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USGS2013

Effects of hydrologic connectivity on aquatic macroinvertebrate assemblages in different marsh types

Hydrologic connectivity can be an important driver of aquatic macroinvertebrate assemblages. Its effects on aquatic macroinvertebrate assemblages in coastal marshes, however, are relatively poorly studied. We evaluated the effects of lateral hydrologic connectivity (permanently connected ponds: PCPs; temporary connected ponds: TCPs), and other environmental variables on aquatic macroinvertebrate assemblages and functional feeding groups (FFGs) in freshwater, brackish, and saline marshes in Louisiana, USA. We hypothesized that (1) aquatic macroinvertebrate assemblages in PCPs would have higher assemblage metric values (density, biomass, Shannon-Wiener diversity) than TCPs and (2) the density and proportional abundance of certain FFGs (i.e. scrapers, shredders, and collectors) would be greater in freshwater marsh than brackish and saline marshes. The data in our study only partially supported our first hypothesis: while freshwater marsh PCPs had higher density and biomass than TCPs, assemblage metric values in saline TCPs were greater than saline PCPs. In freshwater TCPs, long duration of isolation limited access of macroinvertebrates from adjacent water bodies, which may have reduced assemblage metric values. However, the relatively short duration of isolation in saline TCPs provided more stable or similar habitat conditions, facilitating higher assemblage metric values. As predicted by our second hypothesis, freshwater PCPs and TCPs supported a greater density of scrapers, shredders, and collectors than brackish and saline ponds. Aquatic macroinvertebrate assemblages seem to be structured by individual taxa responses to salinity as well as pond habitat attributes.

Aquatic Biology↗

USGS2021

NASA's surface biology and geology designated observable: A perspective on surface imaging algorithms

The 2017–2027 National Academies' Decadal Survey, Thriving on Our Changing Planet , recommended Surface Biology and Geology (SBG) as a “Designated Targeted Observable” (DO). The SBG DO is based on the need for capabilities to acquire global, high spatial resolution, visible to shortwave infrared (VSWIR; 380–2500 nm; ~30 m pixel resolution) hyperspectral (imaging spectroscopy) and multispectral midwave and thermal infrared (MWIR: 3–5 μm; TIR: 8–12 μm; ~60 m pixel resolution) measurements with sub-monthly temporal revisits over terrestrial, freshwater, and coastal marine habitats. To address the various mission design needs, an SBG Algorithms Working Group of multidisciplinary researchers has been formed to review and evaluate the algorithms applicable to the SBG DO across a wide range of Earth science disciplines, including terrestrial and aquatic ecology, atmospheric science, geology, and hydrology. Here, we summarize current state-of-the-practice VSWIR and TIR algorithms that use airborne or orbital spectral imaging observations to address the SBG DO priorities identified by the Decadal Survey: (i) terrestrial vegetation physiology, functional traits, and health; (ii) inland and coastal aquatic ecosystems physiology, functional traits, and health; (iii) snow and ice accumulation, melting, and albedo; (iv) active surface composition (eruptions, landslides, evolving landscapes, hazard risks); (v) effects of changing land use on surface energy, water, momentum, and carbon fluxes; and (vi) managing agriculture, natural habitats, water use/quality, and urban development. We review existing algorithms in the following categories: snow/ice, aquatic environments, geology, and terrestrial vegetation, and summarize the community-state-of-practice in each category. This effort synthesizes the findings of more than 130 scientists.

Remote Sensing of Environment↗

USGS2005

A direct immunoassay for detecting diatoms in groundwater as an indicator of the direct influence of surface water

Groundwater under the direct influence of surface water (GWUDISW) is of concern in communities where growing public demand on groundwater resources has resulted in increased withdrawals and hydraulic stress near surface water bodies. Under these conditions, contaminants such as methyl-tert butyl ether (MTBE) and biological materials have been detected in domestic wells. Other contaminants and pathogens associated with surface water are not routinely tested for in groundwater-supplied systems. To address the need for methods to easily identify potentially vulnerable supplies, a direct immunoassay for the quantitative detection of diatoms in raw water samples was developed as a measure of surface water influence on groundwater. Cell wall preparations from Nitzschia palea Kützing, a freshwater diatom found throughout North America, were used to produce a polyclonal antibody that was applied in a direct enzyme-linked immunosorbent assay (ELISA) developed to detect the presence of N. palea cell wall components. The direct immunoassay allows detection at 500 cells L −1 , a level similar to diatom concentrations observed in samples of groundwater collected near the test site. This investigation was the first attempt to utilize an ELISA as an indicator of surface water influence on groundwater. Further research is needed to develop more specific diatom-based monoclonal antibodies, determine cross-reactivity, and optimize sample processing and ELISA procedures for development of a standardized method.

