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At least 1,351 records · Page 75Linked to original sources
USGS2014

Floodplains within reservoirs promote earlier spawning of white crappies Pomoxis annularis

Reservoirs impounded over floodplain rivers are unique because they may include within their upper reaches extensive shallow water stored over preexistent floodplains. Because of their relatively flat topography and riverine origin, floodplains in the upper reaches of reservoirs provide broad expanses of vegetation within a narrow range of reservoir water levels. Elsewhere in the reservoir, topography creates a band of shallow water along the contour of the reservoir where vegetation often does not grow. Thus, as water levels rise, floodplains may be the first vegetated habitats inundated within the reservoir. We hypothesized that shallow water in reservoir floodplains would attract spawning white crappies Pomoxis annularis earlier than reservoir embayments. Crappie relative abundance over five years in floodplains and embayments of four reservoirs increased as spawning season approached, peaked, and decreased as fish exited shallow water. Relative abundance peaked earlier in floodplains than embayments, and the difference was magnified with higher water levels. Early access to suitable spawning habitat promotes earlier spawning and may increase population fitness. Recognition of the importance of reservoir floodplains, an understanding of how reservoir water levels can be managed to provide timely connectivity to floodplains, and conservation of reservoir floodplains may be focal points of environmental management in reservoirs.

Environmental Biology of Fishes↗
USGS2013

Distance, dams and drift: What structures populations of an endangered, benthic stream fish?

Spatial population structure plays an important role in species persistence, evolution and conservation. Benthic stream fishes are diverse and frequently imperilled, yet the determinants and spatial scaling of their population structure are understudied. We investigated the range-wide population genetic structure of Roanoke logperch ( Percina rex ), an endangered, benthic stream fish of the eastern United States. Fish were sampled from 35 sites and analysed at 11 microsatellite DNA loci. Clustering models were used to sort individuals into genetically cohesive groups and thereby estimate the spatial scaling of population structure. We then used Bayesian generalized linear mixed models (BGLMMs) to test alternative hypotheses about the environmental factors most responsible for generating structure, as measured by the differentiation statistic F ST . Clustering models delineated seven discrete populations, whose boundaries coincided with agents of fragmentation, including hydroelectric dams and tailwaters. In the absence of hydrological barriers, gene flow was extensive throughout catchments, whereas there was no evidence for contemporary dispersal between catchments across barriers. In the best-supported BGLMM, F ST was positively related to the spatial distance and degree of hydrological alteration between sites and negatively related to genetic diversity within sites. Whereas the effect of tailwaters was equivocal, dams strongly influenced differentiation: the effect of a dam on F ST was comparable to that of a between-site distance of over 1200 km of unimpounded river. Overall, the effect of distance-mediated dispersal was negligible compared to the combined effects of fragmentation and genetic drift. The contemporary population structure of P. rex comprises a few geographically extensive ‘islands’ that are fragmented by hydroelectric projects. This information clarifies the importance of a catchment-scale perspective on conserving the species and suggests that its recovery may require genetic and/or demographic reconnection of presently isolated populations.

North Carolina, Virginia↗
USGS2017

Songbirds are resilient to hurricane disturbed habitats during spring migration

The Gulf of Mexico is a conspicuous feature of the Neotropical–Nearctic bird migration system. Traveling long distances across ecological barriers comes with considerable risks, and mortality associated with intercontinental migration may be substantial, including that caused by storms or other adverse weather events. However, little, if anything, is known about how migratory birds respond to disturbance-induced changes in stopover habitat. Isolated, forested cheniere habitat along the northern coast of the Gulf of Mexico often concentrate migrants, during weather conditions unfavorable for northward movement or when birds are energetically stressed. We expected hurricane induced degradation of this habitat to negatively affect the abundance, propensity to stopover, and fueling trends of songbirds that stopover in coastal habitat. We used spring banding data collected in coastal Louisiana to compare migrant abundance and fueling trends before (1993–1996 and 1998–2005) and after hurricanes Rita (2006) and Ike (2009). We also characterized changes in vegetative structure before (1995) and after (2010) the hurricanes. The hurricanes caused dramatic changes to the vegetative structure, which likely decreased resources. Surprisingly, abundance, propensity to stopover, and fueling trends of most migrant species were not influenced by hurricane disturbance. Our results suggest that: 1) the function of chenieres as a refuge for migrants after completing a trans-Gulf flight may not have changed despite significant changes to habitat and decreases in resource availability, and 2) that most migrants may be able to cope with habitat disturbance during stopover. The fact that migrants use disturbed habitat points to their conservation value along the northern coast of the Gulf of Mexico.

