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USGS2008

Ecosystem conceptual model- Mercury

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

Report↗

USGS2014

Evaluation of juvenile salmonid behavior near a prototype weir box at Cowlitz Falls Dam, Washington, 2013

Collection of juvenile salmonids at Cowlitz Falls Dam is a critical part of the effort to restore salmon in the upper Cowlitz River because the majority of fish that are not collected at the dam pass downstream and enter a large reservoir where they become landlocked and lost to the anadromous fish population. However, the juvenile fish collection system at Cowlitz Falls Dam has failed to achieve annual collection goals since it first began operating in 1996. Since that time, numerous modifications to the fish collection system have been made and several prototype collection structures have been developed and tested, but these efforts have not substantially increased juvenile fish collection. Studies have shown that juvenile steelhead (Oncorhynchus mykiss), coho salmon (Oncorhynchus kisutch), and Chinook salmon (Oncorhynchus tshawytscha) tend to locate the collection entrances effectively, but many of these fish are not collected and eventually pass the dam through turbines or spillways. Tacoma Power developed a prototype weir box in 2009 to increase capture rates of juvenile salmonids at the collection entrances, and this device proved to be successful at retaining those fish that entered the weir. However, because of safety concerns at the dam, the weir box could not be deployed near a spillway gate where the prototype was tested, so the device was altered and re-deployed at a different location, where it was evaluated during 2013. The U.S. Geological Survey conducted an evaluation using radiotelemetry to monitor fish behavior near the weir box and collection flumes. The evaluation was conducted during April–June 2013. Juvenile steelhead and coho salmon (45 per species) were tagged with a radio transmitter and passive integrated transponder (PIT) tag, and released upstream of the dam. All tagged fish moved downstream and entered the forebay of Cowlitz Falls Dam. Median travel times from the release site to the forebay were 0.8 d for steelhead and 1.2 d for coho salmon. Most fish spent several days in the dam forebay; median forebay residence times were 4.4 d for juvenile steelhead and 5.7 d for juvenile coho salmon. A new radio transmitter model was used during the study period. The transmitter had low detection probabilities on underwater antennas located within the collection system, which prevented us from reporting performance metrics (discovery efficiency, entrance efficiency, retention efficiency) that are traditionally used to evaluate fish collection systems. Most tagged steelhead (98 percent) and coho salmon (84 percent) were detected near the weir box or collection flume entrances during the study period; 39 percent of tagged steelhead and 55 percent of tagged coho salmon were detected at both entrances. Sixty-three percent of the tagged steelhead that were detected at both entrances were first detected at the weir box, compared to 52 percent of the coho salmon. Twelve steelhead and 15 coho salmon detected inside the weir box eventually left the device and were collected in collection flumes or passed the dam. Overall, collection rates were relatively high during the study period. Sixty-five percent of the steelhead and 80 percent of the coho salmon were collected during the study, and most of the remaining fish passed the dam and entered the tailrace (24 percent of steelhead; 13 percent of coho salmon). The remaining 11 percent of steelhead and 7 percent of coho salmon did not pass the dam while their transmitters were operating. We were able to confirm collection of tagged fish at the fish facility using three approaches: (1) detection of radio transmitters in study fish; (2) detection of PIT-tags in study fish; (3) observation of study fish by staff at the fish facility. Data from all three methods were used to develop a multistate mark-recapture model that estimated detection probabilities for the various monitoring methods. These estimates then were used to describe the percent of tagged fish that were collected through the weir box and collection flumes. Detection probabilities of PIT-tag antennas in the collection flumes were 0.895 for juvenile steelhead and 0.881 for juvenile coho salmon, although radiotelemetry detection probabilities were 0.654 and 0.646 for the two species, respectively. The multistate model estimates showed that all steelhead and most coho salmon (94.5 percent) that were collected at the dam entered the collection system through the flumes rather than through the weir box. None of the tagged steelhead and only 5.5 percent of the tagged coho salmon were collected through the weir box. These data show that juvenile steelhead and coho salmon collection rates were much higher through the collection flumes than through the weir box. Low detection probabilities of tagged fish in the fish collection system resulted in uncertainty for some aspects of our evaluation. Missing detection records within the collection system for fish that were known to have been collected resulted in four tagged steelhead and seven tagged coho salmon being removed from the dataset, which was used to assess discovery rates of the weir box and collection flumes. However, the multistate model allowed us to provide unbiased estimates of the percentage of tagged fish that were collected through each route, and these data showed that few fish were collected through the weir box. Overall, the fish collection system performed reasonably well in collecting juvenile steelhead and coho salmon during the 2013 collection season. Fish collection efficiency estimates from the Washington Department of Fish and Wildlife showed that steelhead collection efficiency was slightly higher than the 10-year average (46 percent compared to 42 percent), whereas coho salmon collection efficiency was more than twice as high as the 10-year average (63 percent compared to 30 percent). However, the performance of the weir box was poor because most fish were collected through the collection flumes.