Journal of Applied Phycology↗

USGS2008

Chapter 24 Lateral variability of the estuarine turbidity maximum in a tidal strait

The behavior of the estuarine turbidity maximum (ETM) in response to freshwater flow, tidal forcing, and bed dynamics has been studied extensively by many researchers. However, the majority of investigations focus on the longitudinal position and strength of the ETM, which can vary over tidal, spring-neap, and seasonal timescales. ETMs may become longitudinally fixed due to bathymetric constraints, and thus the lateral position may vary significantly on differing timescales. Lateral dynamics of the ETM may affect contaminant uptake in biologically active regions, while local deposition patterns may be affected by the dominant lateral position. A longitudinally fixed ETM in Carquinez Strait, California, was studied to specifically investigate the dynamics of lateral ETM variability during April 2004. an abrupt topographical control on the north side restricts gravitational circulation resulting in convergence and particle trapping, creating the ETM. The cross-section was continuously monitored with two upward-looking velocity profilers and four optical backscatterance sensors. In addition, cross-sectional measurements over one tidal cycle were performed during a spring tide with boat-mounted velocity and water quality profilers. The lateral and vertical positions of the ETM center of mass varied by a maximum of 250 and 5 m, respectively (20% of width and 17% of depth) over the tidal timescale, while tidally averaged lateral and vertical positions varied substantially less (50 and 1 m, respectively). ETM position responded to tidal energy (Urms), with higher vertical position and a laterally centered position resulting from increased mixing during spring tides, and a northerly lateral position from decreased mixing during neap tides. Hydrodynamic and sediment transport modeling of this period reproduces the lateral and vertical movements of the ETM center of mass. Modeling results indicate increased gravitational circulation in the strait and enhanced particle trapping on the north side during neap tides, thus displacing the ETM center of mass to the north. The south side has no topographical control, and therefore no particle trapping mechanism exists on the south side. Secondary circulation is strengthened on spring tides, distributing near-bed sediment toward the south. The field and modeling results are in agreement with previous work in Carquinez Strait and further elucidate the strong lateral variation of the ETM, even in narrow, energetic tidal straits. ?? 2008 Elsevier B.V. All rights reserved.

Proceedings in Marine Science↗

USGS2015

Stable carbon isotope fractionation during bacterial acetylene fermentation: Potential for life detection in hydrocarbon-rich volatiles of icy planet(oid)s

We report the first study of stable carbon isotope fractionation during microbial fermentation of acetylene (C 2 H 2 ) in sediments, sediment enrichments, and bacterial cultures. Kinetic isotope effects (KIEs) averaged 3.7 ± 0.5&permil; for slurries prepared with sediment collected at an intertidal mudflat in San Francisco Bay and 2.7 ± 0.2&permil; for a pure culture of Pelobacter sp. isolated from these sediments. A similar KIE of 1.8 ± 0.7&permil; was obtained for methanogenic enrichments derived from sediment collected at freshwater Searsville Lake, California. However, C 2 H 2 uptake by a highly enriched mixed culture (strain SV7) obtained from Searsville Lake sediments resulted in a larger KIE of 9.0 ± 0.7&permil;. These are modest KIEs when compared with fractionation observed during oxidation of C 1 compounds such as methane and methyl halides but are comparable to results obtained with other C 2 compounds. These observations may be useful in distinguishing biologically active processes operating at distant locales in the Solar System where C 2 H 2 is present. These locales include the surface of Saturn's largest moon Titan and the vaporous water- and hydrocarbon-rich jets emanating from Enceladus.

Astrobiology↗

USGS2011

Summary of oceanographic and water–quality measurements in West Falmouth Harbor and Buzzards Bay, Massachusetts, 2009–2010

This data report presents oceanographic and water-quality observations made at six locations in West Falmouth Harbor and Buzzards Bay, Massachusetts, from August 2009 to September 2010. Both Buzzards Bay and West Falmouth Harbor are estuarine embayments; the input of freshwater on the eastern margin of Buzzards Bay adjacent to Cape Cod and West Falmouth Harbor is largely due to groundwater. In West Falmouth Harbor, the groundwater that seeps into the harbor is characterized by relatively high levels of nitrate. This high nitrate load has modified the ecology of the harbor (Howes and others, 2006) and may be a significant source of nitrate to Buzzards Bay during seasons with low biological nitrate uptake. The U.S. Geological Survey undertook these measurements to improve understanding of circulation, residence time, and water quality in the harbor and bay. We set up and monitored multiple sites in both Buzzards Bay and West Falmouth Harbor, measuring depth, water velocity,salinity, pH, dissolved oxygen, chlorophyll-a, and nitrate concentration. In this report we present the processed time-series data at these locations and provide access to the data and metadata. The results will be used to understand circulation mechanisms and verify numerical models of hydrodynamics and biogeochemistry.