Louisiana↗
USGS2001

Status of shallow-aquifer mapping in the Northern Front Range Area, Colorado

Mapping of shallow aquifers in the northern Front Range area of Colorado has been completed as part of the U.S. Geological Survey Front Range Infrastructure Resources Project. The aquifer mapping was undertaken as part of a comprehensive effort to better define the mineral, energy, cartographic, biological, and water resources that are critical to the support and development of the area's infrastructure, such as streets. highways, airports, and buildings. The aquifer mapping was undertaken in cooperation with the Colorado Division of Water Resources and the Colorado Water Conservation Board. The shallow aquifers have been mapped in a 2,450-square-mile area extending as an approximately 30-mile-wide band from north of Fort Collins to the Arapahoe-Douglas County line south of Denver (fig. I). The shallow aquifer mapping in the Denver metropolitan area was published in 1996 as Hydrologic Investigations Atlas HA-736 (Robson. 1996). Shallow aquifer mapping in the Greeley-Nunn area was published as HA-746A (Robson, Arnold, and Heiny, 2000a); mapping in the Fort Collins-Loveland area was published as HA-746B (Robson, Arnold, and Heiny, 2000b); mapping in the Fort Lupton-Gilcrest area was published as HA-746C (Robson, Heiny, and Arnold, 2000c); and mapping in the Boulder-Longmont area was published as HA-746D (Robson, Heiny, and Arnold, 2000d). Each of the five atlases contains five map sheets at 1:50,000 scale showing: 1. The thickness and extent of the unconsolidated sediments (loose gravel. sand. silt, and clay) that overlie the bedrock formations in the area (fig. 2). 2. The altitude and configuration of the bedrock surface. 3. The altitude of the water table and direction of ground-water movement. 4. The saturated thickness of the shallow aquifers. 5. The depth to the water table in the shallow aquifers.

Fact Sheet↗
USGS2004

Cloning, expression, cellular distribution, and role in chemotaxis of a C5a receptor in rainbow trout: The first identification of a C5a receptor in a nonmammalian species

C3a, C4a, and C5a anaphylatoxins generated during complement activation play a key role in inflammation. C5a is the most potent of the three anaphylatoxins in eliciting biological responses. The effects of C5a are mediated by its binding to C5a receptor (C5aR, CD88). To date, C5aR has only been identified and cloned in mammalian species, and its evolutionary history remains ill-defined. To gain insights into the evolution, conserved structural domains, and functions of C5aR, we have cloned and characterized a C5aR in rainbow trout, a teleost fish. The isolated cDNA encoded a 350-aa protein that showed the highest sequence similarity to C5aR from other species. Genomic analysis revealed the presence of one continuous exon encoding the entire open reading frame. Northern blot analysis showed significant expression of the trout C5a receptor (TC5aR) message in PBLs and kidney. Flow cytometric analysis showed that two Abs generated against two different areas of the extracellular N-terminal region of TC5aR positively stained the same leukocyte populations from PBLs. B lymphocytes and granulocytes comprised the majority of cells recognized by the anti-TC5aR. More importantly, these Abs inhibited chemotaxis of PBLs toward a chemoattractant fraction purified from complement-activated trout serum. Our data suggest that the split between C5aR and C3aR from a common ancestral molecule occurred before the emergence of teleost fish. Moreover, we demonstrate that the overall structure of C5aR as well as its role in chemotaxis have remained conserved for >300 million years.

