Nematode assemblages from submarine caves in Hong Kong

Abstract

Nematode assemblages from sediments of two submarine caves in subtropical Hong Kong waters were investigated, and compared with those from other local sublittoral sediments. A total of 48 putative nematode species from 44 genera and 18 families were identified from the caves. Species richness of the cave nematode assemblages lay between those of adjacent sandy control sites and muddy control sites. Species diversity of the cave assemblages was much lower than those of the sandy control sites but was comparable with those of local muddy sediment. Nematodes at Conic Island Cave were dominated by non‐selective deposit feeders, while at Steep Island Cave most nematodes were omnivores/predators. This is in contrast with the more even composition of trophic guilds at the nearby non‐cave sites. Multivariate analyses revealed no clear demarcation of community structure among the cave, non‐cave and wreck nematode assemblages, indicating no nematode species association endemic to the cave sediment. Sediment characteristics and water depth are suggested as fundamental in determining nematode community structure and trophic composition in the area investigated. Submarine cave sediment provided a sheltered habitat with limited food resources favourable for non‐selective deposit feeders and omnivores/predators.