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At least 739 records · Page 41Linked to original sources
USGS2003

Fish faunal resurgence in Lake Nabugabo, East Africa

In Lake Nabugabo, Uganda, a small satellite of the equatorial Lake Victoria, approximately 50% of the indigenous fish species disappeared from the open waters subsequent to establishment of the introduced predatory Nile perch ( Lates niloticus ). However, several of these species persisted in wetland refugia. Over the past decade, Nile perch in Lake Nabugabo have been intensively fished. Herein we report a resurgence of some indigenous species in open waters. In a multiyear study, we used annual transects in inshore and offshore waters of exposed ( no wetland ) and wetland habitats to document the pattern of resurgence. In 1995, haplochromine cichlids were largely confined to inshore areas, particularly wetland ecotones, and were rare in Nile perch stomachs, as were most other indigenous species. By 2000 haplochromine cichlids were abundant in inshore and offshore areas of both exposed and wetland transects. Several indigenous noncichlids also reappeared in the main lake, including three of the four original mormyrid species. Between 1995 and 1999, there was a dramatic increase in the proportion of haplochromines in the diet of Nile perch. When haplochromines were rare ( 1995 ), Nile perch switched from an invertebrate-dominated diet to piscivory at a large size ( 30 cm total length ). In 2000, however, Nile perch were strongly piscivorous by 5–10 cm total length. The pattern of faunal loss and recovery in Lake Nabugabo demonstrates the importance of refugia in providing the seeds of resurgence and provides a model with which to understand some changes in Lake Victoria.

Conservation Biology↗
USGS2016

California State Waters map series — Offshore of Aptos, California

Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar bathymetric data (the undersea equivalent of satellite remote-sensing data in terrestrial mapping), acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology. The Offshore of Aptos map area is located on the Pacific Coast, on the north side of Monterey Bay, about 105 km southeast of San Francisco. The largest incorporated city in the map area, Capitola, and numerous unincorporated towns including Aptos, lie on uplifted marine terraces between the shoreline, and the northwest-trending Santa Cruz Mountains, part of California’s Coast Ranges. The map area includes the northernmost part of Santa Cruz Harbor, and Moss Landing Harbor is located about 10 km south of the map area. The offshore part of the map area is entirely within California’s State Waters and is also part of the Monterey Bay National Marine Sanctuary. In the southern part of the map area, the Soquel Canyon State Marine Conservation Area extends eastward from the limit of California’s State Waters across Soquel Canyon. The Offshore of Aptos map area is on the western margin of North American Plate—the only continental margin in the world delineated largely by transform faults. The San Andreas Fault Zone cuts through the Santa Cruz Mountains just 3.5 km northeast of the map area. The San Gregorio Fault Zone, another major plate-boundary structure, cuts through Monterey Canyon about 13 km southwest of the map area. Ongoing deformation associated with and between these major fault zones has uplifted the Santa Cruz Mountains and formed well-developed sets of marine terraces that characterize almost the entire coastal zone of the map area. The offshore part of the map area consists of relatively flat and shallow continental shelf which is underlain by variable amounts (0 to 30 m) of upper Quaternary shelf, estuarine, and fluvial sediments deposited as sea level fluctuated in the late Pleistocene. Along the southern edge of the map area, the shelf is incised by the head of Soquel Canyon, a northeast-trending tributary to the west-trending Monterey Canyon. During the last sea-level lowstand (the Last Glacial Maximum [LGM], about 21,000 years ago) Soquel Creek flowed through a paleochannel across the emergent shelf into the head of Soquel Canyon. This canyon was disconnected from its onshore watershed during the post-LGM sea-level rise of about 125 m; the abandoned paleochannel was subsequently filled with marine sediment. Coastal sediment in the Offshore of Aptos map area is supplied by coastal watersheds and bluff erosion. Sediment transport in this part of the Santa Cruz littoral cell is primarily from the northwest to the southeast and terminates in the submarine Monterey Canyon. Longshore drift is impeded by jetties at Santa Cruz Harbor, resulting in high beach erosion rates east of the harbor. Sediment dredged from the harbor mouth (estimated 300,000 yds 3 /yr) is currently being used to nourish beaches directly to the east. Farther downcoast, the rapidly eroding beach at Capitola was stabilized by construction of an about 75-m-long groin. This part of central California is exposed to large North Pacific swells from the northwest throughout the year. North Pacific swell heights range from 2 to 10 meters, with larger swells occurring from October to May. During El Niño-Southern Oscillation (ENSO) events, winter storms track farther south than they do in normal (non-ENSO) years, thereby impacting the map area more frequently and with waves of larger heights. Bedrock exposed in coastal cliffs is relatively erosion-resistant, and significant erosional events primarily are restricted to storm-wave activity that also erodes the overlying unconsolidated marine-terrace sediments. The Offshore of Aptos map area lies within the cold-temperate biogeographic zone that is called either the “Oregonian” province or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, the eastern limb of the North Pacific subtropical gyre that flows from southern British Columbia to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 310 km southeast of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off of central California has experienced a warming over the last 50 years that is driving an ecosystem shift away from the productive subarctic regime towards a depopulated subtropical environment. Seafloor habitats in the Offshore of Aptos map area lie within the “Shelf” Megahabitat class and include patchy rocky habitats, gravel-rich scour depressions, minor bedrock habitat, and predominantly sandy inner shelf. Sandy shelf habitats grade offshore to mud-dominated habitats on the midshelf in deeper water. Biological productivity resulting from coastal upwelling supports populations of Sooty Shearwater, Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. California sea lions and Pacific harbor seals are abundant in the map area. Common bottlenose dolphins are often observed very close to shore and in the surf zone. The large extent of exposed inner shelf bedrock supports large forests of “bull kelp,” which is well adapted for high-wave-energy environments. The kelp beds are the northernmost known habitat for the population of southern sea otters. Common fish species found in the kelp beds and rocky reefs include blue rockfish, black rockfish, olive rockfish, kelp rockfish, gopher rockfish, black-and-yellow rockfish, painted greenling, kelp greenling, and lingcod.

