Interactive effects of phosphorus a

Interactive effects of phosphorus and copper on Hyalella Azteca via periphyton in aquatic ecosystems
Abstract
This research examined the interaction between dissolved copper and phosphorus, with respect to their
effects on the freshwater amphipod Hyalella azteca feeding on periphyton. Field-collected periphyton
communities were exposed to different nutrient and metal conditions in indoor recirculating streams.
H. azteca were then exposed to water and periphyton from these streams. There was rapid Cu
accumulation by periphyton but the total Cu concentration of periphyton was not directly related to
dissolved P. In terms of H. azteca growth, an interactive effect was found between Cu and P as growth
was reduced more than expected in the low Cu-high P treatment. Our data suggest that eutrophic
conditions result in greater Cu toxicity to benthic macroinvertebrates at lower metal concentrations,
likely due to higher assimilation efficiency of dietary Cu from periphyton incubated under eutrophic
conditions. These results imply that non-additive interactions between multiple stressors may cause
ecosystem effects as detected in standard laboratory bioassays conducted under controlled conditions.