Testing taxonomic resolution levels for detecting environmental impacts using macrobenthic assemblages in tropical waters.

Macrobenthic assemblages are widely used as a tool for ecological assessment studies and monitoring programs. However, studies of macrobenthic assemblages have been limited in tropical coastal and marine environments in comparison with those in temperate zones. This study characterized at different resolution of taxonomic levels the responses of macrobenthic assemblages inhabiting subtidal areas in Bahrain to sewage effluents and heavy metal contamination. Macrobenthic assemblages impacted by nutrient enrichment showed lower levels of biodiversity, richness and evenness, and higher degree of disturbance. Multivariate statistical analyses revealed that faunal patterns of species were sufficiently comparable to those of genus and family taxonomic levels and showed 98% and 95% similarity, respectively. Ammonia, phosphate, and depth were the main environmental parameters responsible for explaining 41% of the community patterns in the study areas.