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At least 451 records · Page 25Linked to original sources
USGS2012

Assessing fish predation on migrating juvenile steelhead and a retrospective comparison to steelhead survival through the Priest Rapids Hydroelectric Project, Columbia River, Washington, 2009-11

The U.S. Geological Survey (USGS) and the Washington Department of Fish and Wildlife (WDFW) have been working with the Public Utility District No. 2 of Grant County, Washington (Grant PUD), to increase their understanding of predator-prey interactions in the Priest Rapids Hydroelectric Project (PRP), Columbia River, Washington. For this study, the PRP is defined as the area approximately 6 kilometers upstream of Wanapum Dam to the Priest Rapids Dam tailrace, 397.1 miles from the mouth of the Columbia River. Past year’s low survival numbers of juvenile steelhead ( Oncorhynchus mykiss ) through Wanapum and Priest Rapids Dams has prompted Grant PUD, on behalf of the Priest Rapids Coordinating Committee, to focus research efforts on steelhead migration and potential causal mechanisms for low survival. Steelhead passage survival in 2009 was estimated at 0.944 through the Wanapum Development (dam and reservoir) and 0.881 through the Priest Rapids Development and for 2010, steelhead survival was 0.855 for Wanapum Development and 0.904 for Priest Rapids Development. The USGS and WDFW implemented field collection efforts in 2011 for northern pikeminnow ( Ptychocheilus oregonensis ), smallmouth bass ( Micropterus dolomieu ), and walleye ( Sander vitreus , formerly Stizostedion vitreum ) and their diets in the PRP. For predator indexing, we collected 948 northern pikeminnow, 237 smallmouth bass, 18 walleye, and two largemouth bass ( Micropterus salmoides ). The intent of this study was to provide standardized predation indices within individual reaches of the PRP to discern spatial variability in predation patterns. Furthermore, the results of the 2011 study were compared to results of a concurrent steelhead survival study. Our results do not indicate excessively high predation of Oncorhynchus spp. occurring by northern pikeminnow or smallmouth bass in any particular reach throughout the study area. Although we found Oncorhynchus spp. in the predator diets, the relative proportion was small. Predation index values in 2011 were highest in the Priest Rapids mid-reservoir reach for northern pikeminnow and smallmouth bass. Predation indices generally were high in the tailrace areas for northern pikeminnow, and high in the forebay areas for smallmouth bass. Steelhead survival in 2011 was consistently high throughout the study period and the PRP, although predation indices were relatively low, which suggests that fish predation did not significantly affect steelhead survival throughout the study area. Our efforts to correlate retrospective predation indices with survival estimates for 2009 and 2010 did provide some evidence for high predation occurring in some of the same reaches, which had low steelhead survival, such as the Priest Rapids tailrace in 2009. However, for 2010, our results indicated that the loss of salmonids to predation were more contradictory to the survival results, where predation indices were higher for reaches in the Priest Rapids Development than in the Wanapum Development. Establishing correlations between steelhead survival and observed predation indices for previous research years, in 2009 and 2010 was confounded by the lack of coordination of these two studies during the initial study design, implementation period for such an analysis. Future efforts to correlate steelhead survival with fish predation would benefit from efforts to better coordinate the studies with consistent study reaches, and better timing of concurrent efforts.

Washington↗
USGS2023

Evaluating brook trout egg and alevin survival at different temperatures in simulated karst environments with marl sedimentation

