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At least 829 records · Page 46Linked to original sources
USGS2019

Sand Creek characterization study for Oncorhynchus clarkii virginalis (Rio Grande Cutthroat Trout), Great Sand Dunes National Park and Preserve, Colorado

The Oncorhynchus clarkii virginalis (Rio Grande cutthroat trout, RGCT) has undergone extensive declines in distribution and population. The RGCT is the southernmost distributed subspecies of cutthroat trout. Native to the Rio Grande Basin in Colorado and New Mexico, the subspecies is also found in the headwaters of the Pecos River and Canadian River basins in New Mexico. Currently, RGCT populations represent approximately 12 percent of the historic distribution. There are many factors that have contributed to the decline of the RGCT including small population sizes; hybridization with non-native salmonids; competition with non-native salmonids; angling; and loss of habitat resulting from wildfire, stream drying, disease, increased water temperatures; and poor land management. The eastern side of Colorado’s Rio Grande Basin is also home to Great Sand Dunes National Park and Preserve and the Sand Creek watershed. This study was designed to (1) characterize current physical and biological conditions of waterbodies within the Sand Creek watershed, from headwaters to lower terminus near the dune field; (2) characterize the spatial extent of existing fisheries within the Sand Creek watershed to inform the scope of potential future reclamation efforts; and (3) evaluate key limiting factors for a future native RGCT reintroduction. Bathymetric profiles were completed for two lakes within the upper Sand Creek drainage to characterize the physical geometry of each lake and to estimate the total lake volume required for future piscicide treatment and (or) fish removal efforts. Physical and biological conditions evaluated included stream water temperature and intermittency, discharge, and the genetics and existing fish community distribution and composition within the Sand Creek watershed were key components of this study. A baseline established the geographic extent and biological constraints factored into future piscicide treatment planning and native trout reintroduction efforts. As a result of this work, the Sand Creek watershed can be broken up into several distinct categories: Lakes that are good candidates for reclamation and reintroduction of RGCT, lakes that are poor candidates for reclamation, streams that currently have fish and are good candidates for reclamation and reintroduction, streams that currently lack fish and may be good candidates for introduction of RGCT, and streams that currently lack fish and are not good candidates for introduction of RGCT. This characterization study report is intended to inform State and Federal managers of the likelihood that the Sand Creek watershed can support a sustainable population of RGCT should they be reintroduced.

Colorado↗
USGS2022

Critical thermal maximum of stream fishes including distinct populations of Smallmouth Bass

Understanding the thermal tolerances of stream fishes, including sport fishes, is important for assessing thermal stressors that are common across the landscape. Our study objectives were to determine the thermal tolerances of 17 stream fishes (15 species and 2 genetically distinct populations of juvenile Smallmouth Bass Micropterus dolomieu : the Neosho subspecies M. dolomieu velox and the Ouachita strain M . sp. cf. dolomieu velox ). Fish were collected from the field and acclimated to laboratory conditions at 20°C or 25°C, with dissolved oxygen maintained above 6 mg/L. We determined the critical thermal maximum (CTM) using an incomplete block design with 9–11 replications for each species. During trials, we increased the water temperature at a rate of 2°C per hour until fish experienced loss of equilibrium. The estimated CTM ranged from 32.43°C to 38.26°C among species. The CTM values differed significantly between taxonomic groups and species, including the genetically distinct populations of Smallmouth Bass. The Neosho subspecies of Smallmouth Bass had a significantly lower thermal tolerance than the Ouachita strain at both acclimation temperatures; however, the magnitude of the difference was about 0.5°C greater at the higher acclimation temperature. Closely related species, including the Bigeye Shiner Notropis boops and Kiamichi Shiner N . ortenburgeri , had significantly different thermal tolerances despite occupying similar riverine locations. Our results suggest that our perceptions of a species’ thermal tolerance based on that of closely related species or that of species using similar habitat may be incorrect. Moreover, the differences in thermal tolerances among populations may be an important consideration for conservation and management actions, such as stocking decisions. Laboratory data such as those provided in this study can be integrated with field data to better assess thermal responses of fishes in a changing environment.

