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At least 613 records · Page 34Linked to original sources
USGS2000

Diversity, distribution, and conservation status of the native freshwater fishes of the southern United States

The Southeastern Fishes Council Technical Advisory Committee reviewed the diversity, distribution, and status of all native freshwater and diadromous fishes across 51 major drainage units of the southern United States. The southern United States supports more native fishes than any area of comparable size on the North American continent north of Mexico, but also has a high proportion of its fishes in need of conservation action. The review included 662 native freshwater and diadromous fishes and 24 marine fishes that are significant components of freshwater ecosystems. Of this total, 560 described, freshwater fish species are documented, and 49 undescribed species are included provisionally pending formal description. Described subspecies (86) are recognized within 43 species, 6 fishes have undescribed subspecies, and 9 others are recognized as complexes of undescribed taxa. Extinct, endangered, threatened, or vulnerable status is recognized for 28% (187 taxa) of southern freshwater and diadromous fishes. To date, 3 southern fishes are known to be extinct throughout their ranges, 2 are extirpated from the study region, and 2 others may be extinct. Of the extant southern fishes, 41 (6%) are regarded as endangered, 46 (7%) are regarded as threatened, and 101 (15%) are regarded as vulnerable. Five marine fishes that frequent fresh water are regarded as vulnerable. Our assessment represents a 75% increase in jeopardized southern fishes since 1989 and a 125% increase in 20 years. The trend for fishes in the southern United States is clear; jeopardized fishes are successively being moved from the vulnerable category to that of imminent threat of extinction.

Fisheries↗
USGS2016

A hierarchical model of daily stream temperature using air-water temperature synchronization, autocorrelation, and time lags

Water temperature is a primary driver of stream ecosystems and commonly forms the basis of stream classifications. Robust models of stream temperature are critical as the climate changes, but estimating daily stream temperature poses several important challenges. We developed a statistical model that accounts for many challenges that can make stream temperature estimation difficult. Our model identifies the yearly period when air and water temperature are synchronized, accommodates hysteresis, incorporates time lags, deals with missing data and autocorrelation and can include external drivers. In a small stream network, the model performed well (RMSE = 0.59°C), identified a clear warming trend (0.63 °C decade −1 ) and a widening of the synchronized period (29 d decade −1 ). We also carefully evaluated how missing data influenced predictions. Missing data within a year had a small effect on performance (∼0.05% average drop in RMSE with 10% fewer days with data). Missing all data for a year decreased performance (∼0.6 °C jump in RMSE), but this decrease was moderated when data were available from other streams in the network.

PeerJ↗
USGS2012

Base flow (1966-2009) and streamflow gain and loss (2010) of the Brazos River from the New Mexico-Texas State line to Waco, Texas

