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Geology topics

D. R. Clark

Publications and source records attributed to D. R. Clark.

At least 37 records · Page 2Linked to original sources
USGS1990

Dicofol (Kelthane®)-induced eggshell thinning in captive american kestrels

Reproductive parameters of American kestrels ( Falco sparverius ) were measured through two breeding seasons. Exposure to Kelthane® (containing no DDT-related compounds) at dietary concentrations of 0 (control), 1,3, 10 and 30 μg/g (wet weight) began in late November before, and continued through, the second season. Kelthane thinned eggshells and lowered the thickness index at dietary concentrations ≥3 μg/g and it reduced shell weight at ≥10μg/g when comparisons were to concurrent controls. Kelthane reduced the thickness index at ≥3 μg/g and it reduced shell thickness and weight at ≥10 μg/g when comparisons were to the same birds during the previous season. All changes were dose-related. It was not previously known that as little as 3 μg/g dicofol could cause these effects. Kestrels resembled previously studied eastern screech-owls ( Otus asio ) in that 10 μg/g reduced hatchability of eggs. Both these raptors showed eggshell changes without serious effects on production of young. Available data show dicofol only equal to or less effective than DDE as a shell-thinning agent. Also, DDE may have more impact than dicofol on such critical aspects of reproduction as egg hatchability and survivability of hatchlings. Field studies of dicofol residues in food chains and of residue concentrations in eggs vs. nesting success from areas of heavy dicofol use are needed to judge this chemical's ecological impact.

Environmental Toxicology and Chemistry↗
USGS1989

Pesticide contamination of endangered gray bats and their food base in Boone County, Missouri, 1982

Gray bat guano from Devil's Icebox and Hunters Caves contained dieldrin at levels previously associated with gray bat mortality. Two of four gray bats found dead in Holton Cave had lethal brain concentrations of dieldrin. Twenty-five of 28 (86%) insect samples from bat foraging areas contained measurable dieldrin, heptachlor epoxide or both. Beetle samples were most heavily contaminated containing up to 2.2 ppm and 1.1 ppm heptachlor epoxide. The addition of Holton Cave brings to five the number of Missouri caves where gray bats have died of food chain pesticide poisoning.

Missouri↗
USGS1988

Northern Alabama colonies of the endangered grey bat Myotis grisescens: organochlorine contamination and mortality

From 1976 to 1986, dead and dying grey bats Myotis grisescens and grey bat guano were collected from caves along the Tennessee River in northern Alabama to determine the possible role of organochlorine chemicals — in particular wastes from a former DDT manufacturing plant near Huntsville—in the mortalities. Concentrations of chemical residues in brains were less than known lethal levels; certain observations and analyses did indicate the possibility of past organochlorine-induced bat deaths. Levels of contaminants in bats declined slowly during the 10-year sampling period, but heavy residue burdens persist. The high ratio of DDD to DDE in residues from the former DDT plant made them identifiable as far as 140 km downriver. Grey bats concentrated chemical residues to higher levels and demonstrated the presence of these residues over much greater distances than did red-winged blackbirds Agelaius phoenicus . Grey bats may be the most sensitive indicator available for monitoring the contamination from this former DDT manufacturing site.

Alabama↗
USGS1988

Environmental contaminants and the management of bat populations in the United States

Food-chain residues of organochlorine pesticides probably have been involved in declines of some U.S. bat populations; examples include free-tailed bats at Carlsbad Cavern, New Mexico, and the endangered gray bat at sites in Missouri and Alabama. If a long-lived contaminant has not been dispersed in large amounts over large areas, its impact may be controlled by administrative action that stops its use or other environmental discharge, or that results in physical isolation of localized contamination so that it no longer enters food chains

Book chapter↗
USGS1988

How sensitive are bats to insecticides?

Concern about the loss of bat populations to insecticides, first stated by Mohr (1953) has stimulated toxicological research to quantify the sensitivity of bats to these chemicals. This report is a review of results of research to date and a discussion of implications for bats in the wild.

