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At least 415 records · Page 23Linked to original sources
USGS2017

The state of the world’s mangroves in the 21st century under climate change

Concerted mangrove research and rehabilitation efforts over the last several decades have prompted a better understanding of the important ecosystem attributes worthy of protection and a better conservation ethic toward mangrove wetlands globally. While mangroves continue to be degraded and lost in specific regions, conservation initiatives, rehabilitation efforts, natural regeneration, and climate range expansion have promoted gains in other areas, ultimately serving to curb the high mangrove habitat loss statistics from the doom and gloom of the 1980s. We highlight those trends in this article and introduce this special issue of Hydrobiologia dedicated to the important and recurring Mangrove and Macrobenthos Meeting. This collection of papers represents studies presented at the fourth such meeting (MMM4) held in St. Augustine, Florida, USA, on July 18–22, 2016. Our intent is to provide a balanced message about the global state of mangrove wetlands by describing recent reductions in net mangrove area losses and highlighting primary research studies presented at MMM4 through a collection of papers. These papers serve not only to highlight on-going global research advancements, but also provide an overview of the vast amount of data on mangrove ecosystem ecology, biology and rehabilitation that emphasizes the uniqueness of the mangrove community.

Hydrobiologia↗
USGS2023

Biodiversity connections—‘ties that bind’

Connectivity is a foundational concept in ecology and conservation and was the organising theme for the 2022 Annual Meeting of the Southeastern Fishes Council, a professional organisation dedicated to the study and conservation of freshwater fishes native to the southeast region of the United States (US). We introduce a Special Contribution of six papers selected from presentations at that meeting that illustrate perspectives on connections created by fish migration and dispersal, evolved life histories and habitat affinities and interspecific facilitation. Although focused on streams of the southeast US, each of these topics is broadly relevant to freshwater fish conservation, particularly with respect to causes and consequences of migratory fish depletion, population fragmentation and species declines. Many other connections relevant to the ecology and conservation of freshwater fishes remain relatively unexplored but could substantively advance conservation. We highlight the potential that species evolutionary histories, that is connections through time, reconstructed using species distributions and phylogenies may improve predictions of species responses to environmental change. Identifying species interdependencies, including undiscovered interactions that support survival or reproduction, could provide insights into how species losses may cascade as aquatic communities unravel. Finally, efforts to elucidate diverse connections between people and freshwater biodiversity, particularly where fisheries are historic and streams mostly go unnoticed, may prove essential to building public support for conservation measures. A research agenda anchored on ‘biodiversity connections’ has the potential to advance ecological understanding and public engagement, elements essential to conserving freshwater fishes.

Ecology of Freshwater Fish↗
USGS2014

Bathymetric and velocimetric surveys at highway bridges crossing the Missouri River between Kansas City and St. Louis, Missouri, April-May, 2013

Bathymetric and velocimetric data were collected by the U.S. Geological Survey, in cooperation with the Missouri Department of Transportation, in the vicinity of 10 bridges at 9 highway crossings of the Missouri River between Lexington and Washington, Missouri, from April 22 through May 2, 2013. A multibeam echosounder mapping system was used to obtain channel-bed elevations for river reaches ranging from 1,640 to 1,840 feet longitudinally and extending laterally across the active channel between banks and spur dikes in the Missouri River during low- to moderate-flow conditions. These bathymetric surveys indicate the channel conditions at the time of the surveys and provide characteristics of scour holes that may be useful in the development of predictive guidelines or equations for scour holes. These data also may be useful to the Missouri Department of Transportation to assess the bridges for stability and integrity issues with respect to bridge scour during floods. Bathymetric data were collected around every pier that was in water, except those at the edge of water or in very shallow water (less than about 6 feet). Scour holes were present at most piers for which bathymetry could be obtained, except at piers on channel banks, near or embedded in lateral or longitudinal spur dikes, and on exposed bedrock outcrops. Scour holes observed at the surveyed bridges were examined with respect to depth and shape. Although exposure of parts of foundational support elements was observed at several piers, at most sites the exposure likely can be considered minimal compared to the overall substructure that remains buried in channel-bed material; however, there were several notable exceptions where the bed material thickness between the bottom of the scour hole and bedrock was less than 6 feet. Such substantial exposure of usually buried substructural elements may warrant special observation in future flood events. Previous bathymetric surveys had been done at all of the sites in this study during the flood of 2011. Comparisons between bathymetric surfaces from the previous surveys and those of this study generally indicate a consistent increase in the elevation of the bed and decrease in the size of scour holes at these sites, both likely caused by a substantial decrease in discharge and water-surface elevation compared to the 2011 surveys at most sites. However, multiple surveys at one of the sites indicate that the flow condition is not the sole variable in the determination of the size of scour holes at sites with a dual bridge configuration. Furthermore, another site had a smaller and shallower scour hole even though the discharge in this study was slightly greater than in 2011. Pier size, nose shape, and alignment to flow also had a substantial effect on the size of the scour hole observed.