Massachusetts↗

USGS2011

Sedimentation and occurrence and trends of selected nutrients, other chemical constituents, and cyanobacteria in bottom sediment, Clinton Lake, northeast Kansas, 1977-2009

A combination of available bathymetric-survey information and bottom-sediment coring was used to investigate sedimentation and the occurrence of selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 25 trace elements, cyanobacterial akinetes, and the radionuclide cesium-137 in the bottom sediment of Clinton Lake, northeast Kansas. The total estimated volume and mass of bottom sediment deposited from 1977 through 2009 in the conservation (multi-purpose) pool of the reservoir was 438 million cubic feet and 18 billion pounds, respectively. The estimated sediment volume occupied about 8 percent of the conservation-pool, water-storage capacity of the reservoir. Sedimentation in the conservation pool has occurred about 70 percent faster than originally projected at the time the reservoir was completed. Water-storage capacity in the conservation pool has been lost to sedimentation at a rate of about 0.25 percent annually. Mean annual net sediment deposition since 1977 in the conservation pool of the reservoir was estimated to be 563 million pounds per year. Mean annual net sediment yield from the Clinton Lake Basin was estimated to be 1.5 million pounds per square mile per year. Typically, the bottom sediment sampled in Clinton Lake was at least 99 percent silt and clay. The mean annual net loads of total nitrogen and total phosphorus deposited in the bottom sediment of Clinton Lake were estimated to be 1.29 million pounds per year and 556,000 pounds per year, respectively. The estimated mean annual net yields of total nitrogen and total phosphorus from the Clinton Lake Basin were 3,510 pounds per square mile per year and 1,510 pounds per square mile per year, respectively. Throughout the history of Clinton Lake, total nitrogen concentrations in the deposited sediment generally were uniform and indicated consistent inputs to the reservoir over time. Likewise, total phosphorus concentrations in the deposited sediment generally were uniform. Although, for two of three coring sites, a possible positive trend in phosphorus deposition was indicated. The Wakarusa River possibly was a larger contributor of nitrogen and phosphorus to Clinton Lake than was Rock Creek. As a principal limiting factor for primary production in most freshwater environments, phosphorus is of particular importance because increased inputs can contribute to accelerated reservoir eutrophication and the production of algal toxins and taste-and-odor compounds. Trace-element concentrations in the bottom sediment of Clinton Lake generally were uniform over time. As is typical for eastern Kansas reservoirs, arsenic, chromium, and nickel concentrations typically exceeded the threshold-effects guidelines, which represent the concentrations above which toxic biological effects occasionally occur. Zinc concentrations frequently exceeded the threshold-effects guideline. Trace-element concentrations did not exceed the probable-effects guidelines (available for eight trace elements), which represent the concentrations above which toxic biological effects usually or frequently occur. Cyanobacterial akinetes (cyanobacteria resting stage) in the bottom sediment of Clinton Lake, combined with historical water-quality data on chlorophyll-a and total phosphorus concentrations, indicated that the reservoir likely has been eutrophic throughout most of its history. A statistically significant increase in cyanobacterial akinetes in the bottom sediment indicated that Clinton Lake may have become more eutrophic over the life of the reservoir. The increase in cyanobacterial akinetes may, in part, be related to a possible increase in total phosphorus concentrations.

Scientific Investigations Report↗

USGS1991

Freshwater molluscs as indicators of bioavailability and toxicity of metals in surface-water systems

During the past several decades, studies from a variety of locations have demonstrated widespread occurrence of metals in surface waters at concentrations significantly higher than background levels. Elevated concentrations are not limited to certain water types or polluted areas; they appear in all types of systems and in all geographic areas. It is clear that metals enter the aquatic systems from diverse sources, both point and nonpoint, and they can be readily transported from one system to another. Transport routes include atmospheric, terrestrial, subterranean, aquatic, and biological pathways (Elder 1988; Salomons and Forstner 1984).

Book chapter↗

USGS2016

Effects of climate change on tidal marshes along a latitudinal gradient in California

Public Summary The coastal region of California supports a wealth of ecosystem services including habitat provision for wildlife and fisheries. Tidal marshes, mudflats, and shallow bays within coastal estuaries link marine, freshwater and terrestrial habitats, and provide economic and recreational benefits to local communities. Climate change effects such as sea-level rise (SLR) are altering these habitats, but we know little about how these areas will change over the next 50–100 years. Our study examined the projected effects of three recent SLR scenarios produced for the West Coast of North America on tidal marshes in California. We compiled physical and biological data, including coastal topography, tidal inundation, plant composition, and sediment accretion to project how SLR may alter these ecosystems in the future. The goal of our research was to provide results that support coastal management and conservation efforts across California. Under a low SLR scenario, all study sites remained vegetated tidal wetlands, with most sites showing little elevation and vegetation change relative to sea level. At most sites, mid SLR projections led to increases in low marsh habitat at the expense of middle and high marsh habitat. Marshes at Morro Bay and Tijuana River Estuary were the most vulnerable to mid SLR with many areas becoming intertidal mudflat. Under a high SLR scenario, most sites were projected to lose vegetated habitat, eventually converting to intertidal mudflats. Our results suggest that California marshes are vulnerable to major habitat shifts under mid or high rates of SLR, especially in the latter part of the century. Loss of vegetated tidal marshes in California due to SLR is expected to impact ecosystem services that are dependent on coastal wetlands such as wildlife habitat, carbon sequestration, improved water quality, and coastal protection from storms.