California↗
USGS2008

USGS Gulf Coast Science Conference and Florida Integrated Science Center Meeting: Proceedings with abstracts, October 20-23, 2008, Orlando, Florida

Welcome! The USGS is the Nation's premier source of information in support of science-based decision making for resource management. We are excited to have the opportunity to bring together a diverse array of USGS scientists, managers, specialists, and others from science centers around the Gulf working on biologic, geologic, and hydrologic issues related to the Gulf of Mexico and the State of Florida. We've organized the meeting around the major themes outlined in the USGS Circular 1309, Facing Tomorrow's Challenges - U.S. Geological Survey Science in the Decade 2007-2017. USGS senior leadership will provide a panel discussion about the Gulf of Mexico and Integrated Science. Capstone talks will summarize major topics and key issues. Interactive poster sessions each evening will provide the opportunity for you to present your results and talk with your peers. We hope that discussions and interactions at this meeting will help USGS scientists working in Florida and the Gulf Coast region find common interests, forge scientific collaborations and chart a direction for the future. We hope that the meeting environment will encourage interaction, innovation and stimulate ideas among the many scientists working throughout the region. We'd like to create a community of practice across disciplines and specialties that will help us address complex scientific and societal issues. Please take advantage of this opportunity to visit with colleagues, get to know new ones, share ideas and brainstorm about future possibilities. It is our pleasure to provide this opportunity. We are glad you're here.

Open-File Report↗
USGS1996

Physical, chemical, and biological data for four wetland habitats in Canaan Valley, West Virginia

This report contains data collected during 1992 as part of a project designed to identify microenvironmental factors affecting rates of denitrification in wetlands in Canaan Valley, West Virginia. Four wetland habitats were selected for the study--a moss-lichen wetland, a persistent emergent wetland, a scrub-shrub wetland, and a riverine wetland. Physical, chemical, and biological characteristics of each habitat were determined by field measurements and laboratory analyses. Samples were collected in March, June, August, and October. Sediment pH, temperature, and oxidation-reduction potential were measured in the field. Sediment samples were analyzed for concentrations of calcium, sodium, magnesium, potassium, nitrate and nitrite, ammonia, ammonia plus organic nitrogen, phosphorus, inorganic carbon, and total carbon. The most probable number of denitrifying bacteria was determined by a multiple-tube test. The dominant plant species were identified by plant-community analysis. The moss-lichen wetland was characterized by low pH (3.4 to 5.0) and small populations of denitrifying bacteria (70 to 400 per gram of wet soil). The scrub-shrub wetland was also acidic (pH 4.0 to 5.0), but supported larger numbers of denitrifying bacteria (510 to 11,000 per gram of wet soil). The number of denitrifying bacteria in the persistent emergent wetland exceeded 1,000,000 per gram of wet soil in early summer and pH in this habitat was higher (5.1 to 6.6) than in the bogs. Riverine wetland pH ranged from 5.4 to 6.9, and the number of denitrifying bacteria ranged from 200 to 11,000 per gram of wet soil.