Washington↗

USGS2009

Trends in Water Quality in the Southeastern United States, 1973-2005

As part of the U.S. Geological Survey National Water-Quality Assessment Program, water-quality data for 334 streams in eight States of the Southeastern United States were assessed for trends from 1973 to 2005. Forty-four U.S. Geological Survey sites were examined for trends in pH, specific conductance, and dissolved oxygen, and in concentrations of dissolved solids, suspended sediment, chloride, sodium, sulfate, silica, potassium, dissolved organic carbon, total nitrogen, total ammonia, total ammonia plus organic nitrogen, dissolved nitrite plus nitrate, and total phosphorus. An additional 290 sites from the U.S. Environmental Protection Agency Storage and Retrieval database were tested for trends in total nitrogen and phosphorus concentrations for the 1975-2004 and 1993-2004 periods. The seasonal Kendall test or Tobit regression was used to detect trends. Concentrations of dissolved constituents have increased in the Southeast during the last 30 years. Specific conductance increased at 62 percent and decreased at 3 percent of the sites, and pH increased at 31 percent and decreased at 11 percent of the sites. Decreasing trends in total nitrogen were detected at 49 percent of the sites, and increasing trends were detected at 10 percent of the sites. Ammonia concentrations decreased at 27 percent of the sites and increased at 6 percent of the sites. Nitrite plus nitrate concentrations increased at 29 percent of the sites and decreased at 10 percent of the sites. These results indicate that the changes in stream nitrogen concentrations generally coincided with improved municipal wastewater-treatment methods. Long-term decreasing trends in total phosphorus were detected at 56 percent of the sites, and increasing trends were detected at 8 percent of the sites. Concentrations of phosphorus have decreased over the last 35 years, which coincided with phosphate-detergent bans and improvements in wastewater treatment that were implemented beginning in 1972. Multiple regression analysis indicated a relation between changes in atmospheric inputs and agricultural practices, and changes in water quality. A long-term water-quality and landscape trends-assessment network for the Southeast is needed to assess changes in water quality over time in response to variations in population, agricultural, wastewater, and landscape variables.

Scientific Investigations Report↗

USGS2015

Physical characteristics and fish assemblage composition at site and mesohabitat scales over a range of streamflows in the Middle Rio Grande, New Mexico, winter 2011-12, summer 2012

In winter 2011–12 and summer 2012, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers, Albuquerque District and the U.S. Fish and Wildlife Service New Mexico Fish and Wildlife Conservation Office in Albuquerque, New Mexico, evaluated the physical characteristics and fish assemblage composition of available mesohabitats over a range of streamflows at 15 sites on the Middle Rio Grande in New Mexico. The fish assemblage of the Middle Rio Grande includes several minnow species adapted to hydrologically variable but seasonably predictable rivers, including the Hybognathus amarus (Rio Grande silvery minnow), a federally listed endangered species. Gaining a better understanding of habitat usage by the Rio Grande silvery minnow was the impetus for studying physical characteristics and fish assemblages in the Middle Rio Grande during different streamflow conditions. Data were collected at all 15 sites during winter 2011–12 (moderate streamflow), and a subset was collected at the 13 most downstream sites in summer 2012 (low streamflow). Sites were grouped into four river reaches separated by diversion dams listed in downstream order (names of the diversion dams are followed by short names of the sites nearest each dam in parentheses, listed in downstream order): (1) Cochiti (Peña Blanca), (2) Angostura (Bernalillo, La Orilla, Barelas, Los Padillas), (3) Isleta (Los Lunas I, Los Lunas II, Abeytas, La Joya, Rio Salado), and (4) San Acacia (Lemitar, Arroyo del Tajo, San Pedro, Bosque del Apache I, and Bosque del Apache II). Stream habitat was mapped in the field by using a geographic information system in conjunction with a Global Positioning System. Fish assemblage composition was determined during both streamflow regimes, and fish were collected by seining in each mesohabitat where physical characteristic data (depth, velocity, dominant substrate type and size, and percent embeddedness) and water-quality properties (temperature, dissolved oxygen, specific conductance, and pH; during summer 2012 only) were measured. Nineteen species of fish were collected among the 15 sites and four reaches over both sampling periods; 10 of these 19 species are introduced. Fish-species richness (total number of fish species collected at each site during each sampling event) among sites that were sampled during both sampling periods ranged from 6 at Rio Salado to 12 at La Orilla. Fish were most abundant at the Lemitar site (1,786 individuals) and least abundant at the San Pedro site (275 individuals). The native Cyprinella lutrensis (red shiner) was the most abundant species collected among all of the sites, accounting for about 42 percent of fish collected. Fish-species richness and catch per unit effort (CPUE) were higher (or equivalent) at all sites during summer 2012 compared to winter 2011–12. The relations between fish assemblage composition (that is, total abundance, which refers to the number of individuals of each species that were collected) and selected environmental variables (physical characteristic data collected at the mesohabitat scale [depth, velocity, and substrate particle size], and mesohabitat types) were explored by using canonical correspondence analysis. Environmental variables explained 8 percent (p=0.48) of the variability in the Middle Rio Grande fish assemblage during winter 2011–12, and Rio Grande silvery minnow were weakly associated with sand substrates, relatively moderate velocities (qualitative descriptors are derived from synthetic gradients extracted from CCAs), and relatively shallow depths. Environmental variables explained 14 percent (p < 0.01) of the variability in the Middle Rio Grande fish assemblage during summer 2012, when Rio Grande silvery minnow were associated with run mesohabitats, relatively high velocities, sand substrates, and relatively moderate depths. The mean fish-species richness was greater in summer 2012 than in winter 2011–12 for each mesohabitat type, and the overall fish-species richness across all mesohabitat types was 0.62 during winter 2011–12, compared to 1.49 during summer 2012. The highest mean CPUE during winter 2011–12 was in isolated pools (54.3 fish per 100 square meters [m 2 ]), whereas the lowest was in flats (18.9 fish per 100 m 2 ). Ranges in CPUE were higher in summer 2012 relative to winter 2011–12 in each mesohabitat type sampled. As in winter 2011–12, the highest mean CPUE during summer 2012 was in isolated pools (233 fish per 100 m 2 ), whereas the lowest was in flats (29.6 fish per 100 m 2 ). Overall mean CPUE per mesohabitat across all mesohabitat types was 29.1 fish per 100 m 2 during winter 2011–12 compared to 85.3 fish per 100 m 2 during summer 2012. Four species of minnows (red shiner, Rio Grande silvery minnow, Pimephales promelas [fathead minnow], and Platygobio gracilis [flathead chub]) were selected to compare preferred mesohabitat characteristics because all are small-bodied minnows and because more than 200 individuals of each of these species were collected. Red shiner were collected across the largest range of depths in both winter 2011–12 (0.02–4.31 feet [ft]) and summer 2012 (0.05–3.4 ft), as well as the largest range of velocities (0.0–4.31 feet per second [ft/s]) during winter 2011–12 among the four minnow species of interest. Rio Grande silvery minnow occurred in the narrowest range of depths (0.30–2.1 ft) during summer 2012, as well as the narrowest range of velocities in both winter 2011–12 (0.0–3.18 ft/s) and summer 2012 (0.02–1.51 ft/s). Water-quality properties were only collected during summer 2012, when low-streamflow conditions existed and water-quality properties were thought to be potentially most limiting to aquatic life. Area-weighted mean water temperatures tended to be higher at the sites that were sampled in August 2012 (25.57 degrees Celsius [°C]) compared to June 2012 (24.61 °C). The highest area-weighted mean water temperature at a given site (29.03 °C) was measured at the Lemitar site on August 7, 2012, coincident with the lowest measured discharge (4.13 cubic feet per second [ft 3 /s]). Area-weighted mean dissolved oxygen concentrations tended to be lower in August (7.46 milligrams per liter [mg/L]) compared to June (8.33 mg/L). The highest area-weighted mean dissolved oxygen concentration (9.13 mg/L) was measured at the Lemitar site on August 7, 2012, and the lowest area-weighted mean dissolved oxygen concentration (6.23 mg/L) was measured at the Los Padillas site on August 10, 2012. Area-weighted specific conductance in the sites upstream from La Joya did not exceed 400 microsiemens per centimeter (μS/cm) at 25 °C, whereas the area-weighted mean specific conductance at La Joya (837 μs/cm at 25 °C), Rio Salado (857 μs/cm at 25 °C), and Lemitar (1,300 μs/cm at 25 °C) were all well above the average of the area-weighted means for the 10 remaining sites (433 μs/cm at 25 °C). Lower area-weighted mean pH values were measured at the 3 sites in and near Albuquerque (La Orilla, Barelas, and Los Padillas—7.98, 8.08, and 7.81, respectively) compared to any of the 10 remaining sites, which had an overall mean pH of 8.44.

