Sun-block lotions threaten corals

 
Last Updated: Saturday 04 July 2015

sunscreens almost always figure in a swimmer's paraphernalia. While it protects the skin from ultraviolet rays of the sun, it also causes considerable damage to marine life. If the idea appears far-fetched, consider this: a recent study has found that chemicals in sunscreen products threaten about 10 per cent of coral reefs worldwide.

Tropical reefs die due to bleaching. Scientists at the Polytechnic University, Italy, who carried out the study, say chemical compounds in sunscreen products, even at extremely low concentrations--10 l/l--can cause abrupt and complete bleaching of hard corals.

They studied the effect of sunscreen exposure on samples from tropical reefs--from the Red Sea, the Caribbean Sea, the Indian Ocean off Thailand and the Pacific Ocean near Indonesia. The corals were suspended in bags of virus-free seawater supplemented with various quantities of sunscreen lotions. The samples were compared with the controls--those in seawater without sunscreen. They found that the corals started bleaching within a few hours and it took them just four days to get completely bleached. The controls remained healthy. The study was published in the April issue of Environmental Health Perspectives.

The researchers found that sunscreens stimulated dormant viruses in zooxanthellae, the symbiotic algae that live in a healthy coral. The chemicals--paraben, benzophenone, cinnamate and camphor--caused the virus within the algae to replicate until the algae exploded. That led to spilling of the viruses into the surrounding seawater, which spread the infection to coral communities in the vicinity.

Corals, among the most biologically productive and diverse ecosystems of the world, are highly sensitive to changes in their environment. Scientists have predicted that over half the population of coral reefs in the world maybe destroyed by 2030. Coral reefs in India are found in the Andaman and Nicobar Islands, Gulf of Kutch, Lakshwadeep and the Gulf of Mannar. "While the impact of tourism on coral reefs in India is low, corals here get bleached due to sedimentation, increase in water temperature and coastal developments,'' said Sudarshan Rodrigues of the Coastal and Marine programme of Ashoka Trust for Research in Ecology and the Environment, Bangalore.

While corals are being threatened by sunscreen products, plans are underway to use corals in sunscreen products in some parts of the world. The Australian Institute of Marine Sciences has tied up with Sunscreen Technologies Pvt Ltd, an Australian company, to develop a sunscreen using corals.

The year 2030, for sure, is only 22 years away.

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