Open-File Report↗
USGS1996

Water-quality assessment of the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia; organochlorine compounds in Asiatic clam (Corbicula fluminea) soft tissues and whole redbrest sunfish (Lepomis auritus) 1992-93

The analysis of potential contaminants in biological tissues is an important part of many water-quality assessment programs, including the National Water-Quality Assessment (NAWQA) Program. Tissue analyses often are used to provide information about (1) direct threats to ecosystem integrity, and (2) the occurrence and distribution of potential contaminants in the environment. During 1992-93, Asiatic clam (Corbicula fluminea) soft tissues and whole redbreast sunfish (Lepomis auritus) samples were collected and analyzed to obtain information about the occurrence and distribution of organochlorine compounds in the Albemarle-Pamlico drainage Basin of North Carolina and Virginia. The investigation was conducted as part of the NAWQA Program. Relatively few organochlorine compounds were detected and of the compounds detected, all were detected in relatively low concentrations. The organochlorine compounds detected were p,p'-DDD, p,p'-DDE, p,p'-DDT, dieldrin, trans-nonachlor, PCB's, and toxaphene. Multiple compounds were detected at 16 of 19 sites sampled. Compared to Asiatic clams, redbreast sunfish appear to be better bioindicators of organochlorine contamination in aquatic systems. Except for one detection of toxaphene, pesticide concentrations are well below the National Academy of Sciences and National Academy of Engineering (NAS/NAE) guidelines for the protection of fish-eating wildlife.

North Carolina, Virginia↗
USGS2013

Data management challenges in species distribution modeling

An important component in the fields of ecology and conservation biology is understanding the environmental conditions and geographic areas that are suitable for a given species to inhabit. A common tool in determining such areas is species distribution modeling which uses computer algorithms to determine the spatial distribution of organisms. Most commonly the correlative relationships between the organism and environmental variables are the primary consideration. The data requirements for this type of modeling consist of known presence and possibly absence locations of the species as well as the values of environmental or climatic covariates thought to define the species habitat suitability at these locations. These covariate data are generally extracted from remotely sensed imagery, interpolated/gridded historical climate data, or downscaled climate model output. Traditionally, ecologists and biologists have constructed species distribution models using workflows and data that reside primarily on their local workstations or networks. This workflow is becoming challenging as scientists increasingly try to use these modeling techniques to inform management decisions under different climate change scenarios. This challenge stems from the fact that remote sensing products, gridded historical climate, and downscaled climate models are not only increasing in spatial and temporal resolution but proliferating as well. Any rigorous assessment of uncertainty requires a computationally intensive sensitivity analysis accounting for various sources of uncertainty. The scientists fitting these models generally do not have the background in computer science required to take advantage of recent advances in web-service based data acquisition, remote high-powered data processing, or scientific workflow systems. Ecologists in the field of modeling are in need of a tractable platform that abstracts the inherent computational complexity required to incorporate the burgeoning field of coupled climate and ecological response modeling. In this paper we describe the computational challenges in species distribution modeling and solutions using scientific workflow systems. We focus on the Software for Assisted Species Modeling (SAHM) a package within VisTrails, an open-source scientific workflow system.

