|PRINT ISSN : 2319-7692
Online ISSN : 2319-7706
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Index Copernicus ICV 2015: 85.95
NAAS RATING 2017: 5.38
Accelerated exploitation of oil and gas resources planned and implemented by ONGC and BGEIPL in west coast offshore region would result into stress particularly on marine environment. The long term physical, chemical and biological changes due to routine discharges from offshore installations can best be assessed through a study on accumulation of hydrocarbons and heavy metals in fishes, plankton and sediments which together form biotic and abiotic components of marine environment. The accumulation of hydrocarbon and heavy metals are considered as major threat to biota when concentration levels exceed the levels of toxicity either in abiotic or biotic environment. The existing scenario is based on the data generated in the offshore area of west cost of India. Studies were carried out to find out the levels of hydrocarbons and heavy metals and their accumulation in marine fish tissues of liver, muscle, grills and reproductive organs in and around offshore oil and natural Gas field in west cost of India. Data was collected for post monsoon and pre-monsoon seasons. It was observed that levels of hydrocarbons in gills were found to be high (2128 µg/g) during pre-monsoon and might be the primary uptake site of hydrocarbons through water and the micellar layer in grills might be playing an important role in absorption/adsorption of hydrophobic hydrocarbons. However, hydrocarbons levels in the water column, during the study were observed in the range of ND – 2.5 µg/l, presence of high levels of hydrocarbons in fish tissues, could be explained only through the process of both bioaccumulation and biomagnification. Accumulation of hydrocarbons in marine fishes was studied with respect to its food value. Liver was considered as an indicator organ to assess the degree of detoxification and deposition. High food value fishes were observed to be prone to accumulation in following descending order: Scoliodon laticaudus>Epinephelus diacanthus>Psettodes erumei>Scoliodon sorrowkowah whereas luxury food value fish species showed affinity in following order: Scomberomorous guttatus>Eleutronema tetradactylum>Eleuthronema heptadactylus and Pampus argentenus. Concentration levels of heavy metals in fish tissues revealed maximum bioaccumulation in liver, the site of detoxification. Levels of cadmium were found to be lower than the normally reported values (0.1 to 2.1 µg/g) except in a few cases. In present study, levels of copper were observed to be higher than reported value (2.2 µg/g) and exceeded the human taste threshold value of <0.5 to 0.75 µg/g, in both pre-monsoon and post-monsoon seasons with levels in pre-monsoon recorded higher values as compared to post-monsoon. There was no seasonal variation in levels of lead, zinc and chromium. Zinc levels in fish have been observed to seldom exceed 50 µg/g. however, in many cases, zinc exceeded this value (as high as 161.2 µg/g in Megalaspis cordyla) in testis/ ovaries and also in other tissues. Accumulation of heavy metals in fishes was studied based on their food value. In this case also, liver was considered as indicator organ to assess the degree of detoxification and deposition. High food value fishes were observed to be prone to accumulation in following descending order: Scoliodon sorrowkowah > Scoliodon laticaudus > Eleuthronema diacanthus > Psettodes erumei, whereas for luxury food value, the sequence in descending order was Pampus argenteus> Scomberomorous guttatus> Eleuthronema heptadactylus and Eleuthronema tetradactylum. Levels of heavy metals recorded in fish tissues during the present study corroborates with those reported for fishes from Northern India Ocean.