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At least 487 records · Page 27Linked to original sources
USGS2006

Use of sediment rating curves and optical backscatter data to characterize sediment transport in the Upper Yuba River watershed, California, 2001-03

Sediment transport in the upper Yuba River watershed, California, was evaluated from October 2001 through September 2003. This report presents results of a three-year study by the U.S. Geological Survey, in cooperation with the California Ecosystem Restoration Program of the California Bay-Delta Authority and the California Resources Agency. Streamflow and suspended-sediment concentration (SSC) samples were collected at four gaging stations; however, this report focuses on sediment transport at the Middle Yuba River (11410000) and the South Yuba River (11417500) gaging stations. Seasonal suspended-sediment rating curves were developed using a group-average method and non-linear least-squares regression. Bed-load transport relations were used to develop bed-load rating curves, and bed-load measurements were collected to assess the accuracy of these curves. Annual suspended-sediment loads estimated using seasonal SSC rating curves were compared with previously published annual loads estimated using the Graphical Constituent Loading Analysis System (GCLAS). The percent difference ranged from -85 percent to +54 percent and averaged -7.5 percent. During water year 2003 optical backscatter sensors (OBS) were installed to assess event-based suspended-sediment transport. Event-based suspended-sediment loads calculated using seasonal SSC rating curves were compared with loads calculated using calibrated OBS output. The percent difference ranged from +50 percent to -369 percent and averaged -79 percent. The estimated average annual sediment yield at the Middle Yuba River (11410000) gage (5 tons/mi2) was significantly lower than that estimated at the South Yuba River (11417500) gage (14 tons/mi2). In both rivers, bed load represented 1 percent or less of the total annual load throughout the project period. Suspended sediment at the Middle Yuba River (11410000) and South Yuba River (11417500) gages was typically greater than 85 percent silt and clay during water year 2003, and sand concentrations at the South Yuba River (11417500) gage were typically higher than those at the Middle Yuba River (11410000) gage for a given streamflow throughout the three year project period. Factors contributing to differences in sediment loads and grain-size distributions at the Middle Yuba River (11410000) and South Yuba River (11417500) gages include contributing drainage area, flow diversions, and deposition of bed-material-sized sediment in reservoirs upstream of the Middle Yuba River (11410000) gage. Owing to its larger drainage area, higher flows, and absence of man-made structures that restrict sediment movement in the lower basin, the South Yuba River transports a greater and coarser sediment load.

Scientific Investigations Report↗
USGS2016

Estimating peak-flow frequency statistics for selected gaged and ungaged sites in naturally flowing streams and rivers in Idaho

