Establishing baseline biological conditions and monitoring metrics for stream benthic macroinvertebrates and fish in an area of potential shale gas development

Abstract

Potential for shale gas production is linked to regional geology, which influences water chemistry of freshwater systems. However, there has been little work to establish baseline ecological conditions of rivers within areas of shale gas development. In this study, water chemistry and monitoring metrics for fish and benthic macroinvertebrates were compared among varying-sized streams in New Brunswick, Canada, with different underlying geology. Water chemistry and biotic community structure differed strongly among geological age classes. Early Carboniferous stations, with highest potential for shale gas production, had the highest ions, invertebrate abundances, and richness of invertebrates and fish, with strongest differences between Early Carboniferous and Older Classes of bedrock. A reference condition model indicated numerous sites deviated from normal, but this was not specific to geological classes and reflected the lack of model reference site coverage. These results highlight the importance of selecting appropriate reference sites for bioassessment in areas of resource development to ensure that response to perturbation is differentiated from natural variability along environmental gradients in geology and resource-dependent variables that potentially influence aquatic ecosystem composition.