During 2010–11, the U.S. Geological Survey (USGS), in cooperation with the Texas Water Development Board, used hydrograph separation to quantify historical base flow at 11 USGS streamflow-gaging stations between water years 1966–2009 and streamflow gains and losses from two sets of synoptic measurements of streamflow and specific conductance (the first in June 2010, followed by another set in October 2010) in the upper Brazos River Basin from the New Mexico–Texas State line to Waco, Texas. The following subbasins compose the study area: Salt Fork Brazos River Basin, Double Mountain Fork Brazos River Basin, Clear Fork Brazos River Basin, North Bosque River Basin, and the Brazos River Basin (main stem) (including its tributaries). Base-flow analysis was done using historical streamflow data from 11 USGS streamflow-gaging stations in the upper Brazos River Basin to compute yearly base-flow indexes (base flow divided by total streamflow) for each station. The base-flow index was used to indicate the fraction of flow consisting of base flow on an annual basis for the period of record evaluated at each streamflow-gaging station. At nine stations there were long-term streamflow data from water years 1966–2009 (October 1965 through September 2009); at two stations slightly shorter periods of record (water years 1967–2009 and 1969–2009) were available. The median base-flow indexes were 0.16 and 0.15 at USGS streamflow-gaging stations 08082000 Salt Fork Brazos River near Aspermont, Tex., and 08080500 Double Mountain Fork Brazos River near Aspermont, Tex., respectively. The amount of the total streamflow consisting of base flow was larger at sites in the Clear Fork Brazos River Basin compared to sites in the Salt Fork Brazos River Basin or Double Mountain Fork Brazos River Basin; at USGS streamflow-gaging stations 08084000 Clear Fork Brazos River at Nugent, Tex., and at 08085500 Clear Fork Brazos River at Fort Griffin, Tex., the median base-flow indexes were 0.28 and 0.23, respectively. The largest median base-flow index for any station was 0.35 at USGS streamflow-gaging station 08091500 Paluxy River at Glen Rose, Tex. The second largest base-flow index was 0.30 at USGS streamflow-gaging station 08095000 North Bosque River near Clifton, Tex. Median base-flow indexes on the main stem of the Brazos River upstream from Possum Kingdom Lake were 0.22 at USGS streamflow-gaging station 08082500 Brazos River at Seymour, Tex., and 0.24 at USGS streamflow-gaging station 08088000 Brazos River near South Bend, Tex. The base-flow indexes for stations between Possum Kingdom Lake and Lake Granbury were 0.19 and 0.27 at USGS streamflow-gaging stations 08089000 Brazos River near Palo Pinto, Tex., and 08090800 Brazos River near Dennis, Tex., respectively. A median base-flow index of 0.19 was also measured at USGS streamflow-gaging station 08091000 Brazos River near Glen Rose, Tex., located between Lake Granbury and Lake Whitney. A Mann-Kendall trend analysis test was performed on annual base-flow index values from each of the 11 streamflow records that were analyzed. Upward trends in base-flow index values indicating increasing flows during the study period were found for USGS streamflow-gaging stations 08080500 Double Mountain Fork Brazos River near Aspermont, Tex., 08089000 Brazos River near Palo Pinto, Tex., and 08090800 Brazos River near Dennis, Tex. Flows at these three streamflow-gaging stations are regulated by reservoir releases, and additional analyses are needed before these streamflow trends can be characterized as indicative of changes in base flow over time. Streamflow was measured at 66 sites from June 6–9, 2010, and at 68 sites from October 16–19, 2010, to identify reaches in the upper Brazos River Basin that were gaining or losing streamflow. Gaining reaches were identified in each of the five subbasins. The gaining reach in the Salt Fork Brazos River Basin began at USGS streamflow-gaging station 08080940 Salt Fork Brazos River at State Highway 208 near Clairemont, Tex. (site SF–6), upstream from where Duck Creek flows into the Salt Fork Brazos River and continued downstream past USGS streamflow-gaging station 08082000 Salt Fork Brazos River near Aspermont, Tex. (site SF–9), to the outlet of the basin. In the Double Mountain Fork Brazos River Basin, a gaining reach from near Post, Tex., downstream to the outlet of the basin was identified. Two gaining reaches were identified in the Clear Fork Brazos River Basin—one from near Roby, Tex., downstream to near Noodle, Tex., and second from Hawley, Tex., downstream to Nugent, Tex. Most of the North Bosque River was characterized as gaining streamflow. Streamflow gains were identified in the main stem of the Brazos River from where the Brazos River main stem forms at the confluence of the Salt Fork Brazos River and Double Mountain Fork Brazos River near Knox City, Tex., downstream to near Seymour, Tex.

New Mexico, Texas↗
USGS1988

Amino-acid diagenesis and its implication for late Pleistocene lacustrine sediment, Clear Lake, California

The diagenesis of amino acids in sediments from Clear Lake core CL-80-1 is indicated by changes in amino acid concentrations, compositions, and stereochemistry. Concentrations of total amino acids decrease with depth, but the decrease is not systematic, possibly reflecting a nonuniformity in sedimentary and postdepositional processes affecting the amino acids. Ratios of neutral/acidic amino acids may indicate that the pH of interstitial water is slightly alkaline to slightly acidic and that the organic matter is well humified. Ratios of nonprotein/protein amino acids suggest that some changes in amino acids with depth result from microbial degradations. The extent of racemization of alanine increases with depth; the trends of these data may be explained, in part, by rapid sedimentation within the lake. Agreement between extents of alanine racemization for sediments from equivalent depths in two cores from the lake suggests that diagenetic temperatures are uniform within the sediments of the northern basin of Clear Lake.

