Effects of Chronic, Low Concentrations of Dietary Methylmercury on the Behavior of Juvenile Great Egrets

Bouton, Shannon N.; Frederick, Peter C.; Spalding, Marilyn G.; McGill, Heather

doi:10.1897/1551-5028(1999)018<1934:eoclco>2.3.co;2

Cited by 34 publications

(57 citation statements)

References 16 publications

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“…For the low dose group we found no neurohistologic changes that would explain the subtle behavioral changes noted by Bouton et al (1999) between low and control groups, and our only other evidence of neurological manifestations of mercury dosing was of dingy feathers. We did not see, nor can we address developmental neuropathologic changes reviewed by Burbacher et al (1990) for mammals, since all our groups received similar uncontrolled background levels during embryonic development and were not dosed during the first wk of captivity.…”

Section: Nervous Systemcontrasting

confidence: 61%

“…While little to no quantitative information is available about the effects of this degree of anemia in birds, a 20% reduction in PCV is likely to have an effect on stamina. Anemia may have been responsible for the lethargy and decrease in active behaviors that was observed in this experiment (see Bouton et al, 1999), but it should be noted that when these observations were made, PCV was returning to normal. Evidence of red cell regeneration, polychromasia, occurred transiently after initiation of the higher dose, but we suspect that this regeneration was impaired later in the experiment based upon the findings of hypocellular bone marrow and continued PCV decline.…”

Section: Hematology and Immunologymentioning

confidence: 74%

“…We then compared growth, appetite, health, immune function, survival, behavior, and hunting ability in relation to mercury dose. The effects on growth, appetite, tissue mercury concentrations (Spalding et al, 2000), behavior (Bouton et al, 1999), and tissue and plasma biochemistry (D. J. Hoffman et al, unpubl.…”

Section: Introductionmentioning

confidence: 99%

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Histologic, Neurologic, and Immunologic Effects of Methylmercury in Captive Great Egrets

Spalding

Frederick

McGill

et al. 2000

Journal of Wildlife Diseases

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115

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Captive great egret (Ardea albus) nestlings were maintained as controls or were dosed with methylmercury chloride at low (0.5), and high doses (5 mg/kg, wet weight) in fish. Low dosed birds were given methylmercury at concentrations comparable to current exposure of wild birds in the Everglades (Florida, USA). When compared with controls, low dosed birds had lower packed cell volumes, dingy feathers, increased lymphocytic cuffing in a skin test, increased bone marrow cellularity, decreased bursal wall thickness, decreased thymic lobule size, fewer lymphoid aggregates in lung, increased perivascular edema in lung, and decreased phagocytized carbon in lung. High dosed birds became severely ataxic and had severe hematologic, neurologic, and histologic changes. The most severe lesions were in immune and nervous system tissues. By comparing responses in captive and wild birds, we found that sublethal effects of mercury were detected at lower levels in captive than in wild birds, probably due to the reduced sources of variation characteristic of the highly controlled laboratory study. Conversely, thresholds for more severe changes (death, disease) occurred at lower concentrations in wild birds than in captive birds, probably because wild birds were exposed to multiple stressors. Thus caution should be used in applying lowest observed effect levels between captive and wild studies.

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Section: Nervous Systemcontrasting

confidence: 61%

Section: Hematology and Immunologymentioning

confidence: 74%

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Histologic, Neurologic, and Immunologic Effects of Methylmercury in Captive Great Egrets

Spalding

Frederick

McGill

et al. 2000

Journal of Wildlife Diseases

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115

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“…Connectivity of these population sinks within the regional metapopulation of loons is currently being assessed. Other piscivorous birds in which Hg has been shown to harm reproductive success of populations include the bald eagle (Haliaeetus leucocephalus) in Maine (DeSorbo and Evers 2005), and wading birds such as the great egret (Ardea alba) in Florida (Bouton et al 1999;Spalding et al 2000) and snowy egret (Egretta thula) in Nevada (Henny et al 2002).…”

Section: Aquatic Ecosystemsmentioning

confidence: 99%

Effects of Air Pollution on Ecosystems and Biological Diversity in the Eastern United States

Lovett

Tear

Evers

et al. 2009

Annals of the New York Academy of Sciences

183

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Conservation organizations have most often focused on land-use change, climate change, and invasive species as prime threats to biodiversity conservation. Although air pollution is an acknowledged widespread problem, it is rarely considered in conservation planning or management. In this synthesis, the state of scientific knowledge on the effects of air pollution on plants and animals in the Northeastern and Mid-Atlantic regions of the United States is summarized. Four air pollutants (sulfur, nitrogen, ozone, and mercury) and eight ecosystem types ranging from estuaries to alpine tundra are considered. Effects of air pollution were identified, with varying levels of certainty, in all the ecosystem types examined. None of these ecosystem types is free of the impacts of air pollution, and most are affected by multiple pollutants. In aquatic ecosystems, effects of acidity, nitrogen, and mercury on organisms and biogeochemical processes are well documented. Air pollution causes or contributes to acidification of lakes, eutrophication of estuaries and coastal waters, and mercury bioaccumulation in aquatic food webs. In terrestrial ecosystems, the effects of air pollution on biogeochemical cycling are also very well documented, but the effects on most organisms and the interaction of air pollution with other stressors are less well understood. Nevertheless, there is strong evidence for effects of nitrogen deposition on plants in grasslands, alpine areas, and bogs, and for nitrogen effects on forest mycorrhizae. Soil acidification is widespread in forest ecosystems across the eastern United States and is likely to affect the composition and function of forests in acid-sensitive areas over the long term. Ozone is known to cause reductions in photosynthesis in many terrestrial plant species. For the most part, the effects of these pollutants are chronic, not acute, at the exposure levels common in the eastern United States. Mortality is often observed only at experimentally elevated exposure levels or in combination with other stresses such as drought, freezing, or pathogens. The notable exceptions are the acid/aluminum effects on aquatic organisms, which can be lethal at levels of acidity observed in many surface waters in the region. Although the effects are often subtle, they are important to biological conservation. Changes in species composition caused by terrestrial or aquatic acidification or eutrophication can propagate throughout the food webs to affect many organisms beyond those that are directly sensitive to the pollution. Likewise, sublethal 100Annals of the New York Academy of Sciences doses of toxic pollutants may reduce the reproductive success of the affected organisms or make them more susceptible to potentially lethal pathogens. Many serious gaps in knowledge that warrant further research were identified. Among those gaps are the effects of acidification, ozone, and mercury on alpine systems, effects of nitrogen on species composition of forests, effects of mercury in terrestrial food webs, interactiv...