New Mexico↗

USGS1977

Application of a hydrometeorological model to the south-central Sierra Nevada of California

A hydrometeorological streamflow-prediction model (HM model) developed for the North Cascades of Washington has been tested in the south-central Sierra Nevada of California. Twenty-four drainages ranging in mean altitude from 770 to 3,160 metres, including several of the major ones such as those of the Kern, Kings, and Merced Rivers, were examined. Eight U.S. National Oceanic and Atmospheric Administration precipitation stations were evaluated. Of these, three proved to be of significant value for nearly all the drainages used. Results are given for predictions on February 1, March 1, and April 1 of monthly runoff of five major drainages for the April-September season. Also demonstrated is the April 1 prediction of a daily hydrograph for the April-September season for 2 diverse years. The altitude distribution of storage and runoff, both observed and predicted, is determined by using several drainages with different area-altitude profiles. Results of this calculation for two drainages show that, on the average, approximately 50 percent of the April-July runoff originates above 2,800 m. The influence of subsequent precipitation on prediction accuracy is determined by relating prediction error and actual precipitation occurring after the prediction day. Results for three basins show that about 75 percent of the error of a January-September prediction on January 1 is due to precipitation occurring during the prediction season. Comparisons of prediction accuracy are made for five major drainages: the Kern River near Kernville; the Kings River below North Fork, near Trimmer (inflow to Pine Flat Dam); the Kings River at Piedra; the Merced River at Pohono Bridge, near Yosemite; and the Merced River below Merced Falls Dam, near Snelling. The accuracy of the HM model appears to be about 24 percent higher than existing operational methods in predicting the April-July runoff on April 1.

California↗

USGS1994

Disruption of Drift glacier and origin of floods during the 1989-1990 eruptions of Redoubt Volcano, Alaska

Melting of snow and glacier ice during the 1989–1990 eruption of Redoubt Volcano caused winter flooding of the Drift River. Drift glacier was beheaded when 113 to 121 × 10 6 m 3 of perennial snow and ice were mechanically entrained in hot-rock avalanches and pyroclastic flows initiated by the four largest eruptions between 14 December 1989 and 14 March 1990. The disruption of Drift glacier was dominated by mechanical disaggregation and entrainment of snow and glacier ice. Hot-rock avalanches, debris flows, and pyroclastic flows incised deep canyons in the glacier ice thereby maintaining a large ice-surface area available for scour by subsequent flows. Downvalley flow rheologies were transformed by the melting of snow and ice entrained along the upper and middle reaches of the glacier and by seasonal snowpack incorporated from the surface of the lower glacier and from the river valley. The seasonal snowpack in the Drift River valley contributed to lahars and floods a cumulative volume equivalent to about 35 × 10 6 m 3 of water, which amounts to nearly 30% of the cumulative flow volume 22 km downstream from the volcano. The absence of high-water marks in depressions and of ice-collapse features in the glacier indicated that no large quantities of meltwater that could potentially generate lahars were stored on or under the glacier; the water that generated the lahars that swept Drift River valley was produced from the proximal, eruption-induced volcaniclastic flows by melting of snow and ice.

