Inter- and intraclutch variation in egg mercury levels in marine bird species from the Canadian Arctic

Akearok, Jason A.; Hebert, Craig E.; Braune, Birgit M.; Mallory, Mark L.

doi:10.1016/j.scitotenv.2009.11.039

Cited by 65 publications

(55 citation statements)

References 32 publications

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“…Random sampling of individual herring during the 2 months before the mean date of egg laying in the population provided 10 tissue samples for isotopic and mercury analysis. Arch Environ Contam Toxicol (2012) 62:494-501 495 Because intraclutch variability has previously been reported in marine birds in which the first egg in a clutch has higher mercury than subsequent eggs (Becker 1992;Morera et al 1997;Akearok et al 2010), eggs were marked with a permanent marker as they were laid to establish laying order and investigate this trend in penguins. Approximately 1 week after laying, eggs were candled to determine if they were fertile; a subsample of 5 whole infertile eggs were collected and frozen for isotopic and mercury analysis.…”

Section: Captive Penguin Tissue Collectionmentioning

confidence: 99%

“…Egg laying is a major elimination route in female birds through which mercury is deposited into the egg yolk, albumen, membrane, and shell (Kennamer et al 2005). Egg mercury concentrations are significantly correlated with female blood mercury concentrations, as well as prey mercury concentrations, and are therefore equally informative of contamination levels (Evers et al 2003;Brasso et al 2010).Although most studies use homogenized albumen and yolk to determine the mercury concentration of an egg, the shell and membrane can also be used document mercury concentrations (Morera et al 1997;Evers et al 2003;Akearok et al 2010). It is imperative to understand how mercury is allocated into the major components of bird eggs (shell, membrane, albumen, and yolk) to make comparisons across species and studies using different components.…”

mentioning

confidence: 99%

“…Although most studies use homogenized albumen and yolk to determine the mercury concentration of an egg, the shell and membrane can also be used document mercury concentrations (Morera et al 1997;Evers et al 2003;Akearok et al 2010). It is imperative to understand how mercury is allocated into the major components of bird eggs (shell, membrane, albumen, and yolk) to make comparisons across species and studies using different components.…”

mentioning

confidence: 99%

“…Similarly, Morera et al (1997) found a significant relationship between the shell and homogenized albumen and yolk mercury concentrations in Audouin's gulls. Because migratory patterns, foraging strategies, the toxicodynamics of mercury in eggs, and the process of egg formation can vary among species, it is important to establish species-specific tissue ratios to ensure accurate assessment of the mercury signal from any one tissue (Evers et al 2003;Kennamer et al 2005;Akearok et al 2010;Morrissey et al 2010). These wellestablished intertissue comparisons can allow for sampling in remote areas, such as the Antarctic, where access to multiple tissue types may not be practical.…”

mentioning

confidence: 99%

“…Because the toxicodynamics of mercury in avian tissues can vary with differences in certain factors, such as dietary composition and foraging strategies (Anderson et al 2009;Akearok et al 2010), it was important to the present study to investigate whether patterns of mercury elimination detected were robust at different trophic positions and dietary mercury exposure (as determined by differences in nitrogen stable isotope [d 15 N] values and mercury concentrations in eggs components and prey). d 15 N can be used to infer trophic position because the isotopic abundance in a consumer's tissues is related to the isotopic composition of its prey (Rau et al 1991;Anderson et al 2009).…”

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confidence: 99%

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Pattern of Mercury Allocation into Egg Components is Independent of Dietary Exposure in Gentoo Penguins

Brasso

Abel²,

Polito

2011

Arch Environ Contam Toxicol

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Avian eggs have become one of the most common means of evaluating mercury contamination in aquatic and marine environments and can serve as reliable indicators of dietary mercury exposure. We investigated patterns of mercury deposition into the major components of penguin eggs (shell, membrane, albumen, and yolk) using the Gentoo penguin (Pygoscelis papua) as a model species. Eggs were collected from both wild and captive populations of Gentoo penguins to compare the allocation of mercury into individual egg components of birds feeding at disparate trophic positions as inferred by stable isotope analysis. Mercury concentrations in captive penguins were an order of magnitude higher than in wild birds, presumably because the former were fed only fish at a higher trophic position relative to wild penguins that fed on a diet of 72-93% krill (Euphausia spp.). Similar to previous studies, we found the majority of total egg mercury sequestered in the albumen (92%) followed by the yolk (6.7%) with the lowest amounts in the shell (0.9%) and membrane (0.4%). Regardless of dietary exposure, mercury concentrations in yolk and membrane, and to a lesser degree shell, increased with increasing albumen mercury (used as a proxy for whole-egg mercury), indicating that any component, in the absence of others, may be suitable for monitoring changes in dietary mercury. Because accessibility of egg tissues in the wild varies, the establishment of consistent relationships among egg components will facilitate comparisons with any other study using eggs to assess dietary exposure to mercury.

