Studies on the macrobenthic communities of the Sungai Ibai estuary, Terengganu [Malaysia]

A study on the benthic community was carried out along the coastal waters of Sungai Ibai estuary in Terengganu to record and evaluate the present existing forms of macrobenthic communities found within the area as a result of physical disturbance. The estuary has been subjected to serious physical changes and structural modifications which were meant to restructure the whole estuarine area for land development. Samplings were done aboard a research vessel, UNIPERTAMA III and macrobenthic samples were taken using the Smith-McIntyre`s sediment grab of 0.05 m square gape area. A total of five replicate sediment samples were taken from 18 stations established along the coastline. Sediment sample was also taken to determine the particle size distribution in the area. Systematic identification were done up to family level using various identification manuals available in the region and determination of the particle size distribution was done according to the standard pipette method. A total of 72 different families of macrobenthic organisms belonging to four major groups of taxa were sampled. Annelida in the form of polychaete worms were the most abundant form of macrobenthic organisms found, followed by crustacean, echinodermata and mollusca. Glyceridae, nereidae and orbibiidae were among the dominant form of polychaete families recorded from the study area. Tellinidae, Holothuriidae and Penaeidae were respectively the most dominant family of mollusca, echinodermata and crustacean gathered in the samples. Other organisms include the chordates, sipunculids and brachiopods but they were found to be rarely present in the samples acquired. It was observed that more diversity of macrobenthic organisms were found in sandy loam sediment as compared to the sandy type substrate. The overall results were comparable with other related studies done earlier in the same region and thus it may be concluded that the physical disturbance occurring during the study period did not show any immediate significant changes to the macrobenthic communities.