MERGANSER: An Empirical Model To Predict Fish and Loon Mercury in New England Lakes

Abstract

MERGANSER (MERcury Geo-spatial AssessmeNtS for the New England Region) is an empirical least-squares multiple regression model using mercury (Hg) deposition and readily obtainable lake and watershed features to predict fish (fillet) and common loon (blood) Hg in New England lakes. We modeled lakes larger than 8 ha (4404 lakes), using 3470 fish (12 species) and 253 loon Hg concentrations from 420 lakes. MERGANSER predictor variables included Hg deposition, watershed alkalinity, percent wetlands, percent forest canopy, percent agriculture, drainage area, population density, mean annual air temperature, and watershed slope. The model returns fish or loon Hg for user-entered species and fish length. MERGANSER explained 63% of the variance in fish and loon Hg concentrations. MERGANSER predicted that 32-cm smallmouth bass had a median Hg concentration of 0.53 μg g(-1) (root-mean-square error 0.27 μg g(-1)) and exceeded EPA's recommended fish Hg criterion of 0.3 μg g(-1) in 90% of New England lakes. Common loon had a median Hg concentration of 1.07 μg g(-1) and was in the moderate or higher risk category of >1 μg g(-1) Hg in 58% of New England lakes. MERGANSER can be applied to target fish advisories to specific unmonitored lakes, and for scenario evaluation, such as the effect of changes in Hg deposition, land use, or warmer climate on fish and loon mercury.

Modelling mercury concentrations in prey fish: Derivation of a national-scale common indicator of dietary mercury exposure for piscivorous fish and wildlife

“…While more precise methods exist for standardizing Hg concentrations in fish (Sonesten, 2003;Tremblay et al, 1998), these approaches are limited to site-specific assessments and cannot be used to estimate Hg concentrations in species that may be present, but were not actually sampled. More complex whole-ecosystem models can be used to predict Hg concentrations in fishes when applied to intensively studied ecosystems (Knightes et al, 2009), but at present, success over larger geographic regions is limited (Knightes and Ambrose, 2007) and there are significant technical challenges that must be addressed before such modelling approaches become tractable for sub-continental or continental scales of interest (but see Shanley et al, 2012).…”

Spatial and temporal patterns of mercury concentrations in freshwater fish across the Western United States and Canada

“…A consistent conclusion among all of these studies was that even after controlling for sources of inherent variation, such as species and size, fish Hg concentrations showed substantial heterogeneity across the landscape. Additionally, landscape and habitat factors together influence fish Hg concentrations (Drenner et al, 2013;Shanley et al, 2012), thus gradients in those factors are likely important drivers of this heterogeneity.…”

Patterns of co-contamination in freshwater and marine fish of the northeastern United States

“…Each of the three EPA datasets was analyzed separately using the variables available. Environmental predictor variables (Table 2) included those used in previous analyses of individual contaminants [18, [30][31][32]. Fish length, trophic level, lipid content, and species were used to control for sh characteristics, except for EMAP which does not include sh length and NRSA which does not include lipid concentration.…”