Changes in littoral benthic macroinvertebrate communities in relation to water chemistry in 17 Precambrian Shield lakes

Few studies of biological recovery from acidification have dealt with community responses to changes in water chemistry, despite the importance of environmental tolerance and biological interactions that may only be visible by examining the community as a whole. In this study, we examined the ability of pH and several water chemistry covariables to explain temporal changes in the littoral benthic macroinvertebrate communities of lakes recovering from acidification. Data from 17 lakes sampled from 1988 to 2002 were summarized using correspondence analysis and compared using Procrustes analysis. Canonical correspondence analysis was used to examine the relationship between chemical variables and community structure. Benthic community composition changed over the sampling period, with significant year- to- year changes from 1993 to 1998. Community composition and water chemistry were highly correlated throughout the study period, although the strongest correlations were found from 1993 to 1997, coinciding with the period of greatest change in the benthic community. These results suggest that benthic macroinvertebrate communities in these lakes have changed in response to changes in water chemistry that are consistent with recovery from acidification.