Zooplankton composition in Dharamtar creek adjoining Bombay harbor

Abstract

Dharamtar creek maintained rich zooplankton standing stock (av. 30.3 ml.100 m-3) with peak production during August-November. Zooplankton production rate for the entire system amounted to 10.32 mg C.100 m-3. d-1 with an annual turnover of 29 ton C.km-2. A major share of the zooplankton community was contributed by copepods (71.9%), decapods (11.4%) and chaetognaths (8.3%). Copepod diversity was maximum in October. Among the 46 species of copepods, Acartia spinicauda and Acrocalanus sp. dominated the outer and inner zones of the creek respectively. Brachyuran larvae predominated among the decapods. Swarming of Lucifer was observed in November at the outer zone. Three species of chaetognaths were found in the area and Sagitta bedoti was the true inhabitant. In general zooplankton production indicated 1.5 fold increase, towards the upper reaches of the creek where salinity variations were drastic. A more diversified faunal assemblage of oceanic and neritic species characterised the lower estuarine zone having less salinity fluctuations.