Missouri↗
USGS2010

Locations and magnitudes of historical earthquakes in the Sierra of Ecuador (1587–1996)

The whole territory of Ecuador is exposed to seismic hazard. Great earthquakes can occur in the subduction zone (e.g. Esmeraldas, 1906, M w 8.8), whereas lower magnitude but shallower and potentially more destructive earthquakes can occur in the highlands. This study focuses on the historical crustal earthquakes of the Andean Cordillera. Several large cities are located in the Interandean Valley, among them Quito, the capital (∼2.5 millions inhabitants). A total population of ∼6 millions inhabitants currently live in the highlands, raising the seismic risk. At present, precise instrumental data for the Ecuadorian territory is not available for periods earlier than 1990 (beginning date of the revised instrumental Ecuadorian seismic catalogue); therefore historical data are of utmost importance for assessing seismic hazard. In this study, the Bakun & Wentworth method is applied in order to determine magnitudes, locations, and associated uncertainties for historical earthquakes of the Sierra over the period 1587–1976. An intensity-magnitude equation is derived from the four most reliable instrumental earthquakes ( M w between 5.3 and 7.1). Intensity data available per historical earthquake vary between 10 (Quito, 1587, Intensity ≥VI) and 117 (Riobamba, 1797, Intensity ≥III). The bootstrap resampling technique is coupled to the B&W method for deriving geographical confidence contours for the intensity centre depending on the data set of each earthquake, as well as confidence intervals for the magnitude. The extension of the area delineating the intensity centre location at the 67 per cent confidence level (±1σ) depends on the amount of intensity data, on their internal coherence, on the number of intensity degrees available, and on their spatial distribution. Special attention is dedicated to the few earthquakes described by intensities reaching IX, X and XI degrees. Twenty-five events are studied, and nineteen new epicentral locations are obtained, yielding equivalent moment magnitudes between 5.0 and 7.6. Large earthquakes seem to be related to strike slip faults between the North Andean Block and stable South America to the east, while moderate earthquakes ( M w ≤ 6) seem to be associated with to thrust faults located on the western internal slopes of the Interandean Valley.

Geophysical Journal International↗
USGS1950

Pollution in the lower Columbia Basin in 1948 with particular reference to the Willamette River

Development of the salmon resources of the lower Columbia River Basin appears as sound insurance against the threat of a serious reduction in the runs to the upper river areas through the multiple-purpose programs of water development now under way by the Corps of Engineers, the Bureau of Reclamation, and private interests. Any comprehensive plan for the full development of the fisheries resources in the lower Columbia Basin must be predicated upon accurate knowledge of the waters therein polluted to a degree affecting fish life. Pollution surveys have been made in the lower Columbia Basin at various times in the past -- the most intensive studies having been made in the Willamette Valley.

