Interrelationships between Fish Tissue Mercury Concentrations and Water Quality for South Dakota Natural Lakes and Impoundments

Abstract

The purpose of this study was to determine whether water quality parameters commonly associated with primary productivity may be used to predict the susceptibility of a specific water body to exceed proposed fish consumption advisory limitation of 0.3 mg kg −1 . South Dakota currently has nine lakes and impoundments that exceed fish tissue mercury advisory limits of 1.0 mg kg −1 total mercury, far exceeding US Environmental Protection Agency and Food and Drug Administration 0.3 mg kg −1 consumption criteria. Previous studies suggest that increased aquatic productivity may mitigate the effects of biological production and subsequent uptake of methyl mercury through bio-dilution; however, it is uncertain whether these trends may exist within highly alkaline and highly productive aquatic conditions common to South Dakota lakes and impoundments. Water quality parameters and fish tissue mercury data for northern pike and walleye were collected and assessed using existing South Dakota Department of Environment and Natural Resources and Game Fish and Parks data. The data was initially screened using both parametric linear regression and non-parametric Mann-Whitney rank sum comparisons and further assessed using binary logistic regression and stepwise logistic regression methodology. Three separate phosphorus measurements (total, total dissolved, and Trophic State Index) and pH were determined to significantly correlate with increased mercury concentrations for the northern pike-in-impoundments model. However, phosphorus surprisingly was not a strong predictor for the remaining scenarios modeled. For the northern pike-in-natural lakes models, alkalinity was the most significant water quality parameter predicting increased mercury concentrations. Mercury concentrations for the walleye-in-natural lakes models were further influenced by pH and alkalinity. The water quality and fish tissue mercury interrelationships determined within this study suggest aquatic productivity, and consequential eutrophication processes appear to be reasonable indicators of fish tissue mercury susceptibility for aquatic conditions common to South Dakota and highlight the continuing need to minimize eutrophication through effective watershed management strategies.

Bottom-up nutrient and top-down fish impacts on insect-mediated mercury flux from aquatic ecosystems

“…The p values from the test of simple main effects are reported in Supplemental Data, Table S2. with MeHg concentrations in biota [15,16,[40][41][42][43]. The hypothesized mechanism for the observed positive relationship between MeHg concentration and productivity is the stimulation of MeHg production by microbial communities.…”

Effect of eutrophication on mercury (Hg) dynamics in subtropical reservoirs from a high Hg deposition ecoregion

“…Other possible mechanisms that can lower fish Hg concentrations in eutrophic systems include shifts in algal cell size (Pickhardt and Fisher ) and growth dilution in zooplankton and fish (Simoneau et al ; Karimi et al ). However, lower fish Hg concentrations with eutrophication are not always observed as evidenced by higher Hg concentrations in top predators from temperate eutrophic reservoirs (Stone et al ). Using indicators of eutrophication to predict how nutrient enrichment will affect Hg dynamics is a critical research need to identify fisheries that are at risk of Hg contamination.…”

It’s Complicated and It Depends: A Review of the Effects of Ecosystem Changes on Walleye and Yellow Perch Populations in North America

“…For instance, mercury concentrations in Walleye were highest in the least agricultural watersheds in Iowa, suggesting a negative relationship between nutrient loading and mercury (Mills et al 2019). In contrast, system phosphorus was not related to mercury concentrations in fish tissues in a variety of systems (Parks et al 1994; Ethier et al 2008; Stone et al 2011; Kolka et al 2019). Indirect effects of nutrients on mercury via fish growth may also confound these relationships as higher ecosystem productivity can lead to higher fish weight or biomass and therefore higher mercury concentrations (Essington and Houser 2003; Miller et al 2012).…”