California↗
USGS2020

Local to landscape-level controls of water fluxes through Hawaiian forests: Effects of invasive animals and plants on soil infiltration capacity across substrate and moisture gradients

Given the potential effect of invasive plants and animals to water fluxes through forests, the invasive-driven degradation of native ecosystems is a topic of great concern for many downstream land and water managers. The infiltration rate determines the partitioning between runoff and infiltration into soil in Hawaiian forests and beyond. Thus, to explore the ecohydrological effects of plant and animal invasion in mesic and wet forests in Hawaii, we measured soil infiltration capacity in multiple fenced (i.e., ungulate-free)/unfenced and native/invaded forest sites along moisture and substrate age gradients across the islands of Hawai‘i and Kaua‘i. We also characterized forest composition and structure and soil characteristics at these sites to assess the direct and vegetation-mediated impacts of invasive species on infiltration capacity. Infiltration capacity is highly variable across forested sites and the wider landscape. Much of this variability is determined by a complex set of soil, vegetation, and disturbance factors that affect infiltration capacity at the immediate surrounding of measurement plots. Consequently, the effect of any given factor can be masked by variability in other factors. However, by controlling for variability in soil and vegetation conditions at a local plot level, we found that the presence of invasive species in forests has complex and sometimes non-intuitive effects on infiltration. Our final models showed that invasive ungulates negatively affect soil infiltration capacity consistently across the wide moisture and substrate age gradients considered. Additionally, because several soil characteristics known to be affected by ungulates were associated with local infiltration rates (e.g., soil organic matter, bare soil cover, soil depth), the long-term secondary effects of high ungulate densities in Hawaiian forests may be higher than effects observed in this study. These results provide clear evidence for land managers that ungulate control efforts likely improve ecohydrologic function to mesic and wet forest systems critical to protecting downstream and nearshore resources and maintaining groundwater recharge. Compared to ungulate effects, the effect of invasive plants on water infiltration capacity in Hawaiian forests appeared much more complex. In general, elements of forest structure including increased canopy, understory and floor cover, greater presence of large roots, and lower grass and bare soil covers were positively associated with water infiltration. Whether native or not, a plant species’ potential to alter infiltration rates in Hawaiian forests was likely to depend on its physiognomy and how it affects forest community structure. For instance, while the cover of native dominant tree ‘ōhi‘a, Metrosideros polymorpha, was found to be positively associated with infiltration capacity (perhaps as an indicator of overall forest integrity), invasive Himalayan ginger, Hedychium gardnerianum, was also positively correlated with infiltration capacity, possibly due to preferential flow channels created by the presence of large root mats. Few studies have conducted comprehensive integrated ecological and hydrological sampling in forests of high conservation value. While we show there are large benefits to understanding how conservation efforts may help shape water fluxes, we also found that the commonly used study design for infiltration studies used here and elsewhere (i.e., adjacent paired sites) could be modified to provide more accurate effects of invasion in future studies for ecosystems in Hawaii and beyond.

Hawaii↗
USGS2015

Dominance of 'Gallionella capsiferriformans' and heavy metal association with Gallionella -like stalks in metal-rich pH 6 mine water discharge

Heavy metal-contaminated, pH 6 mine water discharge created new streams and iron-rich terraces at a creek bank in a former uranium-mining area near Ronneburg, Germany. The transition from microoxic groundwater with ~5 m m Fe(II) to oxic surface water may provide a suitable habitat for microaerobic iron-oxidizing bacteria (FeOB). In this study, we investigated the potential contribution of these FeOB to iron oxidation and metal retention in this high-metal environment. We (i) identified and quantified FeOB in water and sediment at the outflow, terraces, and creek, (ii) studied the composition of biogenic iron oxides ( Gallionella -like twisted stalks) with scanning and transmission electron microscopy (SEM, TEM) as well as confocal laser scanning microscopy (CLSM), and (iii) examined the metal distribution in sediments. Using quantitative PCR, a very high abundance of FeOB was demonstrated at all sites over a 6-month study period. Gallionella spp. clearly dominated the communities, accounting for up to 88% of Bacteria , with a minor contribution of other FeOB such as Sideroxydans spp. and ‘ Ferrovum myxofaciens ’. Classical 16S rRNA gene cloning showed that 96% of the Gallionella -related sequences had ≥97% identity to the putatively metal-tolerant ‘ Gallionella capsiferriformans ES-2’, in addition to known stalk formers such as Gallionella ferruginea and Gallionellaceae strain R-1. Twisted stalks from glass slides incubated in water and sediment were composed of the Fe(III) oxyhydroxide ferrihydrite, as well as polysaccharides. SEM and scanning TEM-energy-dispersive X-ray spectroscopy revealed that stalk material contained Cu and Sn, demonstrating the association of heavy metals with biogenic iron oxides and the potential for metal retention by these stalks. Sequential extraction of sediments suggested that Cu (52–61% of total sediment Cu) and other heavy metals were primarily bound to the iron oxide fractions. These results show the importance of ‘ G. capsiferriformans ’ and biogenic iron oxides in slightly acidic but highly metal-contaminated freshwater environments.

