Analysis of macrobenthic assemblages of Lake Illawarra, New South Wales

1 A survey of the macrobenthos community was carried out in Lake Illawarra, NSW, Australia, during April and May 2011. 2 The aim of this study was to understand the current status of the characteristic macrobenthic fauna community, and the temporal changes over the past 30 years, as well as the impacts of anthropogenic activities on the benthic ecosystem. 3Fifteen stations were selected as representative of three main areas of the lake (the entrance channel, the central basin and the sublittoral fringe), which might be impacted by different kinds of human activities. 4 A total of 45 macrobenthic species were identified. Mollusca represented the most abundant taxon with 17 species, followed by Crustacea with 16 species. Three species were dominant, i.e., the mollusk Nassarius burchardi, and the polychaeta Lumbrineris sp. and Nephtys australiensis. 5 The abundance and biomass of the macrobenthos were variable between the three main areas. Based on Bray Curtis similarity of macrobenthos, the 15 sites also divided largely into three groups. 6 MAMBI index analysis indicated that eight stations (57.1%) had 'good' to 'high' ecological status (ES), four stations (28.6%) 'moderate' ES, and two stations (14.3%) with 'poor' to 'bad' ES, which indicates the Lake Illawarra was in reasonably good condition, but evidence of disturbance and impact on benthic communities was obvious at several sites.