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Intercontinental convergence of stream fish community traits along geomorphic and hydraulic gradients

Community convergence across biogeographically distinct regions suggests the existence of key, repeated, evolutionary mechanisms relating community characteristics to the environment. However, convergence studies at the community level often involve only qualitative comparisons of the environment and may fail to identify which environmental variables drive community structure. We tested the hypothesis that the biological traits of fish communities on two continents (Europe and North America) are similarly related to environmental conditions. Specifically, from observations of individual fish made at the microhabitat scale (a few square meters) within French streams, we generated habitat preference models linking traits of fish species to local scale hydraulic conditions (Froude number), Using this information, we then predicted how hydraulics and geomorphology at the larger scale of stream reaches (several pool-riffle sequences) should quantitatively influence the trait composition of fish communities. Trait composition for fishes in stream reaches with low Froude number at low flow or high proportion of pools was predicted as nonbenthic, large, fecund, long-lived, nonstreamlined, and weak swimmers. We tested our predictions in contrasting stream reaches in France (n = 11) and Virginia, USA (n = 76), using analyses of covariance to quantify the relative influence of continent vs. physical habitat variables on fish traits. The reach-scale convergence analysis indicated that trait proportions in the communities differed between continents (up to 55% of the variance in each trait was explained by "continent"), partly due to distinct evolutionary histories. However, within continents, trait proportions were comparably related to the hydraulic and geomorphic variables (up to 54% of the variance within continents explained). In particular, a synthetic measure of fish traits in reaches was well explained (50% of its variance) by the Froude number independently of the continent. The effect of physical variables did not differ across continents for most traits, confirming our predictions qualitatively and quantitatively. Therefore, despite phylogenetic and historical differences between continents, fish communities of France and Virginia exhibit convergence in biological traits related to hydraulics and geomorphology. This convergence reflects morphological and behavioral adaptations to physical stress in streams. This study supports the existence of a habitat template for ecological strategies. Some key quantitative variables that define this habitat template can be identified by characterizing how individual organisms use their physical environment, and by using dimensionless physical variables that reveal common energetic properties in different systems. Overall, quantitative tests of community convergence are efficient tools to demonstrate that some community traits are predictable from environmental features.

Virginia↗

Alkylphenols, other endocrine-active chemicals, and fish responses in three streams in Minnesota — Study design and data, February-September 2007

This report presents the study design and environmental data for an integrated chemical and biological study of three streams (South Fork Crow River, Redwood River, and Grindstone River) that receive wastewater in Minnesota. The objective of the study was to identify distribution patterns of endocrine-active chemicals and other organic chemicals indicative of wastewater, and to identify fish responses in the same streams. Endocrine-active chemicals are a class of chemicals that interfere with the natural regulation of endocrine systems, and an understanding of their distribution in aquatic systems is important so that aquatic organism exposure can be evaluated. This study was a cooperative effort of the U.S. Geological Survey (USGS), the Minnesota Pollution Control Agency, and St. Cloud State University (St. Cloud, Minn.). The USGS collected and analyzed water and quality-assurance samples and measured streamflow during six sampling events in each of three streams. Water samples were collected upstream from and at two successive points downstream from wastewater-treatment plant (WWTP) effluent discharge and from treated effluent from February through September 2007. Bed-sediment samples were collected during one sampling period at each of the stream locations. Water and bed-sediment samples were analyzed for endocrine-active chemicals including alkylphenols, alkylphenol polyethoxylates, and nonylphenol ethoxycarboxlylates (NPECs). Water samples also were analyzed for major ions, nutrients, and organic carbon. In addition, as part of an intensive time-series investigation, the USGS staff collected daily water samples for 8 weeks from the Redwood River near Marshall, Minn., for analyses of total alkylphenols and atrazine. St. Cloud State University staff collected and analyzed fish to determine male fish responses at all water sampling sites and at an additional site near the discharge of wastewater-treatment plant effluent to these streams. Male fish responses included the presence and concentration of vitellogenin in plasma, gonadosomatic indices, and histological characterizations of liver and testes tissue. Hydrologic, chemical and biological characteristics were different among sites. The percentage of streamflow contributed by WWTP effluent (ranging from less than 1 to 79 percent) was greatest at the South Fork Crow River and least at the Grindstone River. WWTP effluent generally contributed the greatest percentage of streamflow during winter and late summer when streamflows were low. A wide variety of chemicals were detected. More chemicals were detected in WWTP effluent samples than in stream samples during most time periods. The most commonly detected chemicals in samples collected monthly and analyzed at the USGS National Research Program Laboratory were 2,6-di- tert -butyl-1,4-benzoquinone, 2,6-di- tert -butyl-4-methylphenol, 3- beta -coprostanol, 4-methylphenol, 4-nonylphenol (NP), 4- tert -octylphenol, bisphenol A, cholesterol, ethylenediaminetetraacetic acid, and triclosan. The chemicals 4-nonylphenolmonoethoxycarboxylate (NP1EC), 4-nonylphenoldiethoxycarboxylate (NP2EC), and 4-nonylphenoltriethoxycarboxylate (NP3EC) also were detected. Excluding nondetections, the sum of NP1EC through NP3EC concentrations ranged from 5.1 to 260 µg/L among all samples. NP was detected in upstream, effluent, and downstream samples in each stream during at least one time period. NP was detected in 49 percent of environmental samples. Excluding nondetections, concentrations of NP ranged from 100 to 880 nanograms per liter among all samples. NP was also detected in more than one-half of the bed-sediment samples. The most commonly detected wastewater indicator chemicals in samples analyzed by schedule 4433 at the USGS National Water Quality Laboratory were 3,4-dichlorophenyl isocyanate, acetyl-hexamethyl-tetrahydronaphthalene, benzophenone, cholesterol, hexahydrohexamethyl-cyclopenta-benzopyran, N,N-diethyl- meta -toluamide, and tri(dichloroisopropyl) phosphate. Male fish responses were the focus of the fish analyses, and 508 male fish were collected among all sampling sites. Vitellogenin was detected in 57 percent of the 415 male fish analyzed; concentrations ranged from an estimated value of 0.1 to 330 micrograms per milliliter (µg/mL) (average of 17.1 µg/mL). Intersex (the presence of oocytes in testes tissue) was observed in only one fathead minnow from an upstream site on the Grindstone River.

