Aquatic macroinvertebrates are poor indicators of agricultural activity in northern prairie pothole wetlands

The Northern Prairie Pothole Region (NPPR) of Alberta, Canada, contains numerous shallow marshes that serve as important habitat for wildlife and provide essential ecosystem services. Many of these wetlands have been destroyed or degraded by human activity and the majority of remaining wetlands occur in landscapes affected by crop and cattle production. Alberta has implemented a conservation policy which requires the creation of wetland assessment tools. Aquatic macroinvertebrates are frequently used as indicators of environmental condition in rivers, but their effectiveness as indicators in prairie pothole wetlands is not clear. To evaluate the capacity of aquatic macroinvertebrates identified to family-level resolution to serve as regional bioindicators of agricultural disturbance in NPPR wetlands, we sampled macroinvertebrates at 64 fishless wetlands. The wetlands spanned a gradient in the extent of agriculture from 0 to 100% cover within a 500 m buffer around each wetland. We discovered that, contrary to our predictions, macroinvertebrate family richness and community composition could not predict agricultural disturbance (cropping or cattle grazing). We conclude that efforts to develop bioindicators for NPPR wetlands should be redirected to other taxa that are less costly to identify to species and that exhibit sensitivity to agricultural disturbance.