USGS Science⌕ Search

SEARCH · USGS Science

Results for “Freshwater Biology”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
USGS2021

Evaluating establishment success of non-native fishes introduced to inland aquatic habitats of tropical Pacific islands

An information-theoretic approach was used to evaluate non-native freshwater fish species introduced to insular habitats of Hawaii and Guam comparing successful establishments vs. failures. Since the late 1800s, as many as 81 non-native freshwater fish species have been recorded as introduced to Hawaii and Guam (combined) and 50 (62%) of these are documented as having one or more established populations. We examined eleven independent variables to investigate establishment success by creating 21 a priori logistic regression models ranked using Akaike's Information Criterion adjusted for small sample size. An additional eight post-hoc models were included that comprised the best a priori model and various combinations of individual variables. The best overall model of establishment probability included effects of taxonomic affinity (family membership), prior establishment success on other tropical islands, and hypoxia tolerance. Establishment success in Hawaii and Guam was highest for those species established on many other islands, and according to our best model air-breathing fishes were more likely to become established. Six fish families, each with from three to 18 species introduced to Pacific islands, were highly successful at establishment: Cichlidae (16 established of 18 species introduced), Poeciliidae (seven of eight), Cyprinidae (four of seven), Centrarchidae (four of four), Clariidae (three of three), and Loricariidae (three of four). Those that successfully established include both small and moderately large-bodied taxa, while representing a diverse array of other morphological and life-history traits. Pathways and motives associated with fish introductions in the Pacific have been linked to desires to develop aquaculture, enhance wild stocks of food, sport, and bait fishes, for use as biological control agents, or are linked to the ornamental fish trade. We found that many established species were introduced via multiple pathways (up to eight) and our analyses suggest that the combination of prior establishment success on other tropical islands and presence of non-native fishes in multiple pathways was indicative of high propagule pressure. Our study results and conclusions on Pacific tropical island introductions are in general agreement with previous studies on non-native freshwater fishes in other regions of the world and similar to observations in continental ecosystems and temperate zones.

Hawaii↗
USGS2019

A multidisciplinary framework to derive global river reach classifications at high spatial resolution

Projected climate and environmental change are expected to increase the pressure on global freshwater resources. To prepare for and cope with the related risks, stakeholders need to devise plans for sustainable management of river systems, which in turn requires the identification of management-appropriate operational units, such as groups of rivers that share similar environmental and biological characteristics. Ideally, these units are of a manageable size, and are biotically or abiotically distinguishable across a variety of river types. Here, we aim to address this need by presenting a new global river classification framework (GloRiC) to establish a common vocabulary and standardized approach to the development of globally comprehensive and integrated river classifications that can be tailored to different goals and requirements. We define the GloRiC conceptual framework based on five categories of variables: (1) hydrology; (2) physiography and climate; (3) fluvial geomorphology; (4) water chemistry; and (5) aquatic biology. We then apply the framework using hydro-environmental attributes provided by a seamless high-resolution river reach database to create initial instances of three sub-classifications (hydrologic, physio-climatic, and geomorphic) which we ultimately combine into 127 river reach types at the global scale. These supervised classifications utilize a mix of statistical analyses and expert interpretation to identify the classifier variables, the number of classes, and their thresholds. In addition, we also present an unsupervised, multivariable k-means statistical clustering of all river reaches into 30 groups. These first-of-their-kind global river reach classifications at high spatial resolution provide baseline information for a total of 35.9 million kilometers of rivers that have been assessed in this study, and are expected to be particularly useful in remote or data-poor river basins. The GloRiC framework and associated data are primarily designed for broad and rapid applicability in assessments that require stratified analyses of river ecosystem conditions at global and regional scales; smaller-scale applications could follow the same conceptual framework yet use more detailed data sources.

