S Raja Ramanathapuram THE prevention of oxygen flowing into the sea and unprecedented increase in the velocity of wind in the vicinity, were attributed as reasons for the death of large quantities of fish and other marine fauna being washed ashore off Rameswaram. The sudden increase in dead fish and other marine species had unnerved fishermen here. Marine scientists said that the blooming of dinoflagellate (nactiluca), a sea moss that grows on the seabed, has been reported in several parts of the world. The blooming of the plant occurred due to conducive conditions like temperature, availability of feed organisms like diatoms and nutrients. The moss that rises to the surface reduces the oxygen level in water. This resulted in the fish not being able to breathe. The phenomenon was first noticed in Vazhativu island that later spread to other areas, including Keelakarai and Pudumadam. The residents of Periyapattinam and Pudumadam were shocked to see large quantities of fish being washed ashore since October 10. Marine species, including surgeon fish, rabbit fish, lizard fish, tiger fish, some varieties of sea turtles, sea cucumber and sea anemones, had perished due to lack of oxygen. A Central Marine Research Institute, study revealed that since nactiluca had bloomed in the lagoons, it remained stagnant around the islands due to the absence of water currents and wind drift. The intensification of the bloom had led to the reduction of oxygen level resulting in the destruction of marine organisms. This also created ammonia and hydrogen sulphide, causing foul stench in the water. It was also not possible to check the blooming of this flora that could be prevented only by environment and cli matic conditions, the study had concluded. Naganathan, Eco Development Officer, Gulf of Mannar Biosphere Reserve Trust, said the moss had not damaged any coral reefs in the area. A similar phenomenon had occurred in 1936 and 1950 in the east and west coasts, he said. The change was called Red Tides in which the water turns red and brown in colour.