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At least 1,243 records · Page 69Linked to original sources
USGS1978

Seasonal trends in summer diet of the lapland longspur near Barrow Alaska USA

Contents of lapland longspur [Calcarius lapponicus] stomachs and esophagi were sampled near Barrow, Alaska [USA], from May-Aug. in 1969, 1971, 1972 and 1973. Data from stomach contents were corrected for differential digestion of prey items. Longspurs shifted seasonally from larval to adult arthropods and back to larvae, responding to changes in the abundance of these prey items. Seeds were a vital supplementary food in late May and Aug., when arthropods were scarce or inaccessible. One species of crane fly was the major dietary component for longspurs during June and July. Its high abundance and substantial dry weight per individual may contribute to the success of longspurs at Barrow. The diets of longspurs and 4 common shorebirds (Calidris spp.) at Barrow were similar in the range of prey items taken except for seeds and tenthredinid larvae. Their diets overlapped closely when feeding sites were restricted because of snow and surface water (chiefly at the beginning of the season) and when prey was abundant in early to mid-July. Competition is possible early in the season but unlikely in July when surface insects are very abundant. Habitat separation and the advantages of fringillid form apparently contribute to the success of longspors in a tundra community of insectivores dominated by shorebirds.

The Condor↗
USGS1977

Productivity, mortality, and population trends of wolves in northeastern Minnesota

Population parameters, mortality causes, and mechanisms of a population decline were studied in wolves ( Canis lupus lycaon ) from 1968 to 1976 in the Superior National Forest. The main method was aerial radio-tracking of 129 wolves and their packmates. Due to a decline in white-tailed deer ( Odocoileus virginianus ), the wolf population decreased during most of the study. Average annual productivity varied from 1.5 to 3.3 pups per litter, and annual mortality rates from 7 to 65 percent. Malnutrition and intraspecific strife accounted equally for 58 percent of the mortality; human causes accounted for the remainder. As wolf numbers began to decline, pup starvation became apparent, followed by lower pup production, and then by increased intraspecific strife. At higher densities, adult pack wolves were the most secure members of the population, but as the population declined, they became the least secure because of intraspecific strife.

Minnesota↗
USGS1984

Population trends and environmental contaminants in herons in the Tennessee Valley, 1980-81

Great Blue Heron (Ardea herodias) eggs (N = 40) collected in 1980 from four of the largest colonies in the Tennessee Valley contained organochlorine pesticide, polychlorinated biphenyl (PCB), and chromium concentrations below those associated with reduced productivity. Low concentrations of organochlorine pesticide and PCB residues also were found in eggs (N = 31) from three of the larger Black-crowned Night-Heron (Nycticorax nycticorax) colonies in the Tennessee Valley. However, DDE concentrations in two of the Black-crowned Night-Heron eggs exceeded levels associated with reduced nesting success. Mercury was found in all eggs of both species with residues ranging to a high of 2.0 ppm; residues of this magnitude have not been identified as reducing nesting success of either of these two species. Green-backed Heron (Butorides striatus) eggs collected in 1981 near a former DDT manufacturing site in the Tennessee Valley had the highest DDE concentrations ever reported for this species; the effect of these high concentrations on productivity is not known. Eggshell thickness of Great Blue Heron, Green-backed Heron, and Black- crowned Night-Heron eggs averaged 7.5%, 7.6%, and 3% thinner, respectively, than shell thickness of eggs collected before 1947. This amount of thinning is not deleterious; intraclutch variation in shell thickness is often this high. Shell thickness in all three species was correlated (P lt 0.1) with DDE concentrations. The number of nesting pairs of Great Blue Herons and Black-crowned Night-Herons at each of the colonies studied has been stable or increasing during the previous decade. These population data, combined with the residue data, suggest that organochlorine pesticides, PCBs, mercury, and chromium are not adversely affecting these populations. However, we did not assess nesting success which would be a requisite for confirming this.