The U.S. Geological Survey, in cooperation with the Idaho Transportation Department, updated regional regression equations to estimate peak-flow statistics at ungaged sites on Idaho streams using recent streamflow (flow) data and new statistical techniques. Peak-flow statistics with 80-, 67-, 50-, 43-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (1.25-, 1.50-, 2.00-, 2.33-, 5.00-, 10.0-, 25.0-, 50.0-, 100-, 200-, and 500-year recurrence intervals, respectively) were estimated for 192 streamgages in Idaho and bordering States with at least 10 years of annual peak-flow record through water year 2013. The streamgages were selected from drainage basins with little or no flow diversion or regulation. The peak-flow statistics were estimated by fitting a log-Pearson type III distribution to records of annual peak flows and applying two additional statistical methods: (1) the Expected Moments Algorithm to help describe uncertainty in annual peak flows and to better represent missing and historical record; and (2) the generalized Multiple Grubbs Beck Test to screen out potentially influential low outliers and to better fit the upper end of the peak-flow distribution. Additionally, a new regional skew was estimated for the Pacific Northwest and used to weight at-station skew at most streamgages. The streamgages were grouped into six regions (numbered 1_2, 3, 4, 5, 6_8, and 7, to maintain consistency in region numbering with a previous study), and the estimated peak-flow statistics were related to basin and climatic characteristics to develop regional regression equations using a generalized least squares procedure. Four out of 24 evaluated basin and climatic characteristics were selected for use in the final regional peak-flow regression equations. Overall, the standard error of prediction for the regional peak-flow regression equations ranged from 22 to 132 percent. Among all regions, regression model fit was best for region 4 in west-central Idaho (average standard error of prediction=46.4 percent; pseudo-R 2 >92 percent) and region 5 in central Idaho (average standard error of prediction=30.3 percent; pseudo-R 2 >95 percent). Regression model fit was poor for region 7 in southern Idaho (average standard error of prediction=103 percent; pseudo-R 2 <78 percent) compared to other regions because few streamgages in region 7 met the criteria for inclusion in the study, and the region’s semi-arid climate and associated variability in precipitation patterns causes substantial variability in peak flows. A drainage area ratio-adjustment method, using ratio exponents estimated using generalized least-squares regression, was presented as an alternative to the regional regression equations if peak-flow estimates are desired at an ungaged site that is close to a streamgage selected for inclusion in this study. The alternative drainage area ratio-adjustment method is appropriate for use when the drainage area ratio between the ungaged and gaged sites is between 0.5 and 1.5. The updated regional peak-flow regression equations had lower total error (standard error of prediction) than all regression equations presented in a 1982 study and in four of six regions presented in 2002 and 2003 studies in Idaho. A more extensive streamgage screening process used in the current study resulted in fewer streamgages used in the current study than in the 1982, 2002, and 2003 studies. Fewer streamgages used and the selection of different explanatory variables were likely causes of increased error in some regions compared to previous studies, but overall, regional peak‑flow regression model fit was generally improved for Idaho. The revised statistical procedures and increased streamgage screening applied in the current study most likely resulted in a more accurate representation of natural peak-flow conditions. The updated, regional peak-flow regression equations will be integrated in the U.S. Geological Survey StreamStats program to allow users to estimate basin and climatic characteristics and peak-flow statistics at ungaged locations of interest. StreamStats estimates peak-flow statistics with quantifiable certainty only when used at sites with basin and climatic characteristics within the range of input variables used to develop the regional regression equations. Both the regional regression equations and StreamStats should be used to estimate peak-flow statistics only in naturally flowing, relatively unregulated streams without substantial local influences to flow, such as large seeps, springs, or other groundwater-surface water interactions that are not widespread or characteristic of the respective region.

Idaho↗
USGS1974

Characteristics of streamflow and ground-water conditions in the Boise River Valley, Idaho

The quantity, quality, and distribution in time of streamflow in Boise River below Lucky Peak Lake are drastically affected by storage reservoirs, diversions for irrigation, and by domestic, industrial, and agricultural wastes. Reservoirs usually fill during the nonirrigation season, and streamflow for several miles below Lucky Peak Lake is very low, sometimes less than 10 cubic feet per second (0.28 cubic meters per second). On November 18-19, 1971, when the gates at Lucky Peak Dam were closed, inflow to the Boise River in the study reach totaled 1010 ft 3 /s. Practically all inflow was discharged ground water. During the growing season, several thousands of ft 3 /s are released from Lucky Peak Lake, but diversions reduce the flows to near zero below some large diversion points in the study reach. Characteristics of streamflow are described by duration curves, duration hydrographs, and low-flow and high-flow frequency curves. Water released from Lucky Peak Lake is of excellent quality. Dissolved solids are usually less than 80 milligrams per liter. Discharged ground water increases the dissolved solids in the river downstream to 400 milligrams per liter or more when dilution from Lucky Peak Lake is slight. Other measures of water quality likewise show the deterioration in a downstream direction in the study reach.

Idaho↗
USGS1980

Hydrologic analysis of the proposed Badger-Beaver Creeks artificial-recharge project: Morgan County, Colorado

A hydrologic analysis of the proposed Badger-Beaver Creeks artificial-recharge project in Morgan County, Colo., was made with the aid of three digital computer models: A canal-distribution model, a ground-water flow model, and a stream-aquifer model. Statistical summaries of probable diversions from the South Platte River based on a 27-year period of historical flows indicate that an average-annual diversion of 96,000 acre-feet and a median-annual diversion of 43,000 acre-feet would be available. Diversions would sustain water in ponds for waterfowl habitat for an average of about five months per year, with a miximum pond surface area of about 300 acres with the median diversions and a maximum pond surface area of about 1,250 acres at least one-half of the years with the historic diversions. If the annual diversion were 43,000 acre-feet, recharge to the two alluvial aquifers would raise water levels sufficiently to create flowing streams in the channels of Beaver and Badger Creeks while allowing an increase in current ground-water pumping. The only area of significant waterlogging would be along the proposed delivery canal on the west edge of Badger Creek valley. If the total water available were diverted, the aquifer system could not transmit the water fast enough to the irrigation areas to avoid considerable waterlogging in the recharge areas. The impact of the proposed project on the South Platte River basin would be minimal once the ground-water system attained steady-state conditions, but that may take decades with a uniform diversion of the 43,000 acre-feet annually.