Journal of Immunology↗
USGS1996

Integrating research and management to conserve wildfowl (Anatidae) and wetlands in the Mississippi Alluvial Valley, U.S.A

Efforts to conserve winter habitat for wildfowl, Anatidae, in the alluvial valley of the lower Mississippi River, U.S.A., are directed by the Lower Mississippi Valley (LMV) Joint Venture of the North American Waterfowl Management Plan (NA WMP). The Joint Venture is based on a biological framework developed through cooperative planning by wildfowl researchers and managers. Important elements of the framework include: (1) numeric population goals, (2) assumptions about potential limiting factors, (3) explicit relationships between wildfowl abundance and habitat characteristics, (4) numeric foraging habitat goals, and (5) criteria for evaluating success. The population goal of the Joint Venture for the Mississippi Alluvial Valley (MA V) is to enable 4.3 million ducks to, survive winter and join continental breeding populations in spring. Currently, available data suggest that foraging habitat is the primary factor limiting duck populations in the MA II. To establish a goal for foraging habitat, we assumed the length of the wintering period is 110 days and calculated that a population of 4.3 million breeding ducks (plus 15% to account for winter mortality) would need 546 million duck-days of food in the preceding winter. Then, we used estimates of daily energy requirements, food densities, and food energy values to calculate the carrying capacity or number of duck-days of food available in the three primary foraging habitats in the MAV (flooded croplands, forested wetlands, and moist-soil wetlands). Thus, availability of foraging habitat can be used as a criterion for evaluating success of the Joint Venture if accurate inventories of foraging habitat can be conducted. Development of an explicit biological framework for the Joint Venture enabled wildfowl managers and researchers to establish specific objectives for management of foraging habitat and identify priority problems requiring further study.

Book chapter↗
USGS2009

Critical uncertainties and research needs for the restoration and conservation of native lampreys in North America

We briefly reviewed the literature, queried selected researchers, and drew upon our own experience to describe some critical uncertainties and research needs for the conservation and restoration of native lampreys in North America. We parsed the uncertainties and research needs into five general categories: (1) population status; (2) systematics; (3) passage at dams, screens, and other structures; (4) species identification in the field; and (5) geneal biology and ecology. For each topic, we describe why the subject is important for lampreys, briefly smmarize our current state of knowledge, and discuss the key data or information gaps.

American Fisheries Society Symposium↗
USGS1999

Behaviour and ecology of sea ducks

In November 1995... a full-day symposium on the biology of sea ducks was held. The papers in this volume were presented at this symposium. It is hoped that by synthesizing this information, more informed management decisions for sea ducks may emerge. The symposium contents help to emphasize the seriousness of some conservation issues facing sea ducks, notably the possible endangerment of the eastern population of Barrow's Goldeneye and the dwindling number of eider ducks in the Nearctic, while also providing new data on the behaviour and habitat use of this beautiful group of ducks.

Occasional Paper of the Canadian Wildlife Service↗
USGS2017

Small-scale genetic structure in an endangered wetland specialist: possible effects of landscape change and population recovery

The effects of anthropogenic landscape change on genetic population structure are well studied, but the temporal and spatial scales at which genetic structure can develop, especially in taxa with high dispersal capabilities like birds, are less well understood. We investigated population structure in the Hawaiian gallinule ( Gallinula galeata sandvicensis ), an endangered wetland specialist bird on the island of O`ahu (Hawai`i, USA). Hawaiian gallinules have experienced a gradual population recovery from near extinction in the 1950s, and have recolonized wetlands on O`ahu in the context of a rapidly urbanizing landscape. We genotyped 152 Hawaiian gallinules at 12 microsatellite loci and sequenced a 520 base-pair fragment of the ND2 region of mitochondrial DNA (mtDNA) from individuals captured at 13 wetland locations on O`ahu in 2014–2016. We observed moderate to high genetic structuring (overall microsatellite F ST = 0.098, mtDNA F ST = 0.248) among populations of Hawaiian gallinules occupying wetlands at very close geographic proximity (e.g., 1.5–55 km). Asymmetry in gene flow estimates suggests that Hawaiian gallinules may have persisted in 2–3 strongholds which served as source populations that recolonized more recently restored habitats currently supporting large numbers of birds. Our results highlight that genetic structure can develop in taxa that are expanding their range after severe population decline, and that biologically significant structuring can occur over small geographic distances, even in avian taxa.