Oregon↗
USGS1981

Organic geochemistry in the Deep Sea Drilling Project

Since the beginning of the Deep Sea Drilling Project DSDP in 1968 and extending through 1975 organic geochemical studies have been undertaken on about 2300 samples recovered on Legs I through 44 from sediments beneath the ocean floors These studies have provided fundamental information regarding the distribution of carbon in oceanic sediments and have yielded a better understanding of the processes that alter and transform organic matter in the marine environment. Beginning with Leg 38 organic geochemists have been included as members of the scientific staffs of those legs of particular organic geochemical interest They have advised operations personnel on matters concerning potential hazards such as drilling into significant accumulations of oil and gas and have collected samples for the scientific community The shipboard organic geochemical laboratory is equipped with sophisticated instrumentation to provide those meassurements helpful in advising the drilling operation. Since Leg 15 samples for organic geochemical studies have been maintained at 180Cat the DSDP sample repository at the Scripps Institution of Oceanography La Jolla California Samples aredistributed to the scientific community but at least one quarter of all cores is retained for possible future studies. Organic geochemical studie sgenerally relate to one of these topic areas (I) petroleum potential source rock evaluation (2) thermal history and gradients (3) diagenesis (4) gas hydrates (5) novel geochemical fossils (6) sources of organic materials (7) paleo depositional environments and (8) geochronology Much of the organic geochemical work on hydrocarbons and kerogen has been directed to the potential of sediments as sources of petroleum The organic matter found thus far during drilling is dominantly of terrestrial origin and thermally immature but much of the organic matter could be a potential source of petroleum mainly gas if buried more deeply. Three new technologies will help advance organic geochemical knowledge of ocean sediments I pressure core barrel for evaluation of gas hydrates 2 hydraulic piston core to study in detail sources and early diagenesis of organic matter and 3 riser for the study of late diagenesis and catagenesis

Society of Economic Geologists Special Publication↗
USGS2003

Organochlorine pesticides, PCBs, trace elements and metals in western pond turtle eggs from Oregon

With increased concern over the status of reptile populations globally, contaminant studies should be part of species evaluations. We analyzed eggs of western pond turtles from Fern Ridge Reservoir in western Oregon for 20 organochlorine (OC) pesticides or metabolites, 42 congener-specific polychlorinated biphenyls (PCBs), and 16 trace elements or metals. These eggs represent the first of this species analyzed. The OC pesticides and PCB residue concentrations in the western pond turtle eggs were generally low and similar to those found in eggs of snapping turtles from a remote site in Ontario, Canada. Western pond turtle eggs also contained mercury and chromium, which are metals of special concern. Although few reptilian eggs have been analyzed for metals, the 44.9 mug/g dry weight chromium in a western pond turtle egg in this study may be the highest reported in a reptilian egg. We found no significant difference in contaminant concentrations in eggs from nests in Oregon, where all turtle eggs failed to hatch compared to those where some eggs hatched. During this initial project, however, we were unable to assess fully the role of OCs, PCBs and other contaminants in the western pond turtle decline. Factors other than contaminants may be involved. In another study, snapping turtle eggs near the Great Lakes-St. Lawrence River basin were much more contaminated with evidence reported of effects on sex differentiation and reproductive endocrine function. Egg hatchability, the only reproductive parameter monitored, may not be the most sensitive endpoint. Other endpoints, including endocrine function, deformity rates, growth rates, and sex determination need study.

Northwest Science↗
USGS2011

Appropriate uses and considerations for online surveying in human dimensions research

Online surveying has gained attention in recent years for its applicability to human dimensions research as an efficient and inexpensive data-collection method; however, online surveying is not a panacea. In this article, we provide some guidelines for alleviating or avoiding the criticisms and pitfalls suggested of online survey methods and explore two case studies demonstrating different approaches to online surveying. The first was a mixed-mode study of visitors to 52 participating National Wildlife Refuges. The response rate was 72%, with over half of respondents completing the survey online, resulting in cost-savings and efficiencies that would not have otherwise been realized. The second highlighted an online-only approach targeting specialized users of satellite imagery. Through branching and skipping, the online mode allowed flexibilities in administration impractical in a mail survey. The response rate of 53% was higher than typical for online surveys. Both case studies provide examples of appropriate uses of online surveying.

