COMPOSITION AND DISTRIBUTION OF INTERSTITIAL MEIOFAUNA OF THE SANDY BEACH AT GOPALPUR, SOUTH ORISSA COAST

Harpacticoid copepods are the most dominant group, forming nearly 70% of the total interstitial population of the beach. Nematodes (14.68%) are second in overall abundance. Other common groups are turbellaria, archiannelida, polychaeta and isopoda. Mean annual population densities are 245, 1401 and 191 individuals per 10 cm2 respectively at high, mid and low tide levels. Seasonal changes in faunal densities are pronounced. The total fauna exhibits 2 peaks, one of a very high magnitude (3225-5249) in summer (March-May) and another of a lesser intensity in December. Horizontally the fauna is concentrated around the mid tide level and numbers drop off rapidly more towards low water than at the upper levels. Vertically the fauna extends deep down to the water table, but the bulk of the population is confined to the top 20 cm. Spatial and temporal variations are controlled by physical factors of which temperature, salinity and beach stability are important.