Alaska↗

USGS2018

Climate model assessment of changes in winter-spring streamflow timing over North America

Over regions where snow-melt runoff substantially contributes to winter-spring streamflows, warming can accelerate snow melt and reduce dry-season streamflows. However, conclusive detection of changes and attribution to anthropogenic forcing is hindered by brevity of observational records, model uncertainty, and uncertainty concerning internal variability. In this study, a detection/attribution of changes in mid-latitude North American winter-spring streamflow timing is examined using nine global climate models under multiple forcing scenarios. In this study, robustness across models, start/end dates for trends, and assumptions about internal variability is evaluated. Marginal evidence for an emerging detectable anthropogenic influence (according to four or five of nine models) is found in the north-central U.S., where winter-spring streamflows have been coming earlier. Weaker indications of detectable anthropogenic influence (three of nine models) are found in the mountainous western U.S./southwestern Canada and in extreme northeastern U.S./Canadian Maritimes. In the former region, a recent shift toward later streamflows has rendered the full-record trend toward earlier streamflows only marginally significant, with possible implications for previously published climate change detection findings for streamflow timing in this region. In the latter region, no forced model shows as large a shift toward earlier streamflow timing as the detectable observed shift. In other (including warm, snow-free) regions, observed trends are typically not detectable, although in the U.S. central plains we find detectable delays in streamflow, which are inconsistent with forced model experiments.

Journal of Climate↗

USGS2011

Bridging the energy gap: Anadromous blueback herring feeding in the Hudson and Mohawk rivers, New York

Adult blueback herring Alosa aestivalis (N = 116) were collected during the 1999, 2000, and 2002-2004 spawning runs from sites on the Hudson and Mohawk rivers, and gut contents were analyzed. Thirty-four fish (33% of those examined) were found to contain food material. Food items were present in 41% of Mohawk River samples and 11% of Hudson River samples; all Hudson River fish containing food were captured in small tributaries above the head of tide. Hudson River fish predominantly consumed zooplankton, while Mohawk River fish consumed benthic aquatic insects in large quantities, including Baetidae, Ephemeridae, and Chironomidae. Using stable isotope analysis and a mixing model, we found that fish collected later in the season had significantly decreased marine-derived C. Condition indices of later-season fish were equal to or greater than those of fish collected earlier in the season. Blueback herring in this system may face increased energy requirements as they migrate farther upstream during spawning runs, and feeding may provide energy subsidies needed to maintain fitness over their expanded migratory range. ?? Copyright by the American Fisheries Society 2007.

Transactions of the American Fisheries Society↗

USGS1993

Effects of climatic variations over 11 years on nitrate-nitrogen concentrations in the Raccoon River, Iowa

Nitrate-nitrogen (NO3-N) concentrations at public water supply intakes on the Des Moines and Raccoon Rivers in Iowa exceeded the maximum contaminant level (MCL) of 10 mg L-1 for public water supplies established by the USEPA for extended periods of time from March through early August 1990. The excessive NO3-N levels followed 2 yr of less-than normal precipitation in 1988 and 1989. The largest daily NO3-N load (771 t) transported during the last 17 yr in the Raccoon River occurred in June 1990. The streamflow hydrograph for the Raccoon River for March 1990 prior to seasonal fertilizer application indicates that high NO3-N concentrations characterize the recession side of the hydrograph. High NO3-N concentrations in streamflow persisted as streamflow decreased to baseflow conditions. This implies that substantial quantities of NO3-N were being leached from the soil and transported by subsurface flow during early 1990. A multiple linear-regression model was developed to predict NO3-N concentrations in the Raccoon River from readily-obtainable streamflow and climatic data. The four-variable model explained about 70% of the variability in the concentration of NO3-N. The mean streamflow for the previous 7-d period accounted for about 50% of the total variability.

Iowa↗

USGS2008

Davis Pond freshwater prediversion biomonitoring study: freshwater fisheries and eagles

