Low abundances and diversities of benthic faunas of shallow, coastal sediments in the Solomon Islands and their implications for assessing environmental impacts of logging

Abstract

The diversity and abundance of benthic organisms were examined in relation to logging impacts in Western Province, Solomon Islands. Organisms occupying sediments offshore from the mouths of logged and unlogged streams in two areas were sampled at three depths during a single survey. Overall abundances of organisms were low, and patterns varied between areas. At Kolombangara, ANOVA showed that numbers of molluscs and crustaceans were higher at mouths of rivers with unlogged catchments than with logged catchments, but numbers of individuals, taxa, and polychaetes differed among river mouths within treatments. At Vangunu, numbers of taxa varied inconsistently among depths in the different logging treatments, whereas numbers of individuals were greater at river mouths of unlogged than logged catchments. Multivariate analyses (MDS, ANOSIM) showed differences among river mouths within treatments but not among treatments. In general, there were indications of logging impacts but the effects were not consistent across taxa. Because of this inconsistency, the low abundance and diversity of animals, and the relatively high cost of processing samples, benthic macrofaunal variables were not considered to be cost-effective measurement variables for longer term monitoring of the effects of run-off from logging operations on inshore marine habitats at these study sites.