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. 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. So, it is observed that highest diverse species of benthic organisms which are marine and estuarine species were found at the lower region, whereas abundant less diverse fresh water species were found at the upper region of the River. There are well known that fresh water shrimp (Macrobrachium sp.) are being abundantly observed at the upper part of Thanlwin River (Attran and Gyaing rivers) where is fresh water influence, wheras Harpadon sp. (Bombay duck) are at the lower region of (Mawlamyine and Da-Rebauk rivers) where the area is inundated by sea water. So, the area is subjected to be one of the highest diverse species of benthos for all fresh, marine and brackish water species coincided with high sediment oscillation and fresh water discharge. From this condition, the community structure and habitat of benthic organisms related with fisheries of the Thanlwin River Mouth may change if they acquire any environmental disturbanc
สนทนาAmong 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. 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. So, it is observed that highest diverse species of benthic organisms which are marine and estuarine species were found at the lower region, whereas abundant less diverse fresh water species were found at the upper region of the River. There are well known that fresh water shrimp (Macrobrachium sp.) are being abundantly observed at the upper part of Thanlwin River (Attran and Gyaing rivers) where is fresh water influence, wheras Harpadon sp. (Bombay duck) are at the lower region of (Mawlamyine and Da-Rebauk rivers) where the area is inundated by sea water. So, the area is subjected to be one of the highest diverse species of benthos for all fresh, marine and brackish water species coincided with high sediment oscillation and fresh water discharge. From this condition, the community structure and habitat of benthic organisms related with fisheries of the Thanlwin River Mouth may change if they acquire any environmental disturbanc
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