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Understanding drivers of mercury in lake trout (Salvelinus namaycush), a top-predator fish in southwest Alaska’s parklands
Citation:
Bartz, K., M. Hannam, T. Wilson, R. Lepak, J. Ogorek, D. Young, C. Eagles-Smith, AND D. Krabbenhoft. Understanding drivers of mercury in lake trout (Salvelinus namaycush), a top-predator fish in southwest Alaska’s parklands. ENVIRONMENTAL POLLUTION. Elsevier Science Ltd, New York, NY, 330:121678, (2023). https://doi.org/10.1016/j.envpol.2023.121678
Impact/Purpose:
Using a conceptual model with four broad categories of factors, representing various processes whereby Hg reaches piscivorous lake fish we parameterized a statistical model to identify drivers of Hg concentrations in lake trout. We found that fish age and body condition best explained variation in Hg concentration among fish within a lake. Plankton methylmercury content, fish species richness, volcano proximity, and glacier loss, best explained variation in lake trout Hg concentration among lakes. Collectively, these results provide evidence that multiple, hierarchically nested factors control fish Hg levels in these lakes.
Description:
Mercury (Hg) is a widespread element and persistent pollutant, harmful to fish, wildlife, and humans in its organic, methylated form. The risk of Hg contamination is driven by factors that regulate Hg loading, methylation, bioaccumulation, and biomagnification. In remote locations, with infrequent access and limited data, understanding the relative importance of these factors can pose a challenge. Here, we assessed Hg concentrations in an apex predator fish species, lake trout (Salvelinus namaycush), collected from 14 lakes spanning two National Parks in southwest Alaska, U.S.A. We then examined factors associated with the variation in fish Hg concentrations using a Bayesian hierarchical model. We found that total Hg concentrations in water were consistently low among lakes (0.11-0.50 ng?L-1). Conversely, total Hg concentrations in lake trout spanned a thirty-fold range (101-3,046 ng?g-1 dry weight), with median values at 7 lakes exceeding Alaska’s human consumption threshold. Model results showed that fish age and, to a lesser extent, body condition best explained variation in Hg concentration among fish within a lake, with Hg elevated in older, thinner lake trout. Other factors, including plankton methyl Hg content, fish species richness, volcano proximity, and glacier loss, best explained variation in lake trout Hg concentration among lakes. Collectively, these results provide evidence that multiple, hierarchically nested factors control fish Hg levels in these lakes.
URLs/Downloads:
DOI: Understanding drivers of mercury in lake trout (Salvelinus namaycush), a top-predator fish in southwest Alaska’s parklands
https://pubmed.ncbi.nlm.nih.gov/37119998/