Plastic bags don't just pollute, they kill!
If one takes a walk on the coastal towns of Neelankarai and Marina in Chennai between December and April, distinct tracks in the sand will be visible from the beach till the shore. These are the unmistakeable tracks of the Olive Ridley sea turtles that nest on these beaches.
Olive Ridley sea turtles are a medium sized species that are found in warm tropical waters, abundantly so in the Indian Oceans. They lay their eggs on the coast of Chennai from January to March, which is the nesting season. 45 days later, the hatchlings start to emerge out of their nests in order to go back into the ocean.
Follow the light
"Coastal development in the form of increased lighting on the streets lining the beaches is a major issue", says Akila Balu of the Student's Sea Turtle Conservation Network (SSTCN), a voluntary organization based in Chennai. She explains that once the hatchlings are out of the nests and on the beach, their eyes look for light to follow. The glimmer of the moonlight on the waves attracts them back into the ocean. But in coastal areas, the street lights are a lot brighter, which makes them follow these light onto the streets. Eventually, they die of dehydration, exhaustion or are eaten by stray dogs and crows.
Coastal development is also leading to the loss of a nesting habitat for these turtles. Beach erosion, entanglement in marine debris and fishing activities are also major threats for these turtles. Mortality and morbidity is associated with boat collisions and accidental takes in fishing. These turtles often get caught in trawl nets, and other fishing practices.
The SSTCN have been working towards the conservation of the Olive Ridleys for decades by creating a hatchery on the beach. The volunteers regularly walk the beaches at night and collect eggs from the nests. They then recreate similar conditions in the hatchery until the hatching season. The volunteers then make sure the hatchlings are safely directed back to the sea.
Plastic: A nuisance not just for humans
The Olive Ridleys feed on jelly fish in the ocean but plastic bags floating in the ocean have an uncanny resemblance to them. So the turtles end up feeding on these plastic bags that ultimately leads to their death. The survival rates of Olive Ridleys are abyssmally low at 1 per 1000.
"We have seen dead turtles on the shore with plastic poking out of their rectum", says Akila and adds that water pollution is not just an issue in sea water, but also fresh water. The Adyar estuary in Chennai is a popular nesting ground for the Olive Ridleys. The estuary is the section where the river meets the Bay of Bengal. Because the river receives a large amount of untreated sewage from Chennai, the ecology of the estuary is under grave threat. (1)
Importance of sea turtles to oceans
Sea turtles have been in existence for 66 million years. They have thrived in the tropical waters of the world until recent times. Presently, increased human activity and development has lead to their diminishing population. The importance of sea turtles in the ocean are unknown to many. However, they play an important role in ocean ecosystems in terms of maintaining healthy seagrass beds and coral reefs which inturn are habitats for other marine life. Sea turtles also help in balancing the marine food web by transporting nutrients between land and sea. Sea turtles, by carrying algae and other organisms, provide food for small fish and shrimp. (2)
As the population of sea turtles decline, so does their ability to perform important roles in maintaining healthy maine ecosystems. The SSTCN are doing their bit in trying to educate young people about Olive Ridleys and organize turtle walks along the beaches of Chennai over the weekends.
References:
(1) Lakshmi, K.; Deepa H Ramakrishnan (29 September 2011). "Untreated sewage pollutes waterways". The Hindu (Chennai: The Hindu).