Abstract:
Fish consumption advisories for the contaminant mercury (Hg) are common in rivers and highlight connections between landscape sources of Hg and downstream river ecosystems. However, it is unclear how Hg emerging from diverse landscapes changes downstream through connected river systems and how these changes associate with Hg accumulation in fish tissues. We monitored concentrations of Hg in water from over 80 tributaries and major rivers across Alberta, and concentrations of Hg in fish collected from major rivers. Using cluster analysis, linear mixed models, and ANCOVA analysis, we found that local Hg concentrations at major river stations were more important associates with Hg concentrations in fish than were broad upstream landscape conditions. Consequently, site-specific, targeted monitoring of Hg concentrations in water and fish is a preferred study design when assessing regional-level patterns in fish tissue concentrations.