Discussion
Among the species, Polychaetes were the highest prevalence
group along the coast and characterized almost all the stations.
Parulekar et al. 1981 stated that Polychaetes represents an
important group in soft bottom communities and their spatial
structure is always closely related to grain size and other factors
such as organic content.
The highest diverse species of benthic organisms were observed
at the lower portions of Thanlwin River mouth (Mawlamyine and
Da-Rebauk rivers) where are dominated by high intrusion of sea
water.
However, polychaetes and other soft organisms avoid the regions
of coarse sand and high sediment oscillation. It is seemed to be
difficult to survive in the coarse sand.
So, the community structure and habitat of benthic organisms
will be changed for any environmental disturbance especially the
condition of their substrate.
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The polychaete Capitella capitata is known to occur
abundantly in the organically rich environment and so it is
used as an indicator for organic pollution.
Amphipods are also abundantly found along the Thanlwin
River Mouth and represented 30% of the faunal composition
of most of the stations. However, the diverse species were
observed at the lower part of the River.
Terrestrial arthropods are abundantly found in riparian zones
(upper parts of the River), and insect larvae are also
abundantly found which are a major dietary component for
some fish species.