Wildlife Society Bulletin↗
USGS1987

Orthene® toxicity to little brown bats (Myotis lucifugus): Acetylcholinesterase inhibition, coordination loss, and mortality

The 24-h LD50 of Orthener̀ (active ingredient acephate, acetylphosphoramidothioic acid o,s -dimethyl ester, CAS 30560-19–1) to little brown bats (Myotis lucifugus) was high (> 1,500 mg acephate/kg) and at least several times greater than the LD50 for mice (Mus musculus) (720 mg/kg). Twenty-four hours after dosing, all surviving mice appeared behaviorally normal, but 9 of 30 surviving bats could not right themselves when placed on their backs. When dead and incapacitated bats were combined to calculate an ED50 (median effective dose), the resultant estimate (687 mg/kg) did not differ ( p > 0.05) from the LD50 for mice. Serum cholinesterase (ChE) activity in control bats was 3.2 times greater than in mice. The relationship between this naturally high level of ChE and the relative tolerance of bats to organophosphorus insecticides is unexplained. Toxicity of Orthene was clearly less than that reported elsewhere for methyl parathion (phosphorothioic acid o,o -dimethyl o-[4-nitrophenyl] ester, CAS 298–00-0). This finding may be useful in selection of a chemical for agricultural use, but conclusions about the safety of Orthene to this bat species, or to others, must remain tentative until confirmed by studies under field conditions. Because bats are long-lived with low reproductive rates and slow recruitment, any additional mortality in the wild could be critical to population survival.

Environmental Toxicology and Chemistry↗
USGS1987

Selenium accumulation in mammals exposed to contaminated California irrigation drainwater

In May 1984, 332 mammals of 10 species were collected at Kesterson Reservoir (San Joaquin Valley, Merced Co., CA), which had received selenium-laden irrigation drainwater, and at the nearby Volta Wildlife Area, which had not. The study concentrated on the California vole ( Microtus californicus ); 88 were taken at Kesterson, 89 at Volta. Mean selenium concentrations in livers were as much as 522 times higher at Kesterson. There were species-to-species differences at Kesterson; higher selenium concentrations occurred in carnivorous species and/or species that feed on foods closely linked to pond water. There were also pond-to-pond differences at Kesterson; drainwater historically was delivered to Ponds 1 and 2, where concentrations in 1984 were higher, with subsequent flow to other ponds, where they were lower. Whereas none of 50 adult female voles from Kesterson was pregnant, 12 of 41 (29%) from Volta were pregnant. However, this cessation of reproductive activity at Kesterson was probably not due to selenium toxicity but could have resulted because drying conditions at Kesterson forced voles to a seed diet earlier than at Volta. One malformation was found among five embryonic litters of three species from Kesterson. Mammals seem much less susceptible to selenium-induced embryonic abnormalities than birds. No adverse impacts of selenium on wild mammals were demonstrated; however, some sensitive species might have been extirpated from Kesterson before this study began. In addition, high concentrations in small mammal species at Kesterson may threaten predatory birds and mammals that feed on them, with the endangered San Joaquin kit fox ( Vulpes macrotis mutica ) of particular concern.

Science of the Total Environment↗
USGS1986

Toxicity of methyl parathion to bats: Mortality and coordination loss

The 24-h oral LD50 of methyl parathion (phosphorothioic acid O, O -dimethyl O-(4-nitrophenyl) ester) to little brown bats ( Myotis lucifugus ) (372 mg/kg) was 8.5 times the LD50 for mice ( Mus musculus ) (44 mg/kg). However, orally dosed mice either died or appeared behaviorally normal after 2 to 3 h, whereas many dosed bats, although alive at 24 h, could not right themselves when placed on their backs. The oral dose estimated to cause this loss of coordination in 50% of a sample of big brown bats ( Eptesicus fuscus ) was one-third or less the LD50 of this species. Cholinesterase activity depression in brains of little brown bats was similar whether dosage was oral or dermal. With death as the criterion, bats proved relatively insensitive to methyl parathion in 24-h tests, but considerations of the chemical's potential to cause coordination loss, leading to capture and death by predators, coupled with bats' naturally low reproductive rates, suggest possible injury to exposed bat populations.

