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At least 199 records · Page 11Linked to original sources

Physical, chemical, and biological data for detailed study of irrigation drainage in the Salton Sea area, California, 1988-90

This report contains physical, chemical, and biological data associated with irrigation drainage in the Salton Sea area collected during the late 1980's. The data were collected in support of the u.S. Department of the Interior's National Irrigation Water Quality Program in the Western United States to evaluate effects on the environment from potential toxics in irrigation-induced drainage. The data have been used to support interpretations in several recent publications. This data report is the companion to a comprehensive U.S. Geological Survey interpretive report that describes the geochemical and biological pathways of potential toxics, especially selenium, in the study area. The report contains data on concentra- tions of a broad suite of trace elements in soil, irrigation (Colorado River) water, drainwater, surface water (including the Salton Sea), ground- water, aquatic plants, invertebrates, amphibians, reptiles, fish, birds, bird eggs, and turtle eggs. Included, also, are light stable isotope (hydrogen, oxygen, carbon, nitrogen, and sulfur), tritium, and radiocarbon data for selected aqueous samples and organochlorine-pesticide concentrations in biota. Geochemical samples were collected from more than 100 drainwater-collection sites, several surface- water locations, 15 fields, 3 multiple-depth lysimeter and piezometer installations, and the Alamo River Delta on the southeastern shore of the Salton Sea, and from laboratory evaporations of Colorado River water. Biological samples were collected from 39 sites, including 16 Salton Sea shore locations, 5 streams, 7 freshwater impound- ments, 11 drainwater ditches, and 2 additional locations in the Imperial Valley. (USGS)

Open-File Report↗

Development, evaluation, and application of sediment quality targets for assessing and managing contaminated sediments in Tampa Bay, Florida

Tampa Bay is a large, urban estuary that is located in west central Florida. Although water quality conditions represent an important concern in this estuary, information from numerous sources indicates that sediment contamination also has the potential to adversely affect aquatic organisms, aquatic-dependent wildlife, and human health. As such, protecting relatively uncontaminated areas of the bay from contamination and reducing the amount of toxic chemicals in contaminated sediments have been identified as high-priority sediment management objectives for Tampa Bay. To address concerns related to sediment contamination in the bay, an ecosystem-based framework for assessing and managing sediment quality conditions was developed that included identification of sediment quality issues and concerns, development of ecosystem goals and objectives, selection of ecosystem health indicators, establishment of metrics and targets for key indicators, and incorporation of key indicators, metrics, and targets into watershed management plans and decision-making processes. This paper describes the process that was used to select and evaluate numerical sediment quality targets (SQTs) for assessing and managing contaminated sediments. These SQTs included measures of sediment chemistry, whole-sediment and pore-water toxicity, and benthic invertebrate community structure. In addition, the paper describes how the SQTs were used to develop site-specific concentration-response models that describe how the frequency of adverse biological effects changes with increasing concentrations of chemicals of potential concern. Finally, a key application of the SQTs for defining sediment management areas is discussed.

Florida↗

An assessment of injury to sediments and sediment-dwelling organisms in the Grand Calumet River and Indiana Harbor Area of Concern, USA

This article is the first in a series of three that describe the results of a Natural Resource Damage Assessment (NRDA) conducted in the Grand Calumet River and Indiana Harbor Area of Concern (IHAOC). The assessment area is located in northwest Indiana and was divided into nine reaches to facilitate the assessment. This component of the NRDA was undertaken to determine if sediments and sediment-dwelling organisms have been injured due to exposure to contaminants that have accumulated in sediments as a result of discharges of oil or releases of other hazardous substances from industrial, municipal, and nonpoint sources. To support this assessment, information was compiled on the chemical composition of sediment and pore water; on the toxicity of whole sediments, pore water, and elutriates; and on the status of benthic invertebrate communities. The data on each of these indicators were compared to regionally relevant benchmarks to assess the presence and extent of injury to surface water resources (i.e., sediments) or biological resources (i.e., sediment-dwelling organisms). The results of this assessment indicate that sediment injury has occurred throughout the assessment area, with up to four distinct lines of evidence demonstrating injury within the various reaches. The primary contaminants of concern (i.e., those substances that are present at concentrations that are sufficient to cause or substantially contribute to sediment injury) include metals, polycyclic aromatic hydrocarbons, and total polychlorinated biphenyls.

