Bioaccumulation of mercury in yellow perch (Perca flavescens) and common loons (Gavia immer) in relation to lake chemistry in Atlantic Canada

Abstract

Mercury biomagnifies in aquatic foodwebs in freshwater lakes, and common loons (Gavia immer) breeding in eastern Canada can be exposed to reproductively toxic concentrations of mercury in their fish prey. We assessed the bioaccumulation and biomagnification of mercury in juvenile and adult common loons, and their preferred prey: yellow perch (Perca flavescens) in Kejimkujik National Park (KNP), Nova Scotia by measuring mercury levels and stable isotope ratios in tissues. Total mercury levels and stable-carbon (d 13 C) and nitrogen isotope ratios (d 15 N) were determined in composite whole-fish samples from lakes in KNP and blood samples from juvenile and adult loons captured on lakes in KNP and southern New Brunswick. Geometric mean mercury concentrations were 0.15 and 0.38 lg/g (wet wt.) in small (9-cm fork length) and large (17-cm fork length) yellow perch, and were 0.43 and 2.7 lg/g (wet wt.) in blood of juvenile and adult common loons, respectively. Mercury concentrations in perch and loons were positively associated with body mass and d 15 N values. Juvenile loons and large yellow perch had similar mercury levels and d 15 N values, indicating similar trophic status despite their 22-fold difference in body mass. Mercury concentrations were higher in yellow perch and common loons in acidic lakes. Our findings highlight the importance of both chemical and ecological factors in understanding mercury biomagnification in lakes and associated risks to fish-eating wildlife.

Mercury and other Contaminants in Common Loons Breeding in Atlantic Canada

“…Bioaccumulation of MeHg in yellow perch in Kejimkujik is negatively correlated with both lake pH and with perch growth rates (Drysdale et al, 2005). Hg levels in common loon blood and their fish prey (primarily yellow perch; Barr, 1996) are highly correlated in Atlantic Canada and elsewhere (Scheuhammer et al, 1998b;Burgess and Hobson, 2005;Champoux et al, 2005). The greater bioaccumulation of persistent contaminants in slow-growing prey fish in acidic lakes may account for the correlations observed between plasma PCBs and both the metals and other organochlorines in loon blood, plasma and feathers.…”

“…However, spatial patterns of loon blood Hg levels within northeast North America and within Atlantic Canada do not relate closely to patterns in atmospheric Hg deposition VanArsdale et al, 2005). While spatial trends in loon body mass and atmospheric Hg deposition probably influence loon blood Hg levels at a broad geographic scale, the high variability in loon blood Hg levels observed at a local scale (see Evers et al, 2005) appears to be influenced more by differences in watershed characteristics, lake chemistry and aquatic food-web structure, through their effects on MeHg bioavailability and biomagnification (Wiener et al, 2003;Burgess and Hobson, 2005;Chen et al, 2005;Drysdale et al, 2005;Kamman et al, 2005).…”

“…Study sites for breeding common loons in Atlantic Canada. previously described by Evers et al (1998) and Burgess and Hobson (2005). In early August each year, we attempted to capture all adult loons that had successfully produced chicks, and their young.…”

“…All of these fish-Hg studies included yellow perch (Perca flavescens), which is the preferred prey of common loons (Barr, 1996). Burgess and Hobson (2005) found that Hg levels in adult and juvenile loons were highly correlated with Hg concentrations in yellow perch and lake pH in Atlantic Canada. Taken together, these studies indicate that loons breeding in Atlantic Canada face potentially high Hg exposure through their fish diet.…”

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

“…Hg bioaccumulates in animals as they age (Evers et al 1998), and many of its effects on common loons have been previously determined (see Evers et al 2005Evers et al , 2008. For example, concentrations of Hg in adult common loons and their eggs are often great enough to cause substantial reproductive impairment and can result in population-level impacts in high Hg-concentration areas (Scheuhammer et al 2001;Burgess et al 2005;Burgess and Hobson 2006;Evers et al 2008). At the Great Lakes, Hg remains available to organisms despite increased awareness of health issues from contamination (Hogan et al 2007).…”