Hepatic Concentrations of Inorganic Contaminants and Their Relationships with Nutrient Reserves in Autumn-Migrant Common Loons at Lake Erie

Abstract

Common loons (Gavia immer) are piscivorous, high-trophic level feeders that bioaccumulate inorganic contaminants at concentrations that can negatively impact their health and reproduction. Concentrations of inorganic contaminants, especially mercury (Hg), in blood, organs, and muscle have been quantified in common loons on breeding grounds, but these data are limited for migrating loons. We investigated sex- and age-related hepatic concentrations of inorganic contaminants in common loons (n = 53) that died from botulism and were salvaged at a Great Lakes staging area (i.e., Long Point, Lake Erie) during November 2005. We also investigated if hepatic concentrations of inorganic contaminants influenced lipid, protein, and mineral in our sample of migrant common loons. Last, we determined if there was correlation between Hg and selenium (Se). Consistent with data from breeding grounds, mean concentrations of Hg in liver were approximately 2.5 times greater in adult ([Formula: see text] = 14.64 ± 16.69 μg g(-1)) compared with juvenile birds ([Formula: see text] = 3.99 ± 2.27 μg g(-1)). Elements detected in liver at potentially harmful levels were Hg and Se, of which lipid reserves varied negatively with Hg concentrations but positively with Se concentrations. In addition, Hg and Se were correlated (r = 0.65) at greater then a demethylation threshold (total Hg ≥ 8.5 μg g(-1) dw) but not lower than that. Concentrations of inorganic contaminants did not influence protein and mineral levels in our sample of common loons. Our results suggest that Hg accumulation negatively affects lipid levels in migrant common loons. Results are also consistent with a nontoxic Hg-Se protein complex protecting loons migrating through areas that are relatively Se rich. Although the acquisition of Se during the nonbreeding season may decrease the toxicity of Hg, future research should consider the synergistic Hg-Se effect on reproduction in common loons that migrate through Se-rich locales, such as the Great Lakes.

Blood mercury levels and the stopover refueling performance of a long-distance migratory songbird

“…To my knowledge, the influence of mercury on the stopover refueling rates of migratory birds has not been previously investigated. Mercury levels in the livers of migrating ducks and loons were found to be unrelated and negatively related, respectively, to their fat mass (Anteau et al 2007;Schummer et al 2012), but static measures of body composition do not reflect the time it took a bird to acquire its current energetic condition and therefore do not provide a true measure of refueling performance (Williams et al 1999;Anteau and Afton 2008). Additionally, the migration of waterbirds, which stage for long periods of time, and that of songbirds, which make frequent and short stopovers where refueling must occur rapidly, are highly disparate and may not be affected by mercury in similar ways or to similar extents.…”

Hepatic and nephric mercury and selenium concentrations in common mergansers, mergus merganser, from baltic region, Europe

“…Data concerning complete Se, THg, InHg, MeHg, and Hg:Se molar ratios, as well as relationships between both element concentrations, in freshwater fish and nonmarine piscivorous birds and mammals, are very limited and mostly from North America . North American wild fish and piscivorous birds, such as the common loon ( Gavia immer ), bald eagle ( Haliaeetus leucocephalus ), and common mergansers ( Mergus merganser ) used in ecotoxicological investigations concerning Hg and Se mostly come from a continent with adequate or high Se levels and varying degrees of Hg contamination . In many large areas of Europe (including Scandinavia and Poland), soils and surface waters have a naturally low Se content .…”