Archives of Environmental Contamination and Toxico↗

The reach-scale biogeomorphic effect of submerged macrophytes on trout habitat suitability

Submerged macrophytes have complex effects on spatiotemporal characteristics of river ecosystems, including trout habitat. We investigated the impact of submerged macrophyte coverage on trout habitat in the Henrys Fork of the Snake River, Idaho, USA. We hypothesized that higher submerged macrophyte coverage would create new habitat types beneficial for trout growth. We assessed river physical and biotic attributes, trout habitat preferences, and estimated trout growth potential with bioenergetics models across a gradient of submerged macrophyte coverage (32–94%). We identified four distinct habitat types within the riverscape shaped by submerged macrophyte coverage. Increased submerged macrophyte coverage increased the frequency of habitat types with higher trout growth potential but reduced the occurrence of preferred habitat types. We observed no relationship between reach-scale trout growth potential and submerged macrophyte coverage. However, an outlier of very high trout growth potential at 94% submerged macrophyte coverage suggests a potential threshold effect. More study is required but our observations suggest macrophyte growth homogenized physical habitat characteristics, reduced flow velocities, and increased invertebrate drift, thereby enhancing trout growth potential. Our findings underscore the complex interplay between submerged macrophytes and trout habitat dynamics across scales, emphasizing the importance of considering both physical and biological effects on trout habitat.

Idaho↗

Relative abundance of deformed wing virus, Varroa destructor virus 1, and their recombinants in honey bees (Apis mellifera) assessed by kmer analysis of public RNA-Seq data

Deformed wing virus (DWV) is a major pathogen of concern to apiculture, and recent reports have indicated the local predominance and potential virulence of recombinants between DWV and a related virus, Varroa destructor virus 1 (VDV). However, little is known about the frequency and titer of VDV and recombinants relative to DWV generally. In this study, I assessed the relative occurrence and titer of DWV and VDV in public RNA-seq accessions of honey bee using a rapid, kmer-based approach. Three recombinant types were detectable graphically and corroborated by de novo assembly. Recombination breakpoints did not disrupt the capsid-encoding region, consistent with previous reports, and both VDV- and DWV-derived capsids were observed in recombinant backgrounds. High abundance of VDV kmers was largely restricted to recombinant forms. Non-metric multidimensional scaling identified genotypic clusters among DWV isolates, which was corroborated by read mapping and consensus generation. The recently described DWV-C lineage was not detected in the searched accessions. The data further highlight the utility of high-throughput sequencing to monitor viral polymorphisms and statistically test biological predictors of titer, and point to the need for consistent methodologies and sampling schemes.

Journal of Invertebrate Pathology↗

A diverse suite of pharmaceuticals contaminates stream and riparian food webs

A multitude of biologically active pharmaceuticals contaminate surface waters globally, yet their presence in aquatic food webs remain largely unknown. Here, we show that over 60 pharmaceutical compounds can be detected in aquatic invertebrates and riparian spiders in six streams near Melbourne, Australia. Similar concentrations in aquatic invertebrate larvae and riparian predators suggest direct trophic transfer via emerging adult insects to riparian predators that consume them. As representative vertebrate predators feeding on aquatic invertebrates, platypus and brown trout could consume some drug classes such as antidepressants at as much as one-half of a recommended therapeutic dose for humans based on their estimated prey consumption rates, yet the consequences for fish and wildlife of this chronic exposure are unknown. Overall, this work highlights the potential exposure of aquatic and riparian biota to a diverse array of pharmaceuticals, resulting in exposures to some drugs that are comparable to human dosages.