Brook trout ( Salvelinus fontinalis ) have been extirpated from many karst-geology streams in West Virginia; however, the causes are not fully understood. Specifically, the impact of calcareous precipitate (marl), which is common in hard-water environments, has not been evaluated as an im- pediment to juvenile survival. Accordingly, two lab-based studies were conducted to determine if brook trout egg and alevin survival is inhibited by marl. In the first study, three aeration treatments were applied to water from a limestone spring source (13–14 C; ~300 mg L–1 hardness), resulting in different pH levels and an increasing degree of marl precipitate. Treatments included raw/untreated (RU; no marl), once-aerated (OA; limited marl), and continuously aerated (CA; significant marl) water. Brook trout eggs obtained from a local hatchery were fertilized and stocked among gravel-filled trays receiving each water type. Mortality occurred faster in CA water where marl coated egg surfaces, but cumulative survival was negligible for all water types. After 53 days, no surviving alevins remained in RU or CA, and 1% survival was observed in OA water. However, extra eggs maintained in a marl-producing system at 8 C without gravel demonstrated >50% survival. A second study was carried out to investigate this discrepancy. Survival was evaluated at three temperatures with and without gravel while producing a thin coating of marl. Increased prevalence of alevin deformities and significantly lower survival were observed at 13.7 C versus 8.1 and 11.2 C, but gravel inclusion did not affect these variables. Potentially harmful effects of marl were observed; however, juvenile brook trout survival was higher during Study 2. This research suggests that brook trout reintroduction efforts in karst-geology streams should be focused on microhabitats with limited marl production and adequate water temperatures for juvenile survival.

Journal of the Southeastern Association of Fish an↗
USGS2020

Catalogue of polar bear (Ursus maritimus) maternal den locations in the Beaufort and Chukchi Seas and nearby areas, 1910–2018

This report presents data on the approximate locations and methods of discovery of 530 polar bear ( Ursus maritimus ) maternal dens observed in the Beaufort and Chukchi Seas and neighboring areas from 1910 to 2018, and archived partly by the U.S. Geological Survey, Alaska Science Center, and partly by the U.S. Fish and Wildlife Service, Marine Mammals Management, in Anchorage, Alaska. A description of data collection methods and their associated biases, primary data collection time periods, and estimated position uncertainty are provided. Polar bears in the Beaufort and Chukchi Seas den on sea ice and land. Standardized very high frequency (VHF) aircraft surveys and satellite radio telemetry data provide a general understanding of where polar bears have denned in this region over the past 3 decades. Den observations made during other research activities and anecdotal reports from other government agencies, coastal residents, and industry personnel also are reported. These data on past polar bear maternal den locations are provided to inform decision making by natural resource agencies and for public use.

Alaska↗
USGS2022

The gap between experts, farmers and non-farmers on perceived environmental vulnerability and the influence of values and beliefs

Science has played a mixed role in guiding conservation and sustainability-oriented decision-making by individuals, policymakers, institutions, and governments. Not all science-based conservation and sustainability initiatives that address issues facing humanity and ecosystems and global problems have gained public support. Conservation decisions and policy prescriptions are and may be based on perceptions about and experiences with the environment, local land use, and ecosystems that may not align with or be grounded in science or evidence from experts in the field. Values, beliefs, and perceptions associated with nature play a critical role in how individuals view biodiversity conservation, sustainability, and natural resource management . This study first examines the gap between experts (scientists and other field experts) and the public (farmers and non-farmers) about the state of water and land resources, wildlife and associated habitats, and aquatic biodiversity in the Smoky Hill River Watershed in western Kansas. Second, the study examines the role that values and beliefs play in shaping environmental perceptions for farmers and non-farmers. Analysis confirms that a gap between experts and farmers/non-farmers does exist, especially with respect to the state of the Ogallala Aquifer, playas, rivers and streams, lakes and reservoirs, native grasslands, wildlife habitats, farmland, native fish populations, and wildlife species. Ordered-logistic regression analyses, meanwhile, indicate that farmer and non-farmer perceptions about the state of the local environment are influenced by traditional and self-interested values, as well as environmental values and beliefs, but less so by religiosity and political ideology. Despite broad takeaways, results exhibited heterogeneity across the farmer and non-farmer subpopulations. If environmental professionals cannot align ecological data, stakeholders’ values/perceptions, and policies, then the existing body of technical research and management on sustainability in natural and social sciences may be of little value.

