ADAPTIVE CHANGES IN RESPIRATORY MOVEMENTS OF AN AIR BREATHING FISH TILAPIA MOSSAMBICUS EXPOSED TO ENDOSULFAN
The acute toxicity of endosulfan as the freshwater fish Tilapia mossambicus has been studied here, The sublethal (LC0) Median (LC50) and Lethal (LC100) concentration of endosulfan for 120hrs were assessed as 190, 240 and 260 ppm respectively.From the 120 hrs LC50 value, the 1/3rd and 1/6th sublethal concentration were calculated as 80ppm and 40ppm respectively, to which the fishes were exposed. The pattern of changes in the respiratory movements of endosulfan exposed Tilapia mossambicus were taken to suggest that the fish showed adaptive increase in its frequency of surfacing with a tremendous drop in its opercular movements during first hour of exposure to higher concentration of endosulfan.The reduced opercular movement is also considered adaptive for the fish to prevent itself.
G. MUTHUKUMAR , K. RADHA KRISHNAN AND R. ANBALAGAN
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