L - Cochin University of Science and Technology

Difference in biomass and density noticed by earlier workers may be due to
the use of different types of gears (Neyman, 1969; Parulekar and Wagh, 1975;
Parulekar et al., 1976; Harkantra et al., 1980; Parulekar et al., 1982a; Qasim, 1982)
or due to sampling in different seasons from diverse ecosystems (Ansari et al., 1996).
In addition to the above reasons, biomass reported by Parulekar et al., (1982a) was a
total of both macro and meiobenthos. The average biomass value (4.53g1m 2 ) for the
study area as a whole during pre-monsoon season in the NW coast is well
comparable to that of Joydas (2002) who reported an average value of 5.3g1 m 2 in the
northwest coast of India during pre-monsoon.
During post-monsoon biomass was generally high in shallow depths (30 m
and 50 rn) and during pre-monsoon season it was high from 30 to 75 m and low in
the deeper stations beyond 75 m. Density also followed more or less the same trend
with high values in shallow stations and low in deeper depths in both seasons. This
was in agreement with earlier reports (Kurian, 1953, 1967,1971; Neyman, 1969;
Parulekar, 1973; Parulekar and Dwivedi, 1974; Parulekar and Wagh, 1975; Parulekar
et al., 1976; Ansari et al., 1977b; Harkantra et al., 1980 & 1982; Parulekar et al.,
1982 b; Qasim, 1982; Devassy et al., 1987; Prabhu et al., 1993; Ansari et aI., 1996;
Joydas and Damodaran, 2001). Enrichment of coastal waters due to riverine flow and
land run off seems to be one of the factors contributing to richness of fauna in the
nearshore regions (Parulekar, 1973). Devassy et al., (1987) reported high biomass in
the near shore region and attributed it to the influx of nutrient rich river water.
Influence of nutrient rich water is reported by other workes also (Kurian, 1971;
Harkantra et al., 1980; Harkantra and parulekar, 1981 ). But the work of
Gopalkrishnan and Nair (1998) recorded low benthic population in the nearshore
areas (Srn) and rich fauna in 20 m contour of Mangalore. Ansari et al., (1996) also
reported a decreasing standing crop with increasing depth and distance from the
shore. They reported that neritic coastal waters of continental shelf (up to 200m
depth) were often highly productive and many of the world's commercial fisheries
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