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“…Particular emphasis has been placed on larger species for which trophic status is potentially greatest; such species include the common loon (Meyer et al, 1995Burgess et al, 1998a, b;Evers et al, , 2003Scheuhammer et al, 1998bScheuhammer et al, , 2001Fevold et al, 2003;Burgess and Hobson, in press;Champoux et al, in press), bald eagle (Grier, 1974;Wiemeyer et al, 1984;Frenzel and Anthony, 1989;Bowerman et al, 1994;Anthony et al, 1999;Bowerman et al, 2002), osprey (Cahill et al, 1998;DesGranges et al, 1998), wading birds (Gariboldi et al, 1998;Bouton et al, 1999;Spalding et al, 2000b;Henny et al, 2002), and seabirds (Braune, 1987;Burger and Gochfeld, 1995;Furness, 1995, 1997;Braune et al, 2001). Other foodweb pathways important for MeHg transfer are generally of lesser concern because trophic status of the endpoint species is generally lower than piscivores.…”

Section: Species Hg Exposure Patternsmentioning

confidence: 99%

Patterns and Interpretation of Mercury Exposure in Freshwater Avian Communities in Northeastern North America

et al. 2005

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Abstract. A large data set of over 4,700 records of avian mercury (Hg) levels in northeastern North America was compiled and evaluated. As Hg emissions remain poorly regulated in the United States and Canada, atmospheric deposition patterns and associated ecological responses continue to elicit interest by landscape managers, conservation biologists, policy makers, and the general public. How avian Hg exposure is interpreted greatly influences decision-making practices. The geographic extent and size of this data set is valuable in understanding the factors that affect the exposure of Hg to birds. Featured are differences found among tissues, major aquatic habitats and geographic areas, between age class and gender, and among species. While Hg concentrations in egg and blood reflect short-term Hg exposure, Hg concentrations in liver and feather provide insight into long-term Hg exposure. Blood is a particularly important matrix for relating site-specific exposure to methylmercury (MeHg). The level of MeHg is generally 5-10x greater in adults compared to nestlings. Age also influences MeHg bioaccumulation, particularly for individuals where MeHg intake exceeds elimination. Gender is of interpretive concern when evaluating Hg exposure for species exhibiting sexual dimorphism and niche partitioning. Based on two indicator species, the belted kingfisher (Ceryle alcyon) and bald eagle (Haliaeetus leucocephalus), we found MeHg availability increased from marine, to estuarine and riverine systems, and was greatest in lake habitats. A large sample of >1,800 blood and egg Hg levels from the common loon (Gavia immer) facilitated a suitable comparison of geographic differences. Although some clusters of highly elevated Hg exposure (i.e., blood levels >3.0 lg/g, ww and egg levels >1.3 lg/g, ww) were associated with hydrological and biogeochemical factors known to increase MeHg production and availability, others were not. Geographic areas without a relationship between Hg exposure and biogeochemical processes were associated with emission or waterborne point sources. Differences in Hg exposure among species are primarily correlated with trophic position and availability of MeHg. Although piscivorous species were repeatedly *To whom correspondence should be addressed: Tel.: 207-839-7600; Fax: 207-839-7655; E-mail: david.evers@briloon.org Ecotoxicology, 14, 193-221, 2005 Ó 2005 shown to have some of the highest MeHg levels of the 38 species analyzed, insectivorous birds in both aquatic and terrestrial habitats (such as montane areas) were also found with elevated MeHg levels. A better understanding of the factors confounding interpretation of Hg exposure provides an effective basis for choice of indicator species and tissues according to 12 selected scenarios. This and the national need for spatiotemporal monitoring of MeHg availability require careful consideration of indicator species choice. Only then will local, regional, continental, and even global monitoring efforts be effective.

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Effects of Chronic, Low Concentrations of Dietary Methylmercury on the Behavior of Juvenile Great Egrets

Cited by 34 publications

References 16 publications

Histologic, Neurologic, and Immunologic Effects of Methylmercury in Captive Great Egrets

Histologic, Neurologic, and Immunologic Effects of Methylmercury in Captive Great Egrets

Effects of Air Pollution on Ecosystems and Biological Diversity in the Eastern United States

Patterns and Interpretation of Mercury Exposure in Freshwater Avian Communities in Northeastern North America

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