In January 2001, the construction of the Davis Pond freshwater diversion structure was completed by the U.S. Army Corps of Engineers. The diversion of freshwater from the Mississippi River is intended to mitigate saltwater intrusion from the Gulf of Mexico and to lessen the concomitant loss of wetland areas. In addition to the freshwater inflow, Barataria Bay basin would receive nutrients, increased flows of sediments, and water-borne and sediment-bound compounds. The purpose of this biomonitoring study was, therefore, to serve as a baseline for prediversion concentrations of selected contaminants in bald eagle ( Haliaeetus leucocephalus ) nestlings (hereafter referred to as eaglets), representative freshwater fish, and bivalves. Samples were collected from January through June 2001. Two similarly designed postdiversion studies, as described in the biological monitoring program, are planned. Active bald eagle nests targeted for sampling eaglet blood (n = 6) were generally located southwest and south of the diversion structure. The designated sites for aquatic animal sampling were at Lake Salvador, at Lake Cataouatche, at Bayou Couba, and along the Mississippi River. Aquatic animals representative of eagle prey were collected. Fish were from three different trophic levels and have varying feeding strategies and life histories. These included herbivorous striped mullet ( Mugil cephalus ), omnivorous blue catfish ( Ictalurus furcatus ), and carnivorous largemouth bass ( Micropterus salmoides ). Three individuals per species were collected at each of the four sampling sites. Freshwater Atlantic rangia clams ( Rangia cuneata ) were collected at the downstream marsh sites, and zebra mussels ( Dreissena spp.) were collected on the Mississippi River. The U.S. Geological Survey (USGS) Biomonitoring of Environmental Status and Trends (BEST) protocols served as guides for fish sampling and health assessments. Fish are useful for monitoring aquatic ecosystems because they accumulate pesticides and other contaminants. Biomarker data on individual fish, generated at the USGS National Wetlands Research Center (Lafayette, La.), included percent white blood cells in whole blood, spleen weight to body weight ratio, liver weight to body weight ratio, condition factor, splenic macrophage aggregates, and liver microsomal 7-ethoxyresorufin-o-deethylase (EROD) activity. Fish age was estimated by comparing total lengths with values from the same species in the Southeast United States as determined from the literature. Contaminant analyses were coordinated by the U.S. Fish and Wildlife Service (USFWS) Analytical Control Facility (Laurel, Md.), where residues of organochlorine (OC) pesticides, total polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (AHs), and trace elements were determined. The organic contaminant data were generated at the Mississippi State University Chemical Lab (Mississippi State, Miss.), and the inorganic contaminant data were generated by the Texas A&M University Geochemical and Environmental Research Group (College Station, Tex.). Statistical tests were performed to assess relationships among contaminants, fish age, fish species, and collection sites. Trends in interspecific differences among fish in concentrations of contaminants were noted. Striped mullet (hereafter mullet) frequently displayed the highest chemical concentrations. Levels of contaminants were generally higher in samples obtained from the Mississippi River than in those collected from the diversion area and were higher in mussels and clams (hereafter bivalves) than in fish. Because the Mississippi River sampling site for mullet and largemouth bass was downriver of the structure and south of New Orleans and the catfish site was upriver, the downriver data may not be directly reflective of the results from the receiving waters at the Davis Pond structure. Compared to the Caernarvon freshwater prediversion study in 1990 that assessed possible influx of contaminants with the freshwater diversion, contaminant levels in fishes and bivalves in this study were generally lower, yet three nontoxic inorganic elements in Davis Pond fish samples exhibited ranges of concentrations that were more than two times higher than did those from Caernarvon. Levels in bivalves were different between diversions but about equal in the numbers of trace elements showing high levels per location. Contaminant values were compared to those listed in various literature and agency sources, both regional and national, including the National Contaminant Biomonitoring Program (NCBP), in which the 85th percentile and above represents what is considered to be an elevated contaminant concentration and cause for concern. Generally, bivalves were at the high end of their ranges for both organic and inorganic contaminants. In this study, OCs were detectable in 67 percent of fish from the Mississippi River site, ranging from 0.15 to 1.09 μg/g wet weight (ww) or fresh weight (fw), and in 11 percent of the fish from the marsh sites, ranging from 0.06 to 0.612 μg/g ww. Bivalves from the Mississippi River had OC levels of 0.096 μg/g ww, whereas none were detectable in bivalves at the marsh sites. In this study, p,p ’-dichlorodiphenyldichloroethylene ( p,p’ -DDE) (a biodegradation product of DDT [dichlorodiphenyl trichloroethane]) and total PCBs were the most frequently detected OCs and were primarily from the Mississippi River. For total OC content, using adjusted least squares means, some significant interactions were noted between fish species and sites. PAHs were detected in aquatic animals at all sites (range of 0.017–17.534 μg/g ww), as were AHs (range of 0.423–4.549 μg/g ww); the highest levels of PAHs and AHs were found in bivalves from the Mississippi River. When analysis of variance (α = 0.05) was performed with data from aquatic animals, there were only two significant relationships between PAHs, AHs, and OCs between species, site, and age or the interaction among these variables. There was an interaction between fish species and n-decane (an AH) in that mullet and largemouth bass had significantly higher levels than did catfish ( P = 0.0175). When general linear means were used to investigate associations of inorganic contaminants among fish species, site, and age or any interactions among these variables, no significant results were noted for arsenic, cadmium, lead, beryllium, boron, molybdenum, or nickel. The range of mercury in fish in this study was 0.04–0.14 μg/g ww (0.14– 0.48 μg/g dry weight [dw]), with the most elevated levels detected in predatory largemouth bass at the sampling point farthest downstream from the structure and within the marsh area. Mercury was positively correlated with fish age ( P = 0.0152), where levels were estimated to increase 0.0253 parts per million (ppm) dw per year. In the Mississippi River, catfish showed significantly higher levels of mercury than did mullet or largemouth bass ( P = 0.00167). Among fish species, mullet displayed the highest levels in fish of aluminum, barium, manganese, and iron, all considered to have low toxicity in hydrologic systems. An interaction between fish and site was seen with aluminum ( P = 0.0031), where concentrations in mullet were significantly higher in the Mississippi River than at the other sites, as was also seen with barium ( P = 0.0009), chromium ( P = <0.0001), manganese ( P = 0.0004), strontium ( P = 0.0074), vanadium ( P = 0.0156), and zinc ( P = 0.0059). For iron ( P = 0.0.0001), mullet and largemouth bass at both the Mississippi River and Lake Salvador showed higher levels than did catfish, and these two species showed higher levels at two of the four sites. An interaction between fish and site was also seen with chromium ( P = <0.0001) in that concentrations in mullet were significantly higher in the Mississippi River than at the other sites, as was also seen with strontium ( P = 0.0074), vanadium ( P = 0.0156), and zinc ( P = 0.0059), metals for which deleterious effects have been demonstrated in other ecosystems. The NCBP program lists the 85th percentile for zinc at 34.2 μg/g fw (117.9 μg/g dw). In the Davis Pond prediversion biomonitoring study (hereafter the current study), one fish (MUL31RIVER, fish ID 8) showed values higher than that (125.4 μg/g dw or 37.54 μg/g ww), and the Mississippi River bivalve sample (MUSSRIVER) had a value of 140 μg/g dw (41.2 μg/g ww). In the current study, approximately 86 percent of the fish had measurable selenium levels, yet none reached the 85th percentile. The 85th percentile for selenium from the NCBP was 0.73 μg/g ww. Significantly higher levels of selenium were seen in mullet than in largemouth bass and catfish ( P = 0.0023). The NCBP 85th percentile for lead is 0.22 μg/g ww (0.76 μg/g dw). In the current study, the range of concentrations of lead was as much as 18.3 ppm dw (MUL31RIVER, fish ID 8), with the three most elevated values (range of 3.46–5.31 μg/g ww) coming from mullet from the Mississippi River. Biomarker data are measurable and directly reflect the condition of the animal, and measuring more than one biomarker in an individual increases confidence in health assessments. In the current study, biomarkers included macrophage aggregates (MAs), liver (hepatosomatic index [HSI]) and spleen (splenosomatic index [SSI]) weight to body weight ratios, percent white blood cells (WBCs) in whole blood, and condition factor. Few significant differences were noted with any of the biomarkers between sites, and there were no relationships between species and sites. For improved use of biomarker assessments, an increase in fish sample size would be useful for postdiversion sampling, as would comparisons of fish of the same sex and reproductive condition. During the current study, success for eagle nests in the diversion area and reference sites was similar as determined by numbers of nestlings fledged. When temperatures were below average during winter 2000, nests in both regions similarly failed. At each nest, the primary evidence of food items was small mammals. Eaglets (n = 6) generally appeared healthy, and whole blood concentrations of organic contaminants exceeded detection limits with three incidences of p,p’ -DDE (0.002–0.006 μg/L ww) and one incidence of oxychlordane (0.002 μg/L ww). The levels of p,p’ -DDE were well below those that have been inversely correlated with productivity and success rates of nesting bald eagles on a regional scale. The low values found in the whole blood samples for OC pesticides and PCBs were even lower when corrected for plasma volume. Aluminum values were 3.66 and 5.75 μg/L in two samples, zinc ranged from 5.21 to 6.77 μg/L ww in six samples, and silicon ranged from 1.7 to 4.6 μg/L in four samples. Selenium was detectable in each bird with the range at 0.332–0.566 μg/L ww, and strontium ranged from 0.0581 to 0.0975 μg/L ww. Mercury was detectable in blood samples from each bird and ranged from 0.0254 to 0.0845 μg/L ww, whereas lead was detectable in four samples and ranged from 0.0042 to 0.0136 μg/L ww. Although no detectable levels of total PCBs were found (also correlated with decreased reproductive productivity), 70 percent of the aquatic animals from the Mississippi River contained total PCBs (range 0.13–0.79 μg/L), whereas only about 7 percent of the aquatic animals sampled from the marsh area contained PCBs. Suggestions for postdiversion sampling include lowering the analytical detection limit for some metals, sampling aquatic animals over the course of a single season, obtaining a higher sample number of mature fish of one species (for example, blue catfish) within a range of total lengths for biomarker analyses, obtaining otoliths for estimating fish ages, assessing dioxins in eaglet blood, examining triazines in water, and obtaining all Mississippi River fish samples as close to the Davis Pond structure intake as possible. Because contaminants found in blood of eaglets reflect their prey species and because of the contaminant levels found in fish in the current study, eaglets may not be consuming primarily these species; therefore, obtaining juvenile nutria ( Myocastor coypus ) or turtle species for contaminant analyses might be considered, as well as collecting greater blood volume and using plasma to measure OCs and PCBs. Data obtained postdiversion will be compared with prediversion data to monitor changes.