Colorado↗
USGS1998

Evaluation of the hydrologic system and selected water-management alternatives in the Owens Valley, California

The Owens Valley, a long, narrow valley along the east side of the Sierra Nevada in east-central California, is the main source of water for the city of Los Angeles. The city diverts most of the surface water in the valley into the Owens River-Los Angeles Aqueduct system, which transports the water more than 200 miles south to areas of distribution and use. Additionally, ground water is pumped or flows from wells to supplement the surface-water diversions to the river- aqueduct system. Pumpage from wells needed to supplement water export has increased since 1970, when a second aqueduct was put into service, and local residents have expressed concerns that the increased pumping may have a detrimental effect on the environment and the native vegetation (indigenous alkaline scrub and meadow plant communities) in the valley. Native vegetation on the valley floor depends on soil moisture derived from precipitation and from the unconfined part of a multilayered ground-water system. This report, which describes the evaluation of the hydrologic system and selected water-management alternatives, is one in a series designed to identify the effects that ground-water pumping has on native vegetation and evaluate alternative strategies to mitigate any adverse effects caused by pumping. The hydrologic system of the Owens Valley can be conceptualized as having three parts: (1) an unsaturated zone affected by precipitation and evapotranspiration; (2) a surface-water system composed of the Owens River, the Los Angeles Aqueduct, tributary streams, canals, ditches, and ponds; and (3) a saturated ground-water system contained in the valley fill. Analysis of the hydrologic system was aided by development of a ground-water flow model of the "aquifer system," which is defined as the most active part of the ground-water system and which includes nearly all of the Owens Valley except for the area surrounding the Owens Lake. The model was calibrated and verified for water years 1963-88 and used to evaluate general concepts of the hydrologic system and the effects of past water-management practices. The model also was used to evaluate the likely effects of selected water-management alternatives designed to lessen the adverse effects of ground-water pumping on native vegetation. Results of the model simulations confirm that a major change in the hydrologic system was caused by the additional export of water from the valley beginning in 1970. Average ground-water pumpage increased by a factor of five, discharge from springs decreased almost to zero, reaches of the Owens River that previously had gained water from the aquifer system began losing water, and total evapotranspiration by native plants decreased by about 35 percent. Water-management practices as of 1988 were defined and evaluated using the model. Simulation results indicate that increased ground-water pumpage since 1985 for enhancement and mitigation projects within the Owens Valley has further stressed the aquifer system and resulted in declines of the water table and reduced evapotranspiration. Most of the water-table declines are beneath the western alluvial fans and in the immediate vicinity of production wells. The water-table altitude beneath the valley floor has remained relatively constant over time because of hydrologic buffers, such as evapotranspiration, springs, and permanent surface-water features. These buffers adjust the quantity of water exchanged with the aquifer system and effectively minimize variations in water-table altitude. The widespread presence of hydrologic buffers is the primary reason the water-table altitude beneath the valley floor has remained relatively constant since 1970 despite major changes in the type and location of ground-water discharge. Evaluation of selected water-management alternatives indicates that long-term variations in average runoff to the Owens Valley of as much as 10 percent will not have a significant effect on the water-table altitude. However, reductions in pumpage to an average annual value of about 75,000 acre-ft/yr are needed to maintain the water table at the same altitude as observed during water year 1984. A 9-year transient simulation of dry, average, and wet conditions indicates that the aquifer system takes several years to recover from increased pumping during a drought, even when followed by average and above-average runoff and recharge. Increasing recharge from selected tributary streams by additional diversion of high flows onto the alluvial fans, increasing artificial recharge near well fields, and allocating more pumpage to the Bishop area may be useful in mitigating the adverse effects on native vegetation caused by drought and short-term increases in pumpage. Analysis of the optimal use of the existing well fields to minimize drawdown of the water table indicates no significant lessening of adverse effects on native vegetation at any of the well fields at the end of a 1-year simulation. Some improvement might result from pumping from a few high-capacity wells in a small area, such as the Thibaut-Sawmill well field; pumping from the upper elevations of alluvial fans, such as the Bishop well field; or pumping in an area surrounded by irrigated lands, such as the Big Pine well field. Use of these water-management techniques would provide some flexibility in management from one year to another, but would not solve the basic problem that increased ground-water pumpage causes decreases in evapotranspiration and in the biomass of native vegetation. Furthermore, the highly transmissive and narrow aquifer system will transmit the effects of pumping to other more sensitive areas of the valley within a couple of years. Other possible changes in water management that might be useful in minimizing the short-term effects of pumping on native vegetation include sealing well perforations in the unconfined part of the aquifer system; rotating pumpage among well fields; continuing or renewing use of unlined surface-water features such as canals and ditches; developing recharge and extraction facilities in deeper volcanic deposits near Big Pine or in alluvial fan deposits along the east side of the valley; installing additional wells along the west side of the Owens Lake; and conjunctively using other ground-water basins between the Owens Valley and Los Angeles to store exported water for subsequent extraction and use during droughts.