California↗

USGS2006

Fish-assemblage variation between geologically defined regions and across a longitudinal gradient in the Monkey River Basin, Belize

Linkages between geology and fish assemblages have been inferred in many regions throughout the world, but no studies have yet investigated whether fish assemblages differ across geologies in Mesoamerica. The goals of our study were to: 1) compare physicochemical conditions and fish-assemblage structure across 2 geologic types in headwaters of the Monkey River Basin, Belize, and 2) describe basin-scale patterns in fish community composition and structure for the benefit of conservation efforts. We censused headwater-pool fishes by direct observation, and assessed habitat size, structure, and water chemistry to compare habitat and fish richness, diversity, evenness, and density between streams in the variably metamorphosed sedimentary geologic type typical of 80% of Belize’s Maya Mountains (the Santa Rosa Group), and an anomalous extrusive geologic formation in the same area (the Bladen Volcanic Member). We also collected species-presence data from 20 sites throughout the basin for analyses of compositional patterns from the headwaters to the top of the estuary. Thirty-nine fish species in 21 families were observed. Poeciliids were numerically dominant, making up 39% of individuals captured, followed by characins (25%), and cichlids (20%). Cichlidae was the most species-rich family (7 spp.), followed by Poeciliidae (6 spp.). Habitat size and water chemistry differed strongly between geologic types, but habitat diversity did not. Major fish-assemblage differences also were not obvious between geologies, despite a marked difference in the presence of the aquatic macrophyte, Marathrum oxycarpum (Podostemaceae), which covered 37% of the stream bottom in high-nutrient streams draining the Santa Rosa Group, and did not occur in the low-P streams draining the Bladen Volcanic Member. Correlation analyses suggested that distance from the sea and amount of cover within pools are important to fish-assemblage structure, but that differing abiotic factors may influence assemblage structure within each geologic type. The fauna showed weak compositional zonation into 3 groups (headwaters, coastal plain, and nearshore). Nearly 20% of the fish species collected have migratory life cycles (including Joturus pichardi , Agonostomus monticola , and Gobiomorus dormitor ) that use freshwater and marine habitats. Some of these species probably rely on a natural flow regime and longitudinal connectivity for reproduction and dispersal of young, and natural flow regime and longitudinal connectivity are important factors for maintenance of functional linkages between the uplands and the coast in the ridge-to-reef corridor where the Monkey River is located. Therefore, we suggest that the viability of migratory fish populations may be a good biological indicator of upland-to-estuary connectivity important both to fishes and coastal ecosystem function. We recommend follow-up studies to substantiate the relative strengths of relationships between community structure and abiotic factors in contrasting geologies and to examine potential bottom−up responses of stream biota to the higher nutrient levels that were observed in stream waters draining the Santa Rosa Group geologic type.

Journal of the North American Benthological Societ↗

USGS2024

Local environmental conditions structured discrete fish assemblages in Arctic lagoons

Rapid changes in sea ice extent and changes in freshwater inputs from land are rapidly changing the nature of Arctic estuarine ecosystems. In the Beaufort Sea, these nearshore habitats are known for their high productivity and mix of marine resident and diadromous fishes that have great subsistence value for Indigenous communities. There is, however, a lack of information on the spatial variation among Arctic nearshore fish communities as related to environmental drivers. In summers of 2017–2019, we sampled fishes in four estuarine ecosystems to assess community composition and relate fish abundance to temperature, salinity, and wind conditions. We found fish communities were heterogeneous over larger spatial extents with rivers forming fresh estuarine plumes that supported diadromous species (e.g., broad whitefish Coregonus nasus ), while lagoons with reduced freshwater input and higher salinities were associated with marine species (e.g., saffron cod Eleginus gracilis ). West–East directional winds accounted for up to 66% of the community variation, indicating importance of the wind-driven balance between fresh and marine water masses. Salinity and temperature accounted for up to 54% and 37% of the variation among lagoon communities, respectively. Recent sea ice declines provide more opportunity for wind to influence oceanographic conditions and biological communities. Current subsistence practices, future commercial fishing opportunities, and on-going oil and gas activities benefit from a better understanding of current fish community distributions. This work provides important data on fish spatial distributions and community composition, providing a basis for fish community response to changing climatic conditions and anthropogenic use.

