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Species-specific toxicity of major ion salts 1: Fathead minnows and pond snails
Citation:
Hockett, R., R. Erickson, B. Forsman, T. Highland, C. Jenson, Dave Mount, AND T. Norberg-King. Species-specific toxicity of major ion salts 1: Fathead minnows and pond snails. SETAC North America, Minneapolis, MN, November 12 - 16, 2017.
Impact/Purpose:
Surface waters can become enriched with major ions Adverse effects from increased concentrations of major geochemical ions (Na, K, Ca, Mg, Cl, SO4, HCO3) to aquatic organisms have been demonstrated or implied in many settings. Appropriate assessment and management of ion enrichment requires and understanding of how these ions affect aquatic organisms. This presentation provides an overview of the acute toxicity of ion mixtures to several aquatic species, comparing and contrasting their responses, and exploring how the differences and similarities might influence attempts to assess potential risks to aquatic communities.
Description:
Elevated major ion concentrations (Na, K, Ca, Mg, Cl, SO4, HCO3) have been recognized as a cause of surface water impairment and the toxicity of these major ions has been shown to be dependent on the specific ion composition of the water. A long-term research project was initiated at the USEPA Mid-Continent Ecology Division-Duluth to develop models that predict the toxicity of combinations of major ions. Research efforts initially focused on characterizing the toxicity of major ions and salt mixtures to Ceriodaphnia dubia. Subsequently, tests have been conducted with additional species with the goal of expanding the models to be more inclusive so that they can be better used to estimate risk in aquatic environments. This poster presents the results of acute toxicity tests conducted with two additional species: the fathead minnow (Pimephales promelas) and the great pond snail (Lymnaea stagnalis). Over 200 acute toxicity tests were conducted with these species to determine: 1) the effect of the ion composition of background (dilution) water on the toxicity of salts and 2) the toxicity of different salt mixtures. Generally speaking, fathead minnows and snails are less sensitive to major ion salts than are C. dubia.There are also some notable qualitative differences in their response to mixtures; for example, mixtures of Na and Mg salts indicate independent action of two mechanisms for C. dubia, but concentration additivity and a single mechanism for fathead minnows. Such differences suggest differences in toxic mechanism among the species.