Oklahoma↗
USGS2006

Tracer test with As(V) under variable redox conditions controlling arsenic transport in the presence of elevated ferrous iron concentrations

To study transport and reactions of arsenic under field conditions, a small-scale tracer test was performed in an anoxic, iron-reducing zone of a sandy aquifer at the USGS research site on Cape Cod, Massachusetts, USA. For four weeks, a stream of groundwater with added As(V) (6.7 μM) and bromide (1.6 mM), was injected in order to observe the reduction of As(V) to As(III). Breakthrough of bromide (Br − ), As(V), and As(III) as well as additional parameters characterizing the geochemical conditions was observed at various locations downstream of the injection well over a period of 104 days. After a short lag period, nitrate and dissolved oxygen from the injectate oxidized ferrous iron and As(V) became bound to the freshly formed hydrous iron oxides. Approximately one week after terminating the injection, anoxic conditions had been reestablished and increases in As(III) concentrations were observed within 1 m of the injection. During the observation period, As(III) and As(V) were transported to a distance of 4.5 m downgradient indicating significant retardation by sorption processes for both species. Sediment assays as well as elevated concentrations of hydrogen reflected the presence of As(V) reducing microorganisms. Thus, microbial As(V) reduction was thought to be one major process driving the release of As(III) during the tracer test in the Cape Cod aquifer.

Journal of Contaminant Hydrology↗
USGS1995

Critical thermal maxima of coho salmon ( Oncorhynchus kisutch ) fry under field and laboratory acclimation regimes

Juvenile coho salmon ( Oncorhynchus kisutch ) from three populations in Washington State were captured in the field and tested for critical thermal maximum (CTM). Tolerances varied among the populations (mean CTMs were 28.21, 29.13, and 29.23 °C) and exceeded published data from some laboratory tests. The population from a relatively cool stream had a lower CTM than the two populations from warmer streams. However, after the salmon had been in the laboratory for 3 months under constant, common temperature regimes, the CTMs no longer differed, indicating that the population-specific differences resulted from different acclimation regimes rather than from genetic adaptation.

Washington↗
USGS1957

The control of the upstream movement of fish with pulsated direct current

Alternating-current electromechanical devices installed in the mouths of streams have proved effective in stopping the spawning migrations of the parasitic sea lamprey (Petromyzon marinus) which has seriously damaged Great Lakes fisheries. In a few streams, excessive mortality has occurred to other fish at the alternating-current barriers. A direct-current unit was developed in an attempt to reduce this mortality. This direct-current “diversion device” consists of a row of suspended negative electrodes which begins at the end of a trap wing and extends across the river at a downstream angle of 45° and a series of pipes (positive electrodes) driven into the stream bank. A second array, consisting of horizontal pipes installed downstream and parallel to the suspended electrodes and connected to a series of rods driven into the bank near the positive electrodes, controls the electrical field and dissipates the collecting influence of the positive side of the circuit. The electrical field is established from the end of the trap wing to the opposite bank. Fish are diverted away from the negative electrodes and toward the bank near which the trap is located. The array is activiated by pulsated direct current of essentially square wave shape with pulses at a duty cycle of 0.66 and a repetition rate of 3 per second. Direct-current diversion devices were operated in conjunction with alternating-current barriers during 1956 in the Chocolay River, Marquette County, and the Silver River, Baraga County, Michigan. A total of 15,814 fish comprising 21 species was handled at the Chocolay River with a mortality of 930, or 5.9 percent. If mortalities of fish moving downstream are disregarded, only 287, or 1.9 percent, of the fish moving upstream were killed in the Chocolay River. In the Silver River, 78,648 fish comprising 21 species were taken from the trap of the direct-current diversion device. The total kill of fish moving upstream, including 289 sea lampreys, was 1,016, or 1.3 percent. This river had presented a serious problem in the operation of an alternating-current control device during previous seasons. In 1955, 85.5 percent of three important species of fish were killed at the control structure. During 1956, this mortality was reduced to 8.1 percent by the operation of the direct-current equipment.

