Acute and chronic toxicity of aluminum to a unionid mussel (Lampsilis siliquoidea) and an amphipod (Hyalella azteca) in water‐only exposures

Ning Wang, Chris D. Ivey, Eric L. Brunson, Danielle Cleveland, Chris G. Ingersoll, William A. Stubblefield, Allison S. Cardwell

The US Environmental Protection Agency (USEPA) is reviewing the protectiveness of the national ambient water quality criteria (WQC) for aluminum (Al) and compiling a toxicity dataset to update the WQC. Freshwater mussels are one of the most imperiled groups of animals in the world, but little is known about the sensitivity of mussels to Al. The objective of the present study was to evaluate acute 96-h and chronic 28-d toxicity of Al to a unionid mussel (Lampsilis siliquoidea) and a commonly tested amphipod (Hyalella azteca) at a pH of 6 and water hardness of 100 mg/L as CaCO3 . Acute 50% effect concentration (EC50) for survival of both species was >6,200 µg total Al/L. The EC50 was greater than all acute values in the USEPA acute Al dataset for freshwater species at pH range of 5.0 to <6.5 and hardness normalized to 100 mg/L, indicating that the mussel and amphipod were insensitive to Al in acute exposures. Chronic 20% effect concentration (EC20) based on dry weight was 163 µg total Al/L for the mussel and 409 µg total Al/L for the amphipod. Addition of the EC20s to the USEPA chronic Al dataset for pH 5.0 to <6.5 would rank the mussel (L. siliquoidea) as the 4(th) most sensitive species and rank the amphipod (H. azteca) as the 5th most sensitive species, indicating the two species were sensitive to Al in chronic exposures. The USEPA proposed acute and chronic WQC for Al would adequately protect the mussel and amphipod tested; however, inclusion of the chronic data from the present study and recalculation of the chronic criterion would likely lower the proposed chronic criterion. This article is protected by copyright. All rights reserved.