Hawai'i↗
USGS2025

Forecasting sea otter recolonization: Insights from isotopic analysis of modern and zooarchaeological populations

Retrospective datasets offer essential context for conservation by revealing species’ ecological roles before industrial-era human impacts. We analysed isotopic compositions of pre-industrial and modern sea otters ( Enhydra lutris ) to reconstruct pre-extirpation ecology and offer insights for management. Our study focuses on southeast Alaska (SEAK), where sea otters are recolonizing, and northern Oregon, where translocations are being considered. We measured bulk bone collagen δ 13 C and δ 15 N values and essential amino acid δ 13 C values of extirpated sea otters from archaeological contexts, and bulk isotopic values from vibrissae of modern SEAK sea otters. We compare these results with published isotopic data of potential prey and additional archaeological datasets. In SEAK, our data show pre-industrial sea otter populations consumed infaunal bivalves and used soft-sediment (33%) and kelp forest habitats (67%), with sub-regional variation. We anticipate current populations will expand into this historical niche, and conflict with regional traditional/subsistence bivalve fisheries will persist. In northern Oregon, isotopic data from extirpated sea otters indicate past consumption of low trophic level invertebrates and a stronger reliance on kelp forests (88%) rather than soft-sediment habitats, highlighting the importance of kelp forests for future translocations. Our work exemplifies the value of historical ecology in informing conservation strategies for recovering species.

Alaska, Oregon↗
USGS2023

Fish functional gradients along a reservoir cascade

1.The transformations of fish assemblages caused by reservoir cascades can be severe at the reach scale, but basin-scale effects are less clear. However, prevailing river concepts provide a framework for predicting basin-scale effects. 2. To determine if predictions made by the River Continuum Concept relative to the function of fish assemblages are sustained in a temperate river transformed into a reservoir cascade, we examined longitudinal trends in the distribution of fish functional traits over 23 reservoirs of the Tennessee River, USA. 3. In all, 115 species were recorded representing 62 traits, with trait richness increasing longitudinally in a downstream direction. Trophic, reproductive, and habitat traits showed various increasing and decreasing patterns up and down the reservoir cascade. The observed gradients in trait richness and trait distributions were generally consistent with those expected in unregulated rivers, with few unexpected results. 4. The transformation of lotic systems into lentic ones has changed habitats and sources of food and encouraged the proliferation of certain feeding (e.g., detritivores, planktivores, invertivores, piscivores), reproduction (e.g., nest spawners polyphils, broadcast spawners phytolithophils), and habitat (slow current, lacustrine, large river) traits. In essence, reservoirs have expanded downstream habitats in an upstream direction, and thus allowed upstream expansion of species and traits that would have normally not been well represented in upper reaches of the Tennessee River basin. Nevertheless, the impounded Tennessee River has maintained much of its functional integrity, despite extensive alterations to the riverscape. 5. We suggest that while reservoirs have been shown to have major local-scale effects on riverine fish assemblages, with access to riverine habitats, and with proactive conservation strategies, fish functional richness can remain remarkably high at the basin scale.

Alabama, Georgia, Kentucky, North Carolina, South ↗
USGS1981

Surface-water quality, Twin Ponies watershed, Pottawattamie and Mills Counties, Iowa

Existing surface-water quality in the Twin Ponies watershed is significantly affected by runoff from agricultural lands that comprise most of the area. Runoff effects include the addition of phosphate, organic nitrogen, fecal bacteria, trace metals, pesticides and notably suspended sediment to streaMflow, because runoff commonly is a transport mechanism for these constituents. Low-flow water quality generally is characterized by dissolvedoxygen concentrations near saturation, dissolved-solids concentrations of about 450 milligrams per liter, suspendedsediment concentrations less than 200 milligrams per liter, and a pH of 8.2. However~ samples collected during runoff contained biological and chemical concentrations 10 to 30 times greater than concentrations obtained from samples collected during periods of low flow. Suspended-sediment concentrations obtained during runoff ranged froM 1,000 to 7,000 milligrams per liter. Iowa Class "B" standards for dissolved oxygen, ammonia, fecal coliforms, chromium, copper, lead, and mercury in streams were exceeded in numerous samples collected during runoff. It is probable that the variations between constituent concentrations in samples collected during runoff and those collected during low flow will be similar after grade-stabilization structures have been constructed on streams and after land-treatment measures have been implemented in the watershed as proposed by the U.S. Soil Conservation Service. Grade-stabilization structures should reduce gully and channel erosion in the watershed by dissipating the erosive energy of streamflow during significant runoff. Land-treatment measures to be implemented in conjunction with the project would help reduce sediment yield to stream channels. With the impoundments~ a decrease in velocity of the in-flowing water should produce a decrease of both the suspended~sediment concentrations and the chemical and biological constituents associated with the suspended sediMent in the impounded water.

