Comparative observational and laboratory investigations on the effects of pollution from roads on stream communities.

Abstract

The use of road salt contributes to pollution from roads, which can be potentially detrimental to aquatic ecosystems. The effects of road salt are particularly problematic as they can decrease the activity of important functional groups, such as leaf shredders, and thus consequences could resonate throughout an ecosystem. In our study, we hypothesized that the effect of pollution from roads on a stream community's diversity, richness and abundance increases with the stream's proximity to the road. Specifically, we predicted that these three measures will decrease with proximity to the road because intensity of pollution will be greater from runoff from the road's surface. We also hypothesized that there would be an effect of road salt, sodium chloride, on the leaf shredding activity of caddisfly (Trichoptera) larvae and predicted that increasing concentrations of sodium chloride will decrease leaf shredding activity. Linear regression analyses were conducted and while increased distance from road had a positive trend towards increased species richness, abundance and diversity, these relationships were not significant. However, the relationship between distance from the road and caddisfly abundance at two sites was found to be significant. More streams should be sampled in order to more strongly support this relationship and to determine if these changes would have effects on higher trophic levels and therefore larger implications for the function of a stream ecosystem.