December-April is nesting season for the Olive Ridley Sea Turtles. These are the only marine animals that come and nest on India’s eastern shores. They nest along the beaches of the Bay of Bengal in my home state of Tamil Nadu. Odisha’s coasts are witness to mass nesting – La arribada – Spanish for the arrival. 2017 witnessed 620,000 female turtles mass nest on Odisha’s beaches. Like with many things climate change is threatening the survival of the Olive Ridleys and other sea turtles as well. The reefs of the Gulf of Mannar between India and Sri Lanka are a haven for adult sea turtles in between nesting.
Female turtles return to the beach they were born on to nest. It takes 45 to 60 days for the eggs to hatch and the hatchlings need to make it on their own to the sea. Human involvement in protecting nests and hatchlings – the Moana moment as it were – are ways by which humans can help instead of hinder sea turtle survival. No mother turtle returns to guide baby turtles. It’s brutal survival games and as Dr. Supraja Dharini, founder of Tree Foundation involved with turtle rescue since 2002, put it “even cobras and crocodiles protect their eggs and hatchlings and but not the sea turtles!” Only one in every thousand hatchling survives to adulthood.
Olive Ridley Turtle | Photo courtesy Laranapeleona via Wikimedia Commons
The hatchlings emerge from the sands after hatching, usually at night. They make it into the waves guided by moonlight, starlight and bioluminescence in the sea. This perilous journey is made into a death race by predators, trash barring the way, plastics to choke the hatchlings and light pollution from street lights and beach houses lining the shore that can guide baby turtles away from the sea on onto the roads. The baby sea turtles then make it to the Indian Monsoon gyre in the northern Indian Ocean, and live off the vegetation there. The problem is the Indian Ocean gyre has become the Indian Ocean garbage patch thanks to irresponsible behavior! So both global warming and marine and plastic pollution are putting the turtles at risk.
Sea turtle survival is another reason to work to keep temperature rise under 1.5° Celsius. Climate Change is adding its own special twist to the sea turtle hunger games! Bleaching of reefs as a result of increased ocean temperatures and acidity as a result of ever-increasing levels of carbon dioxide in the atmosphere is a kind of habitat destruction for the sea turtles. Next, if the ice caps continue to melt at the rate they are the beaches these sea turtles were born on will be no more! As seen in Finding Nemo turtles use the ocean currents to navigate the seas. Global warming is affecting ocean currents as well as global weather patterns! More immediately worrying is the effect of global warming on the eggs and hatchlings. The sex of a sea turtle is determined by the temperature and humidity of the sand it hatches from: this is the phenomenon of temperature-dependent sex determination, or TSD that global warming is wreaking havoc with.
With our planet getting warmer every year south Indian coastal ‘winters’ – the Olive Ridley nesting season – are getting as hot as summer. Eggs that incubate at below 28° Celsius produce male turtles, and those incubating above 30° Celsius produce female turtles. “Cool dudes and hot chicks” as Dr. Dharini put it in at the Turtle Walk I recently participated in. Beyond the obvious – fewer males to mate with the females there is still a problem. We’d imagine many female turtles is a good thing when they are at risk but the problem with hot dry sand above 35° Celsius is that it behaves like an oven and bakes the eggs rendering them hard and useless. ‘Winter’ – the last two months of the year – is the rainy season in the east coast of India but climate change disrupts this cycle. Failure of the north-east monsoon in December 2017-January 2018 has resulted in a dryer and hotter nesting season. The dew and moisture that keep the beach sands from turning into an hāngi (Maori for pit oven) or umu (Samoan for earth oven) are minimal and the heat has since destroyed many eggs. Daytime temperatures have touched the thirties regularly in the first quarter of 2018. There were a few successful hatchings in the last few days of February but World Wildlife Day (March 3, 2018) saw temperatures soar to 35° Celsius.
An olive ridley turtle hatchling at a beach in Chennai, Tamil Nadu, India (Photo by Thangaraj Kumaravel on Flickr, Creative Commons license)
Ironically the climate change intensified rains and cyclones that ravaged the shores of Tamil Nadu in December 2015 & 2016 were actually a boon in disguise to sea turtle survival. It kept the trawlers beached and fewer nesting Olive Ridleys were drowned in the nets or injured or killed by fishermen. Human activity and anthropogenic global warming are the main risks to Ridleys!
After seeing many dead and damaged sea turtles on the beaches I walk in regularly over the nesting season for the past four years, this year I finally witnessed a stray Olive Ridley hatchling make it into the sea. Its triumph over many odds at an unusual time of day has given me hope. Meanwhile in order to protect this vital link in the marine eco-system we have another reason to fight climate change, reduce our carbon emissions and curb global warming. In addition to recruiting the fisher community to protect sea turtles at all stages of their development, a low-carbon lifestyle will benefit life on earth in all its forms. Phenomena like La arribada needs to stop being a VIP affair. It needs to be accessible to all who care for nature. Sensitizing and involving local communities in preserving nesting beaches can be a win-win for all. Many Indian fishing communities already view the nesting turtles as daughters of the house returning to the maternal home for delivery – a common Indian practice…now the man-sea turtle bond needs to be amplified beyond the beaches to fight the effects of climate change and ocean pollution.