Iowa↗
USGS2019

Estimating offsets for avian displacement effects of anthropogenic impacts

Biodiversity offsetting, or compensatory mitigation, is increasingly being used in temperate grassland ecosystems to compensate for unavoidable environmental damage from anthropogenic developments such as transportation infrastructure, urbanization, and energy development. Pursuit of energy independence in the United States will expand domestic energy production. Concurrent with this increased growth is increased disruption to wildlife habitats, including avian displacement from suitable breeding habitat. Recent studies at energy-extraction and -generation facilities have provided evidence for behavioral avoidance and thus reduced use of habitat by breeding waterfowl and grassland birds in the vicinity of energy infrastructure. To quantify and compensate for this loss in value of avian breeding habitat, it is necessary to determine a biologically-based currency so that the sufficiency of offsets in terms of biological equivalent value can be obtained. We describe a method for quantifying the amount of habitat needed to provide equivalent biological value for avifauna displaced by energy and transportation infrastructure, based on the ability to define five metrics: impact distance, impact area, pre-impact density, percent displacement, and offset density. We calculate percent displacement values for breeding waterfowl and grassland birds and demonstrate the applicability of our avian-impact offset method using examples for wind and oil infrastructure. We also apply our method to an example in which the biological value of the offset habitat is similar to the impacted habitat, based on similarity in habitat type (e.g., native prairie), geographical location, land use, and landscape composition, as well as to an example in which the biological value of the offset habitat is dissimilar to the impacted habitat. We provide a worksheet that informs potential users how to apply our method to their specific developments and a framework for developing decision-support tools aimed at achieving landscape-level conservation goals.

Ecological Applications↗
USGS2016

Body size distributions signal a regime shift in a lake ecosystem

Communities of organisms, from mammals to microorganisms, have discontinuous distributions of body size. This pattern of size structuring is a conservative trait of community organization and is a product of processes that occur at multiple spatial and temporal scales. In this study, we assessed whether body size patterns serve as an indicator of a threshold between alternative regimes. Over the past 7000 years, the biological communities of Foy Lake (Montana, USA) have undergone a major regime shift owing to climate change. We used a palaeoecological record of diatom communities to estimate diatom sizes, and then analysed the discontinuous distribution of organism sizes over time. We used Bayesian classification and regression tree models to determine that all time intervals exhibited aggregations of sizes separated by gaps in the distribution and found a significant change in diatom body size distributions approximately 150 years before the identified ecosystem regime shift. We suggest that discontinuity analysis is a useful addition to the suite of tools for the detection of early warning signals of regime shifts.

Proceedings of the Royal Society B↗
USGS2003

Application of ecological criteria in selecting marine reserves and developing reserve networks

Marine reserves are being established worldwide in response to a growing recognition of the conservation crisis that is building in the oceans. However, designation of reserves has been largely opportunistic, or protective measures have been implemented (often overlapping and sometimes in conflict) by different entities seeking to achieve different ends. This has created confusion among both users and enforcers, and the proliferation of different measures provides a false sense of protection where little is offered. This paper sets out a procedure grounded in current understanding of ecological processes, that allows the evaluation and selection of reserve sites in order to develop functional, interconnected networks of fully protected reserves that will fulfill multiple objectives. By fully protected we mean permanently closed to fishing and other resource extraction. We provide a framework that unifies the central aims of conservation and fishery management, while also meeting other human needs such as the provision of ecosystem services (e.g., maintenance of coastal water quality, shoreline protection, and recreational opportunities). In our scheme, candidate sites for reserves are evaluated against 12 criteria focused toward sustaining the biological integrity and productivity of marine systems at both local and regional scales. While a limited number of sites will be indispensable in a network, many will be of similar value as reserves, allowing the design of numerous alternative, biologically adequate networks. Devising multiple network designs will help ensure that ecological functionality is preserved throughout the socioeconomic evaluation process. Too often, socioeconomic criteria have dominated the process of reserve selection, potentially undermining their efficacy. We argue that application of biological criteria must precede and inform socioeconomic evaluation, since maintenance of ecosystem functioning is essential for meeting all of the goals for reserves. It is critical that stakeholders are fully involved throughout this process. Application of the proposed criteria will lead to networks whose multifunctionality will help unite the objectives of different management entities, so accelerating progress toward improved stewardship of the oceans.

