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When lights mislead Olive Ridleys....

Last updated: 09 November, 2009

Habitats Olive Ridley turtles in India have stirred conservation movements across the peninsula—from individual nest relocation and monitoring—to attempting to save the entire habitat, writes Divya Karnad

An ideal picture; a dark uninhabited beach, where a baby sea turtle hatches out of its egg and makes its way to the sand amidst a sea of flippers and egg-shells. It takes in the cool air, the reflection of the bright moon bobbing on the water and the shadows of the land closing in. Slowly it makes its way to the glistening sea and is engulfed in the waves.

Sadly, the waves throw up a different picture with every passing year, not merely because sea turtles have become rare, but also because beaches have changed with time. Sea turtles are loners (except during the breeding season); it is only their senses or instincts that help them reach adulthood.
Clumsy and slow on land, they have better chances of survival once they make it to the deep waters. With special visual skills that have evolved over millennia, hatchling turtles reach the sea by following the glow from reflected moonlight and starlight. Human civilisation has also evolved over millennia and is now striving to turn night into day, lighting up houses, offices, streets and bill-boards.

With coastal areas experiencing particularly high concentration of people, the night sky has turned into a light-nightmare for baby turtles. Wasting precious energy reserves heading in the wrong direction, being desiccated by the morning sun and being run over on coastal roads are just some of the pitfalls awaiting the little turtles nowadays.

Inspiring action
Luckily, as conservation icons across the world, sea turtles inspire action. Olive Ridley turtles in India have stirred conservation movements across the peninsula—from individual nest relocation and monitoring, to attempting to save the entire habitat. Starting with a few individuals on a small stretch of beach, many organisations have risen to tackle larger threats to the Olive Ridleys’ nesting habitat ensuing from coastal development policies such as the Coastal Management Zone notification (CMZ) of 2008, the declaration of coastal SEZs and the development of ports such as the one at Dhamra, close to the famous Gahirmatha Olive Ridley mass nesting beach in Orissa.
Between campaigning for the ideal and pragmatic solutions, it is important to bear in mind the insights gained both from on-ground conservation and applied science. At present, the port at Dhamra is well on its way to being built with no “turtle-safety” guidelines as there has been no stay on its construction. Ports such as Dhamra pose an additional problem for turtles—massive light pollution.

A study in Gabon showed sea turtle hatchlings are even misguided by lights originating from several kilometres away. Our new study of the Olive Ridley mass nesting site at Rushikulya found that village lights about three km away misguides more than 60 per cent of the hatchlings.

A previous study found more than 80 per cent of the hatchlings moving landward in response to light from a single industry in the area. Comparing these results to the amount of light we can expect from even a medium-sized port tells us that we will effectively wipe out all the offspring of any turtle that dare nest nearby.
Research tailored to deal with this issue has opened up the possibilities of some solutions that could couple development and conservation.

Simple solutions
Our study has revealed that masking electric lighting behind natural light barriers such as tall sand dunes does a world of good to confused hatchling turtles.
Natural beach vegetation not only acts as a sand dune-builder, it also deters errant turtles and helps them re-orient towards the sea. As sand dunes take time to build up, a lightproof wall can be erected to contain night light.

Modifying the wavelength of the bulbs to monochromatic orange and reducing the height of lamp posts can also prevent the hatchlings from getting disoriented. Simple solutions like these could pave the way for turtle friendly ports and industries in the future.
(The author is with the Centre for Wildlife Studies)
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