Bulletin of the Technical Committee on Data Engine↗
USGS2018

Living on the edge: Opportunities for Amur tiger recovery in China

Sporadic sightings of the endangered Amur tiger Panthera tigris altaica along the China-Russia border during the late 1990s sparked efforts to expand this subspecies distribution and abundance by restoring potentially suitable habitats in the Changbai Mountains. To guide science-based recovery efforts and provide a baseline for future monitoring of this border population, empirical, quantitative information is needed on what resources and management practices promote or limit the occurrence of tigers in the region. We established a large-scale field camera-trapping network to estimate tiger density, survival and recruitment in the Hunchun Nature Reserve and the surrounding area using an open population spatially explicit capture-recapture model. We then fitted an occupancy model that accounted for detectability and spatial autocorrelation to assess the relative influence of habitat, major prey, disturbance and management on tiger habitat use patterns. Our results show that the ranges of most tigers abut the border with Russia. Tiger densities ranged between 0.20 and 0.27 individuals/100 km2 over the study area; in the Hunchun Nature Reserve, the tiger density was three times higher than that in the surrounding inland forested area. Tiger occupancy was strongly negatively related to heavy cattle grazing, human settlements and roads and was positively associated with sika deer abundance and vegetation cover. These findings can help to identify the drivers of tiger declines and dispersal limits and refine strategies for tiger conservation in the human-dominated transboundary landscape. Progressively alleviating the impacts of cattle and human disturbances on the forest, and simultaneously addressing the economic needs of local communities, should be key priority actions to increase tiger populations. The long-term goal is to expand tiger distribution by improving habitats for large ungulates.

Jilin Province↗
USGS2015

California State Waters Map Series — Drakes Bay and vicinity, California

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow (to about 100 m) subsurface geology. The Drakes Bay and Vicinity map area is located in northern California, about 30 km north of San Francisco and about 65 km south of Fort Ross. The map area is in the northern part of the Gulf of the Farallones National Marine Sanctuary, and it includes all or parts of four California Marine Protected Areas. The largely undeveloped onshore part of the map area, which occupies much of the southern and southeastern parts of the Point Reyes peninsula, is used primarily for grazing, as well as recreation, as it is home to the Point Reyes National Seashore. The triangular Point Reyes peninsula, which lies completely west of the San Andreas Fault Zone, is bounded by the steep terrain of Inverness Ridge along its northeastern margin, Tomales Point at its northernmost tip, Point Reyes at its southwesternmost point, and Bolinas at its southern end. The landscape in between includes (from southeast to northwest) the sandy beaches along Drakes Bay, the estuaries of Drakes Estero and Estero de Limantour, and the long, windswept Point Reyes Beach, which is backed by an extensive dune field. The seafloor in the map area generally extends from the shoreline to water depths of about 40 to 50 m, except for the area south of the Point Reyes headland where water depths reach 60 to 70 m. This bathymetric gradient south and west of the Point Reyes headland is related to north-side-up motion along the Point Reyes Fault Zone. Except for the bathymetric gradient across the Point Reyes Fault Zone, the bedrock platform in the nearshore and inner shelf areas (50 to 60 m depth) is relatively flat (less than 1.0°) and is overlain by sand-sized to coarser grained sediment. Finer grained sediments are found in water depths greater than 60 m south of the Point Reyes headland, but they also extend into shallower (less than 40 m) water within Drakes Bay. Surficial and shallow sediments were deposited in the last about 21,000 years during the approximately 125-m sea-level rise that followed the last major lowstand associated with the Last Glacial Maximum, at which time the entire Drakes Bay and Vicinity map area was emergent and the shoreline was about 30 km south and west of the present-day shoreline. Tectonic influences that impact the shelf morphology and geology in the map area are related to local faulting, folding, uplift, and subsidence. Offshore of the Point Reyes headland, granitic basement rocks are offset vertically about 1.4 km along the Point Reyes Fault Zone; this uplift, combined with west-side-up offset on the San Andreas Fault Zone, has resulted in uplift of the Point Reyes peninsula and the adjacent shelf. Late Pleistocene uplift of marine terraces on the southern Point Reyes peninsula suggests active deformation of offshore structures west of the San Andreas Fault Zone. Pervasive stratal thinning within inferred uppermost Pliocene and Pleistocene deposits above the west strand of the Point Reyes Fault Zone suggests Quaternary active shortening of the curvilinear, northeast- to north-dipping Point Reyes Fault Zone. Lack of clear deformation in the uppermost Pleistocene and Holocene deposits suggests that activity along the Point Reyes Fault Zone has ceased or slowed since about 21,000 years ago. Seafloor habitats in the Drakes Bay and Vicinity map area range from unconsolidated continental-shelf sediment to hard substrate. Rocky-shelf outcrops and rubble are considered to be promising potential habitats for rockfish and lingcod, both of which are recreationally and commercially important species. Circulation over the continental shelf in the map area is dominated by the southward-flowing California Current, the eastern limb of the North Pacific Gyre. Associated upwelling brings cool, nutrient-rich waters to the surface, resulting in high biological productivity. The current flow generally is southeastward during the spring and summer; however, during the fall and winter, the otherwise persistent northwest winds are sometimes weak or absent, causing the California Current to move farther offshore and the Davidson Current, a weaker, northward-flowing countercurrent, to become active. Sediment transport in the map area largely is controlled by surface waves and tidal currents in the nearshore and, at depths greater than 20 to 30 m, by tidal and subtidal currents. In the map area, nearshore littoral drift of sand and coarse sediment is to the south, owing to the dominant west-northwest swell direction, and scour from large waves and tidal currents removes and redistributes sediment over large areas of the inner shelf. Tidal currents are particularly strong over the shelf in the map area, and they dominate the current regime in the nearshore. Further offshore, bottom currents generally flow to the northwest, distributing finer grained sediment accordingly.

