Sea turtles lay their eggs in burrows on sandy beaches. Many species lay their eggs on the exact same beach year after year. On average, sea turtles lay over 100 eggs in a nest and produce between 2 and 8 nests per season.

Animals that produce such large numbers of eggs have this reproductive strategy because so few survive to adulthood. Sea turtle eggs and hatchlings face numerous threats including powerful storms, poachers, marauding birds, and more. Estimates are that only one in thousand sea turtle eggs leads to an adult turtle.

A recent study by the University of South Florida looked at the reproductive strategy of loggerhead sea turtles nesting on Keewaydin Island off the southwestern Gulf coast of Florida. The researchers found that individual females lay numerous clutches of eggs in locations as much as six miles apart from each other to increase the chance that some of their offspring will survive.

As the saying goes, nesting loggerhead turtles don’t lay all their eggs in one basket. The researchers compare the turtles’ strategy to investing in a mutual fund. The female turtles divide their resources among many stocks rather than investing everything in a single stock.

During their 50-year lifetime, a single female loggerhead will produce over 4,000 eggs and scatter them at 40 different sites. This strategy helps reduce the risk of complete reproductive failure caused by hurricanes and thunderstorms that could wash out or flood all their clutches. The combination of unpredictable patterns of nests over time and space results in nearly two-thirds of loggerhead sea turtle hatchlings making it into the Gulf of Mexico. The species still faces significant challenges but it is doing its part to try to survive.

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Not all in one basket: Loggerhead sea turtles lay eggs in multiple locations to improve reproductive success

Photo, posted January 27, 2012, courtesy of Jeroen Looye via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.