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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 91 records · Page 5Linked to original sources
USGS1999

Influence of substrate rocks on Fe-Mn crust composition

Principal Component and other statistical analyses of chemical and mineralogical data of Fe-Mn oxyhydroxide crusts and their underlying rock substrates in the central Pacific indicate that substrate rocks do not influence crust composition. Two ridges near Johnston Atoll were dredged repetitively and up to seven substrate rock types were recovered from small areas of similar water depths. Crusts were analyzed mineralogically and chemically for 24 elements, and substrates were analyzed mineralogically and chemically for the 10 major oxides. Compositions of crusts on phosphatized substrates are distinctly different from crusts on substrates containing no phosphorite. However, that relationship only indicates that the episodes of phosphatization that mineralized the substrate rocks also mineralized the crusts that grew on them. A two-fold increase in copper contents in crusts that grew on phosphatized clastic substrate rocks, relative to crusts on other substrate rock types, is also associated with phosphatization and must have resulted from chemical reorganization during diagenesis. Phosphatized crusts show increases in Sr, Zn, Ca, Ba, Cu, Ce, V, and Mo contents and decreases in Fe, Si, and As contents relative to non-phosphatized crusts. Our statistical results support previous studies which show that crust compositions reflect predominantly direct precipitation from seawater (hydrogenetic), and to lesser extents reflect detrital input and diagenetic replacement of parts of the older crust generation by carbonate fluorapatite.

Deep-Sea Research Part I: Oceanographic Research P↗
USGS2024

Global assessment of aquatic Isoëtes species ecology

Isoëtes are iconic but understudied wetland plants, despite having suffered severe losses globally mainly because of alterations in their habitats. We therefore provide the first global ecological assessment of aquatic Isoëtes to identify their environmental requirements and to evaluate if taxonomically related species differ in their ecology. The assessment resulted in an extensive new database on aquatic Isoëtes , ecological niche analyses, and descriptive species accounts. We compiled a global database that includes all known environmental data collected from 1935 to 2023 regarding aquatic Isoëtes. We then evaluated the environmental drivers of 16 species using 2,179 global records. Additionally, we used hypervolume analysis to quantify the ecological niches of the two species with the greatest number of records, finding significant differences and evidence that Isoëtes echinospora occupies a wider ecological niche than Isoëtes lacustris . Fifty-nine species (30% of the c. 200 Isoëtes species known today) were categorised as aquatic and were mainly reported in the Americas and northern Europe. About 38% of the aquatic species are threatened with extinction or are endemic to a small region, according to the International Union for Conservation of Nature's Red List in 2023. Many species were determined to be sensitive to certain water physical and chemical factors, generally preferring oligotrophic conditions such as low total phosphorus, moderate total nitrogen, moderate to low pH, and low conductivity. This analysis includes ecological data in the assessment of rare/threatened aquatic plants globally. This new database and the ecological analyses completed defined the ecological requirements of several species and identified knowledge gaps, which can aid management actions and future research. This paper highlights ecological significance and environmental sensitivities of aquatic Isoëtes . The current level of knowledge is inadequate for a large proportion of known taxa. We affirm the extreme need to support global, collaborative initiatives on which to build future conservation strategies.

Freshwater Biology↗
USGS2006

The 20th-Century Topographic Survey as Source Data for Long-Term Landscape Studies at Local and Regional Scales

Historical topographic maps are the only systematically collected data resource covering the entire nation for long-term landscape change studies over the 20th century for geographical and environmental research. The paper discusses aspects of the historical U.S. Geological Survey topographic maps that present constraints on the design of a database for such studies. Problems involved in this approach include locating the required maps, understanding land feature classification differences between topographic vs. land use/land cover maps, the approximation of error between different map editions of the same area, and the identification of true changes on the landscape between time periods. Suggested approaches to these issues are illustrated using an example of such a study by the author.

Open-File Report↗
USGS2022

A geospatial knowledge graph prototype for national topographic mapping

Knowledge graphs are a form of database representation and handling that show the potential to better meet the challenges of data interoperability, semi-automated information reasoning, and information retrieval. Geospatial knowledge graphs (GKG) have at their core specialized forms of applied ontology that provide coherent spatial context to a domain of information including non-spatial attributes. This paper discusses research toward the development of a prototype GKG based on national topographic databases of geospatial feature instances, attributes, properties, metadata, and annotations. The challenges are to capture and represent geographic semantics inherent in the source data, to align such graph models with standards where possible, to test logical computations, and to visualize the data using a cartographic user interface. Data integration from outside sources was tested through SPARQL and GeoSPARQL queries. Called the MapKB, the approaches applied in this prototype use a number of software components to build a system architecture aligned with those objectives and are composed entirely of free and open-source software. The system and ontology design were validated through reasoning and competency questions. Technical aspects of the prototype software succeeded, but customization was found to be needed for user-based design.