Geobiology↗
USGS1990

Hydrogeology and ground-water-quality conditions at the Emporia- Lyon County Landfill, eastern Kansas, 1988

Hydrogeology and water-quality conditions at the Emporia-Lyon County Landfill, eastern Kansas, were investigated from April 1988 through April 1989. Potentiometric-surface maps indicated groundwater movement from the northeast and northwest towards the landfill and then south through the landfill to the Cottonwood River. The maps indicate that during periods of low groundwater levels, groundwater flows northward in the north-west part of the landfill, which may have been induced by water withdrawal from wells north of the landfill or by water ponded in waste lagoons south and west of the landfill. Chemical analysis of water samples from monitoring wells upgradient and downgradient of the landfill indicate calcium bicarbonate to be the dominant water type. No inorganic or organic chemical concentrations exceeded Kansas or Federal primary drinking-water standards. Kansas secondary drinking-water standards were equaled or exceeded, however, in water from some or all wells for total hardness, dissolved solids, iron, and manganese. Water from one upgradient well contained larger concentrations of dissolved oxygen and nitrate, and smaller concentrations of bicarbonate, alkalinity, ammonia, arsenic, iron, and manganese as compared to all other monitoring wells. Results of this investigation indicate that groundwater quality downgradient of well MW-2 has increased concentrations of some inorganic and organic compounds. Due to the industrial nature of the area and the changing directions of groundwater flow, it is not clear what the source of these compounds might be. Long-term monitoring, additional wells, and access to nearby waste lagoons and waste-lagoon monitoring wells would help define the sources of increased inorganic and organic compounds. (USGS)

Water-Resources Investigations Report↗
USGS1989

Evidence against pervasively deformed bed material beneath rapidly moving lobes of the southern Laurentide Ice Sheet

During the Wisconsin Glaciation, the ice lobes of the southern part of the Laurentide Ice Sheet moved rapidly as the result of elevated subglacial water pressure. The rapid movement was probably not accompanied by wide-spread pervasive deformation of unfrozen material under the ice. The till stratigraphy of much of this area is well known, and it is clear that the stratigraphic sequence is generally intact. Therefore, such deformation, if it occurred, would have been restricted to the till sheet that was currently being deposited. However, this seems unlikely as well, because the till of the region commonly contains lenses and clasts of unlithified bedded sand that should have been destroyed by pervasive shearing. If unfrozen deformed-till layers were widely present, they must have been confined to the thin upper parts of till sheets.

Minnesota, Wisconsin↗
USGS2019

Coastal wetlands: A synthesis

This book and this synthesis address the pressing need for better management of coastal wetlands worldwide because these wetlands are disappearing at an alarming rate; in some countries the loss is 70%–80% in the last 50 years. Managing requires understanding. Although our understanding of the functioning of coastal wetland ecosystems has grown rapidly over the past decade, still much remains to be learned and understood. We have gained insight into the roles of geomorphic processes, hydrologic dynamics, biotic feedback, and disturbance agents in creating and molding a variety of coastal wetland ecosystems across climatic gradients. The variety is expressed not so much in the more obvious differences in vegetation cover, but rather how physical processes both facilitate and constrain a diversity of plant and animal communities. At one level, coastal wetlands are the product of tidal forces and freshwater inputs at the margin of continents. At another level, the plants control the water currents in the tidal creeks draining the wetlands by generating a tidal current asymmetry that controls sediment transport and results in a deep tidal creek surrounded by shallow vegetated wetlands. The vegetation also influences the physics of water and sediment through several other processes including biofilms, bioturbation of sediments, the buffeting of currents and waves, organic enrichment of sediments, and the closing of nutrient cycles. Few ecosystems provide us with so many clear examples of such feedback controls. What we do understand about the structure and functioning of coastal wetlands should provide the theoretical underpinnings for effective management in protecting them for their many contributions to ecosystem goods and services. What we do not understand should compel us to focus our attention and energies toward seeking optimal solutions to some of the most perplexing and urgent problems facing natural resource management.

Book chapter↗
USGS2018

Environmental risks and challenges associated with neonicotinoid insecticides

Neonicotinoid use has increased rapidly in recent years, with a global shift towards insecticide applications as seed coatings rather than aerial spraying. While the use of seed coatings can lessen the amount of overspray and drift, the near universal and prophylactic use of neonicotinoid seed coatings on major agricultural crops has led to widespread detections in the environment (pollen, soil, water, honey). Pollinators and aquatic insects appear to be especially susceptible to the effects of neonicotinoids with current research suggesting that chronic sub-lethal effects are more prevalent than acute toxicity. Meanwhile, evidence of clear and consistent yield benefits from the use of neonicotinoids remains elusive for most crops. Future decisions on neonicotinoid use will benefit from weighing crop yield benefits versus environmental impacts to non-target organisms and considering whether there are more environmentally benign alternatives.

