L - Cochin University of Science and Technology

crustaceans. This indicated that during post-m on soon most of the groups were
positively correlated with fine sediment and negatively correlated with sand except
for crustaceans. The fuanal distribution with respect to texture also (Table 29)
showed that during post-monsoon polychaetes was abundant in the silty clay and
clayey sediment while crustaceans were more in silty clay and clayey sand. Molluscs
preferred silty clay substratum and miscellaneous groups were present only in silty
clay and clayey sediment. Thus during post-monsoon most of the benthic groups
preferred fine sediment texture with low sand content. This was evident from the
decrease of biomass of all benthic groups with the increase in sand except the
crustaceans. During pre-monsoon, sand prevailed in the deeper depths and clay
content was more in the shallow depths. The abundance of Polychaetes and
miscellaneous groups in the shallow depths indicated their affinity to the fine
sediment and abundance of crustaceans and molluscs in the deeper stations clearly
indicated a positive correlation with sand content. The faunal distribution with
respect to different texture also (Table 29) showed that during pre-monsoon,
polychaetes preferred fine sediment texture with a mixture of sand and clay.
Crustaceans dominated in sandy sediment while molluscs were abundant in the
clayey sand and the sandy sediment. This showed the preference of crustaceans and
molluscs to the sand dominated sediment.
Results showed that total biomass and biomass of polychaetes and
miscellaneous groups were positively correlated with fine sediment and that of
crustaceans with coarser fraction. Molluscs prefer sand or a mixture of sand and mud.
From statistical analysis (Table 27 &28) it was clear that most of the benthic groups
were influenced by sediment texture in their distribution even though it was not at a
significant level. So it can be stated that sediment texture is not the single controlling
factor, texyure together with other ecological factors controls the benthic distribution.
Earlier works also reported the preference of benthos to the substrata. Neyman
(1969) observed that polychaetes, bivalves and echiuroidea were abundant in the
205