Sediment Copper Concentrations, In Situ Benthic Invertebrate Abundance, and Sediment Toxicity: Comparison of Treated and Untreated Coves in a Southern Reservoir

Iwinski, Kyla J.; McQueen, Andrew D.; Kinley, Ciera M.; Calomeni, Alyssa J.; Geer, Tyler D.; Rodgers, John H. Jr

Sediment Copper Concentrations, In Situ Benthic Invertebrate Abundance, and Sediment Toxicity: Comparison of Treated and Untreated Coves in a Southern Reservoir

2016

Copper-based algaecides are used to control algae that compromise uses of lakes and reservoirs. However, there are concerns regarding potential adverse effects to benthic macroinvertebrates following long-term, repeated applications. Multiple lines-of-evidence are useful for evaluating potential ecological risks. These lines-of-evidence are encompassed in the sediment quality triad (SQT) and include sediment copper concentrations, in situ benthic invertebrate abundance, and sediment toxicity testing. The objective of this study was to measure potential ecological risks associated with long-term applications of copper algaecides in coves in Lay Lake, Alabama. Sediments from three coves treated for 7, 10, and 20 years were compared to sediments from three untreated coves in terms of copper concentrations, in situ benthic macroinvertebrate total abundance, and survival of Hyalella azteca and Chironomus dilutus in laboratory sediment toxicity tests. Sediment copper concentrations were not different between treated and untreated coves, with the exception of one treated cove (PC-1S) that contained elevated sediment copper concentrations compared to all other coves. However, the copper was not bioavailable to organisms based on in situ macroinvertebrate abundance and laboratory toxicity tests. In situ benthic invertebrate abundance was not different between treated and untreated coves. In all sediments tested, there were no measurable adverse effects to H. azteca and there were no significant differences in survival of C. dilutus between treated and untreated coves. Based on the weight-of-evidence approach utilized in this study, long-term copper use in three Lay Lake coves has not resulted in adverse effects to benthic invertebrates compared to untreated coves.

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