Transactions of the American Fisheries Society↗
USGS2010

Volcanogenic uranium deposits: Geology, geochemical processes, and criteria for resource assessment

Felsic volcanic rocks have long been considered a primary source of uranium for many kinds of uranium deposits, but volcanogenic uranium deposits themselves have generally not been important resources. Until the past few years, resource summaries for the United States or the world generally include volcanogenic in the broad category of "other deposits" because they comprised less than 0.5 percent of past production or estimated resources. Exploration in the United States from the 1940s through 1982 discovered hundreds of prospects in volcanic rocks, of which fewer than 20 had some recorded production. Intensive exploration in the late 1970s found some large deposits, but low grades (less than about 0.10 percent U 3 O 8 ) discouraged economic development. A few deposits in the world, drilled in the 1980s and 1990s, are now known to contain large resources (>20,000 tonnes U 3 O 8 ). However, research on ore-forming processes and exploration for volcanogenic deposits has lagged behind other kinds of uranium deposits and has not utilized advances in understanding of geology, geochemistry, and paleohydrology of ore deposits in general and epithermal deposits in particular. This review outlines new ways to explore and assess for volcanogenic deposits, using new concepts of convection, fluid mixing, and high heat flow to mobilize uranium from volcanic source rocks and form deposits that are postulated to be large. Much can also be learned from studies of epithermal metal deposits, such as the important roles of extensional tectonics, bimodal volcanism, and fracture-flow systems related to resurgent calderas. Regional resource assessment is helped by genetic concepts, but hampered by limited information on frontier areas and undiscovered districts. Diagnostic data used to define ore deposit genesis, such as stable isotopic data, are rarely available for frontier areas. A volcanic environment classification, with three classes (proximal, distal, and pre-volcanic structures), permits use of geologic features on 1:500,000 to 1:100,000 scale maps. Geochemical databases for volcanic rocks are postulated to be more effective than databases for stream sediments or surface radioactivity, both of which tend to be inconsistent because of variable leaching of uranium from soils. Based on empirical associations, spatial associations with areas of wet paleoclimate, adjacent oil and gas fields, or evaporite beds are deemed positive. Most difficult to estimate is the location of depositional traps and reduction zones, in part because they are mere points at regional scale. Grade and tonnage data are reviewed and discussed for 32 deposits in the world. Experience of mining engineers and geologists in Asia suggests that tonnages could be higher than presently known in the Western Hemisphere. Geological analysis, and new data from Asia, suggest a typical or median deposit tonnage of about 5,000 tonnes U 3 O 8 , and an optimistic forecast of discoveries in the range of 5,000 to 20,000 tonnes U 3 O 8 . The likely grade of undiscovered deposits could be about 0.15 percent U 3 O 8 , based on both western and eastern examples. Volcanic terrane is under-explored, relative to other kinds of uranium deposits, and is considered a favorable frontier area for new discoveries.

Open-File Report↗
USGS2012

Measurements of seepage losses and gains, East Maui Irrigation diversion system, Maui, Hawaiʻi