Environmental Research Letters↗
USGS1999

Canal and wetland flow transport interaction; coupling models for canal and wetland interactions in the South Florida ecosystem

Introduction The U.S. Geological Survey is one of several agencies participating in the scientific effort to provide knowledge that can help protect and preserve the ecosystem of south Florida. One project of the intergovernmental South Florida Ecosystem Program (SFEP) is focused on developing a computer model to simulate the flow of water and analyze the transport of waterborne chemical constituents between canals and wetlands. Quantification of dynamic flows within the south Florida ecosystem is vital to understanding the implications of the residence time of water, potentially nutrient-enriched (with nitrates or phosphates) or contaminant-laden (with metals or pesticides), that can alter plant life and affect biological communities. Nutrients carried in the water conveyed by canals draining agricultural areas and dispersed into wetlands by canal discharges, by levee overflows, or by seepage are considered to be a major contributor to changes in the types of vegetation found in the Everglades. Freshwater inflows, typically of varying magnitudes and durations, not only influence the salinity of Florida Bay but also potentially carry toxic substances that can affect and alter the Bay's aquatic biota. The simulation capability being developed within the SFEP can be useful for identifying approaches to alleviate adverse impacts of excessive or deficient flows and transported constituents. Through strategic use of a simulation model, cause-and-effect relations between discharge sources, flow magnitudes, transport processes, and changes in vegetation and biota can be investigated. The effects of driving forces on nutrient cycling and contaminant transport can then be quantified, evaluated, and considered in the development of remedial management plans.

Florida↗
USGS1997

Effects of climate change on freshwater ecosystems of the south-eastern United States and the Gulf Coast of Mexico

The south-eastern United States and Gulf Coast of Mexico is physiographically diverse, although dominated by a broad coastal plain. Much of the region has a humid, warm temperate climate with little seasonality in precipitation but strong seasonality in runoff owing to high rates of summer evapotranspiration. The climate of southern Florida and eastern Mexico is subtropical with a distinct summer wet season and winter dry season. Regional climate models suggest that climate change resulting from a doubling of the pre-industrial levels of atmospheric CO2 may increase annual air temperatures by 3-4??C. Changes in precipitation are highly uncertain, but the most probable scenario shows higher levels over all but the northern, interior portions of the region, with increases primarily occurring in summer and occurring as more intense or clustered storms. Despite the increases in precipitation, runoff is likely to decline over much of the region owing to increases in evapotranspiration exceeding increases in precipitation. Only in Florida and the Gulf Coast areas of the US and Mexico are precipitation increases likely to exceed evapotranspiration increases, producing an increase in runoff. However, increases in storm intensity and clustering are likely to result in more extreme hydrographs, with larger peaks in flow but lower baseflows and longer periods of drought. The ecological effects of climate change on freshwaters of the region include: (1) a general increase in rates of primary production, organic matter decomposition and nutrient cycling as a result of higher temperatures and longer growing seasons: (2) reduction in habitat for cool water species, particularly fish and macroinvertebrates in Appalachian streams; (3) reduction in water quality and in suitable habitat in summer owing to lower baseflows and intensification of the temperature-dissolved oxygen squeeze in many rivers and reservoirs; (4) reduction in organic matter storage and loss of organisms during more intense flushing events in some streams and wetlands; (5) shorter periods of inundation of riparian wetlands and greater drying of wetland soils, particularly in northern and inland areas; (6) expansion of subtropical species northwards, including several non-native nuisance species currently confined to southern Florida; (7) expansion of wetlands in Florida and coastal Mexico, but increase in eutrophication of Florida lakes as a result of greater runoff from urban and agricultural areas; and (8) changes in the flushing rate of estuaries that would alter their salinity regimes, stratification and water quality as well as influence productivity in the Gulf of Mexico. Many of the expected climate change effects will exacerbate current anthropogenic stresses on the region's freshwater systems, including increasing demands for water, increasing waste heat loadings and land use changes that alter the quantity and quality of runoff to streams and reservoirs. Research is needed especially in several critical areas: long-term monitoring of key hydrological, chemical and biological properties (particularly water balances in small, forested catchments and temperature-sensitive species); experimental studies of the effects of warming on organisms and ecosystem processes under realistic conditions (e.g. in situ heating experiments); studies of the effects of natural hydrological variation on biological communities; and assessment of the effects of water management activities on organisms and ecosystem processes, including development and testing of management and restoration strategies designed to counteract changes in climate.

