How do aquatic communities respond to contaminants? It depends on the ecological context.

Context dependency refers to variation in ecological patterns and processes across environmental or spatiotemporal gradients. Research on context dependency in basic ecology has focused primarily on variation in the relative importance of species interactions (e.g., competition and predation) among communities. In this Focus article, the authors extend this concept to include variation in responses of communities to contaminants and other anthropogenic stressors. Because the structure of communities varies naturally along environmental gradients, their responses to contaminants may also vary. Similar to the way in which aquatic toxicologists assess abiotic factors associated with contaminant bioavailability, observations about context dependency could be used to test hypotheses about ecological mechanisms responsible for differences in sensitivity among communities.