The U.S. Geological Survey conducted a field study from March to October 2011 to identify ditch characteristics and quantify seepage losses and gains in the East Maui Irrigation (EMI) diversion system, east Maui, Hawaiʻi. The EMI diversion system begins at Makapipi Stream in the east and ends at Māliko Gulch in the west. It consists of four primary ditches known as the Wailoa, New Hāmākua, Lowrie, and Haʻikū Ditches. Additional ditches that connect to the four primary ditches include the Koʻolau, Spreckels, Kauhikoa, Spreckels at Pāpaʻaʻea, Manuel Luis, and Center Ditches. Ditch characteristics for about 63 miles of the EMI diversion system, excluding abandoned ditches and stream conveyances, were identified. About 46 miles (73 percent) of the surveyed diversion system are tunnels and 17 miles are open ditches—in which 11 miles are unlined, 3.5 miles are lined, and 2.5 miles are partially lined. The Wailoa, Kauhikoa, and Haʻikū Ditches have greater than 96 percent of their total lengths as tunnels, whereas more than half of the Lowrie Ditch and Spreckels Ditch at Pāpaʻaʻea are open ditches. About 70 percent of the total length of lined open ditches in the EMI diversion system is located along the Koʻolau Ditch, whereas about 67 percent of the total length of unlined open ditches in the diversion system is located along the Lowrie Ditch. Less than 4 percent of the EMI diversion system is partially lined open ditches, and about half of the total partially lined open-ditch length is in the Spreckels Ditch. EMI regularly maintains and repairs the diversion system; therefore, ditch characteristics documented in this report are representative of conditions existing during the period of this study. Discharge measurements were made along 26 seepage-run measurement reaches that are a total of about 15 miles in length. The seepage-run measurement reaches represent 23 percent of the total length of ditches in the EMI diversion system. Discharge measurements were made along the measurement reaches during periods of stable ditch flow in the months of June, August, and September 2011. The discharge measurements indicate that Koʻolau Ditch and Spreckels Ditch at Pāpaʻaʻea generally had seepage losses, whereas Wailoa, Kauhikoa, and New Hāmākua Ditches had seepage gains within the measured reaches. The Manuel Luis, Center, Lowrie, and Haʻikū Ditches had variable seepage losses and gains within the seepage-run measurement reaches. Open-ditch measurement reaches generally had seepage losses that ranged from 0.1 cubic feet per second per mile of ditch at the Lowrie Ditch to 3.0 cubic feet per second per mile at the Koʻolau Ditch. Tunnel measurement reaches generally had seepage gains that ranged from 0.1 cubic feet per second per mile at the Manuel Luis Ditch to 5.2 cubic feet per second per mile at the Wailoa Ditch.

Hawai'i↗
USGS2022

Field investigation of sub-isokinetic sampling by the US D-96-type suspended-sediment sampler and its effect on suspended-sediment measurements

Collection of accurate suspended-sediment data using depth-integrating samplers requires that they operate isokinetically, that is, that they sample at the local stream velocity unaffected by the presence of the suspended-sediment sampler. Sub-isokinetic suspended-sediment sampling causes grain-size dependent positive biases in the suspended-sediment concentration measured by the suspended-sediment sampler. Collapsible bag suspended-sediment samplers like the US D-96 and the lighter US D-96-A1 depth-integrating samplers have shown a tendency to sample sub-isokinetically under low stream velocities (below ~3.5 feet per second), colder water temperatures, and longer sampling durations. Previous work concluded that the time-dependent decrease in the intake efficiency of the US D-96-type sampler could be partially overcome by increasing the venting of water from the sampler cavity by shortening the sampler tray. The standard-length sampler tray partially blocks the rear vent hole; shortening the sampler tray effectively increases the area of the sampler-cavity rear vent hole. This previous work showed that removing the partial blockage of the rear vent hole caused by the sampler tray resulted in both an increase in intake efficiency and a decrease in the positive bias in measured suspended-sand concentration. Herein, a series of tests were conducted on the Colorado River in Arizona using different modifications to a US D-96-A1 sampler to see if physical enlargement of the rear vent hole would produce further improvements in intake efficiency. Results from these tests show that physical enlargement of the rear vent hole, beyond that already effectively achieved by shortening the sampler tray, did not result in any further improvement in intake efficiency. However, these tests also indicated that physically increasing the area of the rear vent hole did not affect the suspended-sediment data collected by the US D-96-A1 sampler. Furthermore, comparisons of suspended-sediment data collected using the US D-96-A1 sampler and the isokinetic US P-61-A1 point-integrating sampler show that the suspended-sediment data collected by the US D-96-type sampler can be accurate in certain circumstances despite the tendency of this sampler to sample sub-isokinetically over the entire depth of a sampling vertical. We surmise that this result could arise from the US D-96-A1 sampler collecting sample isokinetically when the water-sediment mixture enters the nozzle, but that the water-sediment mixture only enters the nozzle intermittently while the sampler transits a sampling vertical.

