Role of salinity in structuring the intertidal meiofauna of a tropical estuarine beach: Field evidence

Abstract

Community structure of meiofauna was studied for 12 months (July 1991-June 1992) on an estuarine intertidal beach at Siridao, Goa (India). The temperature of the surf zone water ranged from 26.5 degrees to 30.7 degrees C; salinity from 8.3 to 34.4 x 10-3, dissolved oxygen from 2.4 to 4.8 ml 1-1; particulate organic carbon from 0.11 to 5.00 mg 1-1 and chlorophyll a 1.04 to 7.51 mu g 1-1. Chlorophyll a and POC concentrations showed significant variations between the sampling months. Mean monthly meiofaunal density recorded at mid-tide level varied between 3.6 and 211 individuals for every 3 cm2 (mean = 115.7 plus or minus 62.6). Fluctuation in meiofaunal density showed significant correlation with salinity fluctuation (r = 0.0607; P≤0.05). Distinct invertebrate communities were associated with different salinity regimes. Since the occurrence and abundance of dominant meiobenthic species were influenced greatly by monsoonal rain, the presence/absence of known species during a particular season could be predicted on the basis of field salinity.