Hydrological Processes↗
USGS1994

San Francisco Bay/delta regional monitoring program plankton and water quality pilot study, 1993, in 1993 Annual Report, San Francisco Estuary Regional Monitoring Program for Trace Substances: San Francisco Estuary Institute

The pilot program described here is motivated by a fundamental principle of the Regional Monitoring Strategy, namely “...the development of data that will provide information on status and trends in the Estuary.” As pointed out in the Strategy, knowledge of status and trends serves two primary purposes: (1) to become aware of or anticipate deleterious conditions in the Estuary, and (2) to assess the effectiveness of management actions. This program addresses these two purposes by focusing on aquatic resources, one of the five key management issues identified by the Comprehensive Conservation and Management Plan and central to the Regional Monitoring Strategy. It also bears on at least two of the other management issues - pollutants and water use. A regional monitoring program must cover many types of resources, including pelagic and benthic channel habitat, shoal habitat, wetlands, river channels, sloughs, and small bays and harbors. This particular program centers on the pelagic channel habitat. However, because of the intimate connection between channel habitat and many or most of these other habitats, channel measurements reflect to some extent the status of and trends in other resource types as well. A primary aim of this program is to provide a high-resolution description of critical aspects of habitat quality, which can be used along with other information (1) to determine the suitability of habitat for aquatic resources; (2) to monitor responsiveness of the habitat to freshwater flow variability; and (3) to provide a context for understanding pollutant distributions. In a single transect, measurements are made throughout the water column at up to 37 stations to define physical (salinity, temperature, suspended particulate matter, and light penetration), chemical (dissolved oxygen) and biological (chlorophyll a ) characteristics that influence both chemical and biological reactions. A second aim of the program is to investigate planktonic indicators of ecosystem structure and function. Phytoplankton production is the major single source of energy for the San Francisco Bay food web. Our measurements of chlorophyll and light penetration can be used to provide an estimate of this production, and therefore the availability of food for organisms at higher trophic levels. Phytoplankton community composition at the species level, which can be a sensitive indicator of habitat change, is also a standard component of this program. Community composition data enable detection of species known to be responsible for harmful or nuisance algal blooms. In 1993, two other indicators were also evaluated, photosynthetic parameters and water column respiration . Photosynthetic parameters partially characterize the physiological state of the phytoplankton and may provide indirect evidence of nutrient deficiency or the effects of pollutants. Water column respiration serves as a simple integrated measure of organic matter metabolism by the plankton, including bacteria, phytoplankton, and microzooplankton. It therefore reflects the total supply of organic matter, whether from photosynthesis, tidal marsh efflux, point sources, or upstream in the Delta. These biological indicators therefore contain much information about the flow of energy into the food web.

California↗
USGS2005

Threats, conservation strategies, and prognosis for suckers (Catostomidae) in North America: insights from regional case studies of a diverse family of non-game fishes

Catostomid fishes are a diverse family of 76+ freshwater species that are distributed across North America in many different habitats. This group of fish is facing a variety of impacts and conservation issues that are somewhat unique relative to more economically valuable and heavily managed fish species. Here, we present a brief series of case studies to highlight the threats such as migration barriers, flow regulation, environmental contamination, habitat degradation, exploitation and impacts from introduced (non-native) species that are facing catostomids in different regions. Collectively, the case studies reveal that individual species usually are not threatened by a single, isolated factor. Instead, species in general face numerous stressors that threaten multiple stages of their life history. Several factors have retarded sucker conservation including widespread inabilities of field workers to distinguish some species, lack of basic natural history and ecological knowledge of life history, and the misconception that suckers are tolerant of degraded conditions and are of little social or ecological value. Without a specific constituent group lobbying for conservation of non-game fishes, all such species, including members of the catostomid family, will continue to face serious risks because of neglect, ignorance, and misunderstanding. We suggest that conservation strategies should incorporate research and education/outreach components. Other conservation strategies that would be effective for protecting suckers include freshwater protected areas for critical habitat, restoration of degraded habitat, and design of catostomid-friendly fish bypass facilities. We believe that the plight of the catostomids is representative of the threats facing many other non-game freshwater fishes with diverse life-history strategies globally.