Arizona↗
USGS2004

Chloride in ground water and surface water in the vicinity of selected surface-water sampling sites of the beneficial use monitoring program of Oklahoma, 2003

The Oklahoma Water Resources Board Beneficial Use Monitoring Program reported exceedances of beneficial-use standards for chloride at 11 surface-water sampling sites from January to October 2002. The U.S. Geological Survey, in cooperation with the Oklahoma Department of Environmental Quality, conducted a study to determine the chloride concentrations in ground water in the vicinity of Beneficial Use Monitoring Program surface-water sampling sites not meeting beneficial use standards for chloride and compare chloride concentrations in ground water and surface water. The chloride-impaired Beneficial Use Monitoring Program surface-water sampling sites are located in the western and southern regions of Oklahoma. The ground-water sampling sites were placed in proximity to the 11 surface-water sampling sites designated impaired by chloride by the Oklahoma Water Resources Board. Two surface-water sampling sites were located on the Beaver River (headwaters of the North Canadian River), three sites on the Cimarron River, one site on Sandy Creek, one site on North Fork Red River, and four sites on the Red River. Six ground-water samples were collected, when possible, from two test holes located upstream from each of the 11 Beneficial Use Monitoring Program surface-water sampling sites. One test hole was placed on the left bank and right bank, when possible, of each Beneficial Use Monitoring Program surfacewater sampling site. All test holes were located on alluvial deposits adjacent to the Beneficial Use Monitoring Program surface-water sampling sites within 0.5 mile of the stream. Top, middle, and bottom ground-water samples were collected from the alluvium at each test hole, when possible. Water properties of specific conductance, pH, water temperature, and dissolved oxygen were recorded in the field before sampling for chloride. The ground-water median chloride concentrations at 8 of the 11 Beneficial Use Monitoring Program sites were less than the surface-water median chloride concentrations. The Turpin and Beaver sites had similar ground-water and surface-water median chloride concentrations. The Buffalo site was the only site that had a large difference between the ground-water and surface-water chloride concentrations. The ground-water median chloride concentration was approximately 14,500 mg/L greater than the surface-water median chloride concentration at the Buffalo site.

Scientific Investigations Report↗
USGS2018

Exposure to synthetic hydraulic fracturing waste influences the mucosal bacterial community structure of the brook trout (Salvelinus fontinalis) epidermis

Production of natural gas using unconventional technologies has risen as demand for alternative fuels has increased. Impacts on the environment from waste generated from these processes are largely unexplored. In particular, the outcomes of organismal exposure to hydraulic fracturing waste have not been rigorously evaluated. We evaluated the effects of exposure to surrogate hydraulic fracturing waste (HF waste) on mucosal bacterial community structure of the brook trout ( Salvelinus fontinalis ) epidermis. Brook trout are fish native to streams at risk to HF waste exposure. Here, fish were exposed to four treatments (control, 0.00%; low, 0.01%; medium, 0.10%; and high, 1.0% concentrations) of surrogate HF waste synthesized to mimic concentrations documented in the field. Epidermal mucus samples were collected and assessed 15 days post-exposure to determine if the associated bacterial community varied among treatments. We observed differences in epidermal mucosal bacterial community composition at multiple taxonomic scales among treatments. These community changes reflected compositional differences in taxa dominance and community similarity rather than losses or gains in taxonomic richness. The dominant bacterial genus that explained the greatest variation in community structure between exposed and unexposed fish was Flavobacterium . Two genera associated with salmonid diseases, Flavobacterium and Pseudomonas , were statistically more abundant in high treatments than controls. These results suggest that exposure to low levels of HF waste influences bacterial colonization and may lead to a disruption that favors bacterial populations associated with fish disease.

Pennsylvania↗
USGS2012

Evaluation of nature-like and technical fishways for the passage of alewives at two coastal streams in New England

