10 results on '"Evers, David C."'
Search Results
2. Introduction: An Overview of Loon Research and Conservation in North America.
- Author
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PARUK, JAMES D., MAGER III, JOHN N., and EVERS, DAVID C.
- Subjects
LOONS ,BIRD conservation ,POPULATION ecology - Abstract
An introduction to several papers on loon research and conservation in North America is presented that include the behavior, life-history, population ecology, movements and migrations, habitat and landscape requirements of Gavia species, and the impacts contaminants have had on loon populations.
- Published
- 2014
- Full Text
- View/download PDF
3. Toxicological significance of mercury in yellow perch in the Laurentian Great Lakes region.
- Author
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Wiener, James G., Sandheinrich, Mark B., Bhavsar, Satyendra P., Bohr, Joseph R., Evers, David C., Monson, Bruce A., and Schrank, Candy S.
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EFFECT of heavy metals on fishes ,HEAVY metal toxicology ,HEAVY metal content of water ,METHYLMERCURY & the environment ,FOOD chains ,COMMON loon ,YELLOW perch ,MERCURY content of fish ,CONTAMINATION of edible fish - Abstract
We assessed the risks of mercury in yellow perch, a species important in the trophic transfer of methylmercury, in the Great Lakes region. Mean concentrations in whole perch from 45 (6.5%) of 691 waters equaled or exceeded 0.20 μg/g w.w., a threshold for adverse effects in fish. In whole perch within the size range eaten by common loons (<100 g), mean concentrations exceeded a dietary threshold (0.16 μg/g w.w.) for significant reproductive effects on loons in 19 (7.3%) of 260 waters. Mean concentrations in fillets of perch with length ≥ 15.0 cm, the minimum size retained by anglers, exceeded the USEPA criterion (0.3 μg/g w.w.) in 26 (6.4%) of 404 U.S. waters and exceeded the Ontario guideline (0.26 μg/g w.w.) in 35 (20%) of 179 Ontario waters. Mercury levels in yellow perch in some waters within this region pose risks to perch, to common loons, and to mercury-sensitive human populations. [Copyright &y& Elsevier]
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- 2012
- Full Text
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4. Mercury contamination in the Laurentian Great Lakes region: Introduction and overview.
- Author
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Wiener, James G., Evers, David C., Gay, David A., Morrison, Heather A., and Williams, Kathryn A.
- Subjects
MERCURY poisoning ,RETROSPECTIVE studies - Abstract
The Laurentian Great Lakes region of North America contains substantial aquatic resources and mercury-contaminated landscapes, fish, and wildlife. This special issue emanated from a bi-national synthesis of data from monitoring programs and case studies of mercury in the region, here defined as including the Great Lakes, the eight U.S. states bordering the Great Lakes, the province of Ontario, and Lake Champlain. We provide a retrospective overview of the regional mercury problem and summarize new findings from the synthesis papers and case studies that follow. Papers in this issue examine the chronology of mercury accumulation in lakes, the importance of wet and dry atmospheric deposition and evasion to regional mercury budgets, the influence of land–water linkages on mercury contamination of surface waters, the bioaccumulation of methylmercury in aquatic foods webs; and ecological and health risks associated with methylmercury in a regionally important prey fish. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
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5. GEOGRAPHIC AND SEASONAL VARIATION IN MERCURY EXPOSURE OF THE DECLINING RUSTY BLACKBIRD.
- Author
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Edmonds, Samuel T., Evers, David C., Cristol, Daniel A., Mettke-Hofmann, Claudia, Powell, Luke L., Mcgann, Andrew J., Armiger, Jacob W., Llane, Oksana P., Tessler, David F., Newell, Patti, Heyden, Kathryn, and O'Driscoll, Nelson J.
- Subjects
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BLACKBIRDS , *MERCURY in the body , *BLOOD , *FEATHERS , *ANIMAL wintering , *FORESTS & forestry - Abstract
The article offers a study on the geographical and seasonal differences in the levels of mercury concentrations in the blood and feathers of rusty blackbirds (Euphagus carolinus) in several North American regions. It says that mercury concentrations in bloods and feathers of birds in Acadian forests were higher than those of the western boreal forests of Alaska and wintering areas in the U.S. Moreover, it states that wintering birds have lower blood mercury levels than those of breeding birds.