Minnesota↗

Occurrence of antibiotics in water from fish hatcheries

The recent discovery of pharmaceuticals in streams across the United States (Kolpin and others, 2002) has raised the visibility and need for monitoring of antibiotics in the environment. Possible sources of antibiotics and other pharmaceuticals in streams may include fish hatcheries. This fact sheet presents the results from a preliminary study of fish hatcheries across the United States for the occurrence and concentration of antibiotics present in fish hatchery water. The study examines both sufonamides and tetracyclines. Sulfonamides are synthetic compounds, and tetracyclines are naturally occurring compounds. The use of antibiotics added to specially formulated feed is a common practice in fish hatcheries to treat and prevent bacterial infections in large fish populations. U.S. Food and Drug Administration (FDA) approved antibiotics are oxytetracycline-HCI, sulfamerazine, and a combination drug containing ormetoprim and sulfadiamethoxine (U.S. Food and Drug Administration, 2003). During January 2001–June 2002, the U.S. Geological Survey (USGS) Organic Geochemistry Research Laboratory (OGRL), Lawrence, Kansas, cooperatively collected water samples from 13 fish hatcheries across the United States (fig. 1) with the assistance of hatchery operators. A method for the analysis of antibiotics was developed and used to identify and quantify these compounds in fish hatchery water (Lindsey and others, 2001). This study was completed to determine if trace levels of antibiotics [approximately 1 microgram per liter (μg/L) or 1 part per billion or greater occurred] in which water associated with fish hatcheries, which are a potential source of these compounds in surface water.

Colorado, Iowa, Kansas, New York, Oklahoma, Oregon↗

Influence of hydrology on life-history parameters of common freshwater fishes from southern Florida

Fishes are essential to the successful functioning of wetland food webs in southern Florida through their roles as prey and predators. Any changes that reduce the population sizes, community composition, or availability of aquatic animals will affect all facets of the ecology of these wetlands. In particular, small and medium-size fishes are important food items for most wading bird species. For this reason, fishes have been recognized by the multi-agency groups responsible for guiding the Everglades restoration process as a key indicator group by which to measure restoration success. Despite the importance of fish for management, gaps in baseline knowledge remain. Basic demographic information, termed life-history parameters, is needed to make predictions about their resilience under alternative management scenarios. These parameters include growth rate, age at maturation, fecundity and life expectancy. However, basic life-history parameters remain to be characterized, even for abundant fish species. Adding to the challenge, life-history characteristics of important Everglades species are known to be plastic in response to environmental conditions and survivorship and recruitment schedules are certain to be influenced by variation in hydroperiod. We intend to study the effect of hydroperiod on recruitment, size/age structure, growth, and fecundity, which, in turn, determine fish population dynamics. At present, data on fish reproduction, age and growth, and other life history characteristics are confined to a few species from a limited area of long-hydroperiod marsh in central Shark River Slough. As we continue the analysis and synthesis of data from the long-term fish collections, life-history information will help explain patterns of fluctuations in the time series. Accurate life-history data are also very important in building credible simulation models like ATLSS. Without empirical life-history data from a range of environments, the model will be simplistic and inadequate.

Florida↗

Physical data and biological data for algae, aquatic invertebrates, and fish from selected reaches on the Carson and Truckee rivers, Nevada and California, 1993-97

