Abstract
Onondaga Lake in Syracuse, New York was once the site of prolific chemical and municipal sewage dumping. However, over the last two decades it has become the target of restoration efforts including the rehabilitation of the fish assemblage. This study compared species richness and Shannon diversity between lake basins and over time, in conjunction with multivariate ordination to assess changes in fish assemblage structure. Species richness of offshore fish increased in this timeframe; however, both richness and diversity declined for the nearshore fish assemblage. There was significant annual variability in species composition for both offshore and nearshore samples based on permutational analyses of variance, but only the composition of offshore samples was significantly different between basins. These results suggest that offshore fish have been responding positively to increasing water quality, while the nearshore fish assemblage has likely been negatively impacted by nearshore habitat homogenization from introduced aquatic invasives.