Assessment of biological characteristics on coastal environment of Murud (Maharashtra) during the oil spill (17 May 1993)

196-202A rupture of a feeder riser pipeline resulted in spillage of crude oil estimated to be 3000-8000 tonnes in Bombay High region on 17 May 1993. The treated spill broken down into several patches and drifted south and finally got deposited on the Murud shores and in the Rajpuri creek. The impact of the spill on biota was studied during 27-30 May 1993. Local abnormal concentrations of dissolved dispersed petroleum hydrocarbons (PHC) in the water column exposed pelagic biota to high levels of oil residues. Levels of chlorophyll-a and phaeophytin varied widely and were unevenly distributed. Few phytoplankton species like Nitzschia sp, were damaged with a coating of black layer of PHC, around the cell. Zooplankton in general were not severely affected though damage restricted to a few species of copepods, Lucifer, Sagitta bedoti and S. enflata showing oily coating on body surfaces or ingestion of PHC into the body leading to death in extreme cases. Drastic reduction in population density of chaetognaths was observed. As the PHC had not sedimented, no adverse impact on macro benthos was evident. Also, there was no evidence of damage to the fish and other marine life. Monitoring of the same area in May 1994 showed normal water quality and biological characteristics indicating the complete recovery of the marine environment off Murud