Journal of Environmental Management↗
USGS2005

Post-harvest field manipulations to conserve waste rice for waterfowl

Rice seeds escaping collection by combines during harvest (hereafter, waste rice) provide quality forage for migrating and wintering waterfowl in the Lower Mississippi Alluvial Valley (MAV) and other rice growing regions in the United States. Recent sample surveys across the MAV have revealed abundance of waste rice in fields declined an average of 71% between harvest and late autumn. Thus, we evaluated the ability of common post-harvest, field-management practices to conserve waste rice for waterfowl until early winter via controlled experiments in Mississippi rice test plots in 2001 and 2003 and analyses of data from MAV-wide surveys of waste rice in rice production fields in 2000-2002. Our experiments indicated test plots with burned rice stubble that were not flooded during autumn contained more waste rice than other treatments in 2001 (P?0.10). Waste-rice abundance in test plots did not differ among postharvest treatments in 2003 (P = 0.97). Our analyses of data from the MAV sample surveys did not detect differences in abundance of waste rice among fields burned, rolled, disked, or left in standing stubble post-harvest (P?0.04; Bonferroni corrected critical ( a= 0.017). Because results from test-plot experiments were inconclusive, we based our primary inference regarding best post-harvest treatments on patterns of rice abundance identified from the MAV surveys and previously documented environmental and agronomic benefits of managing harvested rice fields for wintering waterfowl. Therefore, we recommend leaving standing stubble in rice fields after harvest as a preliminary beneficial management practice. We suggest future research evaluate potential of postharvest practices to conserve waste rice for waterfowl and reduce straw in production rice fields managed for wintering waterfowl throughout the MAV.

Proceedings of the Annual Conference of the Southe↗
USGS2019

Scientific Framework for resilience research on the Upper Mississippi River System

The goal of this research framework is to outline research that would continue to improve our understanding of ecological resilience of the Upper Mississippi River System (UMRS) and inform management of the system for health and resilience. We provide a broad overview of recently completed and ongoing work that has been funded as a part of the UMRS Ecological Resilience Assessment and related efforts to provide context for how proposed research questions build upon our current knowledge and may inform restoration planning and design. We describe two primary objectives within this research framework - the first objective is to investigate hypothesized drivers and feedbacks related to specified resilience, and the second is to expand our utility of general resilience indicators through further development and evaluation. The intended audience for this framework is the Upper Mississippi River Restoration Program (UMRR). The UMRR partnership is made up of natural resource agencies from five states (Illinois, Iowa, Minnesota, Missouri and Wisconsin) and five federal agencies (U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, U.S. Geological Survey, and USDA Natural Resources Conservation Service).

Illinois, Iowa, Minnesota, Missouri, Wisconsin↗
USGS2020

Linking monitoring and data analysis to predictions and decisions for the range-wide eastern black rail status assessment

The US Fish and Wildlife Service has initiated a re-envisioned approach for providing decision makers with the best available science and synthesis of that information, called the Species Status Assessment (SSA), for endangered species decision making. The SSA report is a descriptive document that provides decision makers with an assessment of a species’ current status and predicted future status. These analyses support all manner of decisions under the US Endangered Species Act, such as listing, reclassification, recovery planning, etc. Novel scientific analysis and predictive modeling in SSAs could be an important part of rooting species conservation decisions in current data and cutting edge analytical and modeling techniques. Here we describe a novel analysis of available data to assess current condition of eastern black rail across its range in a dynamic occupancy analysis. We used the results of the analysis to develop a site occupancy projection model where the model parameters (initial occupancy, site persistence, colonization) were linked to environmental covariates, such as land management and land cover change (sea-level rise, development, etc.). We used the projection model to predict future conditions under multiple sea-level rise and habitat management scenarios. Occupancy probability and site colonization were low in all analysis units and site persistence was also low, suggesting low resiliency and redundancy currently. Extinction probability was high for all analysis units in all simulated scenarios except one with significant effort to preserve existing habitat, suggesting low future resiliency and redundancy. With results of these data analyses and predictive modeling, the US Fish and Wildlife Service concluded that protections of the Endangered Species Act were warranted for this subspecies.