Human Dimensions of Wildlife↗
USGS2004

Precarious rock and overturned transformer evidence for ground shaking in the Ms 7.7 Kern County earthquake: An analog for disastrous shaking from a major thrust fault in the Los Angeles basin

Precariously balanced rocks and overturned transformers in the vicinity of the White Wolf fault provide constraints on ground motion during the 1952 Ms 7.7 Kern County earthquake, a possible analog for an anticipated large earthquake in the Los Angeles basin (Shaw et al., 2002; Dolan et al., 2003). On the northeast part of the fault preliminary estimates of ground motion on the footwall give peak accelerations considerably lower than predicted by standard regression curves. On the other hand, on the hanging-wall, there is evidence of intense ground shattering and lack of precarious rocks, consistent with the intense hanging-wall accelerations suggested by foam-rubber modeling, numerical modeling, and observations from previous thrust fault earthquakes. There is clear evidence of the effects of rupture directivity in ground motions on the hanging-wall side of the fault (from both precarious rocks and numerical simulations). On the southwest part of the fault, which is covered by sediments, the thrust fault did not reach the surface ("blind" thrust). Overturned and damaged transformers indicate significant transfer of energy from the hanging wall to the footwall, an effect that may not be as effective when the rupture reaches the surface (is not "blind"). Transformers near the up-dip projection of the fault tip have been damaged or overturned on both the hanging-wall and footwall sides of the fault. The transfer of energy is confirmed in a numerical lattice model and could play an important role in a similar situation in Los Angeles. We suggest that the results of this study can provide important information for estimating the effects of a large thrust fault rupture in the Los Angeles basin, specially given the fact that there is so little instrumental data from large thrust fault earthquakes.

Bulletin of the Seismological Society of America↗
USGS1955

Photogeologic procedures in geologic interpretation and mapping

In the past few years increasing use has been made of aerial photographs for geologic interpretation and mapping within the U.S. Geological Survey. As a specialized technique in interpretation and mapping, however, photogeologic procedures were extensively used (1947-1953) in the Survey's geologic mapping of Naval Petroleum Reserve No. 4 in northern Alaska and in mapping part of the Colorado Plateau of western United States, principally in Utah (1951-present). Photogeologic work was performed by a specialized group of geologists that was organized as the Photogeology Section in June 1953. This group has more recently made studies of northeastern Utah, southern and southeastern Alaska, and central Alaska. Various photogeologic procedures have been used in these studies; some procedures have been modified, and new ones have been developed. It is primarily the purpose of this paper to discuss these procedures. Photogeologic procedures or techniques used outside the Geological Survey are not discussed herein.

Alaska, Utah↗
USGS1973

Field reconnaissance of the effects of the earthquake of April 13, 1973, near Laguna de Arenal, Costa Rica

At about 3:34 a.m. on April 13, 1973, a moderate-sized, but widely-felt, earthquake caused extensive damage with loss of 23 lives in a rural area of about 150 km 2 centered just south of Laguna de Arenal in northwestern Costa Rica (fig. 1). This report summarizes the results of the writer's reconnaissance investigation of the area that was affected by the earthquake of April 13, 1973. A 4-day field study of the meizoseismal area was carried out during the period from April 28 through May 1 under the auspices of the U.S. Geological Survey. The primary objective of this study was to evaluate geologic factors that contributed to the damage and loss of life. The earthquake was also of special interest because of the possibility that it was accompanied by surface faulting comparable to that which occurred at Managua, Nicaragua, during the disastrous earthquake of December 23, 1972 (Brown, Ward, and Plafker, 1973). Such earthquake-related surface faulting can provide scientifically valuable information on active tectonic processes at shallow depths within the Middle America arc. Also, identification of active faults in this area is of considerable practical importance because of the planned construction of a major hydroelectrical facility within the meizoseismal area by the Instituto Costarricense de Electricidad (I.C.E.). The project would involve creation of a storage reservoir within the Laguna de Arenal basin and part of the Río Arenal valley with a 75 m-high earthfill dam across Río Arenal at a point about 10 km east of the outlet of Laguna de Arenal.