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Section: Captive Penguin Tissue Collectionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Pattern of Mercury Allocation into Egg Components is Independent of Dietary Exposure in Gentoo Penguins

Brasso

Abel²,

Polito

2011

Arch Environ Contam Toxicol

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Effect of laying sequence on egg mercury in captive zebra finches: An interpretation considering individual variation

Varian-Ramos

Cristol

2015

Enviro Toxic and Chemistry

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Bird eggs are used widely as noninvasive bioindicators for environmental mercury availability. Previous studies, however, have found varying relationships between laying sequence and egg mercury concentrations. Some studies have reported that the mercury concentration was higher in first-laid eggs or declined across the laying sequence, whereas in other studies mercury concentration was not related to egg order. Approximately 300 eggs (61 clutches) were collected from captive zebra finches dosed throughout their reproductive lives with methylmercury (0.3 μg/g, 0.6 μg/g, 1.2 μg/g, or 2.4 μg/g wet wt in diet); the total mercury concentration (mean ± standard deviation [SD] dry wt basis) of their eggs was 7.03 ± 1.38 μg/g, 14.15 ± 2.52 μg/g, 26.85 ± 5.85 μg/g, and 49.76 ± 10.37 μg/g, respectively (equivalent to fresh wt egg mercury concentrations of 1.24 μg/g, 2.50 μg/g, 4.74 μg/g, and 8.79 μg/g). The authors observed a significant decrease in the mercury concentration of successive eggs when compared with the first egg and notable variation between clutches within treatments. The mercury level of individual females within and among treatments did not alter this relationship. Based on the results, sampling of a single egg in each clutch from any position in the laying sequence is sufficient for purposes of population risk assessment, but it is not recommended as a proxy for individual female exposure or as an estimate of average mercury level within the clutch.

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Egg‐laying sequence influences egg mercury concentrations and egg size in three bird species: Implications for contaminant monitoring programs

Ackerman

Eagles‐Smith

Herzog

et al. 2016

Enviro Toxic and Chemistry

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Bird eggs are commonly used in contaminant monitoring programs and toxicological risk assessments, but intraclutch variation and sampling methodology could influence interpretability. The authors examined the influence of egg-laying sequence on egg mercury concentrations and burdens in American avocets, black-necked stilts, and Forster's terns. The average decline in mercury concentrations between the first and last eggs laid was 33% for stilts, 22% for terns, and 11% for avocets, and most of this decline occurred between the first and second eggs laid (24% for stilts, 18% for terns, and 9% for avocets). Trends in egg size with egg-laying order were inconsistent among species, and overall differences in egg volume, mass, length, and width were <3%. The authors summarized the literature, and among 17 species studied, mercury concentrations generally declined by 16% between the first and second eggs laid. Despite the strong effect of egg-laying sequence, most of the variance in egg mercury concentrations still occurred among clutches (75-91%) rather than within clutches (9%-25%). Using simulations, the authors determined that accurate estimation of a population's mean egg mercury concentration using only a single random egg from a subset of nests would require sampling >60 nests to represent a large population (10% accuracy) or ≥14 nests to represent a small colony that contained <100 nests (20% accuracy). Environ Toxicol Chem 2016;35:1458-1469. Published 2015 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

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Inter- and intraclutch variation in egg mercury levels in marine bird species from the Canadian Arctic

Cited by 65 publications

References 32 publications

Pattern of Mercury Allocation into Egg Components is Independent of Dietary Exposure in Gentoo Penguins

Pattern of Mercury Allocation into Egg Components is Independent of Dietary Exposure in Gentoo Penguins

Effect of laying sequence on egg mercury in captive zebra finches: An interpretation considering individual variation

Egg‐laying sequence influences egg mercury concentrations and egg size in three bird species: Implications for contaminant monitoring programs

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