This report, a product of the National Water- Quality Assessment Program, is a compilation of physical data and biological data for algae, aquatic invertebrates, and fish collected in the Carson and Truckee River Basins, Nevada and California. Most of the data were collected between 1993 and 1996 at selected reaches on the Carson and Truckee Rivers. Algae and aquatic invertebrate samples were collected from cobble riffles, submerged woody-snag habitats, and from depositional areas such as pools. Between 1993 and 1996, fish and crayfish were collected from all wadeable habitats at each of seven basic-fixed sites using either electroshocking methods or seining. Additional fish and crayfish were collected at one site on the Truckee River in 1997. Fish were identified to species, measured for total and standard length, checked for anomalies, and weighed at the collection site. Fish were returned to the stream after measurements were taken. Measurements of water depth, stream velocity, determinations of substrate type and substrate embeddedness were made at each sampling site. Algae and aquatic invertebrate samples were sent to the U.S. Geological Survey National Water-Quality Laboratory for identification and enumeration. A total of 103 semi-quantitative and 55 qualitative algae samples were collected at 20 river reaches on the Carson and Truckee Rivers between 1993 and 1996. These samples represent algae in cobble riffles, on submerged woody snags, and on sediment surfaces in depositional areas. In those 158 samples, 514 algal species, varieties, or forms were identified. Of the 8 algal phyla represented, the diatoms (Phylum Bacillariophyta) were the most abundant with 351 species, varieties, or forms. The green algae (Phylum Chlorophyta) were next in abundance with 108 species, varieties, or forms followed by the blue-green algae (Phylum Cyanophyta) with 41 species, varieties, or forms. A total of 49 semi-quantitative aquatic invertebrate samples were collected at 27 river reaches on the Carson and Truckee Rivers between 1993 and 1996. These samples represent invertebrates in cobble riffles and on submerged woody snags. In those 49 samples, members of 6 phyla were identified. Roundworms were identified only to phylum (Nematoda) and free-living flatworms and snails were identified only to class (Turbellaria and Gastroda). Organisms were identified as belonging to 19 invertebrate orders. Most of the invertebrates that could be identified to genus or species belonged in the orders Ephemeroptera, Plecoptera, and Trichoptera of the arthropod class Insecta. Fish and crayfish populations in the Carson and Truckee Rivers were sampled 29 times between 1993 and 1997. These collections resulted in the identification of 18 fish species and one endemic crayfish species. Twelve of the 18 fish species identified are not native to the Carson and Truckee River Basins.

Open-File Report↗

Native Fish Sanctuary Project - Sanctuary Development Phase, 2007 Annual Report

Notable progress was made in 2007 toward the development of native fish facilities in the Lower Colorado River Basin. More than a dozen facilities are, or soon will be, online to benefit native fish. When this study began in 2005 no self-supporting communities of either bonytail or razorback sucker existed. Razorback suckers were removed from Rock Tank in 1997 and the communities at High Levee Pond had been compromised by largemouth bass in 2004. This project reversed that trend with the establishment of the Davis Cove native fish community in 2005. Bonytail and razorback sucker successfully produced young in Davis Cove in 2006. Bonytail successfully produced young in Parker Dam Pond in 2007, representing the first successful sanctuary established solely for bonytail. This past year, Three Fingers Lake received 135 large razorback suckers, and Federal and State agencies have agreed to develop a cooperative management approach dedicating a portion of that lake toward grow-out and (or) the establishment of another sanctuary. Two ponds at River's Edge Golf Course in Needles, California, were renovated in June and soon will be stocked with bonytail. Similar activities are taking place at Mohave Community College, Cerbat Cliffs Golf Course, Cibola High Levee Pond, Office Cove, Emerald Canyon Golf Course, and Bulkhead Cove. Recruitment can be expected as fish become sexually mature at these facilities. Flood-plain facilities have the potential to support 6,000 adult razorback suckers and nearly 20,000 bonytail if native fish management is aggressively pursued. This sanctuary project has assisted agencies in developing 15 native fish communities by identifying specific resource objectives for those sites, listing and prioritizing research opportunities and needs, and strategizing on management approaches through the use of resource-management plans. Such documents have been developed for Davis Cove, Cibola High Levee Pond, Parker Dam Pond, and Three Fingers Lake. We anticipate similar documents will be developed in the near future for River's Edge Golf Course Ponds, Office Cove, Emerald Canyon Golf Course Ponds, Bulkhead Cove, Mohave Community College, and Cerbat Cliffs Golf Course ponds as these facilities come on line or are developed in the future. The following report discusses the process that went into the development of these facilities. Sites were visited, assessed as to their suitability based on the control of nonnative predators, habitat suitability, conversion cost, logistics, geographical location, and willingness of landowners. They were then prioritized according to their suitability, cost, timely conversion, and willingness of landowners. Existing native fish facilities were included in this evaluation for their value in helping to determine physical and biological parameter ranges. This report describes the approaches that led to success, those leading to failure, and some of the biological, institutional, and management issues of implementing native fish sanctuary development.

Open-File Report↗

Comparison of concentrations and profiles of polycyclic aromatic hydrocarbon metabolites in bile of fishes from offshore oil platforms and natural reefs along the California coast