Endangered Species Research↗
USGS1985

Improving waterfowl production estimates: Results of a test in the prairie pothole region

The U.S. Fish and Wildlife Service in an effort to improve and standardize methods for estimating waterfowl production tested a new technique in the four-county Arrowwood Wetland Management District (WMD) for three years (1982-1984). On 14 randomly selected 10.36 km2 plots, upland and wetland habitat was mapped, classified, and digitized. Waterfowl breeding pairs were counted twice each year and the proportion of wetland basins containing water was determined. Pair numbers and habitat conditions were entered into a computer model developed by Northern Prairie Wildlife Research Center. That model estimates production on small federally owned wildlife tracts, federal wetland easements, and private land. Results indicate that production estimates were most accurate for mallards (Anas platyrhynchos), the species for which the computer model and data base were originally designed. Predictions for the pintail (Anas acuta), gadwall (A. strepa), blue-winged teal (A. discors), and northern shoveler (A. clypeata) were believed to be less accurate. Modeling breeding period dynamics of a waterfowl species and making credible production estimates for a geographic area are possible if the data used in the model are adequate. The process of modeling the breeding period of a species aids in locating areas of insufficient biological knowledge. This process will help direct future research efforts and permit more efficient gathering of field data.

International Congress of Game Biologists↗
USGS2026

How hunters and non-hunters view barriers to allowing hunting access in an urban county

Barriers to allowing hunting of white-tailed deer ( Odocoileus virginianus ) on private land shape hunter recruitment, retention, and reactivation efficacy as well as the ability of wildlife management agencies to use hunting as a management tool. Understanding perceptions of these barriers is crucial in urbanizing landscapes where there are increased challenges to allowing hunting access, and deer may persist in relatively high numbers. We compared barriers to allowing hunting access on one’s property among hunters (n = 281) and non-hunters (n = 874) who did not have hunting occur on their property across urban, suburban, and rural groups in Durham County, North Carolina. (i.e., six groups). Rural landowners tended to perceive geographic barriers (e.g., property size) as less problematic than suburban and urban landowners, irrespective of personal participation in hunting, but landowners who hunted tended to view all barriers as less problematic than those who did not. Small property size, human population density, and housing density were viewed as important barriers to allowing hunting access for all groups, but suburban and urban non-hunters perceived the challenges as greater barriers compared to other groups. Conversely, the complexity of hunting regulations was viewed as a minor barrier to allowing hunting among all landowners. Safety concerns, not knowing other hunters, and disagreement with hunting as a practice showed the greatest contrasts between landowners who hunted and those who did not, with the latter group reporting the barriers as more important. Barriers to hunting identified in this study aligned with variables that predicted whether land is huntable (e.g., property size, housing density) in prior research. Our results indicate that developing public outreach highlighting hunting safety and creating landowner-hunter partnership programs may help facilitate hunting access in urbanizing areas.

North Carolina↗
USGS2018

A critical time for mercury science to inform global policy

Mercury is a global pollutant released into the biosphere by varied human activities including coal combustion, mining, artisanal gold mining, cement production, and chemical production. Once released to air, land and water, the addition of carbon atoms to mercury by bacteria results in the production of methylmercury, the toxic form that bioaccumulates in aquatic and terrestrial food chains resulting in elevated exposure to humans and wildlife. Global recognition of the mercury contamination problem has resulted in the Minamata Convention on Mercury, which came into force in 2017. The treaty aims to protect human health and the environment from human-generated releases of mercury curtailing its movement and transformations in the biosphere. Coincident with the treaty’s coming into force, the 13th International Conference of Mercury as a Global Pollutant (ICMGP-13) was held in Providence, Rhode Island USA. At ICMGP-13, cutting edge research was summarized and presented to address questions relating to global and regional sources and cycling of mercury, how that mercury is methylated, the effects of mercury exposure on humans and wildlife, and the science needed for successful implementation of the Minamata Convention. Human activities have the potential to enhance mercury methylation by remobilizing previously released mercury, and increasing methylation efficiency. This synthesis concluded that many of the most important factors influencing the fate and effects of mercury and its more toxic form, methylmercury, stem from environmental changes that are much broader in scope than mercury releases alone. Alterations of mercury cycling, methylmercury bioavailability and trophic transfer due to climate and land use changes remain critical uncertainties in effective implementation of the Minamata Convention. In the face of these uncertainties, important policy and management actions are needed over the short-term to support the control of mercury releases to land, water and air. These include adequate monitoring and communication on risk from exposure to various forms of inorganic mercury as well as methylmercury from fish and rice consumption. Successful management of global and local mercury pollution will require integration of mercury research and policy in a changing world.

