Effects of trophic status and wetland morphology, hydroperiod, and water chemistry on mercury concentrations in fish

Abstract

We sampled fish and selected water chemistry variables (dissolved organic carbon, sulfate, and pH) in nine southeastern depression wetlands to determine relationships among wetland morphology (surface area and maximum depth), hydrology, water chemistry, and bioaccumulation of mercury (Hg) in fishes. We concentrated on three fish species representing the range of trophic levels occupied by fish in southeastern depression wetlands. Whole-body Hg concentrations were lowest in lake chubsucker (Erimyzon sucetta), a benthic detritivore, and highest in redfin pickerel (Esox americanus americanus), a top carnivore. However, variation in Hg concentrations among wetlands was greater than variation among species. Regression analyses indicated that maximum depth and hydroperiod accounted for significant portions of variation among wetlands in standardized lake chubsucker and redfin pickerel Hg concentrations. Maximum depth and dissolved organic carbon had a negative effect on standardized Hg concentrations in mud sunfish (Acantharchus pomotis). Path analysis confirmed the results of regression analyses, with maximum depth and hydroperiod having relatively large direct negative effects on Hg concentrations. Our results suggest that leaching of Hg from sediments during the drying and reflooding cycle and binding of Hg species by dissolved organic carbon in the water column are primary factors controlling the bioavailability of Hg in southeastern depression wetlands.

Mercury bioaccumulation in the food web of Three Gorges Reservoir (China): Tempo-spatial patterns and effect of reservoir management

“…In our study, there was relatively stable water level at each sampling season. THg concentrations in aquatic organisms exhibited significant difference across sampling seasons (MANOVA, F = 11.93, p b 0.01, Supplementary Table S5 Fuling 13.0 ± 0.3 7.5 ± 0.5 5.7 ± 0.5 5.3 ± 0.5 43 ± 7.3 30 ± 4.2 33 ± 2.1 37 ± 7.1 Wanzhou 11.7 ± 0.4 4.2 ± 0.3 5.2 ± 0.2 4.9 ± 0.2 31 ± 6.4 28 ± 6.2 24 ± 4.8 25 ± 5.7 Zigui 8.5 ± 0.5 5.9 ± 0.2 4.4 ± 0.1 3.8 ± 0.2 20 ± 5.1 16 ± 3.4 14 ± 5.1 10 ± 2.4 Table 3 Comparison of THg concentration (mean or mean ± SD) in the water column, sediment and fish from selected studies (The species code was in accordance to Supplementary (Snodgrass et al, 2000;Sorensen et al, 2005). In Nov. 2011, the water-levelfluctuating zone with external organic matter was inundated, which could activate microbial activity to increase methylmercury production (Sorensen et al, 2005).…”

“…Concentrations of Hg in fish in newly-flooded reservoirs have been found to be affected by the quality of the water (Snodgrass et al, 2000), reservoir size (Hakanson et al, 1988), the time since impoundment (Hylander and Goodsite, 2006), water residence time (Montgomery et al, 2000), and bacterial methylation of Hg found in flooded soils (Blum et al, 2013). Seasonal variation of Hg concentrations in reservoirs is influenced by stratification/de-stratification patterns of the reservoir (Canavan et al, 2000;Dijkstra et al, 2013), but the spatial pattern of Hg in inundated environments can be dominated by internal processes as a result of the availability of organic matter (Kasper et al, 2012).…”

Changes in Fish Diets and Food Web Mercury Bioaccumulation Induced by an Invasive Planktivorous Fish

“…In fishes, the risk of exposure to Hg is directly related to the degree of contamination and methylating potential of their habitats. For example, the extent of wetland boundaries and wetting and drying cycles have been shown to be positively correlated with fish Hg contamination (Snodgrass et al 2000, Greenfield et al 2001, St. Louis et al 2004, Hall et al 2005. Independent of environmental factors, fish Hg accumulation is also strongly driven by the ecological attributes and life history of the fish (Wiener and Spry 1996).…”

Are U, Ni, and Hg an Environmental Risk within a RCRA/CERCLA Unit on the U.S. Department of Energy's Savannah River Site?

“…Availability of Hg to the food web, particularly in wetland habitat types, is associated with episodes of flooding (Rudd 1995) as Hg binds to sediments in combination with an increase in microbial processes during these periods, forming highly bioavailable methylmercury (MeHg; Jackson 1988;Snodgrass et al 2000). Beaver ponds and wetland habitats have also been known to increase Hg methylation (Brigham et al 2009;Driscoll 1998;Krabbenhoft 1999;Mason et al 2000;Roy et al 2009a,b), raising concerns specifically for Tims Branch due to the dynamic habitat types and periods of drought that occur in this system.…”