To determine the environmental consequences of decommissioning offshore oil platforms on local and regional fish populations, contaminant loads in reproducing adults were investigated at seven platform sites and adjacent, natural sites. Specimens of three species (Pacific sanddab, Citharichthys sordidus ; kelp rockfish, Sebastes atrovirens ; and kelp bass, Paralabrax clathratus ) residing at platforms and representing the regional background within the Santa Barbara Channel and within the San Pedro Basin were collected. Some of the most important contaminant classes related to oil operations are polycyclic aromatic hydrocarbons (PAHs) because of their potential toxicity and carcinogenicity. However, acute exposure cannot be related directly to PAH tissue concentrations because of rapid metabolism of the parent chemicals in fish; therefore, PAH metabolites in bile were measured, targeting free hydroxylated PAHs (OH-PAHs) liberated by enzymatic hydrolysis of the bound PAH glucuronides and sulfates. An ion-pairing method was developed for confirmatory analysis that targeted PAH glucuronides and sulfates. Concentrations of hydroxylated PAHs in all samples (76 fish from platforms and 64 fish from natural sites) were low, ranging from less than the limits of detection (5 to 120 nanograms per milliliter bile; 0.03 to 42 nanograms per milligram protein) to a maximum of 320 nanograms per milliliter bile (32 nanograms per milligram protein). A previously proposed dosimeter of PAH exposure in fish, 1-hydroxypyrene, was not detected at any platform site. Low concentrations of 1-hydroxypyrene were detected in 3 of 12 kelp rockfish collected from a natural reef site off Santa Barbara. The most prevalent OH-PAH, 2-hydroxyfluorene, was detected at low concentrations in seven fish of various species; of these, four were from two of the seven platform sites. The greatest concentrations of 2-hydroxyfluorene were found in three fish of various species from Platform Holly and were only about threefold above low, yet quantifiable, concentrations found in three fish from Horseshoe Reef, East Anacapa Island, and Coche Point natural sites; the mean concentrations among all sampling sites were not measurably different.

California↗

Assessing native fish restoration potential in Catoctin Mountain Park

Biological conservation is a fundamental purpose of the National Park system, and Catoctin Mountain Park (CATO) supports high-quality habitat for native fishes in the headwaters of the Chesapeake Bay watershed in eastern North America. However, native Blue Ridge sculpin ( Cottus caeruleomentum ) have been extirpated in Big Hunting Creek above Cunningham Falls in CATO. Prior research indicates that infection by the fungal-like protist Dermocystidium is a likely cause for the extirpation, but elevated stream temperatures also have been observed in the study area, and it remains unknown whether thermal stress may exacerbate infections or otherwise limit habitat suitability for fishes in CATO. The purpose of this study was to quantify spatial variation in summer stream temperatures and to evaluate the effects of temperature on sculpin growth rates and susceptibility to Dermocystidium infection. We used observational and experimental methods to address these objectives. First, we deployed stream temperature gages at 10 sites throughout the study area to assess hourly and daily temperatures during the summer of 2019. Second, we conducted an in situ fish enclosure experiment at five of the temperature sites to assess fish growth and susceptibility to Dermocystidium infection over a 45-day exposure period. For this experiment we collected sculpin from a stream in CATO that supports a robust population of Blue Ridge sculpin (Owens Creek) and held them in quarantine for 50 days in the Experimental Stream Laboratory at the U.S. Geological Survey (USGS) Leetown Science Center. Pre-exposure histopathology confirmed the absence of Dermocystidium infection prior to the introduction of fish into experimental enclosures. We found that stream temperatures were warmer where sculpin have been extirpated than elsewhere in CATO where sculpin persist. However, the fish enclosure experiment revealed a positive effect of temperature on fish growth, suggesting that increased food availability and foraging rates compensated for increased metabolic demands in the warmest sites. Moreover, fish held in enclosures did not develop Dermocystidium infection. Our results therefore suggest that current environmental conditions in upper Big Hunting Creek may be suitable for Blue Ridge sculpin reintroduction, and this could ultimately lead to sportfishing opportunities by increasing the forage base for native brook trout ( Salvelinus fontinalis ).

Maryland↗

Concentrations of selected organochlorine compounds in fish tissue in the Mississippi Embayment Study Unit : Arkansas, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee, 1995-99

Whole fish were collected at 52 sites during 1995-99 to evaluate the occurrence and distribution of selected organochlorine compounds in the Mississippi Embayment Study Unit. Samples were collected as part of the U.S. Geological Survey National Water Quality Assessment Program. From 5 to 8 fish were collected at each site; the fish were composited, and an aliquot of the tissue was analyzed for 28 organo-chlorine compounds, which included pesticides, pesticide degradates, and polychlorinated biphenyls. The use of these organochlorine compounds has been discontinued or severely restricted within the United States, but the continued detection of these compounds or their degradates in the air, water, soil, and biota in national surveys, coupled with known environmental problems associated with these compounds (such as a long half-life and the propensity to accumulate in living tissue), is cause for continued interest in their environmental fate. At least one organochlorine compound was detected in every fish-tissue sample, and as many as 15 different compounds were detected in some. The most frequently detected com-pounds were the degradates of p,p'-dichlorodiphenyltrichlo-roethane (p,p'-DDT); p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) was detected in every sample above the method reporting limit, and p,p'-dichlorodiphenyldichloroethane (p,p'-DDD), was detected in 94 percent of the samples. Polychlorinated biphenyl compounds and dieldrin were detected in 83 and 78 percent of fish-tissue samples, respectively. Because these were whole fish samples, the results are not directly comparable to human health standards, which are based on fish fillets. Comparison of these results, however, to the guidelines for the protection of fish-eating wildlife indicates that concentrations of the p,p'-DDT degradates and toxaphene continue to be of environmental concern.

