Availability and Toxicity of Nickel to Lotic Periphyton and Macroinvertebrates

by Bessom, Stephanie Marie

There is a lack of information regarding the bioaccumulation and toxicity of nickel (Ni) to lotic ecosystems. The objective of this study was to investigate the source, uptake, and toxicity of Ni by periphyton and macroinvertebrates (Hyalella azteca and Daphnia magna) in simulated stream ecosystems that included sediment and water. Periphyton were exposed to two types of sediment, a low-organic sandy mixture and a high organic silt, treated with varying levels of Ni. After 96 h, Ni levels in overlying water and periphyton were related to those in sediments, although differences existed between sediment types. Tests with 64Ni added to overlying water confirmed nearly all of the Ni in periphyton was derived from sediments. Aqueous uptake, as opposed to dietary accumulation from periphyton, was the dominant pathway of Ni assimilation by the macroinvertebrates. Ni was not overtly toxic to either periphyton or the macroinvertebrates.