California↗
USGS2001

Science Plan, U.S. Geological Survey Florida District

This Science Plan has been prepared by the Florida District of the U.S. Geological Survey (USGS) as a tool to provide direction for the scientific work to be accomplished in the District during the next 5-10 years. A Science Plan can serve as a guide to determine the optimum use of the limited financial resources of the USGS in Florida to address water resource issues. The Florida District has four primary operational centers geographically distributed across the State, in Tallahassee, Orlando, Tampa, and Miami, with a laboratory in Ocala and field offices in Jacksonville and Fort Myers. Other USGS discipline offices in Florida are located in Gainesville (biology), St. Petersburg (geology), and Miami (restoration ecology) (fig.1). Although some differences exist in programs among the four water-resource offices because of differing physiographic settings and information needs, many common elements are present and these common elements are the focus of this District Science Plan. Science Plan development was based on other planning documents including individual Science Plans prepared by personnel in each of the four primary Florida water resource offices, and strategic planning documents of the Southeastern Region, Water Resources Discipline (WRD), and the USGS. A broad cross-section of District staff, representing all primary offices, a number of different scientific disciplines, and different programs of the District (data collection, investigations, and research) collaborated on the development of this Science Plan. As part of the development process, input was solicited from staff in every office and considered for inclusion in the plan. The Science Plan will be evaluated on an ongoing basis to ensure its continued relevancy to recognized water resources needs in Florida, and to guide future program development and collaboration with our existing and potential partners and customers, both within and outside the USGS.

Florida↗
USGS1981

Aquatic biology of the Redwood Creek and Mill Creek drainage basins, Redwood National Park, Humboldt and Del Norte counties, California

A 2-year study of the aquatic biota in the Redwood Creek and Mill Creek drainage basins of Redwood National Park indicated that the aquatic productivity is low. Densities of coliform bacteria were low except in Prairie Creek, a tributary to Redwood Creek, where a State park, county fish hatchery, grazing land, lumber mill, and scattered residential areas are potential sources of fecal coliform bacteria. Benthic invertebrate data indicated a diverse fauna which varied considerably between streams and among stream sections. Noteworthy findings include: (1) benthic invertebrates rapidly recolonized the streambed following a major storm, and (2) man-caused disruption or sedimentation of the streambed during low flow can result in drastic reductions of the benthic invertebrate community. Seven species of fish representing species typically found in northern California coastal streams were captured during the study. Nonparametric statistical tests indicate that condition factors of steelhead trout were significantly larger at sampling stations with more insolation, regardless of drainage basin land-use history. Periphyton and phytoplankton communities were diverse, variable in numbers, and dominated by diatoms. Seston concentrations were extremely variable between stations and at each station sampled. The seston is influenced seasonally by aquatic productivity at each station and amount of allochthonous material from the terrestrial ecosystem. Time-series analysis of some seston data indicated larger and sharper peak concentrations being flushed from the logged drainage basin than from the control drainage basin. (USGS)