Water Supply Paper↗
USGS2010

Adaptation and survival of plants in high stress habitats via fungal endophyte conferred stress tolerance

From the Arctic to the Antarctic, plants thrive in diverse habitats that impose different levels of adaptive pressures depending on the type and degree of biotic and abiotic stresses inherent to each habitat (Stevens, 1989). At any particular location, the abundance and distribution of individual plant species vary tremendously and is theorized to be based on the ability to tolerate a wide range of edaphic conditions and habitat-specific stresses (Pianka, 1966). The ability of individual plant species to thrive in diverse habitats is commonly referred to as phenotypic plasticity and is thought to involve adaptations based on changes in the plant genome (Givnish, 2002; Pan et al., 2006; Robe and Griffiths, 2000; Schurr et al., 2006). Habitats that impose high levels of abiotic stress are typically colonized with fewer plant species compared to habitats imposing low levels of stress. Moreover, high stress habitats have decreased levels of plant abundance compared to low stress habitats even though these habitats may occur in close proximity to one another (Perelman et al., 2007). This is particularly interesting because all plants are known to perceive, transmit signals, and respond to abiotic stresses such as drought, heat, and salinity (Bartels and Sunkar, 2005; Bohnert et al., 1995). Although there has been extensive research performed to determine the genetic, molecular, and physiological bases of how plants respond to and tolerate stress, the nature of plant adaptation to high stress habitats remains unresolved (Leone et al., 2003; Maggio et al., 2003; Tuberosa et al., 2003). However, recent evidence indicates that a ubiquitous aspect of plant biology (fungal symbiosis) is involved in the adaptation and survival of at least some plants in high stress habitats (Rodriguez et al., 2008).

Book chapter↗
USGS2021

Diverse patterns of migratory timing, site use, and site fidelity by Alaska-breeding Whimbrels

Birds that conduct long-distance migrations exhibit varied patterns of consistency in migratory timing and site use. Understanding variation in these traits among populations can help uncover mechanisms driving migratory behaviors and identify potential population threats. Whimbrels ( Numenius phaeopus ) are long-distance migratory shorebirds with a Holarctic breeding distribution, and recent studies have documented population-specific migrations that vary in duration (short to long) and frequency of stops (none/few to multiple). Factors driving these population-specific differences are unclear. We studied the migration ecology of Whimbrels breeding in Alaska, USA, using satellite transmitters deployed from 2006 to 2010 and tracked through 2015. Whimbrels moved entirely within the Pacific Americas Flyway, and some conducted nonstop flights that exceeded seven days across ~ 8700 km. Birds dispersed across numerous sites throughout the flyway, often using agriculture or aquaculture habitats. Whimbrels generally exhibited fidelity to breeding and non-breeding sites, but typically only exhibited fidelity to staging sites used prior to long, nonstop migratory flights. The duration of migration for Whimbrels at more southern non-breeding locations was longer than for those at more northern non-breeding sites, and birds at more southern sites also terminated southbound migration later and initiated northbound migration earlier than birds at more northern sites. Alaska-breeding Whimbrels exhibited greater variation in migratory behaviors than those in other populations in the species’ range. We attribute this within-population diversity to the extensive breadth of non-breeding distributions (~ 70° latitude across ~ 8600 km), a range that naturally shaped individual responses to unequal migratory demands.