Colonial Waterbirds↗
USGS1985

Tropical Pacific silicoflagellate zonation and paleotemperature trends of the late Cenozoic

Quantitative study of late Cenozoic silicoflagellates at tropical Pacific DSDP Sites 572 and 575 shows that the greatest amplitude of fluctuation in relative paleotemperature values occurred in the late Miocene. The coolest minimum paleotemperature values (near 75 = 30) also occurred in the late Miocene. The warmest intervals (Ts = 80 to 100) occurred in the middle Miocene and late Pliocene to Quaternary. In detail, the silicoflagellate relative paleotemperature curve correlates fairly well with the eustatic sea-level curve and deep-sea hiatus sequence. The only upper Cenozoic low-latitude biostratigraphic units not identified are the Distephanus speculum haliomma Subzone and Naviculopsis quadrata Zone, owing to the absence of the nominative species, which probably had nontropical ecologic preference. Several Naviculopsis occurrence events within the Naviculopsis ponticula Zone correlate between DSDP Hole 575A and DSDP Hole 495 off Guatemala. Many local and regional biostratigraphic events are recognized. New taxa identified from DSDP Leg 85 include Dictyocha nola Bukry, n. sp., Distephanus stradneri var. grandis Bukry, n. var., Mesocena elliptica var. rhomboidea Bukry, n. van, and Naviculopsis obtusarca var. acicula Bukry, n. var.

Initial Reports of the D.S.D.P.↗
USGS2025

Diverging trends in nitrate and phosphorus loads and yields across Illinois watersheds, 1997–2022

Illinois is a major contributor of nutrients to the northern Gulf of Mexico. As such, the State of Illinois initiated efforts to curb nutrient runoff over the last several decades. To evaluate progress towards these reductions, water-quality data were used to estimate incremental loads and yields of nitrate plus nitrite (NO3) and total phosphorus (TP) from 1997–2022 for 49 Illinois watersheds, defined using eight-digit hydrologic unit codes (HUC8), draining to the Mississippi River Basin. To estimate changes in NO3 and TP loads, recent loads from the period 2018 through 2022 were compared to baseline loads from 1997 through 2011. Nonpoint and point source loads, dissolved phosphorus (DP) loads, and water yields were also estimated. The sum of the incremental NO3 loads from the 49 HUC8s decreased 9% despite a 19% increase in water yield. Much of this decline occurred in HUC8s that had NO3 yields greater than 17 pounds per acre per year (lbs/acre/yr) during a 1997–2011 baseline period. The sum of all incremental HUC8 TP loads increased 25% despite a 27% reduction in point source discharge. Loads and yields were substantially larger for both NO3 and TP in the Chicago area. Outside the Chicago area, central and northern Illinois had higher NO3 yields than southern Illinois and a reverse pattern for TP where higher yields occur in southern Illinois. Nonpoint sources made up an estimated 82% and 78% of the NO3 and TP yields, respectively, across the HUC8s. In general, point source yields have mostly decreased over time, while nonpoint source yields varied depending on location and reflect the changes in the total yield.

Illinois↗
USGS2014

Mercury in the nation's streams - Levels, trends, and implications

Mercury is a potent neurotoxin that accumulates in fish to levels of concern for human health and the health of fish-eating wildlife. Mercury contamination of fish is the primary reason for issuing fish consumption advisories, which exist in every State in the Nation. Much of the mercury originates from combustion of coal and can travel long distances in the atmosphere before being deposited. This can result in mercury-contaminated fish in areas with no obvious source of mercury pollution. Three key factors determine the level of mercury contamination in fish - the amount of inorganic mercury available to an ecosystem, the conversion of inorganic mercury to methylmercury, and the bioaccumulation of methylmercury through the food web. Inorganic mercury originates from both natural sources (such as volcanoes, geologic deposits of mercury, geothermal springs, and volatilization from the ocean) and anthropogenic sources (such as coal combustion, mining, and use of mercury in products and industrial processes). Humans have doubled the amount of inorganic mercury in the global atmosphere since pre-industrial times, with substantially greater increases occurring at locations closer to major urban areas. In aquatic ecosystems, some inorganic mercury is converted to methylmercury, the form that ultimately accumulates in fish. The rate of mercury methylation, thus the amount of methylmercury produced, varies greatly in time and space, and depends on numerous environmental factors, including temperature and the amounts of oxygen, organic matter, and sulfate that are present. Methylmercury enters aquatic food webs when it is taken up from water by algae and other microorganisms. Methylmercury concentrations increase with successively higher trophic levels in the food web—a process known as bioaccumulation. In general, fish at the top of the food web consume other fish and tend to accumulate the highest methylmercury concentrations. This report summarizes selected stream studies conducted by the U.S. Geological Survey (USGS) since the late 1990s, while also drawing on scientific literature and datasets from other sources. Previous national mercury assessments by other agencies have focused largely on lakes. Although numerous studies of mercury in streams have been conducted at local and regional scales, recent USGS studies provide the most comprehensive, multimedia assessment of streams across the United States, and yield insights about the importance of watershed characteristics relative to mercury inputs. Information from other environments (lakes, wetlands, soil, atmosphere, glacial ice) also is summarized to help understand how mercury varies in space and time.