Environmental Science & Technology↗
USGS2012

Geochemical constraints on adakites of different origins and copper mineralization

The petrogenesis of adakites holds important clues to the formation of the continental crust and copper ± gold porphyry mineralization. However, it remains highly debated as to whether adakites form by slab melting, by partial melting of the lower continental crust, or by fractional crystallization of normal arc magmas. Here, we show that to form adakitic signature, partial melting of a subducting oceanic slab would require high pressure at depths of >50 km, whereas partial melting of the lower continental crust would require the presence of plagioclase and thus shallower depths and additional water. These two types of adakites can be discriminated using geochemical indexes. Compiled data show that adakites from circum-Pacific regions, which have close affinity to subduction of young hot oceanic plate, can be clearly discriminated from adakites from the Dabie Mountains and the Tibetan Plateau, which have been attributed to partial melting of continental crust, in Sr/Y-versus-La/Yb diagram. Given that oceanic crust has copper concentrations about two times higher than those in the continental crust, whereas the high oxygen fugacity in the subduction environment promotes the release of copper during partial melting, slab melting provides the most efficient mechanism to concentrate copper and gold; slab melts would be more than two times greater in copper (and also gold) concentrations than lower continental crust melts and normal arc magmas. Thus, identification of slab melt adakites is important for predicting exploration targets for copper- and gold-porphyry ore deposits. This explains the close association of ridge subduction with large porphyry copper deposits because ridge subduction is the most favorable place for slab melting.

Dabie Mountains and the Tibetan Plateau↗
USGS1960

Ecological systems and the water resources

In ancient Sparta there were two principal classes of society, the citizen and the helot. The citizen was trained principally to be a warrior. The helot, a serf, was the tiller of the land but could be called to military duty. The history of Herodotus makes it amply clear that making war was the biggest business of the times. Because the Spartans were always marching off to war with someone, they found the landbound position of their city, located as its is in a small central basin nearly surrounded by mountains, somewhat of a disadvantage. When they were under attack, of course, this situation was a favorable one inasmuch as a seaborne enemy had to march inland to come to grips with the Lacedaemonians. The relatively small size of the independent states meant that the Spartans had no direct access through their own lands to the sea. There is evidence that the Spartans reached an agreement with surrounding states concerning a free corridor. There would be maintained by all the Grecian states of the Peloponnesus an access route stretching essentially from Sparta to Corinth, through which a marching army could have access to a seaport. As a secondary benefit, this no man's land, which in our western lingo might be called a stock driveway, allowed merchants and their caravans to move freely between the flourishing trading port of Corinth and the inland cities to the south and west. Apparently one portion of the agreement between the states with regard to the use of this access zone was that there should be no permanent agricultural or grazing in the driveway. As a result, through several centuries B.C. during which there was high population density in the Aegean area, one strip of land was exempted from the pressures of grazing, lumbering, and agriculture which characterized most of the rest of the landscape. Today this driveway maintains a forest cover. In contrast, mountainsides nearby with an even larger annual rainfall support hardly a tree. It is not entirely apparent why subsequent centuries did not see this area denuded. Even with the scanty details known to me it seems clear that the peculiar history of this one area potentially offers us a greater insight into some aspects of forest and land conditions of classical times than extant written records. The several references to sources of timber and cutting of forests contained in the vivid chronicle of Herodotus are valuable, but they lack species identification for the most part. Though rich in human understanding and psychological insight, his history strongly resembles the travel sagas of the Spanish Conquistadors of our Southwest, who had no real eye for "country." Even a careful reading of the works of early travelers such as Coronado, Garces, and Espejo, gives no picture of the nature of the country, its vegetation, or its rivers. To describe a biota there is no substitute for a sample. It is logical to ask what one might want to know which would require the preservation of a sample. Whether such a question is asked at all is a reflection on the stage of intellectual maturity of a civilization. We take for granted that there is social gain in the erection and maintenance of a museum of fine arts, a museum of natural history, or a historical museum. Sooner or later we should be mature enough to extend this concept to include a "museum" consisting of samples of land types as nearly as possible unaffected by man.

