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

Community structure of meiofauna was studied for 12 months (July 1991-June 1992) on an estuarine intertidal beach at Siridao, Goa (India). The tempera ture of the surf zone water ranged from 26.5 degrees to 30.7 degrees C; sal inity from 8.3 to 34.4 x 10(-3)); dissolved oxygen from 2.4 to 4.8 ml l(-1) ; particulate organic carbon from 0.11 to 5.00 mg l(-1) and chlorophyll a 1 .04 to 7.51 mu g l(-1). Chlorophyll a and POC concentrations showed signifi cant variations between the sampling months. Mean monthly meiofaunal densit y recorded at mid-tide level varied between 3.6 and 211 individuals for eve ry 3cm(2) (mean = 115.7+/-62.6). Fluctuation, in meiofaunal density showed significant correlation with salinity fluctuation (r = 0.607; P less than o r equal to 0.05). Distinct invertebrate communities were associated with di fferent salinity regimes. Since the occurrence and abundance of dominant me iobenthic species were influenced greatly by monsoonal rain, the presence/a bsence of known species during a particular season could be predicted on th e basis of field salinity.