Interactive effects of phosphorus and copper on Hyalella azteca and periphyton

Abstract

Eutrophication is known to be frequently associated with metal pollution in aquatic ecosystems. This research examined the interaction between dissolved copper and phosphorus, with respect to their effects on the growth of a freshwater amphipod Hyalella azteca feeding on periphyton. The study design included two tiers: (1) a laboratory stream experiment where natural periphyton communities accumulated Cu under a gradient of Cu and P concentrations; and (2) a beaker experiment where H.azteca were exposed to water and periphyton from laboratory streams. There was rapid Cu accumulation by periphyton but the total Cu concentration of periphyton was not directly related to the dissolved P treatment in the stream experiment. In terms of Hyalella growth, an interactive effect was found between Cu and P as high phosphorus concentration was related to reduced growth at relatively lower Cu concentration. Our findings suggest that eutrophication may result in greater Cu toxicity to benthic macroinvertebrates as a result of dietary exposure from periphyton.