International Archives of the Photogrammetry, Remo↗
USGS2000

Statistical considerations in monitoring birds over large areas

The proper design of a monitoring effort depends primarily on the objectives desired, constrained by the resources available to conduct the work. Typically, managers have numerous objectives, such as determining abundance of the species, detecting changes in population size, evaluating responses to management activities, and assessing habitat associations. A design that is optimal for one objective will likely not be optimal for others. Careful consideration of the importance of the competing objectives may lead to a design that adequately addresses the priority concerns, although it may not be optimal for any individual objective. Poor design or inadequate sample sizes may result in such weak conclusions that the effort is wasted. Statistical expertise can be used at several stages, such as estimating power of certain hypothesis tests, but is perhaps most useful in fundamental considerations of describing objectives and designing sampling plans.

Research Paper↗
USGS1979

Effects of sevin-4-oil, dimilin, and orthene on forest birds in northeastern Oregon

The possible harmful effect of insecticides on nontarget organisms should be a prominent concern in all attempts to control forest pests. Although all wildlife must be considered, birds are particularly vulnerable. The study reported here was part of the effort to find an environmentally safe method to control one of the major sources of insect damage to forest trees - the Douglas-fir tussock moth ( Orgyia pseudotsugata [McDunnough]). Its larval stage is an important defoliator of true firs ( Abies sp.) and Douglas-fir ( Pseudotsuga menziesii var. glauca [Beissn.] Franco)in western North America. In Oregon, severe infestations have recurred at intervals of about 10 years since 1936 (Wickman and others 1973).

Oregon↗
USGS1975

Impacts of chemicals on waterfowl reproduction and survival

Residues of organochlorine pesticides, PCB's, heavy metals, and other toxic chemicals are ubiquitous in the biosphere and are commonly found in tissues and eggs of wild birds. This paper reviews research on the effects of these chemicals, with particular reference to waterfowl. Extensive mortality of waterfowl has occurred in the Gulf Coast region as a result of ingestion of aldrin-treated rice seed. Populations of fulvous tree ducks (Dendrocygna bicolor) have declined in recent years in that area. DDE impaired reproduction of both mallards (Anas platyrhynchos) and black ducks (Arias rubripes) in experimental studies, resulting in thin shells, cracked eggs, and poor hatching success. Eggs incubated by the hens broke and cracked more frequently than those in incubators. In the field, residues are higher in ducks that feed on animal material than in vegetarians; differences are pronounced both geographically and among species. Mercury at levels that occur in certain heavily polluted areas in the United States and Canada has, in experimental studies, lowered the reproductive success of mallards and black ducks and reduced the survival of ducklings. Oil spills have killed many waterfowl as a result of oiled feathers and the intake of oil and more indirect physiological effects have been shown experimentally. Pollutants may affect waterfowl indirectly by changing the habitat and directly as a result of intake of toxic substances. They are unlikely to have been directly limiting factors in populations of such species as mallards. Their involvement with problem of other species, including canvasbacks (Aythya valisineria) and mergansers has still to be explored.

International Waterfowl Symposium↗
USGS1977

Role of the wolf in a deer decline in the Superior National Forest

White-tailed deer (Odocoileus virginianus) declined in the Superior National Forest of Minnesota between 1968 and 1974. In a 3,000 sq km area of the poorest habitat, deer were decimated. Contributing factors were severe winters, deteriorating habitat, and wolves. Wolves killed older deer, but insufficient fawns were available to replace them.

Research Paper↗
USGS1973

Wolf numbers in the Superior National Forest of Minnesota

Seventy-seven radio-tagged wolves (Canis lupus), including members of 12 adjacent packs, were located more than 3000 times, and observed on 1337 occasions, from 1968 through mid-1973. Projected population estimates for the 4203 square-mile Forest were 405 plus or minus 20 for winter 1971-72, and 388 plus or minus 14 for winter 1972-73.

Research Paper↗
USGS1986

Deer population in the Central Superior National Forest, 1967-1985

Deer were aerially censused each winter from 1976 through 1985 in a 400-sq km2 area near Isabella, Minnesota, in the Central Superior National Forest; a correction factor based on aerial observability of radio-tagged deer in the same region was then applied to the census figures. Deer numbers, which had reached an estimated 3.5/sq km, declined drastically in the early 1970's, fluctuated between about 0.43 and 0.97/sq km from 1976 through 1985, and began increasing in 1983.

