A prominent discolouration of the coastal waters by the blue-green alga Trichodesmium erythraeum was encountered in the east coast of Kalpakkam on 16th March 2007. The bloom persisted only for one day exhibiting visible alteration in physico-chemical properties and phytoplankton community structure of the coastal waters. The Trichodesmium cell density was 4.14 x 106 cells l-1, sharing 74.19 % of the total cell count (5.57 x 106 cells l-1). Only 24 species of phytoplankton were encountered on the day of bloom as compared to the highest number of 44 species in a single observation during pre- and post-bloom periods (1st March to 29th March). Concentration of chlorophyll-a and phaeopigments increased to about 20 times on the day of bloom compared to the pre-bloom values. An abrupt increase in ammonia, total nitrogen and phosphate was noticed on the day of bloom. The impact of this bloom on coastal water quality is reported.
Keywords
Trichodesmium Erythraeum, Algae, Bloom, Marine Cyanobacterium, East Coast, India
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