Ecological Applications↗
USGS2015

Vegetation community response to tidal marsh restoration of a large river estuary

Estuaries are biologically productive and diverse ecosystems that provide ecosystem services including protection of inland areas from flooding, filtering freshwater outflows, and providing habitats for fish and wildlife. Alteration of historic habitats, including diking for agriculture, has decreased the function of many estuarine systems, and recent conservation efforts have been directed at restoring these degraded areas to reestablish their natural resource function. The Nisqually Delta in southern Puget Sound is an estuary that has been highly modified by restricting tidal flow, and recent restoration of the delta contributed to one of the largest tidal salt marsh restorations in the Pacific Northwest. We correlated the response of nine major tidal marsh species to salinities at different elevation zones. Our results indicated that wetland species richness was not related to soil pore-water salinity (R2 = 0.03), but were stratified into different elevation zones (R2 = 0.47). Thus, restoration that fosters a wide range of elevations will provide the most diverse plant habitat, and potentially, the greatest resilience to environmental change.

Washington↗
USGS2025

Book review: Ecology of Dakota landscapes: Past, present, and future, by W. Carter Johnson and Dennis H. Knight

“Ecology of Dakota Landscapes” is an excellent example of fusing observation and scientific studies to describe the origins and development of the landscape of North and South Dakota, the impact of European settlement, the introduction of agriculture to the area, predictions for the future in the face of a changing climate, and a scientific framework for conservation and sustainability. Johnson and Knight bring to this book a personal fascination with this landscape. Their decades of experience and knowledge of the ecosystems of the Dakotas is exhibited in the well written and copiously illustrated thirteen chapters. This book blends observation, geology, biology, ecology, history, the transformation of this landscape by European settlement, and identifies the challenges that will be faced with climate change. Johnson and Knight are master storytellers that allow them to present these important concepts and ideas to a general audience.

Prairie Naturalist↗
USGS2004

Writing refuge management goals and objectives: a handbook

Goals and objectives are the unifying elements of successful refuge management. They identify and focus management priorities, provide a context for resolving issues, guide specific projects, provide rationale for decisions, and offer a defensible link among management actions, refuge purpose(s), Service policy, and the National Wildlife Refuge System (Refuge System) mission. Pursuant to Refuge Planning Policy (602 FW 1, 3, 4), this handbook offers guidance on how to write goals and objectives for national wildlife refuges and provides counsel on their development. While the handbook specifically addresses biology and visitor services, you can also utilize this guidance when developing goals and objectives for other refuge programs. Several assumptions are basic to this handbook. The handbook focuses on the mechanics of writing sound goals and objectives. Detailed guidance on what information to consider, collect, interpret, and synthesize into goals and objectives is beyond the scope of this handbook. It views a vision statement as the synthesis of a refuge’s purpose(s), the Refuge System mission and goals, and other biological, legal, and social concerns in which the refuge has a role. It also assumes a familiarity with the hierarchical nature of planning and where, within a planning process, the writing of goals and objectives occurs. This guidance applies to conceptual management plans, comprehensive conservation plans (CCPs), step-down management plans (e.g., habitat management, visitor services, fire management), or any other planning document incorporating goals and objectives, including strategic documents developed under the Government Performance and Results Act. We intend this guidance for use by an internal audience tasked with writing refuge goals and objectives, primarily refuge managers, biologists, visitor services specialists, planners, and other members of refuge planning teams. Still, it recognizes that we should write goals and objectives so that interested members of the public can understand them, to the extent this does not jeopardize the technical accuracy or reduce the inclusion of necessary information. The terminology and definitions used in this handbook are widely accepted in the planning field and are not inconsistent with more recent application in strategic planning. Perhaps most important, the handbook presumes all goals and objectives must further the specific purpose(s) of the refuge and the broader mission of the Refuge System, as well as be consistent with Refuge Planning Policy and any other relevant Service policy and directives.

Report↗