Circular↗
USGS1964

Mercury - Its occurrence and economic trends

In 1963 the domestic production of primary mercury was less than one-fourth of the domestic consumption, largely because a series of years of declining price led to the closing of most of the domestic mines. During 1963 and 1964 the U.S. price, which usually responds to world price, increased from $180 to about $500 a flask. Should the fluctuation in price and production conform to a previously established pattern, the response of the domestic industry to an increased price will be a predictable increase in production. If the price averages $300 a flask for 1 year or more, annual production may increase to a rate of 30,000-35,000 flasks in 1966 or 1967. If the price averages $400 a flask, production may increase to 45,000-50,000 flasks a year after a timelag of two or three years. New ore bodies would have to be found however, to attain these rates of production, and the mining of lower grade ores would be needed to sustain them for more than a few years. By 1966 the U.S. economy will require at least 67 000 flasks, and the domestic demand for mercury thereafter will continue to increase. The probability that domestic mines will continue to supply a fourth or more of the domestic consumption is dependent upon the price of mercury for the next few years. The outlook for the long-term supply is reassuring, but it is dependent, not only upon price, but upon continued progress in new techniques of discovery.

Circular↗
USGS1966

Regional trends in water-well drilling in the United States

Between the towns of Macon and Taylorville in central Illinois lies a ridge that is part of a system of ridges and knolls largely composed of sand and gravel. This ridge contains an important aquifer. An extensive electrical earth resistivity survey was conducted over the ridged-drift aquifer. Inversion of the resistivity data provided information concerning aquifer thickness and aquifer resistivity. This information, along with pump test data along the aquifer, indicated a direct and geometric relationship between aquifer resistivity and hydraulic conductivity. As a result, it was possible to better define the boundaries and water-producing capabilities of the aquifer. (Author 's abstract)

Circular↗
USGS2016

Long-term trends in naturalized rainbow trout ( Oncorhynchus mykiss ) populations in the upper Esopus Creek, Ulster County, New York, 2009–15

The U.S. Geological Survey, in cooperation with Cornell Cooperative Extension of Ulster County, New York State Energy Research and Development Authority, the New York State Department of Environmental Conservation, and the New York City Department of Environmental Protection, surveyed fish communities annually on the main stem and tributaries of the upper Esopus Creek, Ulster County, New York, from 2009 to 2015. This report summarizes the density, biomass, and size structure of rainbow trout ( Oncorhynchus mykiss ) and brown trout ( Salmo trutta ) populations from the 2015 surveys along with data from the preceding 6 years. The mean density of rainbow trout populations in 2015 was 98 fish per 0.1 hectare, which was the highest value observed since 2010, and the mean biomass of rainbow trout populations in 2015 was 864 grams per 0.1 hectare, which was the highest value observed since 2012.

New York↗
USGS1997

Trends in acetochlor concentrations in surface waters of the White River Basin, Indiana, 1994–96

Corn herbicides are used extensively in the White River Basin and account for about 70 percent of the total agricultural pesticide use in the basin. Acetochlor, a corn herbicide registered for use in 1994, is expected to reduce the total amount of corn herbicides used because of its broad-spectrum weed control and low use rates. Acetochlor is considered to be a probable human carcinogen, and its continued registration is contingent on concentrations in surface and ground water not exceeding target levels. During 1994, acetochlor was detected in only trace concentrations near the mouth of the White River and not at all in a small stream (93-square-mile drainage) in the northern part of the basin. By 1996, peak concentrations were about 2 and 3 micrograms per liter near the mouth of the White River and in the small stream, respectively. The estimated annual average concentration of acetochlor near the mouth of the White River in 1996 was 0.15 micrograms per liter, well below the 2 micrograms per liter criterion for surface-water supplied community-water systems.

Indiana↗