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Geology topics

Anton M. Scheuhammer

Publications and source records attributed to Anton M. Scheuhammer.

4 recordsLinked to original sources
USGS2012

Ecotoxicology of mercury in fish and wildlife: Recent advances

A number of recent studies have documented subtle, yet potentially important effects of mercury on behavior, neurochemistry, and endocrine function in fish and wildlife at currently realistic levels of environmental exposure. Current levels of environmental methylmercury exposure are sufficient to cause significant biological impairment, both in individuals and in whole populations, in some ecosystems. Future toxicological studies on fish and wildlife will focus on linking biomarkers of methylmercury exposure and associated oxidative stress to effects on reproduction and population change; determining the genetic basis for mercury-related neurotoxic and other biological changes; determining the genetic basis for species differences in sensitivity to methylmercury; and linking toxic effects of methylmercury in individual animals to population-level changes.

Book chapter↗
USGS2011

History of wildlife toxicology and the interpretation of contaminant concentrations in tissues

The detection and interpretation of contaminants in tissues of wildlife belongs to the field of toxicology, a scientific discipline with a long, intriguing, and illustrious history. Concern over poisoning of wildlife began in the late nineteenth century, and initially focused more on identifying environmental problems than determining contaminant concentrations in tissues. Endpoint measurements were characterized for sensitivity, specificity, variability, clarity of interpretation, validity, and applicability to field sampling. The use of stable isotopes to identify the environmental source of a metal is a recent development in the field of wildlife toxicology. The chemical forms of Mercury may be changed within some organs (e.g., demethylation by liver), further complicating interpretation of wildlife tissue concentrations. The field of wildlife toxicology has been shaped by chemical use and misuse, ecological mishaps, and research in the allied field of human toxicology. The development and use of new chemicals, and unexpected and unpredicted contamination problems continue to drive this discipline.

Book chapter↗
USGS1998

Geographic trend in mercury measured in common loon feathers and blood

The common loon ( Gavia immer ) is a high‐trophic‐level, long‐lived, obligate piscivore at risk from elevated levels of Hg through biomagnification and bioaccumulation. From 1991 to 1996 feather ( n = 455) and blood ( n = 381) samples from adult loons were collected between June and September in five regions of North America: Alaska, northwestern United States, Upper Great Lakes, New England, and the Canadian Maritimes. Concentrations of Hg in adults ranged from 2.8 to 36.7 μg/g (fresh weight) in feathers and from 0.12 to 7.80 μg/g (wet weight) in whole blood. Blood Hg concentrations in 3 to 6‐week‐old juveniles ranged from 0.03 to 0.78 μg/g (wet weight) ( n = 183). To better interpret exposure data, relationships between blood and feather Hg concentrations were examined among age and sex classes. Blood and feather Hg concentrations from the same individuals were significantly correlated and varied geographically ( r 2 ranged from 0.03 to 0.48). Blood and feather Hg correlated strongest in areas with the highest blood Hg levels, indicating a possible carryover of breeding season Hg that is depurated during winter remigial molt. Mean blood and feather Hg concentrations in males were significantly higher than concentrations in females for each region. The mean blood Hg concentration in adults was 10 times higher than that in juveniles, and feather Hg concentrations significantly increased over 1 to 4‐year periods in recaptured individuals. Geographic stratification indicates a significant increasing regional trend in adult and juvenile blood Hg concentrations from west to east. This gradient resembles U.S. Environmental Protection Agency‐modeled predictions of total anthropogenic Hg deposition across the United States. This gradient is clearest across regions. Within‐region blood Hg concentrations in adults and juveniles across nine sites of one region, the Upper Great Lakes, were less influenced by variations in geographic Hg deposition than by hydrology and lake chemistry. Loons breeding on low‐pH lakes in the Upper Great Lakes and in all lake types of northeastern North America are most at risk from Hg.

Alaska, Maine, Michigan, Minnesota, Montana, New B↗