Biological Conservation↗
USGS2026

Recent scientific contributions by the U.S. Geological Survey in the San Francisco Bay and Sacramento–San Joaquin Delta Estuary

Introduction The San Francisco Bay and Sacramento–San Joaquin Delta Estuary (hereafter, Bay-Delta) is the largest estuary on the West Coast of the United States. The Bay-Delta covers more than 1,600 square miles and drains a watershed of more than 75,000 square miles, which is greater than 40 percent of California. The region surrounding the Bay-Delta is home to about 10 million people, and its habitats (fig. 1) support more than 800 plant and animal species. The waterways of the Bay-Delta are the central hub of California’s extensive freshwater delivery system, supplying water to more than 27 million Californians and 4 million acres of farmland in the Central Valley. The U.S. Geological Survey (USGS) is the primary science agency of the U.S. Department of the Interior, providing a broad range of Earth, water, biological, and mapping data and expertise to inform natural resource management across the country. This fact sheet focuses on research conducted by the USGS in the Bay-Delta region, mostly within the past 5 years. The fact sheet is organized across five major themes: water flow and water quality, fish and wildlife, wetland restoration, invasive species, and hazards. In each of these areas, the USGS works closely with Federal, State, and local agencies; academia; and non-governmental organizations to provide objective, evidence-based science. The data and knowledge gained from USGS research and monitoring are publicly available and are routinely used by agencies, including the U.S. Bureau of Reclamation, U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, California Department of Water Resources, California Department of Fish and Wildlife, California State Water Resources Control Board, Delta Stewardship Council, and many additional organizations and stakeholders to inform management of the Bay-Delta region and its resources.

California↗
USGS2017

Application of paleoecology to ecosystem restoration: A case study from south Florida’s estuaries

Paleoecological analyses of biotic assemblages from cores collected throughout south Florida’s estuaries indicate gradually increasing salinities over approximately the last 2000 years, consistent with rising sea level. Around the beginning of the twentieth century these gradual patterns of change began to shift, corresponding to the beginning of human alteration of the environment via canal construction, railroad construction and other land use changes. Between 1950 and 1960, at a time of significant construction of water management structures another distinctive shift in the biological assemblages occurred. Analysis of the assemblages provides essential information on long-term patterns of change in the estuaries and provides a basis for predicting future trajectories of change. Paleosalinity estimates derived from the cores are providing input to linear regression models to determine related freshwater flow into the estuaries of south Florida. These analyses are being used to help establish performance measures and targets for the Comprehensive Everglades Restoration, established following an Act of Congress in 2000. Restoration of south Florida’s ecosystems is slated to be a 30–50 year effort that will require detailed knowledge of past decadal to centennial-scale changes in climate, freshwater flow and salinity. This historical perspective provides information that allows land managers to set realistic and sustainable goals for restoration, and provides insight into the potential response of south Florida’s ecosystem to various future scenarios of global change.

Florida↗
USGS2024

Bacteriological analysis of unionid hemolymph collected from freshwater mussel populations in the Pacific northwestern United States

Native freshwater mussel (Unionidae) mortality events have been occurring with increased frequency in recent decades, with few investigations into potential etiological agents. In the western United States, no surveys have been published regarding the bacteria associated with unionid mussels. Herein, we examine locations of known mussel mortality events in the Chehalis River (Washington), in the Crooked River (Oregon), and Owyhee River (Oregon). Mussel populations considered healthy were sampled in the Skookumchuck River (Washington) for comparison. A variety of bacteria were isolated from these populations, and most notably, Acinetobacter spp. were identified from 82% of moribund individuals of Gonidea angulata in the Owyhee River. Future work evaluating whether Acinetobacter spp. are pathogenic to freshwater mussels could be valuable in unraveling the factors associated with these enigmatic mortality events.

Oregon, Washington↗
USGS2025

Evidence for size‐based predation risk during Atlantic salmon (Salmo salar) smolt migration.