Environmental Science & Technology↗
USGS2015

U.S. Geological Survey Chesapeake science strategy, 2015-2025—Informing ecosystem management of America’s largest estuary

Executive Summary The U.S. Geological Survey (USGS) has the critical role of providing scientific information to improve the understanding and management of the Chesapeake Bay ecosystem. The USGS works with Federal, State, and academic science partners to provide research and monitoring, and communicate results of these activities to enhance ecosystem management for both the Chesapeake and other National ecosystems. The USGS Chesapeake Science Strategy was prepared to guide science activities to address the Chesapeake Bay Watershed Agreement (2014–2025), to support the Department of the Interior (DOI) involvement in the Bay restoration efforts, and align with the USGS Mission Area (MA) Science strategies. The Chesapeake Bay is our Nation’s largest estuary, and provides critical goods and services to the people, fish, and wildlife that use the 64,000-square-mile watershed. The Chesapeake Bay watershed contains over 3,600 species of fish, wildlife, and plants and provides spawning grounds for many ecologically and economically important species including striped bass and blue crabs. The Bay watershed lies in the heart of the Atlantic Flyway and has 29 species of waterfowl, about 1 million of which winter in the region. The size of the Chesapeake seafood harvest is third in the Nation, only behind the Atlantic and Pacific Oceans. Along with agricultural production, tourism, and recreation, the estimated economic value of the services from the Chesapeake Bay watershed is about $100 billion annually. However, the health of the Bay ecosystem began to decline at the beginning of the 20th century due to overfishing and increasing human population and associated land change. The Chesapeake Bay Program (CBP) is the Federal-State cooperative effort that started in 1983 to restore the Bay and watershed. Given the ecological and economic importance of the Chesapeake ecosystem, President Obama issued an Executive Order (EO) in 2009 for increased Federal leadership in the CBP to enhance the pace of restoration, and the supporting strategy was released in 2010. The EO directed the Federal Government, including the U.S. Department of the Interior (DOI), represented by the National Park Service (NPS), the U.S. Fish & Wildlife Service (FWS), and the USGS, to expand its efforts and increase leadership to restore the Bay and its watershed. The USGS and other Federal agencies expanded their activities in 2011 to meet the President’s Chesapeake EO. Since the EO was released, there have been several important changes in the USGS, DOI, and the CBP including: (1) the Chesapeake Bay Watershed Agreement, (2) increased DOI leadership in the CBP, and (3) the release of the USGS MA science strategies. The EO strategy served as a foundation for the Chesapeake Bay Watershed Agreement that was signed in 2014 by the CBP Partners, and has goals and outcomes to be met by 2025. The USGS developed the Chesapeake Science Strategy to guide our activities to address the Chesapeake Bay Watershed Agreement, DOI leadership in the CBP, and USGS MA strategies. Improving the understanding of fish and wildlife population and health, and the factors affecting their condition is the emphasis of the Strategy. The science focuses on documenting the critical ecosystem connections in the Chesapeake, and providing implications to enhance decision making for restoration and conservation activities. The revised Strategy has four themes that address 7 of the 10 goals in the Chesapeake Bay Watershed Agreement: Enhance science to support restoration, and conservation of fish, wildlife, and critical habitats. Characterize and explain changes in water quality, and its effect on freshwater and estuarine ecosystems. Assess and forecast effects of climate and land change on ecosystem conditions. Synthesize and provide information to support ecosystem management. The structure and function of biological communities of the Bay and its watershed are extremely complex and are affected by a variety of stressors and conditions. To better define the issues being addressed, the USGS has developed cross-cutting questions that define some of the most important scientific challenges where multiple disciplines and collaborators are needed to address an issue. The initial questions include: How do land and climate changes affect freshwater fish communities, health, and habitats? What are the relations among land use, water quality, contaminants, and the health of fish and wildlife? How are coastal wetlands and their carrying capacity for waterbirds affected by changing climate and land use? How is the water quality of rivers and estuaries responding to restoration actions, and changing land use? What are some of the best opportunities for management actions to benefit multiple restoration outcomes?