Scientific Investigations Report↗

Mercury in fish, bed sediment, and water from streams across the United States, 1998-2005

Mercury (Hg) was examined in top-predator fish, bed sediment, and water from streams that spanned regional and national gradients of Hg source strength and other factors thought to influence methylmercury (MeHg) bioaccumulation. Sampled settings include stream basins that were agricultural, urbanized, undeveloped (forested, grassland, shrubland, and wetland land cover), and mined (for gold and Hg). Each site was sampled one time during seasonal low flow. Predator fish were targeted for collection, and composited samples of fish (primarily skin-off fillets) were analyzed for total Hg (THg), as most of the Hg found in fish tissue (95-99 percent) is MeHg. Samples of bed sediment and stream water were analyzed for THg, MeHg, and characteristics thought to affect Hg methylation, such as loss-on-ignition (LOI, a measure of organic matter content) and acid-volatile sulfide in bed sediment, and pH, dissolved organic carbon (DOC), and dissolved sulfate in water. Fish-Hg concentrations at 27 percent of sampled sites exceeded the U.S. Environmental Protection Agency human-health criterion of 0.3 micrograms per gram wet weight. Exceedances were geographically widespread, although the study design targeted specific sites and fish species and sizes, so results do not represent a true nationwide percentage of exceedances. The highest THg concentrations in fish were from blackwater coastal-plain streams draining forests or wetlands in the eastern and southeastern United States, as well as from streams draining gold- or Hg-mined basins in the western United States (1.80 and 1.95 micrograms THg per gram wet weight, respectively). For unmined basins, length-normalized Hg concentrations in largemouth bass were significantly higher in fish from predominantly undeveloped or mixed-land-use basins compared to urban basins. Hg concentrations in largemouth bass from unmined basins were correlated positively with basin percentages of evergreen forest and also woody wetland, especially with increasing proximity of these two land-cover types to the sampling site; this underscores the greater likelihood for Hg bioaccumulation to occur in these types of settings. Increasing concentrations of MeHg in unfiltered stream water, and of bed-sediment MeHg normalized by LOI, and decreasing pH and dissolved sulfate were also important in explaining increasing Hg concentrations in largemouth bass. MeHg concentrations in bed sediment correlated positively with THg, LOI, and acid-volatile sulfide. Concentrations of MeHg in water correlated positively with DOC, ultraviolet absorbance, and THg in water, the percentage of MeHg in bed sediment, and the percentage of wetland in the basin.

Scientific Investigations Report↗

Water-quality models to assess algal community dynamics, water quality, and fish habitat suitability for two agricultural land-use dominated lakes in Minnesota, 2014

Fish habitat can degrade in many lakes due to summer blue-green algal blooms. Predictive models are needed to better manage and mitigate loss of fish habitat due to these changes. The U.S. Geological Survey (USGS), in cooperation with the Minnesota Department of Natural Resources, developed predictive water-quality models for two agricultural land-use dominated lakes in Minnesota—Madison Lake and Pearl Lake, which are part of Minnesota’s sentinel lakes monitoring program—to assess algal community dynamics, water quality, and fish habitat suitability of these two lakes under recent (2014) meteorological conditions. The interaction of basin processes to these two lakes, through the delivery of nutrient loads, were simulated using CE-QUAL-W2, a carbon-based, laterally averaged, two-dimensional water-quality model that predicts distribution of temperature and oxygen from interactions between nutrient cycling, primary production, and trophic dynamics. The CE-QUAL-W2 models successfully predicted water temperature and dissolved oxygen on the basis of the two metrics of mean absolute error and root mean square error. For Madison Lake, the mean absolute error and root mean square error were 0.53 and 0.68 degree Celsius, respectively, for the vertical temperature profile comparisons; for Pearl Lake, the mean absolute error and root mean square error were 0.71 and 0.95 degree Celsius, respectively, for the vertical temperature profile comparisons. Temperature and dissolved oxygen were key metrics for calibration targets. These calibrated lake models also simulated algal community dynamics and water quality. The model simulations presented potential explanations for persistently large total phosphorus concentrations in Madison Lake, key differences in nutrient concentrations between these lakes, and summer blue-green algal bloom persistence. Fish habitat suitability simulations for cool-water and warm-water fish indicated that, in general, both lakes contained a large proportion of good-growth habitat and a sustained period of optimal growth habitat in the summer, without any periods of lethal oxythermal habitat. For Madison and Pearl Lakes, examples of important cool-water fish, particularly game fish, include northern pike ( Esox lucius ), walleye ( Sander vitreus ), and black crappie ( Pomoxis nigromaculatus ); examples of important warm-water fish include bluegill ( Lepomis macrochirus ), largemouth bass ( Micropterus salmoides ), and smallmouth bass ( Micropterus dolomieu ). Sensitivity analyses were completed to understand lake response effects through the use of controlled departures on certain calibrated model parameters and input nutrient loads. These sensitivity analyses also operated as land-use change scenarios because alterations in agricultural practices, for example, could potentially increase or decrease nutrient loads.

