Mercury Concentrations in Fish Related to Size of Remote Canadian Shield Lakes

Abstract

Mercury concentrations in planktivorous, omnivorous, and piscivorous fishes were inversely related to lake size in six lakes in northwestern Ontario. The lakes were remote from direct anthropogenic influences and ranged in surface area from 89 to 35 000 ha. Fish mercury concentrations were not related to ratios of drainage basin area to lake size, to ratios of epilimnetic area to lake size, to lake alkalinity, or to the concentration of mercury in lake sediments. Rates of mercury methylation (M) were positively dependent on water temperature whereas rates of methyl mercury demethylation (D) were inversely related to temperature. Thus, M/D was strongly temperature dependent. Mercury concentrations in four fish species were significantly positively correlated with mean epilimnetic water temperatures (r2's ranged from 0.66 to 0.88). This suggested that higher water temperatures in smaller lakes during the open-water season influenced M/D ratios and were the cause of higher fish mercury levels. No lake size related variation was observed in the mercury concentrations in benthivorous fishes. Our hypothesis that epilimnetic temperature affects mercury concentrations in fish deserves further attention, given the possible effects of climate warming on mercury contamination of fishery resources.

Resistance and Resilience of A Stream Salamander To Supraseasonal Drought

“…There have been decreases in dissolved inorganic nitrogen from greater phytoplankton productivity (Sommaruga-Wograth et al, 1997;Rogora et al, 2003) and greater in-lake alkalinity generation and increases in pH in soft-water lakes (Psenner and Schmidt, 1992). Decreased solubility from higher temperatures significantly contributed to 11-13% of the decrease in aluminium concentration (Vesely et al, 2003), whereas lakes that had warmer water temperatures had increased mercury methylation and higher mercury levels in fish (Bodaly et al, 1993). A decrease in silicon content related to regional warming has been documented in Lake Baikal, Russia.…”

Sustaining Aquatic Ecosystems in Boreal Regions

“…The original community is now under water. The commercial fishery has been destroyed by low catches, poor fish quality, and high mercury concentrations (Bodaly et al 1993). The community was moved to a new location, complete with modern houses and a recreational complex including squash courts.…”

Geochemical and Biological Controls over Methylmercury Production and Degradation in Aquatic Ecosystems

“…New rcsearthon Hg complexation with DOC is highlightul below. Temperature is another important variable (61) as the temperature responses of methylation and~ylation have been reported to differ (/6,62). However,sell#onal changes in Hg complexation that affect methylationaml demethyiatioll differently could account for thc(se observations.…”