Ecological functioning of Johor Strait’s macrobenthic communities

Abstract Trait assessment takes account of physiological features and aspects of the taxa, accurately describes how macrobenthic taxa interact with biotic and abiotic element of the ecosystem; this method is underutilized in in Malaysian waters. This study intended to assess current state of seafloor ecosystem in several key locations of Johor Straits, Malaysia using assemblages of benthic traits. Sampling took place in several key locations in the strait. nMDS and PCA analyses indicated higher percentages of subtraits related to Sedentaria polychaetes in polychaete-dominated communities (POL: J1, J3 and J4), while subtraits related to bivalves were higher in bivalve-dominated communities (BIV) in J2. J10 to J13, comprising the entire key locations at strait’s east end, contained mixed percentages of macrobenthic subtraits from all phyla (MIX). Functional diversity (FD) was highest only in reproductive strategy trait category in POL communities; other trait category, notably feeding mode, adult mobility and body shape, were higher in MIX communities. SIMPER analysis indicated vermiform, burrower and upward-downward conveyors as universal traits, readily available every locations regardless of differences in percentages. BIOENV test identified pH, chl-a and TOC as driving abiotic factor for subtrait differences in Johor Strait (p < 0.05, r = 0.67), but for FD, the parameters were D, Chl-a, Cl and TOC (p < 0.05, r = 0.52). This study identifies subtraits related to Sedentaria polychaetes prevails in ecologically disturbed seafloor habitat, as in central region. This study showcased the effectiveness of using ecological functioning of macrobenthos as indicating subject to understand the extent of environmental damage occurring in Johor Straits, Malaysia.