For eastern Pacific populations of leatherback turtles, the 21st century could be the last. New research suggests that climate change could exacerbate existing threats and nearly wipe out the population.
When leatherback turtle hatchlings dig out of their nests buried in the sandy Playa Grande beach in northwest Costa Rica, they enter a world filled with dangers. This critically endangered species faces threats that include egg poaching and human fishing practices. Now, Drexel University researchers have found that the climate conditions at the nesting beach affect the early survival of turtle eggs and hatchlings. They predict, based on projections from multiple models, that egg and hatchling survival will drop by half in the next 100 years as a result of global climate change.
“Temperature and humidity inside the nest are significant factors affecting egg and hatchling survival,” said Dr. James Spotila, the Betz Chair Professor of Environmental Science in Drexel’s College of Arts and Sciences. Spotila and colleagues therefore examined the relationship between regional climate patterns with leatherback turtles’ nesting success over six consecutive nesting seasons at Playa Grande. This beach is the major nesting site for leatherback turtles in the eastern Pacific Ocean, containing more than 40 percent of nests.
“We have discovered a clear link between climate and survival of this endangered sea turtle population,” said Spotila.
The researchers found that warmer, dryer El Niño conditions were associated with significantly higher mortality for eggs and hatchlings. Using projections of global climate change due to global warming over the next 100 years, they predicted that El Niño conditions will become more frequent and hatchling success will decline throughout the 21st century at Playa Grande and other nesting beaches that experience similar effects.
Leatherback turtles are the largest on Earth, growing up to two meters long and exceeding 900 kilograms. They are critically endangered. Some of the most important populations have collapsed. For example, the rookery in Malaysia, which from 10,155 clutches in 1956 fell to 37 in 1995 in the same stretch of beach.
Leatherbacks can be found in the tropic and temperate waters of the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean Sea. Adult leatherbacks also traverse as far north as Canada and Norway and as far south as New Zealand and South America. Unlike other reptiles, leatherbacks are able to maintain warm body temperatures in cold water.
Leatherback turtles, Spotila says, are in critical need of human help to survive. “Warming climate is killing eggs and hatchlings,” Spotila said. “Action is needed, both to mitigate this effect and, ultimately, to reverse it to avoid extinction. We need to change fishing practices that kill turtles at sea, intervene to cool the beach to save the developing eggs and find a way to stop global warming. Otherwise, the leatherback and many other species will be lost.”
Projected response of an endangered marine turtle population to climate change. Nature Climate Change, July 2012 – Vol 2 Issue 7
El Niño Weather and Climate Change Threaten Survival of Baby Leatherback Sea Turtles
Leatherback Sea Turtle, Dermochelys coriacea