Environmental Toxicology and Chemistry↗
USGS1983

Year and age effects on residues of dieldrin and heptachlor in dead gray bats, Franklin County, Missouri— 1976, 1977, and 1978

Dead gray bats ( Myotis grisescens ) containing lethal concentrations of dieldrin were found beneath a maternity roost in Bat Cave Nos. 2 and 3, Franklin County, Missouri, in 1976, 1977 and 1978. Whereas residues of dieldrin, DDE [1,1-dichloro-2,2-bis( p -chlorophenyl)ethylene] and PCB polychlorinated biphenyls in bats appeared not to change significantly over the 3 years, residues of heptachlor-related chemicals increased in 1977 to potentially dangerous concentrations and remained elevated in 1978. Lethal brain levels of dieldrin in adult bats (geometric mean = 12.1 μg/g), compared with juvenile bats (geometric mean = 6.5 μg/g), indicated that juveniles are nearly twice as sensitive. The estimated population of gray bats (as maximum number of nonflying young) at Bat Cave Nos. 2 and 3 in 1976 and 1978 was 1,800 bats, but in 1979 no bats were present. Dieldrin, perhaps in conjunction with heptachlor, may have caused the decline and disappearance of this colony. However, dieldrin was banned in 1974 and Missouri's authorization to use heptachlor on corn expired in 1981. Furthermore, three organophosphate insecticides (chlorpyrifos, dyfonate and mocap) are to be substituted. We hope that the gray bats remaining in this area of Missouri survive the residues of dieldrin and heptachlor still in their food chains and prove to be unaffected by the new organophosphates.

Environmental Toxicology and Chemistry↗
USGS1983

DDE in brown and white fat of hibernating bats

Samples of brown and white fat from hibernating bats (big brown bat, Eptesicus fuscus ; little brown bat, Myotis lucifugus ; and eastern pipistrelle, Pipistrellus subflavus ) collected in western Maryland, USA, were analysed to determine lipid and DDE content. Amounts of brown fat, expressed as percentages of total bat weight, were the same for all three species. Lipid content of brown fat was significantly less than that of white fat. Lipids of brown fat contained significantly higher (28%) concentrations of DDE than did lipids of white fat. In our mixed-species sample of 14 bats, concentrations of DDE increased exponentially in both brown and white fat as white fat reserves declined. Brown fat facilitates arousal from hibernation by producing heat through rapid metabolism of triglycerides. The question is raised whether organochlorine residues, such as DDE, may be concentrated and then liberated in lethal amounts by the processes of hibernation and arousal.

Maryland↗
USGS1983

Organochlorine pesticides and PCB's: A continuing problem for the 1980s

In general. decreases in OC contamination in North America are unmistakable. This is documented by the NPMP. but. more importantly. it is borne out by improvements in the reproduction and population status of the brown pelican. bald eagle, peregrine falcon, and osprey. However, some OC contamination still persists, and several species, particularly predatory birds and insectivorous bats, continue to be vulnerable. Current OC problems in North America result from present and past usage and from industrial contamination. In addition, some studies suggest that some migrant bird species that winter south of the U.S. border are exposed to higher levels of OC pesticide than non-migrants. However, heavy OC pesticide contamination is known to exist in Arizona, New Mexico, and in southern California where migratory birds might stop during migration. At this time, we do not have the information to assess specifically the sources of contamination for most migrant species. From the number of recent OC problems identified in North America, it is apparent that OC's are not confined to the past and that we must continue to monitor and study OC's during this decade. However, current administrative, management, and research priorities are being directed toward the search for potential impacts of newer pesticides, air pollution. industrial waste, and other contaminants. Although it is necessary to build a body of scientific data on these types of contaminants, we feel that we cannot neglect continued work on OC's for which harmful effects impacting our wildlife resources are already known.

Transactions of the North American Wildlife and Na↗