author(s)
Saritha Sadasivan, Udai Ram Gurjar, SP Shukla, AK Jaiswar, Latha Shenoy and Geetanjali Deshmukhe

abstract
Patalganga-Amba estuarine ecosystem is opening to the southern part of Mumbai harbour, Raigad district of Maharashtra. Since it is one of the most productive and diverse ecosystem, the fishermen community belonging in this area are getting full or partial advantages of estuarine functions and services. There are more than 13 number of industries along the head water of Patalganga River, hydroelectric power station, Karanja boat jetty etc. are adversely affecting and making this ecosystem vulnerable to ecosystem degradation, eutrophication and decline of species abundance. On this background we studied the zooplankton abundance and seasonal distribution in relation with hydrological parameters, which are showing spatial and temporal variations. There were 14 groups of zooplankton identified with a density ranges from 6162 and 181155 no.x 10³ L^-1. Copepods and copepod nauplius were dominant followed by barnacle nauplius and foraminifera. The numerical density of zooplankton was positively correlated with phytoplankton abundance, temperature and pH and negatively correlated with salinity. Spatio-temporal variation of hydrological parameters influences the plankton distribution. H’, J’ and D based on zooplankton abundance ranged between 2.25, 0.874 and 1.25 respectively. The diversity indices were indicating the ecosystem was productive but observed a gradual decline while comparing with the previous studies.