Polar Biology↗

USGS2024

Groundwater-Surface water interactions research: Past trends and future directions

Interactions between groundwater and surface water sustain groundwater-dependent ecosystems and regulate river temperature and biogeochemical cycles, amongst many other processes. These interactions occur in freshwater environments including rivers, springs, lakes, and wetlands, and in coastal environments via tidal pumping, submarine groundwater discharge, and seawater intrusion. Here, we explore groundwater-surface water interactions research using bibliometric analyses of titles, abstracts, and keywords from 20,275 journal papers published between 1970 and 2023 extracted from Scopus. Analyses show that research into groundwater-surface water interactions is highly multi-disciplinary, with growing contributions from the social and biological sciences. The number of groundwater-surface water interactions papers is rapidly increasing with over 1200 papers published per year since 2020. Drawing on our data-driven approach and expert knowledge, we synthesise current research trends and identify critical future research directions. Despite the thousands of papers on groundwater-surface water interactions, important processes are still difficult to quantify or predict at meaningful spatial scales to inform water-resources management. We see benefits in future groundwater-surface water interactions research focusing on: (1) using new technologies including internet-of-things-based sensors, uncrewed vehicles, and remote-sensing approaches for data collection to inform groundwater-surface water interactions at large scales, (2) seeking approaches to upscale site-specific findings to better inform management, and (3) continuing the movement towards multi-disciplinary investigations to better inform the understanding of groundwater-surface water interactions and processes that will enable better management outcomes.

Journal of Hydrology↗

USGS2026

Predicting reach-scale macroinvertebrate community changes due to declining flows in an aridland river

Understanding the connection between streamflow and macroinvertebrate community structure is critical for managing river ecosystems under scenarios of change caused by human activities and drought. Streamflow influences physical habitat characteristics, including depth, water velocity, and substrate composition, which structure macroinvertebrate communities. Although strong empirical evidence has linked macroinvertebrates to these variables, most studies are correlative, and predictive approaches that link altered streamflow to changes in habitat availability and community structure remain limited. To address this gap, we coupled benthic macroinvertebrate surveys with reach-scale, 2-dimensional hydraulic models to quantify changes in community structure in response to altered streamflows. We characterized macroinvertebrate communities and physical habitat conditions in riffle, run, and pool mesohabitats across 3 reaches of a free-flowing section of the Verde River (Arizona, USA) over 3 y and developed hydraulic models using overflight data, ground surveys, and streamflow monitoring. Macroinvertebrate communities differed among mesohabitats, with riffles supporting higher macroinvertebrate densities and pools exhibiting higher taxonomic richness. The 2-dimensional hydraulic models indicated that declining streamflows could reduce the area of suitable habitat in riffles and runs relative to pools, potentially shifting the distribution of mesohabitats and altering community composition. These changes may lead to declines in overall macroinvertebrate diversity and abundance under reduced flow conditions. By explicitly linking streamflow to habitat availability and community structure, this study demonstrates how integrating hydraulic modeling with biological surveys can improve predictions of ecological response to flow alteration. This framework provides a basis for flow management strategies aimed at maintaining habitat heterogeneity and supporting biodiversity in river networks.

Arizona↗

USGS2011

Crims Island-Restoration and monitoring of juvenile salmon rearing habitat in the Columbia River Estuary, Oregon, 2004-10

