The habitat preferences of nematode assemblages in relation to the sediment granulometry in the Ba Lai estuary, Vietnam

Abstract

This study investigated the habitat preference of nematode communities in relation to sediment composition in the Ba Lai dammed estuary, which is a branch of Mekong estuarine system in the southern Vietnam. Sediment samples were collected for granulometry and nematode analyses in dry season from 6 subtidal stations along the estuary starting from its mouth, of which three were in the downstream of the dam and the other three located in the upstream. The present research showed the heterogeneity in sediment granulometry, which is mostly represented by silt component, except sandy sediment in the estuarine mouth and sand–silt sediment in the middle part. The nematode assemblage was low in abundance but high in diversity including genera richness and Shannon–Wiener diversity index. The communities showed differences in the habitat preference associated with sediment. The higher silt component presented in the riverbed was found to be limiting factor for abundance and diversity and genus Pseudochromadora. Pseudochromadora was dominant in the mouth station, which is characterized as sandy sediment, Rhabdolaimus was abundant in sand–silt bottom, while two genera Parodontophora and Theristus thrived in the silty environment.