Nature-like fishways have been designed with the intent to reconnect river corridors and provide passage for all species occurring in a system. The approach is gaining popularity both in Europe and North America, but performance of these designs has not been quantitatively evaluated in a field setting for any North American species. Two nature-like fishways and three technical fishways in New England were evaluated for passage of anadromous adult alewives Alosa pseudoharengus by using passive integrated transponder (PIT) telemetry. A perturbation boulder rock ramp (32 m long; 4.2% slope) constructed in Town Brook (Plymouth, Massachusetts) passed 94% of the fish that made passage attempts, with most fish ascending the ramp in less than 22 min. In the East River (Guilford, Connecticut), a step-pool bypass design (48 m long; 7.1% slope) passed only 40% of attempting fish, with a median transit time of 75 min. In Town Brook, a technical pool-and-weir fishway (14 m long; 14.3% slope) exhibited poor entry and poor passage for the fish. In contrast, in the East River, two technical steeppass fishways (3 m long; 29.6% and 9.6% slopes) passed the majority of available fish, although one of these steeppass fishways may have lacked sufficient flow to attract fish to the entrance. In both Town Brook and the East River, tagged fish passed rapidly downstream through all fishways after spawning. In the East River, the amount of time fish spent in the spawning habitat before migrating downstream ranged from 1 to 41 d. These studies demonstrate that some nature-like and technical fishway designs can effectively facilitate passage of alewives, but a fishway's location in relation to a spillway is important, and further evaluations are required to more precisely identify the influence of the vertical drop per pool and the specific local hydraulics on alewife behaviors and passage performance.

New England↗
USGS1949

Ground water in the Jordan Valley, Utah

The Jordan Valley is a small part of a larger area that during the glacial epoch was covered by an ancient lake known as Lake Bonneville. The Jordan River, the natural drainage path from Utah Lake, flows northward through the center of the valley and empties into Great Salt Lake. The Jordan Valley is a rockbottomed valley in which a great thickness of clay, silt, sand, and gravel has been laid down irregularly. The thickness of this material is not definitely known, but wells in the valley have penetrated as much as 2,000 feet without encountering bedrock. These sediments are chiefly stream and lake deposits. The material at the surface of the valley was deposited in an ancient lake which at its highest stage stood about 1,000 feet above the level of Great Salt Lake. The shore deposits laid down in this lake occur in the form of terraces or benches around the margin of this basin. The two most prominent benches are known as the Bonneville and Provo benches. The Bonneville bench was formed during the highest stage of the lake, and the Provo bench during a later stage about 400 feet lower. Ground water occurs in the valley as (1) shallow ground water overlying the confining layer creating the artesian basin, (2) local perched water bodies, and (3) an artesian basin or reservoir including the recharge area. It occurs chiefly in the pore spaces of the sand and gravel of the stream and lake deposits. The most permeable water-bearing material occurs near the foot of the Wasatch Mountains in the area occupied by the Provo and Bonneville benches. At some distance from the mountains beds of finer material dense silt and clay alternate with more permeable beds of sand and gravel, giving rise to artesian conditions. On the Provo and Bonneville benches the water levels lie at considerable distances below the surface; but in the lower areas along the Jordan River and west of Salt Lake City as far as the lake, artesian conditions exist and many flowing wells have been drilled. The principal sources of ground water in the Jordan Valley are the water that seeps into the ground from the streams entering the valley, the water that penetrates directly from the ram and snow that fall upon the bench lands on the east side of the valley, and the water that percolates downward from irrigation canals and from irrigated lands, chiefly derived from Utah Lake. In addition some deep-seated thermal water rises along the Wasatch fault. Field determinations of the chloride content of the ground water show that nearly all the waters from the main part of the area of artesian flow, extending from Salt Lake City to Murray have a chloride content of less than 100 parts per million, and most of them have less than 50 parts per million. The distribution of waters of different chloride content indicates that the water of the main part of the area of artesian flow is derived chiefly from supplies that contain only small amounts of chloride namely, seepage from the streams that head in the Wasatch Mountains and rain and snow that fall upon the Provo and Bonneville benches and penetrate downward through the permeable materials that underlie these benches