Under the 2004 Biological Opinion for operation of the Federal Columbia River Power System released by the National Marine Fisheries Service, the U.S. Army Corps of Engineers (USACE), the Bonneville Power Administration (BPA), and the Bureau of Reclamation (Reclamation) were directed to restore more than 4,047 hectares (10,000 acres) of tidal marsh in the Columbia River estuary by 2010. Restoration of Crims Island near Longview, Washington, restored 38.1 hectares of marsh and swamp in the tidal freshwater portion of the lower Columbia River. The goal of the restoration was to improve habitat for juveniles of Endangered Species Act (ESA)-listed salmon stocks and ESA-listed Columbian white-tailed deer. The U.S. Geological Survey (USGS) monitored and evaluated the fisheries and aquatic resources at Crims Island in 2004 prior to restoration (pre-restoration), which began in August 2004, and then post-restoration from 2006 to 2009. This report summarizes pre- and post-restoration monitoring data used by the USGS to evaluate project success. We evaluated project success by examining the interaction between juvenile salmon and a suite of broader ecological measures including sediments, plants, and invertebrates and their response to large-scale habitat alteration. The restoration action at Crims Island from August 2004 to September 2005 was to excavate a 0.6-meter layer of soil and dig channels in the interior of the island to remove reed canary grass and increase habitat area and tidal exchange. The excavation created 34.4 hectares of tidal emergent marsh where none previously existed and 3.7 hectares of intertidal and subtidal channels. Cattle that had grazed the island for more than 50 years were relocated. Soil excavated from the site was deposited in upland areas next to the tidal marsh to establish an upland forest. Excavation deepened and widened an existing T-shaped channel to increase tidal flow to the interior of the island. The western arm of the existing 'T-channel' was extended westward and connected to Bradbury Slough to create a second outlet to the main river. New intertidal channels were constructed from the existing 'T-channel' and tidal mudflats became inundated at high tide to increase rearing habitat for juvenile salmonids. The restoration action resulted in a 95-percent increase in available juvenile salmon rearing habitat. We collected juvenile salmon and other fishes at Crims Island and a nearby reference site using beach seines and fyke nets annually from March through August during all years. Benthic invertebrates were collected with sediment corers and drift invertebrates were collected with neuston nets. Juvenile salmon stomach contents were sampled using lavage. Vegetation and sediments characteristics were surveyed and we conducted a topographic/bathymetric survey using a RTK (real time kinematic) GPS (global positioning system). The fish assemblage at Crims Island, composed primarily of threespine stickleback (Gasterosteus aculeatus), non-native banded killifish (Fundulus diaphanus), peamouth chub (Mylocheilus caurinus), subyearling Chinook salmon (Oncorhynchus tshawytscha) (hereinafter referred to as subyearlings), and small numbers of juvenile chum salmon (Oncorhynchus keta), did not differ appreciably pre- and post-restoration. Subyearlings were the primary salmonid collected and were seasonally abundant from April through May during all years. The abundance of juvenile salmon declined seasonally as water temperature exceeded 20 degrees C in the Reference site by mid-June; however, subyearlings persisted at the Mainstem site and in subtidal channels of the Restoration site through the summer in water temperatures exceeding 22 degrees C. Residence times of subyearlings in Crims Island backwaters generally were short consisting of one or two tidal cycles. Median residence time was longer in the Restoration site than in the Reference site pre- and post-restoration. Small (mean = 55.7 millimeters) subyea

Scientific Investigations Report↗

USGS1996

Influences of environmental settings on aquatic ecosystems in the Apalachicola-Chattahoochee-Flint River basin

The watershed boundary of the Apalachicola-Chattahoochee-Flint (ACF) River basin defines an aquatic ecosystem whose water quality is the result of complex interactions of natural and human influences on land and water resources. Topics relating to the basin's environmental setting-its physical, biological, and cultural characteristics-are summarized to provide an understanding of factors that influence water quality and the health of aquatic ecosystems. The ACF River basin lies partly in southwestern Georgia, southeastern Alabama, and northwestern Florida and covers 19,800 square miles in the Blue Ridge, the Piedmont, and the Coastal Plain Provinces. The basin includes the drainages of the Chattahoochee River and the Flint River, which meet to form the Apalachicola River. The Apalachicola River flows into the Gulf of Mexico at Apalachicola Bay. Basin hydrology and water quality are influenced by 16 mainstem reservoirs, 13 of which are on the Chattahoochee River. Ground water in the basin is contained in six aquifers-the surficial aquifer system, the Floridan aquifer system, the Claiborne aquifer, the Clayton aquifer, the Providence aquifer, and the crystalline-rock aquifer. Physiography, climate, and hydrology of the ACF River basin provide natural conditions that support a rich and abundant diversity of plants and animals. Although most of the ACF River basin has been altered by human activities, the basin's environment is noteworthy for its remaining biological diversity and the role it plays in sustaining biological productivity in Apalachicola Bay. The Bay produces 90 percent of Florida's and 13 percent of the Nation's oyster harvest; and functions as a nursery for penaeid shrimp, blue crabs, and a variety of fin fish. The diversity of the basin's aquatic fauna is noteworthy because the basin is home to (1) the largest number of fish species among Gulf Coast drainages east of the Mississippi River, (2) the largest assemblage of freshwater fish in Florida, (3) the largest number of mollusc species among western Florida drainages, and (4) the highest species density of amphibians and reptiles on the continent north of Mexico. Population of the ACF River basin in 1990 was estimated at 2.6 million. Nearly 90 percent of the total population lived in Georgia, and nearly 60 percent lived in the Metropolitan Atlanta area. The 1990 basin population is projected to increase by 15 percent to 3.0 million by the year 2000, and by 30 percent to 3.4 million by 2010. The largest increases in populations are projected for the Metropolitan Atlanta area. In 1972-76, approximately 59 percent of the basin was covered by forest, 29 percent was agricultural, 5 percent was wetland, 4 percent was urban, and 3 percent was water or barren land. Most of the original land cover of the basin has been transformed by human activity. Timber is the basin's largest cash crop and most forests consist of second-growth stands or large acreages of planted pine. The dominant agricultural land use in the Piedmont Province is pasture and confined feeding for dairy, livestock, and poultry production. Row-crop agriculture, orchards, and silviculture are most common in the Coastal Plain Province. The top five crops in order from most to least acres harvested in 1990 were peanuts, corn, soybeans, wheat, and cotton. The water in the basin is used for public and industrial supply, irrigation, power generation, navigation, and recreation. Although most public-supply withdrawals in the Blue Ridge and Piedmont Provinces are from surface-water sources, with the exception of counties near or immediately below the Fall Line, all publicly supplied water in the Coastal Plain is withdrawn from ground-water sources. Ground water supplied 18 percent of the basin's population served by public supply. Total water withdrawn in the ACF River basin in 1990 was 2,098 million gallons per day (Mgal/d), of which Georgia withdrew 82 percent and Florida and Alabama each withdrew 9 percent. Power generation is the single largest water use. Sixteen of the basin's 22 power generating plants are located along the mainstem of the Chattahoochee River. The U.S. Army Corps of Engineers maintains a navigation channel from the mouth of the Apalachicola River to Columbus, Ga., on the Chattahoochee River and to Bainbridge, Ga., on the Flint River. Water quality in the basin is influenced by the operation of 137 municipal wastewater-treatment facilities. In 1990, 354 Mgal/d of municipal wastewater was discharged within the ACF River basin. Eighty-eight percent of the wastewater was discharged into the Chattahoochee River basin, 10.6 percent into the Flint River basin, and 1.4 percent into the Apalachicola River basin. Two-thirds of the 938 stream miles in the Georgia portion of the ACF River basin having water quality that does not meet or only partially meets the designated-use criteria in the Chattahoochee River basin. The Chattahoochee River is the most heavily-used water resource both in the ACF River basin and in Georgia. Urban runoff or unknown nonpoint sources are cited as the causes of water-quality regulations in 72 percent of violations. The remaining causes primarily are combined sewer overflows in the Atlanta area, and discharges from municipal or industrial treatment facilities with inadequate treatment capabilities or operational deficiencies.