California↗
USGS1999

Assessing biological effects from highway-runoff constituents

Increased emphasis on evaluation of nonpoint-source pollution has intensified the need for techniques that can be used to discern the toxicological effects of complex chemical mixtures. In response, the use of biological assessment techniques is receiving increased regulatory emphasis. When applied with documented habitat assessment and chemical analysis, these techniques can increase our understanding of the influence of environmental contaminants on the biological integrity and ecological function of aquatic communities. The contaminants of greatest potential concern in highway runoff are those that arise from highway construction, maintenance, and use. The major contaminants of interest are deicers; nutrients; metals; petroleum-related organic compounds, such as polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethylbenzene, and xylene (BTEX), and methyl tert -butyl ether (MTBE); sediment washed off the road surface; and agricultural chemicals used in highway maintenance. Hundreds, if not thousands, of biological endpoints (measurable responses of living organisms) may be either directly or associatively affected by contaminant exposure. Measurable effects can occur throughout ecosystem processes across the wide range of biological complexity, ranging from responses at the biochemical level to the community level. The challenge to the environmental scientist is to develop an understanding of the relationship of effects at various levels of biological organization in order to determine whether a causal relationship exists between chemical exposure and substantial ecological impairment. This report provides a brief history of the evolution of biological assessment techniques, a description of the major classes of contaminants that are of particular interest in highway runoff, an overview of representative biological assessment techniques, and a discussion of data-quality considerations. Published reports with a focus on the effects of highway runoff on the local ecosystem were reviewed to provide information on (1) the suitability of the existing data for a quantitative national synthesis, (2) the methods available to study the effects of highway runoff on local ecosystems, and (3) the potential for adverse effects on the roadside environment and receiving waters. Although many biological studies have been done, the use of different methods and a general lack of sufficient documentation precludes a quantitative national synthesis on the basis of the existing data. The Federal Highway Administration, the U.S. Environmental Protection Agency, the U.S. Geological Survey, the Intergovernmental Task Force on Monitoring Water Quality, and the National Resources Conservation Service all have developed and documented methods for assessing the effects of contaminants on ecosystems in receiving waters. These published methods can be used to formulate a set of protocols to provide consistent information from highway-runoff studies. Review of the literature indicates (qualitatively) that highway runoff (even from highways with high traffic volume) may not usually be acutely toxic. Tissue analysis and community assessments, however, indicate effects from highway- runoff sediments near discharge points (even from sites near highways with relatively low traffic volumes). At many sites, elevated concentrations of highway-runoff constituents were measured in tissues of species associated with aquatic sediments. Community assessments also indicate decreases in the diversity and productivity of aquatic ecosystems at some sites receiving highway runoff. These results are not definitive, however, and depend on many site-specific criteria that were not sufficiently documented in most of the studies reviewed.

Open-File Report↗
USGS2021

Divergent species‐specific impacts of whole ecosystem warming and elevated CO2 on vegetation water relations in an ombrotrophic peatland

Boreal peatland forests have relatively low species diversity and thus impacts of climate change on one or more dominant species could shift ecosystem function. Despite abundant soil water availability, shallowly rooted vascular plants within peatlands may not be able to meet foliar demand for water under drought or heat events that increase vapor pressure deficits while reducing near surface water availability, although concurrent increases in atmospheric CO 2 could buffer resultant hydraulic stress. We assessed plant water relations of co‐occurring shrub (primarily Rhododendron groenlandicum and Chamaedaphne calyculata ) and tree ( Picea mariana and Larix laricina ) species prior to, and in response to whole ecosystem warming (0 to +9°C) and elevated CO 2 using 12.8‐m diameter open‐top enclosures installed within an ombrotrophic bog. Water relations (water potential [Ψ], turgor loss point, foliar and root hydraulic conductivity) were assessed prior to treatment initiation, then Ψ and peak sap flow (trees only) assessed after 1 or 2 years of treatments. Under the higher temperature treatments, L. laricina Ψ exceeded its turgor loss point, increased its peak sap flow, and was not able to recover Ψ overnight. In contrast, P. mariana operated below its turgor loss point and maintained constant Ψ and sap flow across warming treatments. Similarly, C. calyculata Ψ stress increased with temperature while R. groenlandicum Ψ remained at pretreatment levels. The more anisohydric behavior of L. laricina and C. calyculata may provide greater net C uptake with warming, while the more conservative P. mariana and R. groenlandicum maintained greater hydraulic safety. These latter species also responded to elevated CO 2 by reduced Ψ stress, which may also help limit hydraulic failure during periods of extreme drought or heat in the future. Along with Sphagnum moss, the species‐specific responses of peatland vascular communities to drier or hotter conditions will shape boreal peatland composition and function in the future.