Delaware, Maryland, New York, Pennsylvania, Virgin↗
USGS2007

Wind River Watershed Restoration: Annual Report April 2005 - March 2006

This report summarizes work completed by U.S. Geological Survey’s Columbia River Research Laboratory (USGS-CRRL) in the Wind River subbasin during the period April 2005 through March 2006 under Bonneville Power Administration (BPA) contract 22095. During this period, we collected temperature, flow, and habitat data to characterize habitat condition and variation within and among tributaries and mainstem sections in the Wind River subbasin. We also conducted electrofishing and snorkeling surveys to determine juvenile salmonid populations within select study areas throughout the subbasin. Portions of this work were completed with additional funding from U.S. Fish and Wildlife Service (USFWS) and the Lower Columbia Fish Enhancement Group (LCFEG).

Washington↗
USGS2019

Climate change adaptation for coastal national wildlife refuges

National Wildlife Refuges (NWRs) along the East Coast of the United States protect habitat for a host of wildlife species, while also offering storm surge protection, improving water quality, supporting nurseries for commercially important fish and shellfish, and providing recreation opportunities for coastal communities. Yet in the last century, coastal ecosystems in the eastern U.S. have been severely altered by human development activities as well as sea-level rise and more frequent extreme events related to climate change. These influences threaten the ability of NWRs to protect our nation’s natural resources and to sustain their many beneficial services. Through this project, researchers are collaborating with managers of the North Carolina Coastal Refuges Complex, Cape Romain NWR, South Carolina, and other local interested partners to assist with their long-term planning under uncertain conditions regarding sea-level rise and other global change processes. Researchers are using a variety of state-of-the-art approaches, including formal decision science for systematically analyzing management alternatives and scenario planning methods for engaging with stakeholders to explore possible futures. These approaches are aimed at helping NWR staff develop management objectives, identify and weigh potential management actions for adaptation, and generate decision-support tools and models. Outcomes and products from these efforts will aid managers as they plan for and adapt to the complex challenges facing the NWR system as changing climate and other conditions make their work increasingly more difficult.

Final Project Memorandum↗
USGS2016

Effects of turbidity on predation vulnerability of juvenile humpback chub to rainbow and brown trout

Predation on juvenile native fish by introduced rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta is considered a significant threat to the persistence of endangered humpback chub Gila cypha in the Colorado River in Grand Canyon. Diet studies of rainbow and brown trout in Glen and Grand canyons indicate that these species eat native fish, but impacts are difficult to assess because predation vulnerability is highly variable depending on the physical conditions under which the predation interactions take place. We conducted laboratory experiments to evaluate how short-term predation vulnerability of juvenile humpback chub changes in response to changes in turbidity. In overnight laboratory trials, we exposed hatchery-reared juvenile humpback chub and bonytail Gila elegans (a surrogate for humpback chub) to adult rainbow and brown trout at turbidities ranging from 0 to 1,000 formazin nephlometric units. We found that turbidity as low as 25 formazin nephlometric units significantly reduced predation vulnerability of bonytail to rainbow trout and led to a 36% mean increase in survival (24–60%, 95% CI) compared to trials conducted in clear water. Predation vulnerability of bonytail to brown trout at 25 formazin nephlometric units also decreased with increasing turbidity and resulted in a 25% increase in survival on average (17–32%, 95% CI). Understanding the effects of predation by trout on endangered humpback chub is important when evaluating management options aimed at preservation of native fishes in Grand Canyon National Park. This research suggests that relatively small changes in turbidity may be sufficient to alter predation dynamics of trout on humpback chub in the mainstem Colorado River and that turbidity manipulation may warrant further investigation as a fisheries management tool.

Journal of Fish and Wildlife Management↗
USGS1989

Streamside habitats in southern forested wetlands: Their role and implications for management

The value of streamside forests to fish and wildlife and the influence of forest management on their value have been recognized in a general sense for decades. However, in today’s climate of increasing environmental regulation and intensive forest management, there is need for more detailed understanding of the value of streamside forests to fish and wildlife. Dickson and Huntley (1987:38) described the problem well when they wrote that “quantitative data on the effects of riparian zones on wildlife populations are insufficient to enable wildlife managers to justify the retention of riparian zones in land-use plans on a biological and economical basis.” Due in large part to the passage of water pollution control legislation, as well as legislation mandating multiple-use management in our national forests, progress is being made. During the last l&15 years, a great deal of research has been directed at understanding the value and appropriate management of the riparian zone (Brouha and Parsons 1985). The vast majority of research on riparian habitats has been conducted in western forests and/or narrow zones in otherwise upland areas. Also, much of the work done in southern forested wetlands has applied to entire floodplain forests. In this paper, we review the literature on streamside habitats within southern forested wetlands and, for reasons described in the next section, we make a distinction between streamside forests and floodplain (or riparian) forests. We also discuss in less detail the value of streamside habitats within other southern forest types, such as pine or mixed pine-hardwood.