Louisiana↗

USGS2005

Ground-water hydrology of the Willamette basin, Oregon

The Willamette Basin encompasses a drainage of 12,000 square miles and is home to approximately 70 percent of Oregon's population. Agriculture and population are concentrated in the lowland, a broad, relatively flat area between the Coast and Cascade Ranges. Annual rainfall is high, with about 80 percent of precipitation falling from October through March and less than 5 percent falling in July and August, the peak growing season. Population growth and an increase in cultivation of crops needing irrigation have produced a growing seasonal demand for water. Because many streams are administratively closed to new appropriations in summer, ground water is the most likely source for meeting future water demand. This report describes the current understanding of the regional ground-water flow system, and addresses the effects of ground-water development. This study defines seven regional hydrogeologic units in the Willamette Basin. The highly permeable High Cascade unit consists of young volcanic material found at the surface along the crest of the Cascade Range. Four sedimentary hydrogeologic units fill the lowland between the Cascade and Coast Ranges. Young, highly permeable coarse-grained sediments of the upper sedimentary unit have a limited extent in the floodplains of the major streams and in part of the Portland Basin. Extending over much of the lowland where the upper sedimentary unit does not occur, silts and clays of the Willamette silt unit act as a confining unit. The middle sedimentary unit, consisting of permeable coarse-grained material, occurs beneath the Willamette silt and upper sedimentary units and at the surface as terraces in the lowland. Beneath these units is the lower sedimentary unit, which consists of predominantly fine-grained sediments. In the northern part of the basin, lavas of the Columbia River basalt unit occur at the surface in uplands and beneath the basin-fill sedimentary units. The Columbia River basalt unit contains multiple productive water-bearing zones. A basement confining unit of older marine and volcanic rocks of low permeability underlies the basin and occurs at land surface in the Coast Range and western part of the Cascade Range. Most recharge in the basin is from infiltration of precipitation, and the spatial distribution of recharge mimics the distribution of precipitation, which increases with elevation. Basinwide annual mean recharge is estimated to be 22 inches. Rain and snowmelt easily recharge into the permeable High Cascade unit and discharge within the High Cascade area. Most recharge in the Coast Range and western part of the Cascade Range follows short flowpaths through the upper part of the low permeability material and discharges to streams within the mountains. Consequently, recharge in the Coast and Ranges is not available as lateral ground-water flow into the lowland, where most ground-water use occurs. Within the lowland, annual mean recharge is 16 inches and most recharge occurs from November to April, when rainfall is large and evapotranspiration is small. From May to October recharge is negligible because precipitation is small and evapotranspiration is large. Discharge of ground water is mainly to streams. Ground-water discharge is a relatively large component of flow in streams that drain the High Cascade unit and parts of the Portland Basin where permeable units are at the surface. In streams that do not head in the High Cascade area, streamflow is generally dominated by runoff of precipitation. Ground-water in the permeable units in the lowland discharges to the major streams where there is a good hydraulic connection between aquifers and streams. Ground-water discharge to smaller streams, which flow on the less permeable Willamette silt unit, is small and mostly from the Willamette silt unit. Most ground-water withdrawals occur within the lowland. Irrigation is the largest use of ground water, accounting for 240,000 acre feet of withdrawals, or 81 p