Alaska↗
USGS2024

Exploring and integrating differences in niche characteristics across regional and global scales to better understand plant invasions in Hawaiʻi

The spread of ecosystem modifying invasive plant (EMIP) species is one of the largest threats to native ecosystems in Hawaiʻi. However, differences in niche characteristics between Hawaiʻi’s isolated insular environment and the wider global distribution of these species have not been carefully examined. We used species distribution modeling (SDM) methods to assess similarities and differences in niche characteristics between global and regional scales for 17 EMIPs present in Hawaiʻi. With a clearer understanding of the global context of regional plant invasion, we combined two SDM methods to better understand the potential future regional spread: (1) a nested modeling approach to integrate global and regional invasive species distribution projections; and (2) integrating all available agency and citizen science data to minimize the effect of monitoring gaps and biases. Our results show there are multiple similarities in niche characteristics across regional and global scales for most species, such as similar sets of climatic determinants of distribution, similar responses along environmental gradients, and moderate to high niche overlap between global and regional models. However, some differences were apparent and likely due to several factors including incomplete regional spread, community assembly or diversity effects. Invaders that established earlier showed a higher degree of niche overlap and similar environmental gradient responses when comparing global and regional models. This pattern, coupled with the tendency for regionally-based projections to predict narrower distributions than global projections, indicates a potential for continued spread of several invasive species across the Hawaiian landscape. Our study has broader implications for understanding the distribution and spread of invasive species in other regions, as similar analyses and models, including a novel way to characterize environmental gradient response differences across regions or scales, can likely provide valuable information for conservation and management efforts.

Hawaii↗
USGS2021

Maximizing the science and resource mapping potential of Orbital VSWIR Spectral measurements of Mars

The last 16 years witnessed a rapid growth in understanding the composition and aqueous alteration of Mars’ surface from orbital data from the Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activité (OMEGA) [1] and Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) [2]. Both are sensitive to water-, hydroxyl-, sulfate-, and carbonate-bearing and ferric phases that record past liquid water. As the spatial resolution of such data has improved, and supporting laboratory data have been acquired, the diversity of mineral phases that are recognized has likewise expanded. The same phases typically contain recoverable water, a resource for future human exploration, and are the only near-surface water reservoir in the >50% of Mars over which ice likely does not occur in the shallowest subsurface. Knowledge of the distribution and abundance of these water-bearing phases, and their geologic implications, is limited by spatial resolution of the available data. A revolutionary advance in understanding the inventory, diversity, and stratigraphy of these materials can be obtained from Mars orbit, using two complementary approaches: hyperspectral imaging at ~6 meters per pixel at 0.7–4 µm, and 1 meter-per-pixel imaging at selected VSWIR wavelengths from 0.4–1.7 µm.

Bulletin of the AAS↗
USGS2023

Expanding our view of the cold-water coral niche and accounting of the ecosystem services of the reef habitat

Coral reefs are iconic ecosystems that support diverse, productive communities in both shallow and deep waters. However, our incomplete knowledge of cold-water coral (CWC) niche space limits our understanding of their distribution and precludes a complete accounting of the ecosystem services they provide. Here, we present the results of recent surveys of the CWC mound province on the Blake Plateau off the U.S. east coast, an area of intense human activity including fisheries and naval operations, and potentially energy and mineral extraction. At one site, CWC mounds are arranged in lines that total over 150 km in length, making this one of the largest reef complexes discovered in the deep ocean. This site experiences rapid and extreme shifts in temperature between 4.3 and 10.7 °C, and currents approaching 1 m s −1 . Carbon is transported to depth by mesopelagic micronekton and nutrient cycling on the reef results in some of the highest nitrate concentrations recorded in the region. Predictive models reveal expanded areas of highly suitable habitat that currently remain unexplored. Multidisciplinary exploration of this new site has expanded understanding of the cold-water coral niche, improved our accounting of the ecosystem services of the reef habitat, and emphasizes the importance of properly managing these systems.