Hatchery supplementation is frequently employed during the conservation and recovery of imperilled salmon populations. At the smolt stage, hatchery rearing practices often produce individuals that are larger than wild conspecifics. Under this ‘bigger is better’ strategy, it is assumed that larger fish are less susceptible to predation during migration. We tested this hypothesis on hatchery-reared Atlantic salmon ( Salmo salar ) smolts with fork lengths representative of those of natural and hatchery origins, allowing us to isolate the influence of size from rearing history. From May to June 2023 we characterized predation risk for acoustic-tagged ( n = 50) and tethered ( n = 192) smolts of various sizes through a mostly free-flowing section of the Penobscot River, Maine, USA. Across both methods, more than 50% of smolts were predated, with the majority of predation events being attributed to smallmouth bass ( Micropterus dolomieu ). Tethered smolts of all sizes experienced similar predation risk. In the acoustic telemetry component of this study, smaller, wild-sized smolts incurred greater overall mortality relative to standard hatchery sizes (95% vs. 75%), the majority of which occurred within 3 km of the release site. Collectively, these results allude to a strong predation influence imposed by smallmouth bass on smolts in freshwater sections of the Penobscot River and small-bodied migrants may incur greater predation risk, particularly near stocking sites.

Journal of Fish Biology↗
USGS2007

Variation in salinity tolerance, gill Na+/K+-ATPase, Na+/K+/2Cl– cotransporter and mitochondria-rich cell distribution in three salmonids Salvelinus namaycush, Salvelinus fontinalis and Salmo salar

We compared seawater tolerance, gill Na + /K + -ATPase and Na + /K + /2Cl – cotransporter (NKCC) abundance, and mitochondria-rich cell (MRC) morphology of three salmonids, lake trout Salvelinus namaycush , brook trout Salvelinus fontinalis and Atlantic salmon Salmo salar . They were transferred directly from 0 p.p.t. (parts per thousand; freshwater) to 30 p.p.t. seawater, or transferred gradually from 0 to 10, 20 and 30 p.p.t. at 1-week intervals and kept in 30 p.p.t. for 3 weeks. The survival rates of lake trout, brook trout and Atlantic salmon were 80%, 50% and 100% following direct transfer, and 80%, 100% and 100% during gradual transfer, respectively. Plasma Na + , K + and Cl – concentrations in surviving lake trout increased rapidly and remained at high levels in 30 p.p.t. of both direct and gradual transfer, whereas those in brook trout showed a transient increase following direct transfer but did not change significantly during gradual transfer. Only minor changes in plasma ions were observed in Atlantic salmon smolts in both direct and gradual transfer. These results suggest that lake trout retains some degree of euryhalinity and that brook trout possesses intermediate euryhalinity between lake trout and Atlantic salmon smolts. Gill Na + /K + -ATPase activity of lake trout and brook trout increased in seawater, whereas that of Atlantic salmon smolts was already upregulated in freshwater and remained high after seawater exposure. NKCC abundance was upregulated in parallel with gill Na + /K + -ATPase activity in each species. Immunocytochemistry with anti-Na + /K + -ATPaseα -subunit and anti-NKCC revealed that the two ion transporters were colocalized on the basolateral membrane of gill MRCs. Immunopositive MRCs were distributed on both primary filaments and secondary lamellae in all three species kept in freshwater; following transfer to seawater this pattern did not change in lake trout and brook trout but lamellar MRCs disappeared in Atlantic salmon. Previous studies on several teleost species have suggested that filament and lamellar MRCs would be involved in seawater and freshwater acclimation, respectively. However, our results in lake trout and brook trout suggest that lamellar MRCs could be also functional during seawater acclimation.