Utah↗
USGS2002

Water budget for and nitrogen loads to Northeast Creek, Bar Harbor, Maine

The potential for nutrient enrichment to coastal estuaries on Mt. Desert Island, Maine, may affect the health of these important ecosystems at Acadia National Park. Inputs of water and nitrogen entering one of these coastal estuaries, Northeast Creek, and adjacent wetlands on Mt. Desert Island were quantified in a recent study conducted by the U.S. Geological Survey, in cooperation with the National Park Service. Streamflow and concentra-tions of nitrogen species in the four perennial streams entering the wetland/estuary system were measured monthly for 18 months to estimate loads and develop a water budget. Old Mill Brook was instrumented with a continuous-recording stream-flow gage; the MOVE.1 record-extension technique was used with this and several other nearby continuous gages to estimate daily surface-water inflow to the wetland. Inflow from ungaged basins was estimated from the unit-area yield calculated from data obtained from the gaged basins. Precipitation data collected at the National Atmospheric Deposition Program (NADP) site at Acadia National Park Headquarters and the Acadia National Park weather station were used to calculate atmospheric inputs. Evapotranspiration from the wetland was calculated using Fennessey and Vogel?s regionalized multivariate regression model of Penman-Montieth evapotranspiration. Geologic data collected in the field and taken from published geologic maps indicate that ground water probably does not contribute significantly to the water budget of this wetland system. Surface-water outflow from the wetland was not calculated because of the tidal nature of the outlet of the wetland and the difficulties associated with measuring flow in a tidal stream.

Water-Resources Investigations Report↗
USGS2011

Species traits and environmental conditions govern the relationship between biodiversity effects across trophic levels

Changing environments can have divergent effects on biodiversity–ecosystem function relationships at alternating trophic levels. Freshwater mussels fertilize stream foodwebs through nutrient excretion, and mussel species-specific excretion rates depend on environmental conditions. We asked how differences in mussel diversity in varying environments influence the dynamics between primary producers and consumers. We conducted field experiments manipulating mussel richness under summer (low flow, high temperature) and fall (moderate flow and temperature) conditions, measured nutrient limitation, algal biomass and grazing chironomid abundance, and analyzed the data with non-transgressive overyielding and tripartite biodiversity partitioning analyses. Algal biomass and chironomid abundance were best explained by trait-independent complementarity among mussel species, but the relationship between biodiversity effects across trophic levels (algae and grazers) depended on seasonal differences in mussel species’ trait expression (nutrient excretion and activity level). Both species identity and overall diversity effects were related to the magnitude of nutrient limitation. Our results demonstrate that biodiversity of a resource-provisioning (nutrients and habitat) group of species influences foodweb dynamics and that understanding species traits and environmental context are important for interpreting biodiversity experiments.

Oecologia↗
USGS2010

The Index of Biological Integrity and the bootstrap revisited: an example from Minnesota streams

Multimetric indices, such as the Index of Biological Integrity (IBI), are increasingly used by management agencies to determine whether surface water quality is impaired. However, important questions about the variability of these indices have not been thoroughly addressed in the scientific literature. In this study, we used a bootstrap approach to quantify variability associated with fish IBIs developed for streams in two Minnesota river basins. We further placed this variability into a management context by comparing it to impairment thresholds currently used in water quality determinations for Minnesota streams. We found that 95% confidence intervals ranged as high as 40 points for IBIs scored on a 0–100 point scale. However, on average, 90% of IBI scores calculated from bootstrap replicate samples for a given stream site yielded the same impairment status as the original IBI score. We suggest that sampling variability in IBI scores is related to both the number of fish and the number of rare taxa in a field collection. A comparison of the effects of different scoring methods on IBI variability indicates that a continuous scoring method may reduce the amount of bias in IBI scores.

Minnesota↗
USGS1978

Backwater at bridges and densely wooded flood plains, Tallahala Creek at Waldrup, Mississippi

New techniques for predicting water-surface profiles, needed in the design of economical, structurally sound, and environmentally compatible stream crossings, are under investigation. The investigation has accelerated with the advent of digital computers capable of analyzing large quantities of data. Among the techniques is the development of two-dimensional (2-D) digital models. Field data are essential for development and evaluation of these techniques for predicting water-surface profiles. This atlas is the first of a series that will provide a wide range of field data.

Mississippi↗
USGS1978

Backwater at bridges and densely wooded flood plains, Bogue Chitto near Summit, Mississippi

New techniques for predicting water-surface profiles, needed in the design of economical, structurally sound, and environmentally compatible stream crossings, are under investigation. The investigation has accelerated with the advent of digital computers capable of analyzing large quatities of data. Among the techniques is the development of two-dimensional (2-D) digital models. Field data are essential for development and evaluation of these techniques for predicting water-surface profiles. This atlas is one of a series that provide a wide range of field data.

Mississippi↗