Scientific Reports↗
USGS2017

The use of passive membrane samplers to assess organic contaminant inputs at five coastal sites in west Maui, Hawaii

Five passive membrane samplers were deployed for 28 continuous days at select sites along and near the west Maui coastline to assess organic compounds and contaminant inputs to diverse, shallow coral reef ecosystems. Daily and weekly fluctuations in such inputs were captured on the membranes using integrative sampling. The distribution of organic compounds observed at these five coastal sites showed considerable variation; with high concentrations of terrestrially sourced organic compounds such as C29 sterols and high molecular weight n -alkanes at the strongly groundwater-influenced Kahekili vent site. In comparison, the coastal sites were presumably influenced more by seasonal surface and stream water runoff and therefore had marine-sourced organic compounds and fewer pharmaceuticals and personal care products. The direct correlation to upstream land-use practices was not obvious and may require additional wet-season sampling. Pharmaceuticals and personal care products as well as flame retardants were detected at all sites, and the Kahekili vent site had the highest number of detections. Planned future work must also determine the organic compound and contaminant concentrations adsorbed onto water column particulate matter, because it may also be an important vector for contaminant transport to coral reef ecosystems. The impact of contaminants per individual (such as fecundity and metabolism) as well as per community (such as species abundance and diversity) is necessary for an accurate assessment of environmental stress. Results presented herein provide current contaminant inputs to select nearshore environments along the west Maui coastline captured during the dry season, and they can be useful to aid potential future evaluations and (or) comparisons.

Hawaii↗
USGS2022

Abundance and distribution of eelgrass (Zostera marina) and seaweeds at Izembek National Wildlife Refuge, Alaska, 2007–10

Eelgrass ( Zostera marina ) meadows are expansive along the lower Alaska Peninsula, supporting a rich diversity of marine life, yet little is known about their status and trends in the region. We tested techniques to inventory and monitor trends in the spatial extent and abundance of eelgrass in lagoons of the Izembek National Wildlife Refuge. We determined if Landsat imagery could be used to assess eelgrass spatial extent in shallow (less than 4 meter water depth) coastal waters of the refuge. We determined that this seagrass could be differentiated using Landsat imagery from other cover types (that is, channels and unvegetated tidal flats) with a high degree of accuracy (greater than 80 percent) in Izembek and Kinzarof Lagoons. Eelgrass meadows represented the largest cover type in Izembek (about 16,000 hectares) and Kinzarof (about 900 hectares) Lagoons, comprising between 45 and 50 percent of the spatial extent of these lagoons, respectively. When compared to estimates of spatial extent of eelgrass from previous studies, our results suggest little change in the spatial extent of eelgrass in Izembek Lagoon during the 28-year period 1978 through 2006. Preliminary mapping of eelgrass in other embayments indicated that this seagrass was also expansive in Big Lagoon (about 900 hectares; or 34 percent of the lagoon area) and Hook Bay (about 900 hectares; or 36 percent of the bay area) but not in Cold Bay (about 100 hectares; less than 5 percent of the bay area). We conducted an embayment-wide point sampling technique to assess aboveground biomass and distribution of eelgrass and seaweeds and presence of six macro-invertebrates during a 4-year period (2007–10). We determined that, when present, mean aboveground biomass of eelgrass was greater in Kinzarof Lagoon (182.5 plus or minus 12.1 grams dry weight per square meter) than in Izembek Lagoon (152.1 plus or minus 7.1 grams dry weight per square meter) in 2008–10, possibly reflecting the warmer sea temperatures and higher salinities found on the Gulf of Alaska side of the Alaska Peninsula. Seaweeds were more abundant in Kinzarof Lagoon than in Izembek Lagoon, surpassing aboveground biomass of eelgrass in both lagoons in 2008. Gastropods (4 percent of all points) and Caprella shrimp (25 percent) were the most common of the six macro-invertebrates surveyed in Izembek Lagoon, and Telmessus crab was the most common macro-invertebrate in Kinzarof Lagoon.

