China saw 82 red tides in 2005, a decrease of 15 percent compared with the previous year.
The occurrence of red tides caused direct economic losses of more than 69 million yuan (8.5 million U.S. dollars), according to a report on the environmental quality of Chinese sea water issued by the State Oceanic Administration (SOA).
Red tides affected areas totaling 27,070 square kilometers, basically the same amount of that in 2004, the report said.
However, there were 38 red tides triggered by toxic algae in 2005, affecting a total area of 14,930 square meters, representing a drastic rise both in the number of occurrence and in affected area. East China sea remains the worst-hit area, the report said.
Red tide refers to reddish discoloration of coastal ocean waters that was caused by a bloom of dinoflagellates - minute marine protozoans.Certain dinoflagellates produce toxins that can kill fish and contaminate shellfish.
Eutrophication, unbalanced ratio of nitrogen and phosphorus in the sea water were blamed for causing red tides.
According to SOA spokesperson Li Chunxian, toxic red tides hit the sea waters in east China's Zhejiang Province and north China's Bohai Bay area, affecting an area of 7,000 sq. km. and 3,000 sq. km. respectively, during the period of May and June in 2005.
"But no one was poisoned in the two large red tides, due to rapid and effective measures taken by SOA and the local governments," he said.