- Published
- 2010
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6. A green wave of saltmarsh productivity predicts the timing of the annual cycle in a long-distance migratory shorebird.
- Author
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Smith JAM, Regan K, Cooper NW, Johnson L, Olson E, Green A, Tash J, Evers DC, and Marra PP
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- Animals, Breeding methods, Ecosystem, Georgia, Maine, Massachusetts, New Jersey, North America, Seasons, Temperature, Animal Migration physiology, Birds physiology
- Abstract
Understanding how migratory animals respond to spatial and temporal variation in habitat phenology is critical for identifying selection pressures and tradeoffs at different life history stages. We examined the influence of breeding habitat phenology on life history timing of the eastern willet (Tringa semipalmata semipalmata) across a latitudinal gradient of breeding sites on the east coast of North America. To describe migration and life history timing, we deployed light-level geolocators on willets at breeding sites in New Jersey, Massachusetts and Maine, USA and evaluated additional data on life history timing and migratory connectivity from previous studies, eBird and band recoveries. Willets from Nova Scotia to Georgia winter exclusively on the Atlantic coast of northern South America and share common stopover sites. The timing of wintering site departure, breeding site arrival, nesting and southbound departure was later for birds breeding at higher latitudes while the duration of all life phases was similar across sites. Regardless of latitude, nesting corresponded with a consistent stage of seasonal salt marsh biomass accumulation and with peak spring temperature acceleration (GDD jerk). Temperature acceleration and salt marsh biomass were closely correlated with each other across the 11° latitudinal gradient we examined and with the timing of nest initiation across the northern 6° of this gradient. For this northern 6° of latitude, these results suggest that the timing of migration and breeding events in the annual cycle of eastern willets is constrained by a phenological "green wave" of spring salt marsh productivity at breeding sites.
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- 2020
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7. Historical patterns in mercury exposure for North American songbirds.
- Author
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Perkins M, Lane OP, Evers DC, Sauer A, Adams EM, O'Driscoll NJ, Edmunds ST, Jackson AK, Hagelin JC, Trimble J, and Sunderland EM
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- Animals, Environmental Monitoring, North America, Environmental Pollutants analysis, Environmental Pollution statistics & numerical data, Mercury analysis, Songbirds
- Abstract
Methylmercury (MeHg) is a global environmental contaminant that poses significant risks to the health of humans, wildlife, and ecosystems. Assessing MeHg exposure in biota across the landscape and over time is vital for monitoring MeHg pollution and gauging the effectiveness of regulations intended to reduce new mercury (Hg) releases. We used MeHg concentrations measured in museum specimen feathers (collected between 1869 and 2014) and total Hg concentrations (as a proxy for MeHg) of feathers sampled from wild birds (collected between 2008 and 2017) to investigate temporal patterns in exposure over approximately 150 years for North American songbirds. For individual species, we found greater concentrations for samples collected post-2000 compared to those collected during historic times (pre-1900) for six of seven songbird species. Mean feather concentrations measured in samples collected post-2000 ranged between 1.9 and 17 times (mean 6.6) greater than historic specimens. The proportion of individual songbirds with feather concentrations that exceeded modeled toxicity benchmarks increased in samples collected after 1940. Only 2% of individual songbirds collected prior to 1940 had feather concentrations greater than 2.4 μg/g (a toxicity benchmark related to a 10% decrease in nest success) compared to 35% of individuals collected post-1940. Many species included in this study have a vulnerable or near-threatened conservation status, suggesting recovery actions are needed to address mercury pollution.
- Published
- 2020
- Full Text
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8. Integrated mercury monitoring program for temperate estuarine and marine ecosystems on the North American Atlantic coast.