Circular↗
USGS2012

Upper Clear Creek watershed aquatic chemistry and biota surveys, 2004-5, Whiskeytown National Recreation Area, Shasta County, California

The U.S. Geological Survey, in cooperation with the National Park Service and Whiskeytown National Recreation Area, performed a comprehensive aquatic biota survey of the upper Clear Creek watershed, Shasta County, California, during 2004-5. Data collected in this study can provide resource managers with information regarding aquatic resources, watershed degradation, and regional biodiversity within Whiskeytown National Recreation Area. Surveys of water chemistry, bed-sediment chemistry, algae assemblages, benthic macroinvertebrate assemblages, aquatic vertebrate assemblages, in-stream habitat characteristics, and sediment heterogeneity were conducted at 17 stream sites during both 2004 and 2005, with an additional 4 sites surveyed in 2005. A total of 67 bed-sediment samples were analyzed for major and trace inorganic element concentrations. Forty-six water samples were analyzed for trace metals and nutrients. A total of 224 taxa of invertebrates were collected during these surveys. Eleven fish species, seven of which were native, and two species of larval amphibians, were collected. A total of 24 genera of soft algae and 159 taxa of diatoms were identified. To date, this survey represents the most comprehensive inventory of aquatic resources within Whiskeytown National Recreation Area, and this information can serve as a baseline for future monitoring efforts and to inform management decisions.

California↗
USGS2020

Diversity of diatoms, benthic macroinvertebrates, and fish varies in response to different environmental correlates in Arctic rivers across North America

Climate change poses a significant threat to Arctic freshwater biodiversity, but impacts depend upon the strength of organism response to climate‐related drivers. Currently, there is insufficient knowledge about Arctic freshwater biodiversity patterns to guide assessment, prediction, and management of biodiversity change. As part of the Circumpolar Biodiversity Monitoring Program's first freshwater assessment, we evaluated diversity of diatoms, benthic macroinvertebrates, and fish in North American Arctic rivers. Alpha diversity was assessed in relation to temperature, water chemistry, bedrock geology, and glaciation history to identify important environmental correlates. Biotic composition was compared among groups to evaluate response to environmental gradients. Macroinvertebrate α‐diversity declined strongly with increasing latitude from 48°N to 82°N, whereas diatom and fish diversity peaked around 70°N without a clear latitudinal decline. Macroinvertebrate diversity was significantly positively related to air temperature. Diatom diversity was related to bedrock geology and temperature, whereas fish diversity was related to glaciation history. Fish and macroinvertebrate assemblages differed between sites in western Canada, where invertebrate composition was more variable, and Alaska, where fish composition was more variable. In sites with both diatom and macroinvertebrate data, diatom composition was distinct in Alaska, where richness was highest in former glacial refugia. Macroinvertebrate composition was distinct in lowest‐latitude eastern and high‐latitude western Canadian sites where temperature was highest. Temperature, precipitation, geology, calcium, and substrate size were important environmental correlates for diatoms and macroinvertebrates, although the relative importance of each correlate differed. Diatom taxa were most strongly associated with water chemistry, whereas benthic invertebrate composition related most strongly to precipitation and temperature. This large‐scale study provides the most substantial integration and analysis of river diatom, macroinvertebrate, and fish data from the North American Arctic to date. Findings suggest that macroinvertebrates will show the strongest response to climate‐related shifts in temperature, whereas diatoms and fish are more likely to respond to climate‐induced shifts in nutrients and hydraulic connectivity. However, significant gaps in data coverage limited our ability to reliably evaluate spatial patterns and detect change. These gaps could be reduced by improving collaborative efforts between the U.S.A. and Canada to harmonise future monitoring.

Arctic↗
USGS2018

Groundwater contributions to excessive algal growth in the East Fork Carson River, Carson Valley, west-central Nevada, 2010 and 2012

