Abstract:Marine pollutants in relation to planktonic and benthic organisms were examined at two locations along Karnataka coast, one at Kulai (74 0 47.74" E and 12 0 55.16" N) receiving huge amount of industrial effluents from fertilizer, petroleum and chemical plants along with t he sewage discharges. The other site Padubidri ( 74 0 45" E and 13 0 10" N) is located 20 kms away, which is a typically agricultural and fishing village having no stress of industrial discharges. Although the concentrations of dissolved oxygen (DO), nutrients and trace metals in water and sediment showed marginal differences at these two locations, the concentration of petroleum hydrocarbon (PHC) remained exceptionally high with a maximum of 1523 µg/l at Kulai which is 10 times higher than that at Padubidri (144 µg/l).Biomass and population of phytoplankton and zooplankton showed that the seasonal differences were more conspicuous rather than the regional changes.Macro and meiobenthic population remained high at both the locations during the two seasons. Phytoplankton species indicated that centric diatoms such as

Genotoxic effects of Cadmium on phytoplankton Chaetoceros tenuissimus have been evaluated using DNA damage by comet assay. Cadmium concentrations ranging from 2.4 to 10 mg/L were used to evaluate the effects. Results showed that as the concentration of Cd increased growth of the diatom decreased. Alkaline single-cell gel electrophoresis (Comet assay) method, which is highly sensitive in detection of DNA damage in eukaryotic cells, was used to observe genomic changes in marine diatom cells. DNA damage was measured as percent number of comets and normal cells. 65% cells were found to be damaged at 10 mg/L concentration of Cd as compared to 23% in 2.4 mg/L and only 5% in controls. More than 50% apoptic cells were observed on 8 th day at 10mg/L and 12 th day at 7.5 mg/L concentrations. At lower Cd concentrations (4.5 mg/L and below) the damage was below 30% till the last day. This suggested that higher Cd levels have early damaging effects on cell nuclear material and that % injury increases with advancement of exposure period. One advantage of use of C. tenuissimus is the ease with which it can be cultured in a defined medium. Chaetoceros tenuissimus diatom can be used as an in vivo model for ecogenotoxicity assessment using the Comet assay.

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