- Author
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Evers DC, Mason RP, Kamman NC, Chen CY, Bogomolni AL, Taylor DL, Hammerschmidt CR, Jones SH, Burgess NM, Munney K, and Parsons KC
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- Animals, Atlantic Ocean, Birds, Fishes, Invertebrates, Mammals, North America, Ecosystem, Environmental Monitoring methods, Mercury analysis, Water Pollutants, Chemical analysis
- Abstract
During the past century, anthropogenic activities have altered the distribution of mercury (Hg) on the earth's surface. The impacts of such alterations to the natural cycle of Hg can be minimized through coordinated management, policy decisions, and legislative regulations. An ability to quantitatively measure environmental Hg loadings and spatiotemporal trends of their fate in the environment is critical for science-based decision making. Here, we outline a Hg monitoring program for temperate estuarine and marine ecosystems on the Atlantic Coast of North America. This framework follows a similar, previously developed plan for freshwater and terrestrial ecosystems in the U.S. Methylmercury (MeHg) is the toxicologically relevant form of Hg, and its ability to bioaccumulate in organisms and biomagnify in food webs depends on numerous biological and physicochemical factors that affect its production, transport, and fate. Therefore, multiple indicators are needed to fully characterize potential changes of Hg loadings in the environment and MeHg bioaccumulation through the different marine food webs. In addition to a description of how to monitor environmental Hg loads for air, sediment, and water, we outline a species-specific matrix of biotic indicators that include shellfish and other invertebrates, fish, birds and mammals. Such a Hg monitoring template is applicable to coastal areas across the Northern Hemisphere and is transferable to arctic and tropical marine ecosystems. We believe that a comprehensive approach provides an ability to best detect spatiotemporal Hg trends for both human and ecological health, and concurrently identify food webs and species at greatest risk to MeHg toxicity.
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- 2008
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9. Mercury levels in mink (Mustela vison) and river otter (Lontra canadensis) from northeastern North America.
- Author
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Yates DE, Mayack DT, Munney K, Evers DC, Major A, Kaur T, and Taylor RJ
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- Animals, Brain, Environmental Monitoring, Female, Hair chemistry, Liver chemistry, Male, Mercury analysis, North America, Seasons, Sex Factors, Tissue Distribution, Environmental Pollutants pharmacokinetics, Mercury pharmacokinetics, Mink, Otters
- Abstract
Aquatic ecosystems have received mercury released from anthropogenic sources. The northeast region of North America is at especially high risk because of local and regional emission sources, prevailing wind patterns, and certain hydrological and biogeochemical features. Here we examine regional variation in total mercury (Hg) in brain, liver, and fur from otter and mink collected across New York, New England, and Nova Scotia. Gender and age are examined as factors potentially affecting Hg tissue levels. In addition, temporal relationships are analyzed for New York as well as correlative relationships for tissues from Maine. Animals were collected from 1982 to 2003, mostly from licensed trappers. Liver was the only tissue from otter that exhibited significant regional variation (New York versus Maine) in Hg concentration. Mercury concentration was significantly related to age but not to gender for otter. All tissues in mink exhibited significant, but inconsistent, regional variation in total Hg concentration, with the highest mean Hg concentration in liver samples from Massachusetts/Connecticut. Female mink had significantly greater Hg concentrations in liver than males. Total Hg concentration in the liver of both otter and mink from New York decreased significantly with time. Correlations among tissues for Hg concentration were stronger for male and female mink and male otter than female otter from Maine.
- Published
- 2005
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10. Mercury in northeastern North America: a synthesis of existing databases.
- Author
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Evers DC and Clair TA
- Subjects
- Animals, Databases, Factual, Environmental Monitoring, Food Chain, Humans, North America, Ecosystem, Environmental Pollutants analysis, Mercury analysis
- Abstract
A large number of datasets representing mercury (Hg) levels in northeastern North America were assembled in a standardized format between 2000 and 2003. Based on support from the Northeastern States Research Cooperative, scientists annually gathered and developed an operational template to collaboratively analyze and interpret these data for a series of peer-reviewed publications. The diverse group covered Hg policy connections, Hg in air, sediment and surface water, Hg in biota, and Hg collection, assessment and monitoring tools. A site-specific application of these Hg data is provided to demonstrate the importance of well-placed air monitoring stations, the need for integrative multimedia data sets, and the complexity of linking abiotic and biotic Hg compartments. Demonstrated is the ubiquitous nature of Hg and methylmercury availability and how its heterogeneous distribution is now relatively well understood for northeastern North America.
- Published
- 2005
- Full Text
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