DISTRIBUTION, ABUNDANCE AND ECOLOGY OF THE MEIOFAUNA IN A TROPICAL ESTUARY ALONG THE WEST-COAST OF INDIA

The distribution and abundance of subtidal meiofauna in Mandovi estuary of Goa were studied from June 1983 to June 1984. Monthly faunal abundance ranged from 491 to 2791/10 cm2 and dry weight biomass from 0.16 to 2.80 Mg 10 cm2. Free living nematodes were the dominant group contributing over 75% of the total density and 30 to 42% of the total biomass. Among nematodes the deposit feeders were more abundant in fine muddy substratum while epigrowth feeders dominated in sandy substratum. Harpacticoids were next, comprising 6.9 to 8.7% of the total meiofauna number, followed by turbellaria (3.8-4.5%), polychaeta (2.8-3.2%) and ostracods (1.6-4.5%). The contribution of other groups to faunal density was 4.5-6.2%. In the biomass the ostracods contributed most (29.8-54.7), followed by nematodes (23.8-34.6%). Over 60% of the fauna occurred in the top 2 cm of the sediment and the faunal density reduced significantly with increasing depth in the sediment. The vertical distribution of meiofauna was positively correlated to the vertical distribution of Eh, chlorophyll a and interstitial water. Seasonality was greatly influenced by the south-west monsoon and the fauna quickly repopulated after the monsoon. Salinity, temperature and food influenced the faunal abundance.