Alaska↗
USGS1999

Distributions of uronic acids and O-methyl sugars in sinking and sedimentary particles in two coastal marine environments

Although recent research has indicated that bacteria may contribute an important fraction of biochemical residues in terrestrial and marine environments, it is difficult for geochemists to identify contributions from these ubiquitous and biochemically diverse organisms. Previous studies have suggested uronic acids and O -methyl sugars may be useful indicators of microbial abundance and activity, but have been limited primarily to analyses of a small number of isolated samples. We report here comparative distributions of O -methyl sugars, uronic acids, and aldoses in sediment trap material and sediments from Dabob Bay, WA and nearby Saanich Inlet, BC, where temporal and spatial trends may be used together with well-established patterns in other biochemicals to identify bacterial contributions against the background of other carbohydrate sources. O -methyl sugars and uronic acids were important contributors to the overall flux and burial of polysaccharide material in Dabob Bay and Saanich Inlet, composing ≤12 wt% of the total carbohydrate yields from sediment trap and sediment samples. O -methyl sugars accounted for an average of 5% of the carbohydrate yields from sediment trap materials and sediments, but were found rarely and only in low abundance in vascular plant tissues, phytoplankton, and kelp. In contrast, uronic acids were abundant products of sediment trap material and sediments, as well as vascular plant tissues, where in some cases they predominated among all carbohydrates. Uronic acid abundance in sediment trap material averaged 3% and ranged to >6% of total carbohydrate yields. The persistence of total minor sugar yields in water column collections from Dabob Bay throughout the seasonal cycle indicated they had a primary source that was not directly related to plankton bloom cycles nor pulsed inputs of vascular plant remains. Subsurface maxima in total minor sugar yields (and several individual components) within sediment cores from both sites indicate in situ sedimentary sources. Taken together, the observed environmental distributions strongly suggest that the minor sugar abundances in Dabob Bay and Saanich Inlet were controlled by in situ microbial production.

British Columbia, Washington↗
USGS2021

Does taxonomic and numerical resolution affect the assessment of invertebrate community structure in New World freshwater wetlands?

The efficiency of biodiversity assessments and biomonitoring studies is commonly challenged by limitations in taxonomic identification and quantification approaches. In this study, we assessed the effects of different taxonomic and numerical resolutions on a range of community structure metrics in invertebrate compositional data sets from six regions distributed across North and South America. We specifically assessed the degree of similarity in the metrics (richness, equitability, beta diversity, heterogeneity in community composition and congruence) for data sets identified to a coarse resolution (usually family level) and the finest taxonomic resolution practical (usually genus level, sometimes species or morphospecies) and by presence-absence and relative abundance numerical resolutions. Spearman correlations showed highly significant and positive associations between univariate metrics (richness and equitability) calculated for coarse- and finest-resolution datasets. Procrustes analysis detected significant congruence between composition datasets. Higher correlation coefficients were found for datasets with the same numerical resolutions regardless of the taxonomic level (about 90%), while the correlations for comparisons across numerical resolutions were consistently lower. Our findings indicate that family-level resolution can be used as a surrogate of finer taxonomic resolutions to calculate a range of biodiversity metrics commonly used to describe invertebrate community structure patterns in New World freshwater wetlands without significant loss of information. However, conclusions on biodiversity patterns derived from datasets with different numerical resolutions should be critically considered in studies on wetland invertebrates.

California, Chubut, Georgia, Maine, North Dakota, ↗
USGS2012

Fish passage and abundance around grade control structures on incised streams

This paper summarizes research from separate studies of fish passage over weirs (Larson et al., 2004; Litvan, 2006; Litvan, et al., 2008a-c) and weir hydraulics (Papanicolaou and Dermisis, 2006; Papanicolaou and Dermisis, in press). Channel incision in the deep loess region of western Iowa has caused decreased biodiversity because streams have high sediment loads, altered flow regimes, lost habitat, and lost lateral connectivity with their former floodplains. In-stream grade control structures (GCS) are built to prevent further erosion, protect infrastructure, and reduce sediment loads. However, GCS can have a detrimental impact on fisheries abundance and migration, biodiversity, and longitudinal connectivity. Fish mark-recapture studies were performed on stretches of streams with and without GCS. GCS with vertical or 1:4 (rise/run) downstream slopes did not allow fish migration, but GCS with slopes ??? 1:15 did. GCS sites were characterized by greater proportions of pool habitat, maximum depths, fish biomass, slightly higher index of biotic integrity (IBI) scores, and greater macroinvertebrate abundance and diversity than non-GCS sites. After modification of three GCS, IBI scores increased and fish species exhibiting truncated distributions before were found throughout the study area. Another study examined the hydraulic performance of GCS to facilitate unimpeded fish passage by determining the mean and turbulent flow characteristics in the vicinity of the GCS via detailed, non-intrusive field tests. Mean flow depth (Y) and velocity (V) atop the GCS were critical for evaluating GCS performance. Turbulent flow measurements illustrated that certain GCS designs cause sudden constrictions which form eddies large enough to disorient fish. GCS with slopes ??? 1:15 best met the minimum requirements to allow catfish passage of a flow depth of ??? 0.31 m and a mean flow velocity of ??? 1.22 m/s. ?? 2009 ASCE.