Alabama, Florida, Georgia↗

USGS2014

Assessing streamflow sensitivity to variations in glacier mass balance

The mountains ringing the Gulf of Alaska (GOA) receive upwards of 4–8 m yr −1 of precipitation (Simpson et al.2005; Weingartner et al. 2005; O’Neel 2012), much of which runs off into productive coastal waters. The alpine landscape is heavily glacierized, and storage and turnover of water by glaciers substantially influences the regional surface water balance (Neal et al. 2010). In turn, the land-to-ocean flux of freshwater impacts the biogeochemistry, physical oceanography, freshwater and marine ecology of the downstream components of the GOA ecosystem (e.g., Royer et al. 2001; Hood and Scott 2008). In this way, the links between terrestrial and ocean ecosystems along the GOA have widespread impacts on regional socioeconomic issues including water and hydropower resources, fish populations, and sea level change (Dorava and Milner 2000; Royer and Grosch 2006; Cherry et al. 2010; Gardner et al. 2013). Moreover, predicting future changes in physical, chemical and biological processes in near-shore ecosystems along the GOA hinges, in part, on developing a robust understanding of water storage and transfer by glaciers through streams to the ocean. Glacierized basins (i.e. presently ice covered as opposed to glaciated, or historically ice covered) are very efficient producers of runoff, yielding 2–10 times greater runoff than similarly sized, non-glacierized basins (Mayo 1984). The unique energy balance that characterizes these basins (Jansson et al. 2003; Hock 2005) results in substantial alterations to streamflow, even when fractional ice coverage is very small (Stahl and Moore 2006). Consistent and precise treatment of glacier runoff is key to accurate assessment of hydrologic, ecological and socioeconomic impacts, but previously used definitions for glacier runoff are variable. They include: 1) meltwater produced as negative annual mass balance (e.g., Fountain and Tangborn 1985); 2) storage changes in the monthly water budget, where solid precipitation is balanced by melt and evaporation (Huss 2011, concept #2); 3) meltwater derived from melting ice only (irrespective of melting snow or mass balance) (Nolin et al. 2010; Huss 2011, concept #1); 4) all meltwater derived from the glacier surface (Cogley et al. 2011, meltwater runoff); 5) total runoff from the glacier surface (meltwater runoff plus rain on the glacier) (Neal et al. 2010). Total glacier runoff (Definitions 4 and 5 above) includes a contribution from annual mass balance, i.e. the sum of accumulation and ablation through a mass balance year (Definition 1), or what has historically been referred to as the “net” balance (Cogley et al. 2011). Indeed, annual balance has been shown to be an important driver of streamflow trends in glacierized basins, with periods of persistent negative annual balance resulting in statistically significant increases in streamflow (e.g., Pellicciotti et al. 2010). However, in maritime climates, anomalies in glacier runoff can be disconnected from annual balance because of the high variability in winter precipitation. For example, positive anomalies in winter accumulation can result in elevated levels of glacier runoff in times of positive annual mass balance (Thayyen and Gergan 2010). Quantifying the impacts of changing glacier geometries (annual balance) on glacier runoff is essential for predicting future changes in streamflow in glacierized basins. However, determining the role that this component plays in total glacier runoff (Definition 5) requires consistent measurements of seasonal (or shorter period) mass balances, measurements of precipitation at multiple locations within a basin, and streamflow measurements in close proximity to a glacier’s terminus. Practical and logistical challenges associated with assembling such data sets typically preclude such partitioning. As a result, most analyses of the relationship between annual mass balance and streamflow rely on some component of model output to compute glacier runoff (e.g. Huss et al. 2008; Kaser et al. 2010). Ultimately, developing an understanding of how total glacier runoff will change in the future is critical for predicting downstream ecological impacts associated with changes in riverine fluxes of water, sediment, and solutes (e.g., metals and nutrients) to near-shore coastal ecosystems. The purpose of this paper is to evaluate relationships among seasonal and annual glacier mass balances, glacier runoff and streamflow in two glacierized basins in different climate settings. We use long-term glacier mass balance and streamflow datasets from the United States Geological Survey (USGS) Alaska Benchmark Glacier Program to compare and contrast glacier-streamflow interactions in a maritime climate (Wolverine Glacier) with those in a continental climate (Gulkana Glacier). Our overall goal is to improve our understanding of how glacier mass balance processes impact streamflow, ultimately improving our conceptual understanding of the future evolution of glacier runoff in continental and maritime climates.