General Technical Report↗
USGS2024

Review of the life history and conservation of federally endangered plant species of the Lower Rio Grande Valley, Texas, U.S.A.

This review aims to summarize information critical to the conservation of the federally listed endangered species of South Texas, which occur along the border of Texas and Mexico. This paper describes the characteristics, habitat, population status, distribution, life history, threats, and restoration of endangered plant species of the Lower Rio Grande Valley, Texas, which includes Cameron, Willacy, Hildago, and Starr County. Seven federally listed species are considered including Ambrosia cheiranthifolia, Asclepias prostrata, Astrophytum asterias, Ayenia limitaris, Manihot walkerae, Lesquerella thamnophila (syn. Physaria thamnophila), and Thymophylla tephroleuca. An eighth species, Physostegia correllii is under consideration for federal listing by the U.S. Fish and Wildlife Service. This paper assembles information on the background, biological status, major threats, and conservation to aid managers and the scientific community in restoring and managing these species.

Texas↗
USGS1945

Tularemia, an animal-borne disease

the disease tularemia continues to be of such importance in the United States that the Fish and Wildlife Service is constantly receiving requests for information on its nature and on the procedure recommended by field representatives of the Service in their work wiht the public. Such information is summarized in this leaflet. the information on human infections presented and the recommendations made have been endorsed by the United States Public Health Service.

Wildlife Leaflet↗
USGS2008

Ecosystem conceptual model- Mercury

Mercury has been identified as an important contaminant in the Delta, based on elevated concentrations of methylmercury (a toxic, organic form that readily bioaccumulates) in fish and wildlife. There are health risks associated with human exposure to methylmercury by consumption of sport fish, particularly top predators such as bass species. Original mercury sources were upstream tributaries where historical mining of mercury in the Coast Ranges and gold in the Sierra Nevada and Klamath-Trinity Mountains caused contamination of water and sediment on a regional scale. Remediation of abandoned mine sites may reduce local sources in these watersheds, but much of the mercury contamination occurs in sediments stored in the riverbeds, floodplains, and the Bay- Delta, where scouring of Gold-Rush-era sediment represents an ongoing source. Conversion of inorganic mercury to toxic methylmercury occurs in anaerobic environments including some wetlands. Wetland restoration managers must be cognizant of potential effects on mercury cycling so that the problem is not exacerbated. Recent research suggests that wettingdrying cycles can contribute to mercury methylation. For example, high marshes (inundated only during the highest tides for several days per month) tend to have higher methylmercury concentrations in water, sediment, and biota compared with low marshes, which do not dry out completely during the tidal cycle. Seasonally inundated flood plains are another environment experiencing wetting and drying where methylmercury concentrations are typically elevated. Stream restoration efforts using gravel injection or other reworking of coarse sediment in most watersheds of the Central Valley involve tailings from historical gold mining that are likely to contain elevated mercury in associated fines. Habitat restoration projects, particularly those involving wetlands, may cause increases in methylmercury exposure in the watershed. This possibility should be evaluated. The DRERIP mercury conceptual model and its four submodels (1. Methylation, 2. Bioaccumulation, 3. Human Health Effects, and 4. Wildlife Heath Effects) can be used to understand the general relationships among drivers and outcomes associated with mercury cycling in the Delta. Several linkages between important drivers and outcomes have been identified as important but highly uncertain (i.e. poorly understood). For example, there may be significant wildlife health effect of mercury on mammals and reptiles in the Delta, but there is currently very little or no information about it. The characteristics of such linkages are important when prioritizing and funding restoration projects and associated monitoring in the Delta and its tributaries.

Report↗