Crayfish tissue metabolomes effectively distinguish impacts of wastewater and agriculture in aquatic ecosystems.

Environmental metabolomics has been proposed as a tool for biomonitoring because organisms regulate production or consumption of metabolites in response to environmental conditions. We evaluated the efficacy of the metabolome of three tissues (hepatopancreas, gill, and tail muscle) from the northern crayfish (Faxonius virilis) to detect and differentiate between impacts of human activities (i.e., reference, municipal wastewater, and agriculture). We conducted a reciprocal transfer study exposing crayfish for 1 or 2 weeks in three streams with different amounts and types of human activities in southern Manitoba, Canada. Tissue samples were analyzed using nuclear magnetic resonance spectroscopy to generate a metabolic profile. Findings indicated the gill tissue metabolome best detected and differentiated between human activities. In particular, the gill metabolome was able to rapidly integrate abrupt changes in environmental conditions associated with municipal wastewater activity. In contrast, the tail metabolome best differentiated between crayfish collected at the reference site from those collected at the two impacted sites. Metabolites extracted from hepatopancreas tissue showed limited and inconsistent detection of among site differences. Based on our findings, we conclude that the metabolome of the northern crayfish can be an effective biomonitoring tool, but monitoring purpose will dictate tissue selection. Indeed, we recommend the gill metabolome be used for short-term assays aimed at detecting acute effects, whereas the tail be applied for survey monitoring aimed at detecting deviations in ecological condition at test sites from reference site conditions.