Minnesota↗
USGS2003

Preliminary analysis of cores from north San Francisco Bay, California

During the mid-to late-1800's, large quantities of tailings from hydraulic gold mining in the Sierra Nevada were deposited in San Francisco Bay (Gilbert, 1917; Jaffe et al., 1998; Capiella et al., 1999). This rapid deposition also choked river systems and deposited mercury-contaminated sediments in the rivers and Bay. Hydraulic mining was stopped in 1884 by a California Supreme Court decision. Deposition in the Bay slowed in the late 1800's and early 1900's as a result of this decrease in sediment supply (Jaffe et al., 1998; Capiella et al., 1999). During the mid-1900's, sediment supply was further reduced by water works projects (dams, diversions, etc.), creating an erosional system in the study area by the late 1900's. The re-working of these sediments poses environmental and biological concerns regarding mercury in the bay. The location of these deposits is important for understanding the health of the bay waters. In March 2000, the U.S. Geological Survey collected sediment cores in the study area to determine the location of mercury-contaminated hydraulic mining debris. The study area (Figure 1) comprises 400 km2 and consists of San Pablo Bay and Suisun Bay, both of which are part of the San Francisco Bay estuary. Grizzly Bay, a subembayment of Suisun Bay, is also part of the study area. For the purpose of this report the term Suisun Bay will be used collectively for both areas. The present channel system in Suisun Bay is composed of three channels that flow through the bay. The primary channel runs in the southern section of Suisun Bay. A smaller channel flows between Roe Island and Ryer Island. The deepest channel flows through Suisun Cutoff, north of Ryer Island, and past Grizzly Bay. All three channels join at Carquinez Strait where they continue through the southern section of San Pablo Bay, and into San Francisco Bay. The average depths in San Pablo and Suisun Bays at mean sea level are 3.7 m and 5.8 m, respectively (Smith et al., 2002).

California↗
USGS2002

Ontogenetic behavior and migration of Chinese sturgeon, Acipenser sinensis

The Chinese sturgeon, Acipenser sinensis , is an anadromous protected species that presently only spawns in the Yangtze River. Using laboratory experiments, we examined the behavioral preference of young Chinese sturgeon to physical habitat (water depth, illumination intensity, substrate color, and cover) and monitored their downstream migration. Hatchling free embryos were photopositive, preferred open habitat, and immediately upon hatching, swam far above the bottom using swim-up and drift. Downstream migration peaked on days 0–1, decreased about 50% or more during days 2–7, and ceased by day 8. Days 0–1 migrants were active both day and night, but days 2–7 migrants were most active during the day. After ceasing migration, days 8–11 embryos were photonegative, preferred dark substrate and sought cover. Free embryos developed into larvae and began feeding on day 12, when another shift in behavior occurred–larvae returned to photopositive behavior and preferred white substrate. The selective factor favoring migration of free embryos upon hatching and swimming far above the bottom may be avoidance of benthic predatory fishes. Free embryos, which must rely on yolk energy for activity and growth, only used 19 cumulative temperature degree-days for peak migration compared to 234 degree-days for growth to first feeding larvae, a 1 : 12 ratio of cumulative temperature units. This ratio suggests that sturgeon species with large migratory embryos, like Chinese sturgeon, which require a high level of energy to swim during migration, may migrate only a short time to conserve most yolk energy for growth.

Jingzhou↗
USGS1993

Methods for collecting algal samples as part of the National Water-Quality Assessment Program

Benthic algae (periphyton) and phytoplankton communities are characterized in the U.S. Geological Survey's National Water-Quality Assessment Program as part of an integrated physical, chemical, and biological assessment of the Nation's water quality. This multidisciplinary approach provides multiple lines of evidence for evaluating water-quality status and trends, and for refining an understanding of the factors that affect water-quality conditions locally, regionally, and nationally. Water quality can be characterized by evaluating the results of qualitative and quantitative measurements of the algal community. Qualitative periphyton samples are collected to develop of list of taxa present in the sampling reach. Quantitative periphyton samples are collected to measure algal community structure within selected habitats. These samples of benthic algal communities are collected from natural substrates, using the sampling methods that are most appropriate for the habitat conditions. Phytoplankton samples may be collected in large nonwadeable streams and rivers to meet specific program objectives. Estimates of algal biomass (chlorophyll content and ash-free dry mass) also are optional measures that may be useful for interpreting water-quality conditions. A nationally consistent approach provides guidance on site, reach, and habitat selection, as well as information on methods and equipment for qualitative and quantitative sampling. Appropriate quality-assurance and quality-control guidelines are used to maximize the ability to analyze data locally, regionally, and nationally.

