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|Title: || Effect of Chattonella marina [(Subrahmanyan) Hara et Chihara 1982] bloom on the coastal fishery resources along Kerala coast, India |
|Authors: ||Jugnu, R|
|Keywords: ||Chattonella marina;bloom;fishery impact;drift net;ring seine;taxonomic distinctness|
|Issue Date: ||Mar-2009|
|Abstract: || Chattonella marina, a marine raphidophyte algae which produces haemolytic compounds is capable of damaging fish gills. Blooms of this algae were observed along North Kerala during September 2002, reaching maximum cell density 28×107 cells l-1 and in September 2003 with maximum cell density of 135×105 cells l-1. This results in massive fish kills. During the bloom period hypoxic conditions prevailed with dissolved oxygen content ranging between 0.22 and 1.92 mg l-1 To assess the impact of the bloom on the coastal fishery resources of the region, the fish landing data of five gears such as outboard trawl net, outboard drift net, outboard gill net, outboard ring seine and country craft gill net were analysed in detail. The landings of fishes which belonged to lower trophic levels decreased. Fishes which were mainly zooplankton feeders like Stolephorus spp, Thryssa and Leiognathus were entirely absent. But there was an increase in catch of the predatory fishes mainly Euthynnus, Trichiurus, Carcharhinus, Saurida, Scoliodon, Scomberomorus, and Sepia spp which occupy higher trophic level. The variation in catch rate between the bloom and the non-bloom period was significant (P<0.05) for Cynoglossus spp, Johnius spp, Thryssa spp and Parapenaeopsis stylifera caught in the outboard trawl net. The average taxonomic distinctness (Delta+) was lower during the bloom period and a clear shift in the community structure was observed. The effect of the C. marina bloom on fish community was short-lived, and the taxonomic diversity was restored soon after the bloom subsided. |
|Appears in Collections:||IJMS Vol.38(1) [March 2009]|
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