Phytoplankton pigments and macrobenthos in nearshore waters off an oil terminal at Uran (Maharashtra), west coast of India

Abstract

Significant temporal and tidal variations of chlorophyll <i>a</i> (2.1-11.8 mg m^-3) were noticed. Chlorophyll <i>a</i> was less during low tide (av. 3.8 mg m^-3) as compared to high tide (av. 8.1 mg m^-3). The predominance of <i>Nitzschia closterium, Skeletonema costatum</i> and <i>Melosira sulcata</i> especially during ebb suggested their tolerance to petroleum wastes. The Rocky intertidal zone showed higher macrofaunal density at the upper zone (av 6992 m^-2) as compared to lower zone (av 1373 m^-2) whereas the biomass was comparable between the two zones. The subtidal regions had poor faunal group diversity, faunal density (av 250 m^-2) and biomass (av 0.2 gm^-2) associated with clayey silt bottom enriched with organic matter (3.3%). The subtidal fauna and sediment quality indicate a reducing trend in macrofaunal population and biomass over a period of 8 years.