Minnesota↗

Occurrence and distribution of organochlorine pesticides, polychlorinated biphenyls, and trace elements in fish tissue in the lower Tennessee River basin, 1980-98

The U.S. Geological Survey, as part of the National Water-Quality Assessment Program, evaluated the occurrence and distribution of organochlorine pesticides, polychlorinated biphenyls, and trace elements in fish tissue in samples collected in the lower Tennessee River Basin study unit. Fish tissue analysis provides a time-averaged measurement of contaminants as well as a direct measurement of the contaminants that bioaccumulate in fish tissue. Bioaccumulation of contaminants in fish tissue may result in concentrations that can affect human, wildlife, or aquatic health. Data for two types of tissue analyses were evaluated to assess the occurrence and distribution of contaminants: whole fish for organochlorine pesticides and polychlorinated biphenyls and fish fillets for organochlorine pesticides, polychlorinated biphenyls, and trace elements. The fish tissue data analyzed for this study cover an 18-year span including data collected in 1998 by the U.S. Geological Survey as part of the National Water-Quality Assessment Program; data collected from 1980 through 1997 by the Tennessee Valley Authority; and data collected from 1992 through 1997 by the Tennessee Department of Environment and Conservation. Concentration data for constituents that are on the U.S. Environmental Protection Agency Priority Pollutant List were summarized and compared against existing action levels or guidelines.From the list of organochlorine pesticide compounds analyzed, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), a breakdown product of dichlorodiphenyltrichloroethane (DDT), was the most commonly detected compound with detections at 83 percent of the sites sampled. Eleven p,p'-DDE samples exceeded action levels or guidelines with concentrations ranging from 0.20 to 12.8 milligrams per kilogram. Five other organochlorine compounds, p,p'-dichlorodiphenyldichloroethane (p,p'-DDD), dieldrin, endrin, chlordane, and polychlorinated biphenyls, also exceeded action levels and guidelines, but the detection frequencies at sampling sites generally were less than 70 percent. Mercury, the only trace element to exceed a guideline, was detected at 51 of 102 sites sampled for trace elements. Selenium was detected in fish fillet samples from 70 of 102 sites sampled, which was more sites than for any other trace element; however, selenium did not exceed the 50 micrograms per gram U.S. Environmental Protection Agency screening criteria. Arsenic and cadmium also were detected at 44 and 54 percent of the sampling sites, respectively.

Water-Resources Investigations Report↗

Simulation of Fish, Mud, and Crystal Lakes and the shallow ground-water system, Dane County, Wisconsin

A new MODFLOW lake package (LAK3) that simulates ground-water/lake interaction was used in simulation of Fish, Mud and Crystal Lakes?three shallow seepage lakes located in northwestern Dane County, Wis. The simulations were done to help determine the cause of increasing lake stages and provide a tool to estimate the effect of pumping water from Fish lake on future lake stages. The ground-water-flow model was developed using a telescopic-mesh refinement of the Dane and southwestern Columbia Counties regional model previously developed by the U.S. Geological Survey and the Wisconsin Geological and Natural History Survey. The parameter estimation model, UCODE, was coupled to the steadystate ground-water model to automate and optimize the calibration procedure. The steady-state model was calibrated to measured ground-water levels, Spring Creek streamflow measured at Lodi, and Fish and Crystal Lake stages. The results of the steady-state model were used as initial conditions in a transient simulation beginning in 1966 and ending in 1998. Recharge based on annual baseflow in Black Earth Creek, runoff based on measured coefficients, and precipitation and evaporation from the lake surfaces, were varied during the transient simulation. Measured Fish Lake stage was matched to simulated stage to calibrate the transient model. Model results suggest that the increase in regional ground-water recharge resulted in increased ground-water flow to the lake, which in turn resulted in increased lake stages. Simulation results of withdrawal of water from Fish Lake at 500 gallons per minute, assuming 1990?98 climatic conditions, indicate that after 1 year of pumping the stage of Fish and Mud Lakes would be reduced more than 1 foot and the stage of Crystal Lake would be reduced by less than 0.2 foot. When pumping is stopped, the lake stages would recover to near pre-pumping levels within about 3 years. When pumping is extended to 5 years, Fish and Mud Lake stage would be reduced by a maximum of 3.8 feet and Crystal Lake stage is reduced a maximum of 0.8 feet. After 4 years of recovery, Fish and Mud Lake stages are within 0.9 foot of prepumping levels and Crystal Lake stage is within 0.7 foot.

Wisconsin↗

Response of fish communities to cropland density and natural environmental setting in the Eastern Highland Rim Ecoregion of the lower Tennessee River basin, Alabama and Tennessee, 1999

Response of fish communities to cropland density and natural environmental setting were evaluated at 20 streams in the Eastern Highland Rim Ecoregion of the lower Tennessee River Basin during the spring of 1999. Sites were selected to represent a gradient of cropland densities in basins draining about 30 to 100 square miles. Fish communities were sampled by using a combination of seining and electrofishing techniques. A total of 10,550 individual fish, representing 63 species and 15 families, were collected during the study and included the families Cyprinidae (minnows), 18 species; Percidae (perch and darters), 12 species; and Centrarchidae (sunfish), 12 species. Assessments of environmental characteristics, including instream and terrestrial data and land-cover data, were conducted for each site. Instream measurements, such as depth, velocity, substrate type, and embeddedness, were recorded at 3 points across 11 equidistant transects at each site. Terrestrial measurements, such as bank angle, canopy angle, and canopy closure percentage, were made along the stream bank and midchannel areas. Water-quality data collected included pH, dissolved oxygen, specific conductivity, water temperature, nutrients, and fecal-indicator bacteria. Substrate embeddedness was the only variable correlated with both cropland density and fish communities (as characterized by ordination scores and several community level metrics). Multivariate and nonparametric correlation techniques were used to evaluate fish-community responses to physical and chemical factors associated with a cropland-density gradient, where the gradient was defined as the percentage of the basin in row crops. Principal component analysis and correspondence analysis suggest that the Eastern Highland Rim Ecoregion is composed of three subgroups of sites based on inherent physical and biological differences. Data for the subgroup containing the largest number of sites were then re-analyzed, revealing that several environmental variables, such as nutrient concentrations, stream gradient, bankfull width, and substrate embeddedness, were related to cropland density; however, only a subset of those variables (substrate embeddedness, elevation, and streamflow) were related to fish communities. Results from this analysis suggest that although many water-quality and habitat variables are covariant with cropland density, most of the variables do not significantly affect fish-community composition; instead, fish communities primarily respond to the cumulative effects of sedimentation.

