TEMPORAL DISTRIBUTION OF SHELLFISH ASSEMBLAGE IN THE SANGU RIVER ESTUARY, CHITTAGONG WITH SPECIAL REFERENCE TO SOME ENVIRONMENTAL PARAMETERS
Abstract
The study was conducted in the Sangu river estuary, Chittagong to assess the temporal distribution of shellfish
assemblage with special reference to some environmental parameters. To study the shellfish assemblage catch
from Estuarine Set Bag Net (Behundi jal) as well water samples were collected in four seasons (winter, premonsoon,
monsoon
and
post-monsoon)
from
January
2014
to
December,
2014.
A
total
of
15
species
of
shellfish
belonging
to 9 families was recorded of which Acetes sp. (25.18%), Matuta victor (18.77%), Exopalaemon
styliferus (18.28%), Parapenaeopsis sculptilis (14.22%) were found to be most dominant species during the
study period. Multivariate analyses were performed using the software PRIMER V6 and Canonical
Correspondence Analysis (CCA) was done using the SPSS V17. The Shannon-Wiener diversity index, Margalef
richness index, Pielou’s evenness index and Simpson dominance index were found to be 2.10, 2.83, 0.95 and
0.91 respectively. The diversity index showed significant differences in temporal shellfish assemblage structure.
Three groups were attained at the similarity of 74.8% while winter and pre-monsoon showed separate clustering
from other groups. The Non-metric Multidimensional Scaling (nMDS) showed 50% similarity in all seasons
based on Bray-Curtis similarity matrix. The CCA ordination indicated that temperature was the most important
environmental parameter shaping the shellfish assemblage structure in the Sangu river estuary.