Journal of Experimental Biology↗
USGS2015

Mottled duck (Anas fulvigula) movements in the Texas Chenier Plain Region

As a surrogate species for Strategic Habitat Conservation, the mottled duck (Anas fulgivula) is an indicator species to coastal marsh health and function. Currently, biologists have a relatively poor understanding of regional mottled duck movements. We outfitted adult female mottled ducks with solar satellite transmitters during summer 2009–2011. Movement patterns were measured among years and phenology, in relation to available habitat at the landscape level, and in association to potential disturbance. Movement distances were measured in ArcGIS and then evaluated using analysis of variance for independent variables of year, month, biological time period, and season. Average weekly distances traveled by mottled ducks were relatively short (<5,000m) compared to other waterfowl. Movement occurrence and distance were linked to biological season with longest distances documented during the molt period. Movements also differed among years, with drought conditions associated with longer movement distances. Magnitude of movements may be an indicator of habitat quality for mottled ducks in the Texas Chenier Plain Region. By focusing on providing large freshwater pools and fresh/intermediate marsh during the molt period, managers could positively impact mottled ducks.

Texas↗
USGS2003

Effects of life history variation on size and growth in stream-dwelling Atlantic salmon

A large size variation amongst life histories for stream-dwelling Atlantic salmon Salmo salar was found and the relative effect of life histories on size varied over time. As early as December (age 0+ years), fish that later smolted at age 2+ years were significantly larger than fish that did not smolt at age 2+ years. In contrast, there were no mass differences at age 0+ years between fish that would mature or not at age 1+ years (October). The mass differences between smolts and non-smolts persisted until smolting, and differences between mature and immature fish first appeared in May (age 1+ years). Following September (age 1+ years), there was also a significant interaction between smolting and maturity. Previously mature and immature age 2+ year smolts were not significantly different in size, but immature age 2+ year non-smolts were much lighter than mature age 2+ year non-smolts. Based on mass differences, the apparent 'decision' to smolt occurred c. 5 months before (winter, age 0+ years) the decision to mature (late spring, age 1+ years). In addition to strong seasonal growth variation, sizes of freshwater Atlantic salmon were largely structured by the complex interaction between smolt-age and maturity. ?? 2003 The fisheries Society of the British Isles.

Journal of Fish Biology↗
USGS2003

Application of adaptive cluster sampling to low-density populations of freshwater mussels

Freshwater mussels appear to be promising candidates for adaptive cluster sampling because they are benthic macroinvertebrates that cluster spatially and are frequently found at low densities. We applied adaptive cluster sampling to estimate density of freshwater mussels at 24 sites along the Cacapon River, WV, where a preliminary timed search indicated that mussels were present at low density. Adaptive cluster sampling increased yield of individual mussels and detection of uncommon species; however, it did not improve precision of density estimates. Because finding uncommon species, collecting individuals of those species, and estimating their densities are important conservation activities, additional research is warranted on application of adaptive cluster sampling to freshwater mussels. However, at this time we do not recommend routine application of adaptive cluster sampling to freshwater mussel populations. The ultimate, and currently unanswered, question is how to tell when adaptive cluster sampling should be used, i.e., when is a population sufficiently rare and clustered for adaptive cluster sampling to be efficient and practical? A cost-effective procedure needs to be developed to identify biological populations for which adaptive cluster sampling is appropriate.

Environmental and Ecological Statistics↗
USGS2016

87 Sr/ 86 Sr isotope ratio analysis by laser ablation MC-ICP-MS in scales, spines, and fin rays as a nonlethal alternative to otoliths for reconstructing fish life history

Strontium isotope ratios ( 87 Sr/ 86 Sr) in otoliths are a well-established tool to determine origins and movement patterns of fish. However, otolith extraction requires sacrificing fish, and when working with protected or endangered species, the use of nonlethal samples such as scales, spines, and fin rays is preferred. Unlike otoliths that are predominantly aragonite, these tissues are composed of biological apatite. Laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) analysis of biological apatite can induce significant interference on mass 87, causing inaccurate 87 Sr/ 86 Sr measurements. To quantify this interference, we applied LA-MC-ICP-MS to three marine samples (white seabass ( Atractoscion nobilis ) otolith; green sturgeon ( Acipenser medirostris ) pectoral fin ray; salmon shark ( Lamna ditropis ) tooth), and freshwater walleye ( Sander vitreus ) otoliths, scales, and spines). Instrument conditions that maximize signal intensity resulted in elevated 87 Sr/ 86 Sr isotope ratios in the bioapatite samples, related to a polyatomic interference ( 40 Ca 31 P 16 O, 40 Ar 31 P 16 O). Retuning instrument conditions to reduce oxide levels removed this interference, resulting in accurate 87 Sr/ 86 Sr ratios across all tissue samples. This method provides a novel, nonlethal alternative to otolith analysis to reconstruct fish life histories.