Water-Resources Investigations Report↗

Assessment of fish assemblages and minimum sampling effort required to determine botic integrity of large rivers in southern Idaho, 2002

A critical issue surrounding biomonitoring in large rivers (fifth- through seventh-order) is the minimum sampling-reach distance required to collect an adequate number of fish to represent the fish assemblage within a reach. Excessive sampling effort (excessive reach length) is costly in terms of work hours, reduces the number of sites that can be visited, can compromise field-crew safety, can be logistically unfeasible, and can cause unnecessary injury to captured fish. On the other hand, inadequate sampling effort can produce considerable variability in multiple samples collected at a site and may underrepresent the species or river condition present. During the summer of 2002, the U.S. Geological Survey, in cooperation with the Idaho Department of Environmental Quality, determined the minimum sampling effort required to characterize fish assemblages at 17 large-river sites in southern Idaho. The study was done as part of the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program. Electrofishing methods and multiple gear types were used to collect sample populations of fish in river reach lengths representing 40 and 100 times the wetted channel width. Minimum sampling effort was assessed by comparing the relation between reach length and the number of species collected, total individuals collected, and final Index of Biotic Integrity (IBI) scores. Thirty-two species of fish in the families Catostomidae, Centrarchidae, Cottidae, Cyprinidae, Ictaluridae, Percidae, and Salmonidae were collected. Of these, 12 alien species were collected, representing about 38 percent of all species collected during the study. Wetted channel width was determined to be sufficient for collecting an adequate number of fish to estimate species richness and evaluate biotic integrity. At most sites, about 250 fish were needed to effectively represent 95 percent of the species present. Fifty-three percent of the sites assessed, using an IBI developed specifically for large Idaho rivers, received scores of less than 50, indicating poor biotic integrity.

Idaho↗

Fish communities of fixed sites in the Western Lake Michigan Drainages, Wisconsin and Michigan, 1993-95

Fish communities were surveyed at 20 wadable stream sites during 1993-95 as part of the U.S. Geological Survey's (USGS) National Water- Quality Assessment (NAWQA) Program's assessment of the Western Lake Michigan Drainages. Part of the NAWQA design is to incorporate ecological data into an overall environmental assessment. Collection of fish-community data was part of this ecological assessment. The Western Lake Michigan Drainages study area is located in eastern Wisconsin and parts of the Upper Peninsula of Michigan. To isolate the effects of individual factors on stream quality, the study area was subdivided into 28 environmental settings, or relatively homogeneous units (RHUs), on the basis of land use/land cover, texture of surficial deposits, and bedrock geology. A fixed monitoring site was established on a wadable stream within 8 of these RHUs to determine the status and trends of water quality in a representative stream. Water-quality characteristics, ecological- community data, and stream-habitat factors were measured at these sites during 1993- 95. Fish communities were sampled at the 8 wadable fixed sites once a year during 1993-95. At three of these sites, multiple-reach samples were collected in 1994 to determine within-site variation. Fish communities also were sampled at an additional 12 sites, 11 in 1993 and one in 1995, within the 6 largest RHUs. The sites, 1-3 per each of the 6 RHUs, were located on streams with drainage basins of similar size as the fixed sites within the same RHUs. A total of 44 fish species from 12 families were collected at the 20 sites. The family with the most species represented were the minnows. The number of species per site ranged from one at a small urban site (Lincoln Creek) in 1995 to 21 at an agricultural site (North Branch Milwaukee River) in 1995. The number of individuals collected in one sampling pass ranged from 21 at a stream in the forested northwest part of the study area (Peshekee River) in 1995 to 498 at an agricultural site (East River) in 1995. White sucker (Catostomus commersoni) were collected at 17 sites, the most of any species. Species that are indicative of a coldwater environment were collected at 12 sites. Detrended correspondence analysis (DCA) of multiple-reach and multiple-year data indicated that species composition at each of these sites were fairly consistent between reaches and years. Thus, for simplicity, most analyses were done using 1993 data only. Index of Biotic Integrity (IBI) scores on 1993 data ranged from very poor at a channelized urban site to excellent at 3 sites; 2 in primarily agricultural areas and 1 in a forested area. Seven sites each scored good or fair, and two sites scored poor. Sites with multiple-year or multiple-reach data did not vary significantly within the error factor of the IBI. DCA of fish-community data from 19 sites indicated that coldwater sites were tightly grouped, whereas warmwater sites showed a larger gradient. This was expected, given the potential for greater diversity among warmwater sites. Fixed sites were shown to be representative of the study area as a whole, while specific fish communities could not be attributed to particular RHUs. Cluster analysis revealed two major groups of sites and two outlier sites. The two groups represented coldwater and warmwater streams, while the outlier sites were the urban site and a species- rich site with high biotic integrity that drains primarily agricultural land. Canonical correspondence analysis (CCA) revealed that soil credibility was a significant predictor of species composition. Though not statistically significant, land use, soil permeability, and bedrock permeability also were indicated as predictors of fish-species composition by CCA.