Research Paper↗
USGS1986

Wolf population in the Central Superior National Forest, 1967-1985

Aerial radio-tracking and observation showed total number of wolves per year in 2,060-km2 area varied from 35 to 87 in winter and from 30 to 78 in spring and generally declined because of a decreasing deer herd. Since winter 1977-1978, the population has remained relatively stable because an increasing proportion of it has switched to preying on moose. The number of wolves preying on deer has continued to decline.

Research Paper↗
USGS1977

Status, distribution, and movements of martens in northeastern Minnesota

The decline of martens in Minnesota is reviewed and a recent increase documented. Adjacent and partially overlapping home ranges of 4.3 to 19.9 sq km were determined by telemetry for a female and three males. Habitat use is described. If current trapping and timber management practices persist, martens should continue to increase.

Research Paper↗
USGS1993

Point counts of birds in bottomland hardwood forests of the Mississippi Alluvial Valley: Duration, minimal sample size, and points versus visits

The purpose of the research was to evaluate the efficacy of point count surveys in bottomland hardwood forests. The specific objectives were to determine: (1) whether the recommended distance measures for point count circular plots are useful in bottomland hardwood forests, (2) the optimum duration for each point count, (3) the optimum number of points to sample at each locality, (4) the optimum number of counts at each point during a season, and (5) the minimum sample size to accommodate the variation in bird species distribution and relative abundance throughout the lower MAV.

Research Paper↗
USGS2016

Relation of initial spacing and relative stand density indices to stand characteristics in a Douglas-fir plantation spacing trial

This report presents updated information on a 1981 Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. menziesii ) plantation spacing trial at 33 years from planting. Stand statistics at the most recent measurement were compared for initial spacing of 1 through 6 meters and associated relative densities. There was no clear relationship of spacing to top height. Diameter, live crown ratio, and percent survival increased with spacing; basal area and relative density decreased with increase in spacing. Volume in trees ≥ 4 cm diameter was greatest at 2 m spacing, while utilizable volume (trees ≥20 cm dbh) was greatest at 4 m spacing. Live crown ratio decreased and total crown projectional area increased with increasing relative density indices. Total crown projectional area was more closely related to relative density than to basal area.

Washington↗
USGS1999

Sand lance: A review of biology and predator relations and annotated bibliography

Six species of sand lance ( Ammodytes ) in temperate and boreal regions are currently recognized. Sand lance can occupy a wide range of environmental conditions, but all appear to be dormant predominantly in winter, and one species is in summer also. They lack a swim bladder and spend much of their time buried in specific substrates. Copepods are the primary food. Spawning usually occurs in fall or winter (although some species also spawn in spring), eggs are demersal, and larvae may hatch at times of low food abundance. Sand lance usually occur in schools and are regarded as a relatively high-quality forage fish. Sand lance constitute a major prey for at least some populations of over 100 species of consumer, including 40 species of birds, 12 species of marine mammals, 45 species of fishes, and some invertebrates. Variation in the availability of sand lance (and other forage fishes) can have major effects on the breeding success and survival of their predators. Commercial fishing and other pressures on sand lance populations potentially have ramifying effects on many species of wildlife. The bibliography contains over 1,700 references on the family Ammodytidae, with an emphasis on the genus Ammodytes . Keywords are provided for each reference and have been further organized into taxonomic, geographic, subject, and predator indexes.

Research Paper↗
USGS2016

Assessing the potential for rainbow trout reproduction in tributaries of the Mountain Fork River below Broken Bow Dam, southeastern Oklahoma

Stocked trout (Salmonidae) in reservoir tailwater systems in the Southern United States have been shown to use tributary streams for spawning and rearing. The lower Mountain Fork of the Little River below Broken Bow Dam is one of two year-round tailwater trout fisheries in Oklahoma, and the only one with evidence of reproduction by stocked rainbow trout (Oncorhynchus mykiss). Whether stocked trout use tributaries in this system for spawning is unknown. Furthermore, an inventory of the resident fish communities in these tributaries is lacking. To address these gaps, we surveyed 10 tributaries, from intermittent through third order, for fishes during presumed spawning periods of rainbow trout; we used backpack electrofishing in February and April 2015 and 2016 to determine the composition of the fish assemblages and whether trout were present. Stocked adult trout were found in three tributaries in 2015; wild juvenile rainbow trout were found in Bee Branch in 2015 and in an intermittent tributary of Spillway Creek, just above the “Cold Hole,” in 2016. Fish assemblages were dominated by highland stonerollers (Campostoma spadiceum) in larger, wider systems and by orangebelly darters (Etheostoma radiosum) in smaller, narrower streams. These data fill an information gap in our understanding of small streams in the Ouachita Mountains, and they demonstrate that some streams are suitable for rainbow trout reproduction.

Oklahoma↗