Scientific Investigations Report↗

USGS1985

Effects of climate, vegetation, and soils on consumptive water use and ground-water recharge to the Central Midwest Regional aquifer system, mid-continent United States

The Central Midwest aquifer system, in parts of Arkansas, Colorado, Kansas, Missouri, Nebraska, New Mexico, South Dakota, and Texas, is a region of great hydrologic diversity. This study examines the relationships between climate, vegetation, and soil that affect consumptive water use and recharge to the groundwater system. Computations of potential recharge and consumptive water use were restricted to those areas where the aquifers under consideration were the immediate underlying system. The principal method of analysis utilized a soil moisture computer model. This model requires four types of input: (1) hydrologic properties of the soils, (2) vegetation types, (3) monthly precipitation, and (4) computed monthly potential evapotranspiration (PET) values. The climatic factors that affect consumptive water use and recharge were extensively mapped for the study area. Nearly all the pertinent climatic elements confirmed the extreme diversity of the region. PET and those factors affecting it--solar radiation, temperature, and humidity--showed large regional differences; mean annual PET ranged from 36 to 70 inches in the study area. The seasonal climatic patterns indicate significant regional differences in those factors affecting seasonal consumptive water use and recharge. In the southern and western parts of the study area, consumptive water use occurred nearly the entire year; whereas, in northern parts it occurred primarily during the warm season (April through September). Results of the soil-moisture program, which added the effects of vegetation and the hydrologic characteristics of the soil to computed PET values, confirmed the significant regional differences in consumptive water use or actual evapotranspiration (AET) and potential groundwater recharge. Under two different vegetative conditions--the 1978 conditions and pre-agricultural conditions consisting of only grassland and woodland--overall differences in recharge were minimal. Mean annual recharge under both conditions averaged slightly more than 4.5 inches for the entire study area, but ranged from less than 0.10 inches in eastern Colorado to slightly more than 15 inches in Arkansas.

Arkansas, Colorado, Kansas, Missouri, Nebraska, Ne↗

USGS1974

Some aspects of aquatic insect populations of pools and riffles in gravel bed streams in western United States

Relationships were studied between aquatic-insect populations on rocks of different sizes and variations of populations between different stream localities. All aquatic insects were counted and identified on streambed gravels and cobbles chosen at random from four rivers on three to four types of locations ranging from riffles to pools. The measurements used span 3 to 4 months in 1 year. Insect density (number of insects per unit of rock area) was determined to be a function of rock size. Highest insect densities occurred on rocks between 45 and 90 mm mean diameter, with larger and smaller rocks having lower insect densities. The insect population differed significantly with location within a stream; that is, from pool to riffle, as well as by stream and season.

Journal of Research of the U.S. Geological Survey↗

USGS1991

Diurnal photosynthesis cycle in CAM and non-CAM seasonal pool aquatic macrophytes

Seasonal pools undergo marked diurnal changes in pH, free carbon dioxide, and oxygen levels. Previous studies showed that Isoetes howellii utilized crassulacean acid metabolism (CAM) photosynthesis as a means of assimilating carbon at night when ambient carbon dioxide levels are high. However, much of the pool flora is not CAM. We hypothesized that coexistence under extreme carbon—limiting conditions would select for other photosynthetic characteristics in these non—CAM species. Quantitative carbon uptake measurements wee made in the field on the CAM Isoetes howellii and the non—CAM Eleocharis acicularis, Downingia bella, and Plagiobothrys undulatus. Despite wide phylogenetic separation, thee species are structurally convergent in that they all produce aquatic stage with an isoetid growth form. They are functionally similar in that none appear to utilize bicarbonate, and all are carbon limited through much of the day, as indicated by a marked midday depression in carbon uptake that last through the afternoon. All four species were capable of carbon fixation at night, although only in Isoetes howellii was this accompanied by an overnight accumulation of acid. It was estimated that dark fixation in I. howelli contributed up to 40% of its total carbon gain under submerged conditions, but was <1% under aerial conditions. The role of dark fixation in the other three, non—CAM, species is unknown. Short—term (1 s) steady—term (1 s) steady—state 1 4 C tracer studies in the laboratory revealed that, under submerged conditions in the light, all species assimilated carbon into the C 3 photosynthetic product phosphoglycerate (PGA) and the C 4 photosynthetic products of malate, citrate, and aspartate. The proportion of label fixed into C 4 organic acids was greatest in E. acicularis. The ratio of RuBP carboxylase/PEP carboxylase was broadly similar in all species, ranging from 8.8 to 11.5. When the pools dried down and the plants became aerial, photosynthetic rates increased and a midday depression such as occurred under submergence was not observed. Carbon fixation in the dark became negligible, and the RuBP carboxylase/PEP carboxylase ratio increased. Seasonal changes in biomass showed I. howellii and E. acicularis dominated the pools early in the season, and the biomass of the other two species increased later when the pools dried. The latter species, D. bella and P. undulatus, also had higher rates of photosynthesis under aerial conditions.

