Trait assessment is an alternative but effective method of biomonitoring benthic community in ecosystem, but it was rarely done in Malaysia. An assessment was done to identify the dominant sub-traits, or modalities, within benthic community in seafloor northwards of Pulau Indah, Klang, Malaysia, and to establish possible correlation between modalities with environmental parameters measured in the area. Sampling was conducted in November 2018, during Northwest Monsoon season. Sediments were obtained by using a Ponar Grab and filtered through 500 μm sieve. Sediments were subjected into Loss of Ignition method to extract organic carbon, and filtration method to determine particle size distribution percentages. 37 taxa were recorded in this study, totalling to 848 individuals. Traits assessment indicated vermiform body shape, direct larval development, deposit feeder, non-motile, asexual reproduction, and second-order opportunistic group as most dominant modalities in the study area. Station 1 recorded highest macrobenthos density (21000 ind./m2), while station 5 recorded highest diversity (H’=2.19). Functional diversity (FD) for reproduction method was highest in station 1 (FD=0.61), ecological group in station 4 (FD=0.73); body shape (FD=0.56) and larval development (FD=0.63) in station 5, and lastly, adult mobility (FD=0.70) and feeding mode (FD=0.66) in station 6. Principal component analysis showed Station 1 has most modalities attributed towards it. Pearson correlation analysis suggested particle size distribution as major connector for most modalities (P=0.05). As BTA study is still new in Malaysian waters, it could serve as a good starting point for future assessment related to ecological functioning of benthic community in Malaysian seafloor.

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