Alaska↗

USGS2010

Amplification and transport of an endemic fish disease by an introduced species

The introduction of American shad from the Atlantic to the Pacific coast of North America in the late 1800’s and the subsequent population expansion in the 1980’s resulted in the amplification of Ichthyophonus sp., a Mesomycetozoean parasite of wild marine fishes. Sequence analysis of the ribosomal DNA gene complex (small subunit and internal transcribed spacer regions) and Ichthyophonus epidemiological characteristics indicate a low probability that Ichthyophonus was co-introduced with American shad from the Atlantic; rather, Ichthyophonus was likely endemic to marine areas of the Pacific region and amplified by the expanding population of a highly susceptible host species. The migratory life history of shad resulted in the transport of amplified Ichthyophonus from its endemic region in the NE Pacific to the Columbia River watershed. An Ichthyophonus epizootic occurred among American shad in the Columbia River during 2007, when infection prevalence was 72%, and 57% of the infections were scored as moderate or heavy intensities. The epizootic occurred near the record peak of shad biomass in the Columbia River, and corresponded to an influx of 1,595 mt of infected shad tissues into the Columbia River. A high potential for parasite spillback and the establishment of a freshwater Ichthyophonus life cycle in the Columbia River results from currently elevated infection pressures, broad host range, plasticity in Ichthyophonus life history stages, and precedents for establishment of the parasite in other freshwater systems. The results raise questions regarding the risk for sympatric salmonids and the role of Ichthyophonus as a population-limiting factor affecting American shad in the Columbia River.

Biological Invasions↗

USGS2018

Climate and plant controls on soil organic matter in coastal wetlands

Coastal wetlands are among the most productive and carbon‐rich ecosystems on Earth. Long‐term carbon storage in coastal wetlands occurs primarily belowground as soil organic matter (SOM). In addition to serving as a carbon sink, SOM influences wetland ecosystem structure, function, and stability. To anticipate and mitigate the effects of climate change, there is a need to advance understanding of environmental controls on wetland SOM. Here, we investigated the influence of four soil formation factors: climate, biota, parent materials, and topography. Along the northern Gulf of Mexico, we collected wetland plant and soil data across elevation and zonation gradients within ten estuaries that span broad temperature and precipitation gradients. Our results highlight the importance of climate‐plant controls and indicate that the influence of elevation is scale and location dependent. Coastal wetland plants are sensitive to climate change; small changes in temperature or precipitation can transform coastal wetland plant communities. Across the region, SOM was greatest in mangrove forests and in salt marshes dominated by graminoid plants. SOM was lower in salt flats that lacked vascular plants and in salt marshes dominated by succulent plants. We quantified strong relationships between precipitation, salinity, plant productivity, and SOM. Low precipitation leads to high salinity, which limits plant productivity and appears to constrain SOM accumulation. Our analyses use data from the Gulf of Mexico, but our results can be related to coastal wetlands across the globe and provide a foundation for predicting the ecological effects of future reductions in precipitation and freshwater availability. Coastal wetlands provide many ecosystem services that are SOM dependent and highly vulnerable to climate change. Collectively, our results indicate that future changes in SOM and plant productivity, regulated by cascading effects of precipitation on freshwater availability and salinity, could impact wetland stability and affect the supply of some wetland ecosystem services.

Global Change Biology↗