Michigan, Wisconsin↗

Water-quality assessment of the Rio Grande Valley, Colorado, New Mexico and Texas: Organic compounds and trace elements in bed sediment and fish tissue, 1992-93

The occurrence and distribution of contaminants in aquatic systems are major components of the National Water-Quality Assessment (NAWQA) Program. Bed-sediment samples were collected at 18 sites in the Rio Grande Valley study unit between September 1992 and March 1993 to characterize the geographic distribution of organic compounds, including chlorinated insecticides, polychlorinated biphenyls (PCB's), and other chlorinated hydrocarbons, and also trace elements. Two-millimeter-size- fraction sediment was analyzed for organic compounds and less than 63-micron-size-fraction sediment was analyzed for trace elements. Concentrations of p,p'-DDE were detected in 33 percent of the bed-sediment samples. With the exception of DDT-related compounds, no other organochlorine insecticides or polychlorinated biphenyls were detected in samples of bed sediment. Whole-body fish samples were collected at 11 of the bed- sediment sites and analyzed for organic compounds. Organic compounds were reported more frequently in samples of fish, and more types of organic compounds were found in whole-body fish samples than in bed-sediment samples. Concentrations of p,p'-DDE were detected in 91 percent of whole-body fish samples. Polychlorinated biphenyls, cis-chlordane, trans-chlordane, trans- nonachlor, and hexachlorobenzene were other organic compounds detected in whole-body samples of fish from at least one site. Because of the extent of mineralized areas in the Rio Grande Basin arsenic, cadmium, copper, lead, mercury, selenium, and zinc concentrations in bed-sediment samples could represent natural conditions at most sites. However, a combination of natural conditions and human activities appears to be associated with elevated trace-element concentrations in the bed-sediment sample from the site Rio Grande near Creede, Colorado, because this sample exceeded the background trace-element concentrations calculated for this study. Fish-liver samples were collected at 12 of the bed-sediment sites and analyzed for trace elements. Certain trace elements were detected at higher concentrations in fish-liver samples than in bed-sediment samples from the same site. Both bed-sediment and fish-tissue samples are necessary for a complete environmental assessment of the occurrence and distribution of trace elements.

Colorado, New Mexico, Texas↗

Effects of historical land-cover changes on flooding and sedimentation, North Fish Creek, Wisconsin

North Fish Creek, a Wisconsin tributary to Lake Superior, is an important recreational fishery that is potentially limited by the loss of aquatic habitat caused by accelerated flooding and sedimentation. A study of the historical flooding and sedimentation characteristics of North Fish Creek was done to determine how North Fish Creek responded to human-caused changes in land cover since European settlement of the region in the 1870's. Geomorphic field evidence combined with hydrologic and sediment-transport modeling indicate that historical clear-cut logging, followed by agricultural activity, significantly altered the hydrologic and geomorphic conditions of North Fish Creek. The geomorphic responses to land-cover changes were especially sensitive to the location of the reaches along the main stem and on the timing of large floods. On the basis of geomorphic evidence in flood-plain deposits and abandoned channels, the size of floods and sediment loads also increased in North Fish Creek after conversion of forested land to cropland and pasture. Changes in channel characteristics were particularly noticeable after record floods in 1941 and 1946. The upper main stem channel bed eroded downward at least 3 meters and the channel capacity at least doubled after European settlement. In the lower stem, the post-settlement sedimentation rate on the flood plain and in the channel is 4 to 6 times pre-settlement rates. The water table also appears to be rising near the mouth of North Fish Creek, perhaps consistent with (1) elevated local streambed elevations caused by sedimentation and (2) a slow relative rise in the local level of Lake Superior due to crustal rebound from glaciation. Along a transitional reach of the main stem between the upper and lower main stem, there is evidence of accelerated flood-plain sedimentation initially following European settlement. Since at least the 1940's, however, the channel bed in the transitional reach has eroded about 1 meter and the channel capacity has at least doubled. Results from hydrologic and sediment-transport modeling indicate that modern flood peaks and sediment loads in North Fish Creek may be double that expected under pre-settlement forest cover. During maximum agricultural activity in the mid-1920's to mid-1930's, flood peaks probably were about 3 times larger and sediment loads were about 5 times larger than expected under pre-settlement forest cover. These results indicate that future changes from pasture or cropland to forest will help reduce flood peaks, thereby reducing erosion and sedimentation. The addition of detention basins (to decrease flood peaks) on tributaries to North Fish Creek, or bank and instream restoration (to decrease erosion) in the upper main stem, also may help reduce the contribution of sediment from the upper main stem to the transitional section and lower main stem of the creek.

Wisconsin↗