Open-File Report↗
USGS2019

Adaptive management of flows from R.L. Harris Dam (Tallapoosa River, Alabama)—Stakeholder process and use of biological monitoring data for decision making

Adaptive management has been applied to problems with multiple conflicting objectives in various natural resources settings to learn how management actions affect divergent values regarding system response. Hydropower applications have only recently begun to emerge in the field, yet in the specific example reported herein, stakeholders invested in determining the best management alternatives for attainment of a suite of objectives outlined in a long-term adaptive management program below R.L. Harris Dam, a large, privately owned dam in Alabama. Stakeholders convened an objective-setting workshop to engage a governance structure and developed a decision support model to determine appropriate actions that optimized stakeholder values. The process led to implemented change in dam operation inclusive of incorporating hypothetical responses in system parameters to management. To account for the iterative loop of adaptive management, yearly monitoring of state variables that approximated many stakeholder objectives was performed from 2005 to 2016 and data collected were incorporated into the decision model. Specific analysis of fish and macroinvertebrate population responses indicated a less than satisfactory response for some stakeholders to the flow-management changes at the dam. Uncertainty regarding the best management to provide adequate hydrologic and thermal habitats for fauna and boatable days for recreationists still exists. The project led to a Federal Energy Regulatory Commission process for renewing the license to operate the dam (beginning in 2018); adaptive management could be a viable path forward to ensure stakeholder satisfaction related to new management options.

Alabama↗
USGS2000

Nest predation increases with parental activity: Separating nest site and parental activity effects

Alexander Skutch hypothesized that increased parental activity can increase the risk of nest predation. We tested this hypothesis using ten open-nesting bird species in Arizona, USA. Parental activity was greater during the nestling than incubation stage because parents visited the nest frequently to feed their young during the nestling stage. However, nest predation did not generally increase with parental activity between nesting stages across the ten study species. Previous investigators have found similar results. We tested whether nest site effects might yield higher predation during incubation because the most obvious sites are depredated most rapidly. We conducted experiments using nest sites from the previous year to remove parental activity. Our results showed that nest sites have highly repeatable effects on nest predation risk; poor nest sites incurred rapid predation and caused predation rates to be greater during the incubation than nestling stage. This pattern also was exhibited in a bird species with similar (i.e. controlled) parental activity between nesting stages. Once nest site effects are taken into account, nest predation shows a strong proximate increase with parental activity during the nestling stage within and across species. Parental activity and nest sites exert antagonistic influences on current estimates of nest predation between nesting stages and both must be considered in order to understand current patterns of nest predation, which is an important source of natural selection.

Arizona↗
USGS1980

Water-quality reconnaissance of the Middle and North Branch Park River watersheds, northeastern North Dakota

In order to design a network to monitor the effects of works of improvement in the Middle and North Branch Park River watersheds, and to determine the major factors controlling water-quality conditions in the watersheds, an evaluation of sediment transport, water chemistry, and biology was conducted during the spring and early summer of 1978. Major factors controlling water quality are geology, stream gradient, ground-water seepage, and the duration of streamflow. Sediment loads originate on the Pembina Escarpment. The coarse silt and sand parts of these loads are deposited on the Lake Agassiz Plain. Transport of sediment is lowered and flow duration is increased on the Middle Branch Park River due to the presence of small dams. Observations suggest that bedload transport is a significant process, particularly in the upstream reaches. However, no quantitative bedload data were collected. During periods of low flow, analyses of water from the rivers in both watersheds show downstream increases in sodium and chloride due to ground-water seepage or the unregulated flow of wells. Diversity of benthic invertebrates indicates water-quality conditions are better on the Middle Branch Park River than on the North Branch, and are better at upstream sites than at downstream sites. A program through which the Soil Conservation Service can monitor the effects of present and future works of improvement on the watersheds was designed. The monitoring program consists of intensive sampling at four locations for sediment and water chemistry during spring and early summer runoff events and by profiles of water chemistry during summer base runoff.

Open-File Report↗