Ecology↗

USGS2011

Data logging of body temperatures provides precise information on phenology of reproductive events in a free-living arctic hibernator

Precise measures of phenology are critical to understanding how animals organize their annual cycles and how individuals and populations respond to climate-induced changes in physical and ecological stressors. We show that patterns of core body temperature ( T b ) can be used to precisely determine the timing of key seasonal events including hibernation, mating and parturition, and immergence and emergence from the hibernacula in free-living arctic ground squirrels ( Urocitellus parryii ). Using temperature loggers that recorded T b every 20 min for up to 18 months, we monitored core T b from three females that subsequently gave birth in captivity and from 66 female and 57 male ground squirrels free-living in the northern foothills of the Brooks Range Alaska. In addition, dates of emergence from hibernation were visually confirmed for four free-living male squirrels. Average T b in captive females decreased by 0.5–1.0°C during gestation and abruptly increased by 1–1.5°C on the day of parturition. In free-living females, similar shifts in T b were observed in 78% ( n = 9) of yearlings and 94% ( n = 31) of adults; females without the shift are assumed not to have given birth. Three of four ground squirrels for which dates of emergence from hibernation were visually confirmed did not exhibit obvious diurnal rhythms in T b until they first emerged onto the surface when T b patterns became diurnal. In free-living males undergoing reproductive maturation, this pre-emergence euthermic interval averaged 20.4 days ( n = 56). T b -loggers represent a cost-effective and logistically feasible method to precisely investigate the phenology of reproduction and hibernation in ground squirrels.

Journal of Comparative Physiology B: Biochemical, ↗

USGS2022

Stochastic agent-based model for predicting turbine-scale raptor movements during updraft-subsidized directional flights

Rapid expansion of wind energy development across the world has highlighted the need to better understand turbine-caused avian mortality. The risk to golden eagles ( Aquila chrysaetos ) is of particular concern due to their small population size and conservation status. Golden eagles subsidize their flight in part by soaring in orographic updrafts, which can place them in conflict with wind turbines utilizing the same low-altitude wind resource. Understanding the behavior of soaring raptors in varying atmospheric conditions can therefore be relevant to predicting and mitigating their risk of collision. We present a predictive movement model that simulates individual paths of golden eagles during directional flight (such as migration) that is subsidized by orographic updraft. We modeled eagles in a 50 km by 50 km study area in Wyoming containing three wind power plants with documented golden eagle collisions with turbines. The movement model is applicable to any region where ground elevation is known at turbine scale ( < "> < 50 m) and wind conditions are known at facility scale ( < "> < 3 km). For a given set of atmospheric conditions, the model simulates movements of thousands of orographic soaring eagles to produce a density map quantifying the relative probability of eagle presence. We validated the simulated tracks with GPS telemetry data showing four directional tracks made by golden eagles transiting through the area in 2019 and 2020. For each eagle track, validation was performed using the ratio of the model-simulated eagle presence likelihood with uniform eagle presence and the presence computed using directed random-walk movements. We found that the predictive performance of the model was significantly better (likelihood ratio > "> > 1) for low-altitude movements than high-altitude movements that can involve thermal-soaring. We employed the model to produce seasonal presence maps for migrating golden eagles. We found significant turbine-level variations in eagle presence between northerly and southerly migration routes through the study area. Overall, the proposed model offers a generalizable, probabilistic, and predictive tool to assist wind energy developers, ecologists, wildlife managers, and industry consultants in estimating the potential for conflict between soaring birds and wind turbines, thereby reducing the need for site-specific data on golden eagle movements.

Wyoming↗

USGS2014

Impact of climate variability on runoff in the north-central United States

Large changes in runoff in the north-central United States have occurred during the past century, with larger floods and increases in runoff tending to occur from the 1970s to the present. The attribution of these changes is a subject of much interest. Long-term precipitation, temperature, and streamflow records were used to compare changes in precipitation and potential evapotranspiration (PET) to changes in runoff within 25 stream basins. The basins studied were organized into four groups, each one representing basins similar in topography, climate, and historic patterns of runoff. Precipitation, PET, and runoff data were adjusted for near-decadal scale variability to examine longer-term changes. A nonlinear water-balance analysis shows that changes in precipitation and PET explain the majority of multidecadal spatial/temporal variability of runoff and flood magnitudes, with precipitation being the dominant driver. Historical changes in climate and runoff in the region appear to be more consistent with complex transient shifts in seasonal climatic conditions than with gradual climate change. A portion of the unexplained variability likely stems from land-use change.

Iowa, Kansas, Minnesota, Missouri, Nebraska, North↗

USGS2012

Hunting influences the diel patterns in habitat selection by northern pintails Anas acuta

Northern pintail Anas acuta (hereafter pintail) populations wintering within Suisun Marsh, a large estuarine managed wetland near San Francisco Bay, California,USA, have declined markedly over the last four decades. The reasons for this decline are unclear. Information on how hunting and other factors influence the selection of vegetation types and sanctuaries would be beneficial to manage pintail populations in SuisunMarsh. During 1991-1993, we radio-marked and relocated female pintails (individuals: N = 203, relocations: N = 7,688) within Suisun Marsh to investigate habitat selection during the non-breeding months (winter). We calculated selection ratios for different vegetation types and for sanctuaries, and examined differences in those ratios between hunting season (i.e. hunting and non-hunting), age (hatchyear and after-hatch-year), and time of day (daylight or night hours). We found that diel patterns in selection were influenced by hunting disturbance. For example, prior to the hunting season and during daylight hours, pintails selected areas dominated by brass buttons Cotula coronopifolia, a potentially important food source, usually outside of sanctuary boundaries. However, during the hunting season, pintails did not select brass buttons during daylight hours, but instead highly selected permanent pools, mostly within sanctuaries. Also, during the hunting season, pintails showed strong selection for brass buttons at night. Sanctuaries provided more area of permanent water pools than within hunting areas and appeared to function as important refugia during daylight hours of the hunting season. Wildlife managers should encourage large protected permanent pools adjacent to hunted wetlands to increase pintail numbers within wetland environments and responsibly benefit hunting opportunities while improving pintail conservation.

California↗