Conference Paper↗
USGS2020

DTSGUI: A python program to process and visualize fiber‐optic distributed temperature sensing data

Fiber‐optic distributed temperature sensing (FO‐DTS) has proven to be a transformative technology for the hydrologic sciences, with application to diverse problems including hyporheic exchange, groundwater/surface‐water interaction, fractured‐rock characterization, and cold regions hydrology. FO‐DTS produces large, complex, and information‐rich datasets. Despite the potential of FO‐DTS, adoption of the technology has been impeded by lack of tools for data processing, analysis, and visualization. New tools are needed to efficiently and fully capitalize on the information content of FO‐DTS datasets. To this end, we present DTSGUI, a public‐domain Python‐based software package for editing, parsing, processing, statistical analysis, georeferencing, and visualization of FO‐DTS data.

Groundwater↗
USGS1983

Hydrologic and geomorphic studies of the Platte River basin

The channels of the Platte River and its major tributaries, the South Platte and North Platte Rivers in Colorado, Wyoming, and Nebraska, have undergone major changes in hydrologic regime and morphology since about 1860, when the water resources of the basin began to be developed for agricultural, municipal, and industrial uses. These water uses have continued to increase with growth in population and land development. Diversion of flow from channels, storage of water in reservoirs, and increased use of ground water have affected the distribution and timing of streamflows and the transport of fluvial sediments. All these factors have contributed to changes in channel geometry and the riverine environment. In 1979, the U.S. Geological Survey began investigations in the Platte River basin to determine the effects of water use on the hydrology and morphology of the Platte River and its major tributaries. These investigations also considered the relationship of hydrologic regime to factors that control or affect the habitat of migratory waterfowl in the Platte River valley. This volume brings together the results of several research studies on historical changes in channel morphology, surface-water hydrology, hydraulic geometry, sediment-transport and bedform processes, ground-water and surface-water relations, stochastic models of streamflow and precipitation, and methods for estimating discharge required to maintain channel width. In each of the studies, data on some segment of the Platte River hydrologic system were collected and interpreted. All the studies are interrelated; together they provide some degree of understanding of regime changes that are occurring. The hydrologic research described in the following chapters will be useful in decision-making pertaining to the management of water resources and migratory waterfowl habitats.

Colorado, Nebraska, Wyoming↗
USGS2023

Genetic diversity, structure, and effective population size of an endangered, endemic hoary bat, ʻōpeʻapeʻa, across the Hawaiian Islands

Island bat species are disproportionately at risk of extinction, and Hawaiʻi’s only native terrestrial land mammal, the Hawaiian hoary bat ( Lasiurus semotus) locally known as ʻōpeʻapeʻa, is no exception. To effectively manage this bat species with an archipelago-wide distribution, it is important to determine the population size on each island and connectivity between islands. We used 18 nuclear microsatellite loci and one mitochondrial gene from 339 individuals collected from 1988–2020 to evaluate genetic diversity, population structure and estimate effective population size on the Islands of Hawaiʻi, Maui, Oʻahu, and Kauaʻi. Genetic differentiation occurred between Hawaiʻi and Maui, both of which were differentiated from Oʻahu and Kauaʻi. The population on Maui presents the greatest per-island genetic diversity, consistent with their hypothesized status as the original founding population. A signature of isolation by distance was detected between islands, with contemporary migration analyses indicating limited gene flow in recent generations, and male-biased sex dispersal within Maui. Historical and long-term estimates of genetic effective population sizes were generally larger than contemporary estimates, although estimates of contemporary genetic effective population size lacked upper bounds in confidence intervals for Hawaiʻi and Kauaʻi. Contemporary genetic effective population sizes were smaller on Oʻahu and Maui. We also detected evidence of past bottlenecks on all islands with the exception of Hawaiʻi. Our study provides population-level estimates for the genetic diversity and geographic structure of ‘ōpeʻapeʻa, that could be used by agencies tasked with wildlife conservation in Hawaiʻi.

Hawaii↗