Excessive algal growth and low dissolved oxygen concentrations were observed during low streamflow conditions during summer months along a 5,800-foot reach of the East Fork Carson River in Carson Valley, west-central Nevada. Algal growth from nutrient enrichment of a stream reduces aquatic diversity, threatens fish ecology and stream health, and can be a recreational nuisance. In response to concerns that groundwater discharging to the 5,800-foot reach of the East Fork Carson River may be a source of nutrients to the stream, the U.S. Geological Survey, in cooperation with the Carson Water Subconservancy District and the Nevada Division of Environmental Protection, conducted studies during the summers of 2010 and 2012 to gain an improved understanding of the contributions of nutrients to the stream from groundwater, characterize algal conditions and algal effects on water quality, assess potential sources of nitrate in groundwater discharging to the stream, and evaluate nitrate reduction in groundwater from denitrification. A reconnaissance study in the summer of 2010 along the 5,800-foot study reach located a subreach with clear evidence of nutrient-rich groundwater discharging to the stream. At the subreach, nitrate plus nitrite (referred to hereafter as nitrate) concentrations in groundwater discharging to the stream were high (average 2.75 milligrams per liter as nitrogen) along the right bank. The stream at this location had the highest stream nitrate concentrations (average 0.056 milligrams per liter as nitrogen) compared to other locations upstream and downstream of the subreach. As a result, the 2012 study focused on a 405-foot subreach of the East Fork Carson River centered where results from the 2010 study found the highest stream and groundwater concentrations of nitrate, as well as the greatest observed contributions of groundwater discharge to the stream. Groundwater nutrient concentrations were much higher than stream nutrient concentrations during the summer of 2012 during low streamflow conditions at the 405-foot subreach of the East Fork Carson River. Average groundwater nitrate and orthophosphate concentrations along the right bank of the 405‑foot subreach were 9 and 12 times higher, respectively, than in the stream at this subreach. Groundwater discharge rates to the study reach based on different methods varied from 0.09 to 1.2 cubic feet per second per mile. Estimated groundwater discharge rates to the right bank of the study subreach were used to calculate groundwater nutrient load estimates to the subreach right bank, which were found to be low when compared to stream nutrient loads. Elevated algal biomass levels above nuisance thresholds were observed during the summers of 2010 and 2012. The study reach was characterized as mesotrophic-eutrophic during the 2010 study and eutrophic during the 2012 study. The presence of algae caused daily dissolved oxygen and pH fluctuations in the stream, resulting in exceedances of the State of Nevada water-quality standards owing to low dissolved oxygen concentrations and high pH concentrations, although the standards might not have been applicable during 2012 because of extremely low streamflow. The addition of nutrients to the stream from the constant supply in groundwater discharge sustains the growth of algae during low streamflow conditions. In the summer when streamflow is low or very low, nutrient-rich groundwater discharge enters the stream through the sediment-water interface at the streambed. Because the attached algae is thick and stream velocity is low, the nutrient-rich water pools at the sediment-water interface. Higher nutrient concentrations at the streambed create a favorable microenvironment for algae attached to the substrate to consume available nutrients from the groundwater before the groundwater mixes with overlying stream water. The source of nitrate in groundwater in this subreach is anthropogenic because nitrate concentrations are greater than background groundwater nitrate concentrations in Douglas County, high groundwater nitrate concentrations are only found at the right bank of the stream near a housing development, and organic wastewater compounds indicative of human-derived sources were also detected in groundwater wells on the right bank of the stream. Nitrogen and oxygen isotope concentrations of nitrate in shallow groundwater were used to determine the specific source of the nitrate, but the isotopic values indicated denitrification was occurring. Further investigation is needed to determine the specific anthropogenic source of the nitrate in the groundwater because the denitrification present in all samples obscures the original source of nitrogen.

Nevada↗
USGS1996

Arsenic and selenium in soils and shallow ground water in the Turtle Lake, New Rockford, Harvey Pumping, Lincoln Valley, and LaMoure irrigation areas of the Garrison Diversion Unit, North Dakota

