Abstract:
The present study was carried out to investigate whether the spatial
variation of the macrobenthic community in Negombo estuary is governed by
the physico-chemical parameters in the overlying water and sediment or by the
density of seagrass cover. In this study, six study sites representing the mouth,
body and the head of the estuary was selected and the physico-chemical
parameters of the overlying water, i.e, salinity, pH, temperature, conductivity, DO
and BOO, and the sediment salinity, temperature, pH, % of sand, silt. and clay
and OMC were measured using standard methods. Further, the macrobenthic
fauna and the flora inhabiting in each sample site were also sampled. The
physico-chemical data and the abundance data between the six study sites were
analysed using appropriate univariate and multivariate statistical tests.
Results revealed that the physico-chemical parameters of the overlying
water and sediment varied significantly between the six sites with an increasing
trend of salinity, and sand % and decreasing trend of OMC and silt % towards
the mouth of the estuary. The macrobenthos were abundantly found in the sites
where the bottom is devoid of seagrasses. Further, the macrobenthic community
structure in the Negombo estuary appeared to be correlated with these physicochemical
parameters, but not with the density of seagrass cover. It is evident that
the spatial distribution of macrobenthos in the Negombo estuary is governed by
the physico-chemical parameters in the sediment and the overlying water but
not by the density of seagrass cover.
