Rising toxic algae threaten Indian fisheries

Toxic algal blooms, that results in mass fish mortality, are on the increase in Indian sea waters.

It is disturbing that occurrence of algal blooms has increased in frequency and intensity in the last 20 years causing frequent mass death of fish, a paper presented at international symposium on Marine Ecosystem here said.

The microscopic marine phytoplankton have very important role in the marine ecosystems, forming food for larvae of fish and other organisms. There are about 5,000 species of marine phytoplanktons of which 80 are known to be toxic.

These blooms are very harmful resulting in mass mortality of fishes such as oil sardine, the paper said.

Scientists of the Centre for Marine Resources and Ecology, Kochi, recorded 19 blooms in the Indian seas during 1998-2006.

Intense blooms result in very low oxygen levels. The coastal waters turn into dark green or red, it said.

The Central Marine Research Institute (CMFRI) scientists also reported intense blooms in Gulf of Mannar in October last year, which believed to be the cause for death fishes.

Reducing pollutant load in the coastal waters by treating the domestic and industrial effluents before discharging into the sea will greatly reduce the occurrence of blooms, it said.