Laguna De Arenal↗
USGS2005

The fishes of Pea Ridge National Military Park, Arkansas, 2003

A fish inventory was conducted at Pea Ridge National Military Park, Arkansas, during base-flow conditions in September 2003. Six sites including four streams and two ponds were sampled using conventional electrofishing equipment (a seine also was used at one site). There were 653 individuals collected comprising 18 species (plus 1 hybrid) and 15 genera. The number of species collected at the four stream sites ranged from 1 16. Most fish species collected generally are associated with small streams in the Ozark Plateaus. The two most common species were the banded sculpin and the southern redbelly dace. Three species and a sunfish hybrid were collected from the quarry pond. No fish were collected from the unnamed pond. A preliminary expected species list incorrectly listed 42 species because of incorrect species range or habitat requirements. One species not on the original list was added to the revised list. Upon revising this list, the inventory yielded 18 the 40 species (45 percent) and 1 hybrid. No previous fish inventories have been completed for park but some observations can be made relative to species distributions. There were only five fish species collected in three headwater streams, and it is unlikely that many other species would occur in these three streams because of constraints imposed on the fish community by stream size. Little Sugar Creek, a medium-sized stream, had the most species collected, and it is likely that additional species would be collected from this stream if additional sampling were to occur. Distribution records indicate that all 18 species occur in the general area. Although no species collected in this study are federallylisted threatened or endangered species, three species collected at Pea Ridge National Military Park may be of some special interest to National Park Service managers and others. Two the species collected (cardinal shiner and stippled darter) are endemic to the Ozark Plateaus; both are rather common in certain parts of the Ozark Plateaus. The white sucker has a restricted range in Arkansas because northern Arkansas is at southern edge of the white sucker's distributional range.

Scientific Investigations Report↗
USGS2003

On the trail of Black Scoters

The location of breeding and molting areas of some seaduck species is uncertain, and little is known of seaducks' migrational paths and of habitats used during migration, breeding, and molting. The black scoter is of special concern among the seaducks, because it is both the least common of the three scoter species and the least studied. The Continental Technical Team of the North American Waterfowl Management Plan's Sea Duck Joint Venture recommended that research on this species be conducted to learn more about black scoter movements and to delineate its breeding and molting areas. The team received funding to implant satellite transmitters on this species in Baie des Chaleurs and Restigouche River in New Brunswick, Canada, with the purpose of delineating populations and identifying habitat affinities for staging, breeding, and molting

New Brunswick, Quebec↗
USGS2017

Paleozoic and mesozoic GIS data from the Geologic Atlas of the Rocky Mountain Region: Volume 1

The Rocky Mountain Association of Geologists (RMAG) is, once again, publishing portions of the 1972 Geologic Atlas of the Rocky Mountain Region (Mallory, ed., 1972) as a geospatial map and data package. Georeferenced tiff (Geo TIFF) images of map figures from this atlas has served as the basis for these data products. Shapefiles and file geodatabase features have been generated and cartographically represented for select pages from the following chapters: • Phanerozoic Rocks (page 56) • Cambrian System (page 63) • Ordovician System (pages 78 and 79) • Silurian System (pages 87 - 89) • Devonian System (pages 93, 94, and 96 - 98) • Mississippian System (pages 102 and 103) • Pennsylvanian System (pages 114 and 115) • Permian System (pages 146 and 149 - 154) • Triassic System (pages 168 and 169) • Jurassic System (pages 179 and 180) • Cretaceous System (pages 197 - 201, 207 - 210, 215, - 218, 221, 222, 224, 225, and 227). The primary purpose of this publication is to provide regional-scale, as well as local-scale, geospatial data of the Rocky Mountain Region for use in geoscience studies. An important aspect of this interactive map product is that it does not require extensive GIS experience or highly specialized software.

Book↗
USGS2025

Introduction to the special section on improving measurements of earthquake source parameters

Earthquake source parameters such as magnitude, seismic moment, source dimension, stress drop, and radiated energy are fundamental to understanding earthquake physics, and are also key ingredients in earthquake ground‐motion modeling, rupture simulation, and statistical seismology. However, the uncertainties in these parameters estimated from the radiated seismic wavefield are large due to variability in approaches, including site and attenuation characterizations, and so estimates for an individual earthquake made by different studies can vary greatly. Estimating spectral source parameters remains a popular topic, due to a combination of their intrinsic importance and their apparent ease of measurement, but also a controversial one, due to many sources of variability and large uncertainty. The available methods coupled with necessary parameter choices and assumptions in the analysis make it challenging for researchers to apply methods or understand the reliability in results or reported source parameters. This Special Section on Improving Measurements of Earthquake Source Parameters showcasing comparisons between methods and studies seeks to alleviate some of these difficulties to help the community identify the important components and trade‐offs of decomposing recorded seismograms into their source, path, and site components.

