Stream invertebrate community structure at Canadian oil sands development is linked to concentration of bitumen-derived contaminants

Abstract

In Canada, the Athabasca oil sands deposits are a source of bitumen-derived contaminants, reaching the aquatic environment via various natural and anthropogenic pathways. The ecological effects of these contaminants are under debate. To quantify the effects of bitumen-derived contaminants we monitored the aquatic exposure of polycyclic aromatic hydrocarbons (PAHs), metals, and naphthenic acids as well as the invertebrate community in the Athabasca River and its tributaries. PAH concentrations over 3 consecutive years were related to discharge and were highest in the year with high autumn rainfall. In the year with the highest PAH concentrations, these were linked with adverse effects on the aquatic invertebrate communities. We observed relative effects of the composition and concentration of contaminants on the invertebrate fauna. This is reflected by the composition and abundance of invertebrate species via the use of the species' traits “physiological sensitivity” and “generation time”. Applying the SPEAR approach we observed alterations of community structure in terms of an increased physiological sensitivity and a decrease of generation time for the average species. These effects were apparent at concentrations 100 times below the acute sensitivity of the standard test organism Daphnia magna. To rapidly identify oil sands related effects in the field we designed a biological indicator system, SPEARoil, applicable for future routine monitoring.