Wyoming↗
USGS1998

Water quality assessment of the Sacramento River Basin, California: Environmental setting and study design

This report describes the environmental setting and investigative activities of the Sacramento River Basin study unit of the National Water-Quality Assessment Program. The Sacramento River Basin is one of 60 study units located throughout the United States that has been scheduled for study as part of the National Water-Quality Assessment Program. The Sacramento River Basin is the most important source of freshwater in California. Water quality studies in the Sacramento River Basin study unit focus on the Sacramento Valley because it is here that the principal uses of water and potential impacts on water quality occur. Investigative activities include a network of surface water sites, where water chemistry and aquatic biological sampling are done, and a variety of ground water studies. In addition, investigations of the cycling and distribution of volatile organic compounds in the urban environment and the distribution of total and methyl mercury in the Sacramento River and tributaries will be completed.

California↗
USGS2021

Feeling the squeeze: Adult run size and habitat availability limit juvenile river herring densities in lakes

Maximum densities of juvenile river herring (Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis ) vary among freshwater lakes, likely due to densities of adult spawners. Differences in habitat availability and lake water quality may also contribute to variation in juvenile river herring productivity between populations, yet these relationships have not been tested across a large geographic scope. In this study we investigated relationships between juvenile river herring densities and (1) spawning adult river herring densities, (2) lake habitat availability, and (3) lake water quality in 29 freshwater lakes in the northeastern USA. Purse seines were used at night to sample juvenile river herring monthly in June–August 2014 and 2015, with concurrent collection of lake-specific physical (e.g., lake surface area, mean depth, depth to thermocline), chemical (e.g., nitrogen, phosphorus, dissolved organic carbon [DOC]), and biological (chlorophyll a , adult spawning density) data. Spawning adult density (number of adults per surface area of lake) explained 66.6% of the variation in juvenile densities using a generalized additive model. Juvenile densities increased with increasing adult density, peaking at roughly 1,000 adults/ha, and then declined at higher adult densities, suggesting a limit to carrying capacity in juvenile production. Linear mixed-effects models revealed that differences in water quality and habitat across lakes explained additional variation in juvenile densities. Specifically, DOC was negatively related to juvenile densities, suggesting that DOC limits the amount of suitable, well-oxygenated epilimnion habitat available to juvenile river herring in late summer. Our results can be used to help understand expected juvenile production based on adult density within a lake, to inform expectations about juvenile growth and survival, and to understand the mechanisms for how changes in habitat availability and water quality affect river herring populations.

Connecticut, Maine, Massachusetts, New Hampshire, ↗
USGS2007

A classification of U.S. estuaries based on physical and hydrologic attributes

A classification of U.S. estuaries is presented based on estuarine characteristics that have been identified as important for quantifying stressor-response relationships in coastal systems. Estuaries within a class have similar physical and hydrologic characteristics and would be expected to demonstrate similar biological responses to stressor loads from the adjacent watersheds. Nine classes of estuaries were identified by applying cluster analysis to a database for 138 U.S. estuarine drainage areas. The database included physical measures of estuarine areas, depth and volume, as well as hydrologic parameters (i.e., tide height, tidal prism volume, freshwater inflow rates, salinity, and temperature). The ability of an estuary to dilute or flush pollutants can be estimated using physical and hydrologic properties such as volume, bathymetry, freshwater inflow and tidal exchange rates which influence residence time and affect pollutant loading rates. Thus, physical and hydrologic characteristics can be used to estimate the susceptibility of estuaries to pollutant effects. This classification of estuaries can be used by natural resource managers to describe and inventory coastal systems, understand stressor impacts, predict which systems are most sensitive to stressors, and manage and protect coastal resources. ?? Springer Science+Business Media B.V. 2007.

Environmental Monitoring and Assessment↗