The Garrison Diversion Unit project was authorized as part of the Pick-Sloan Missouri River Basin program to divert water from Lake Sakakawea to irrigation areas in North Dakota. A special Garrison Commission was created to evaluate an environmental concern that return flow from the irrigation areas might contain metals in toxic concentrations. This report summarizes the results of detailed investigations of the Turtle Lake, New Rockford, Harvey Pumping, Lincoln Valley, and LaMoure irrigation areas. A total of 223 soil samples were collected from the irrigation areas and analyzed for elemental composition. Water extractions were done on 40 of the 223 soil samples using a 1:5 soil-to-water extraction method, and the solution from the extraction was analyzed for elemental composition. A total of 52 ground-water samples were collected and analyzed for inorganic constituents and organic carbon. Average arsenic concentrations in the entire soil column ranged from 1.0 milligram per kilogram in the Harvey Pumping irrigation area to 70 milligrams per kilogram in the New Rockford irrigation area. Average selenium concentrations ranged from less than 0.1 milligram per kilogram in the Turtle Lake, New Rockford, Harvey Pumping, and Lincoln Valley irrigation areas to 6.0 milligrams per kilogram in the Turtle Lake irrigation area. In the Turtle Lake irrigation area, average arsenic and selenium concentrations generally increased with depth through the topsoil, oxidized soil, and transition soil but decreased in the reduced soil at the bottom of the sampled horizons. Average arsenic concentrations in the New Rockford irrigation area follow the same pattern as in the Turtle Lake irrigation area, but selenium concentrations do not show a clear pattern of variation with depth. In the Harvey Pumping and Lincoln Valley irrigation areas, arsenic and selenium concentrations do not appear to vary systematically with depth. No correlation is shown between the concentrations in soils and soil extracts, indicating that, based on conditions of laboratory soil-water extraction experiments, trace-element concentrations in soils are not good predictors of trace-element concentrations in irrigation return flow. Arsenic concentrations in the aquifers ranged from less than 1 microgram per liter to 27 micrograms per liter. Arsenic concentrations generally were larger in the deep part of the aquifers underlying the Turtle Lake and New Rockford irrigation areas than in the shallow part of the aquifers. In the shallow part of the aquifers, where oxidizing conditions prevail, arsenic is strongly adsorbed to soil particles. In the deep part of the aquifers, where reducing conditions prevail, arsenic is more mobile. Selenium concentrations in the aquifers ranged from less than 1 microgram per liter to 4 micrograms per liter. Little difference existed between the selenium concentrations in the shallow part of the aquifers underlying the irrigation areas and the concentrations in the deep part of the aquifers.

Water-Resources Investigations Report↗
USGS2021

eDNA metabarcoding outperforms traditional fisheries sampling and reveals fine-scale heterogeneity in a temperate freshwater lake

Understanding biodiversity in aquatic systems is critical to ecological research and conservation efforts, but accurately measuring species richness using traditional methods can be challenging. Environmental DNA (eDNA) metabarcoding, which uses high-throughput sequencing and universal primers to amplify DNA from multiple species present in an environmental sample, has shown great promise for augmenting results from traditional sampling to characterize fish communities in aquatic systems. Few studies, however, have compared exhaustive traditional sampling with eDNA metabarcoding of corresponding water samples at a small spatial scale. We intensively sampled Boardman Lake (1.4 km 2 ) in Michigan, USA, from May to June in 2019 using gill and fyke nets and paired each net set with lake water samples collected in triplicate. We analyzed water samples using eDNA metabarcoding with 12S and 16S fish-specific primers and compared estimates of fish diversity among methods. In total, we set 60 nets and analyzed 180 1 L lake water samples. We captured a total of 12 fish species in our traditional gear and detected 40 taxa in the eDNA water samples, which included all the species observed in nets. The 12S and 16S assays detected a comparable number of taxa, but taxonomic resolution varied between the two genes. In our traditional gear, there was a clear difference in the species selectivity between the two net types, and there were several species commonly detected in the eDNA samples that were not captured in nets. Finally, we detected spatial heterogeneity in fish community composition across relatively small scales in Boardman Lake with eDNA metabarcoding, but not with traditional sampling. Our results demonstrated that eDNA metabarcoding was substantially more efficient than traditional gear for estimating community composition, highlighting the utility of eDNA metabarcoding for assessing species diversity and informing management and conservation.

Michigan↗
USGS2008

Sensitivity of June near‐surface temperatures and precipitation in the eastern United States to historical land cover changes since European settlement

Land cover changes alter the near surface weather and climate. Changes in land surface properties such as albedo, roughness length, stomatal resistance, and leaf area index alter the surface energy balance, leading to differences in near surface temperatures. This study utilized a newly developed land cover data set for the eastern United States to examine the influence of historical land cover change on June temperatures and precipitation. The new data set contains representations of the land cover and associated biophysical parameters for 1650, 1850, 1920, and 1992, capturing the clearing of the forest and the expansion of agriculture over the eastern United States from 1650 to the early twentieth century and the subsequent forest regrowth. The data set also includes the inferred distribution of potentially water‐saturated soils at each time slice for use in the sensitivity tests. The Regional Atmospheric Modeling System, equipped with the Land Ecosystem‐Atmosphere Feedback (LEAF‐2) land surface parameterization, was used to simulate the weather of June 1996 using the 1992, 1920, 1850, and 1650 land cover representations. The results suggest that changes in surface roughness and stomatal resistance have caused present‐day maximum and minimum temperatures in the eastern United States to warm by about 0.3°C and 0.4°C, respectively, when compared to values in 1650. In contrast, the maximum temperatures have remained about the same, while the minimums have cooled by about 0.1°C when compared to 1920. Little change in precipitation was found.

Water Resources Research↗