John Wiley & Sons, Ltd.

Invasive crayfish as vectors of mercury in freshwater food webs of the Pacific Northwest

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Invasive species are important drivers of environmental change in aquatic ecosystems, and can alter habitat characteristics, community composition, and ecosystem energetics. Such changes have important implications for many ecosystem processes, including the bioaccumulation and biomagnification of contaminants through food webs. We measured mercury in two non‐native and one native crayfish species from western Oregon. Non‐native red swamp crayfish had mercury concentrations similar to those in native signal crayfish (0.29 ± 0.05 and 0.36 ± 0.06 μg/g dw, respectively), whereas the non‐native ringed crayfish had lower mercury concentrations (0.10 ± 0.02 μg/g dw) than either of the other species. The mean energy content of muscle was similar between the native signal crayfish and non‐native ringed crayfish, but significantly higher in the non‐native red swamp crayfish. Across species, mercury concentrations were negatively correlated with energy density. Such energetic differences could exacerbate changes in mercury transfer through trophic pathways of food webs, especially via alterations to the growth dynamics of consumers. Thus, it is important to consider the role of energy content in determining effective mercury exposure even when mercury concentrations on a per unit mass basis do not differ between species. Environ Toxicol Chem © 2014 SETAC

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