May 25, 2012
Leatherback Sea Turtle Hatchlings Endangered By El Nino Weather Patterns
Leatherback sea turtle hatchlings, as with other turtle species, face immense danger when emerging from their nests located on the sandy Playa Grande beach in northwest Costa Rica, where nearly forty percent of the nests are burrowed. These dangers include predation by carnivores, egg poaching, and human fishing activities. As if that was not enough, a study conducted at Drexel University provides evidence that El Nino caused by climate change is now a major threat to the already endangered species. From this study, researchers concluded that the current rate of hatchling and egg survival could decline by half within the next one hundred years.
The lead author of the study Dr. James Spotila, Betz Chair Professor of Environmental Science in Drexel´s College of Arts and Sciences, stated, “Temperature and humidity inside the nest are significant factors affecting egg and hatchling survival.” Spotila, along with associates including co-author and lead doctor of the study, Dr. Pilar Santidrian Tomillo of Drexel, focused on the connection between nesting habits of six seasons of leatherback sea turtles and regional climate variations.The findings were published this week, in the online journal PLoS ONE .
“We have discovered a clear link between climate and survival of this endangered sea turtle population,” Spotila stated.
According to the results of the study, the relationship between weather patterns caused by El NiÃ±o Southern Oscillation (ENSO) and the survival of both eggs and hatchings is substantial. ENSO is described as the unbalanced pattern of sporadic climate changes shifting from periods with warmer sea temperatures (El Nino) to cooler temperatures (La Nina), with calm ENSO periods occurring at intervals between the two. El Nino is widely known to affect many ecological courses in varying locations.
Researchers concluded that warmer periods of El Nino caused higher egg and hatchling mortality rates, and by using global climate models projected over the next one hundred years, those rates would increase at Playa Grande, as well as other nesting sites.
According to Spotila, Playa Grande is a prime nesting zone because the offshore water currents move the hatchlings on a “hatchling highway” to rich feeding grounds, and this makes the leatherback sea turtles unable to re-locate their nests to different, less favorable beaches. Dr. George Shillinger of Stanford University led a modeling study of these patterns, of which Spotila was a senior author, and this study was published in the June 2012 issue of Proceedings of the Royal Society B .
According to Spotila, leatherback sea turtles are in serious need of human assistance in order to survive. “Warming climate is killing eggs and hatchlings,” Spotila stated. “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.”
Spotila, who has conducted research on leatherback sea turtles for over twenty-two years at Las Baulas Park in Costa Rica where Playa Grande is located, recently became a faculty member at Drexel´s new Department of Biodiversity, Earth and Environmental Science (BEES). This department was created out of the unique relationship between the University and the Academy of Natural Sciences , the global leader in environmental and biodiversity research and the oldest natural history museum in the United States.
“The focus on field research and experiential learning in the BEES department will enable more research in environmental science in more places around the world,” stated Spotila. “As in our long-term leatherback studies, more research by Drexel and Academy students and scientists will contribute to a better understanding of what actions are needed to protect species and environments in critical danger.”