Bulletin of the Seismological Society of America↗
USGS2006

Linking the concept of scale to studies of biological diversity: evolving approaches and tools.

Although the concepts of scale and biological diversity independently have received rapidly increasing attention in the scientific literature since the 1980s, the rate at which the two concepts have been investigated jointly has grown much more slowly. We find that scale considerations have been incorporated explicitly into six broad areas of investigation related to biological diversity: (1) heterogeneity within and among ecosystems, (2) disturbance ecology, (3) conservation and restoration, (4) invasion biology, (5) importance of temporal scale for understanding processes, and (6) species responses to environmental heterogeneity. In addition to placing the papers of this Special Feature within the context of brief summaries of the expanding literature on these six topics, we provide an overview of tools useful for integrating scale considerations into studies of biological diversity. Such tools include hierarchical and structural-equation modelling, kriging, variable-width buffers, k -fold cross-validation, and cascading graph diagrams, among others. Finally, we address some of the major challenges and research frontiers that remain, and conclude with a look to the future.

Diversity and Distributions↗
USGS2009

Interbasin flow in the Great Basin with special reference to the southern Funeral Mountains and the source of Furnace Creek springs, Death Valley, California, U.S.

Interbasin flow in the Great Basin has been established by scientific studies during the past century. While not occurring uniformly between all basins, its occurrence is common and is a function of the hydraulic gradient between basins and hydraulic conductivity of the intervening rocks. The Furnace Creek springs in Death Valley, California are an example of large volume springs that are widely accepted as being the discharge points of regional interbasin flow. The flow path has been interpreted historically to be through consolidated Paleozoic carbonate rocks in the southern Funeral Mountains. This work reviews the preponderance of evidence supporting the concept of interbasin flow in the Death Valley region and the Great Basin and addresses the conceptual model of pluvial and recent recharge [Nelson, S.T., Anderson, K., Mayo, A.L., 2004. Testing the interbasin flow hypothesis at Death Valley, California. EOS 85, 349; Anderson, K., Nelson, S., Mayo, A., Tingey, D., 2006. Interbasin flow revisited: the contribution of local recharge to high-discharge springs, Death Valley, California. Journal of Hydrology 323, 276-302] as the source of the Furnace Creek springs. We find that there is insufficient modern recharge and insufficient storage potential and permeability within the basin-fill units in the Furnace Creek basin for these to serve as a local aquifer. Further, the lack of high sulfate content in the spring waters argues against significant flow through basin-fill sediments and instead suggests flow through underlying consolidated carbonate rocks. The maximum temperature of the spring discharge appears to require deep circulation through consolidated rocks; the Tertiary basin fill is of insufficient thickness to generate such temperatures as a result of local fluid circulation. Finally, the stable isotope data and chemical mass balance modeling actually support the interbasin flow conceptual model rather than the alternative presented in Nelson et al. [Nelson, S.T., Anderson, K., Mayo, A.L., 2004. Testing the interbasin flow hypothesis at Death Valley, California. EOS 85, 349] and Anderson et al. [Anderson, K., Nelson, S., Mayo, A., Tingey, D., 2006. Interbasin flow revisited: the contribution of local recharge to high-discharge springs, Death Valley, California. Journal of Hydrology 323, 276-302]. In light of these inconsistencies, interbasin flow is the only readily apparent explanation for the large spring discharges at Furnace Creek and, in our view, is the likely explanation for most large volume, low elevation springs in the Great Basin. An understanding of hydrogeologic processes that control the rate and direction of ground-water flow in eastern and central Nevada is necessary component of regional water-resource planning and management of alluvial and bedrock aquifers.

Journal of Hydrology↗