Nature Communications↗

Anadromous sea lampreys ( Petromyzon marinus ) are ecosystem engineers in a spawning tributary

Sea lampreys ( Petromyzon marinus ) disturb the substratum during nest construction and alter the physical habitat, potentially affecting other stream organisms. We quantified differences in depth, velocity, fine-sediment coverage, embeddedness, intragravel permeability and benthic invertebrate assemblages (density and diversity) among nest mounds, nest pits and undisturbed reference locations over a 4-month period after June spawning. In 2010 and 2011, immediate and persistent effects of nest construction were assessed in summer (July) and in autumn (late September to early October), respectively. Randomly selected nests were sampled annually (25 each in summer and autumn). Nest construction increased stream-bed complexity by creating and juxtaposing shallow, swift, rocky habitat patches with deep, slow, sandy habitat patches. Mounds had a 50–143% less cover of fine sediment, and a 30–62% reduction in embeddedness, compared to pits and reference locations. These physical changes persisted into the autumn (almost 4 months). Five insect families contributed 74% of the benthic invertebrate abundance: Chironomidae (27%), Hydropsychidae (26%), Heptageniidae (8%), Philopotamidae (7%) and Ephemerellidae (6%). Densities of Hydropsychidae, Philopotamidae and Heptageniidae were up to 10 times greater in mounds than in pits and adjacent reference habitat. In summer, mounds had twice the density of Chironomidae than did pits, and 1.5 times more than reference habitats, but densities were similar among the habitats in autumn. These results suggest that spawning sea lampreys are ecosystem engineers. The physical disturbance caused by nest-building activity was significant and persistent, increasing habitat heterogeneity and favouring pollution-sensitive benthic invertebrates and, possibly, drift-feeding fish.

Freshwater Biology↗

Options for water-level control in developed wetlands

Wetland habitats in the United States currently are lost at a rate of 260,000 acres/year (105,218 ha/year). Consequently, water birds concentrate in fewer and smaller areas. Such concentrations may deplete food supplies and influence behavior, physiology, and survival. Continued losses increase the importance of sound management of the remaining wetlands because water birds depend on them. Human activities modified the natural hydrology of most remaining wetlands in the conterminous United States, and such hydrologic alterations frequently reduce wetland productivity. The restoration of original wetland functions and productivity often requires the development of water distribution and discharge systems to emulate natural hydrologic regimes. Construction of levees and correct placement of control structures and water-delivery and water-discharge systems are necessary to (1) create soil and water conditions for the germination of desirable plants, (2) control nuisance vegetation, (3) promote the production of invertebrates, and (4) make foods available for wildlife that depends of wetlands (Leaflets 13.2.1 and 13.4.6). This paper provides basic guidelines for the design of wetlands that benefit wildlife. If biological considerations are not incorporated into such designs, the capability of managing wetlands for water birds is reduced and costs often are greater. Although we address the development of palustrine wetlands in migration and wintering areas, many of the discussed principles are applicable to the development of other wetland types and in other locations.

Book chapter↗

User's manual for the National Water-Quality Assessment Program Invertebrate Data Analysis System (IDAS) software, version 5

The Invertebrate Data Analysis System (IDAS) software was developed to provide an accurate, consistent, and efficient mechanism for analyzing invertebrate data collected as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. The IDAS software is a stand-alone program for personal computers that run Microsoft Windows(Registered). It allows users to read data downloaded from the NAWQA Program Biological Transactional Database (Bio-TDB) or to import data from other sources either as Microsoft Excel(Registered) or Microsoft Access(Registered) files. The program consists of five modules: Edit Data, Data Preparation, Calculate Community Metrics, Calculate Diversities and Similarities, and Data Export. The Edit Data module allows the user to subset data on the basis of taxonomy or sample type, extract a random subsample of data, combine or delete data, summarize distributions, resolve ambiguous taxa (see glossary) and conditional/provisional taxa, import non-NAWQA data, and maintain and create files of invertebrate attributes that are used in the calculation of invertebrate metrics. The Data Preparation module allows the user to select the type(s) of sample(s) to process, calculate densities, delete taxa on the basis of laboratory processing notes, delete pupae or terrestrial adults, combine lifestages or keep them separate, select a lowest taxonomic level for analysis, delete rare taxa on the basis of the number of sites where a taxon occurs and (or) the abundance of a taxon in a sample, and resolve taxonomic ambiguities by one of four methods. The Calculate Community Metrics module allows the user to calculate 184 community metrics, including metrics based on organism tolerances, functional feeding groups, and behavior. The Calculate Diversities and Similarities module allows the user to calculate nine diversity and eight similarity indices. The Data Export module allows the user to export data to other software packages (CANOCO, Primer, PC-ORD, MVSP) and produce tables of community data that can be imported into spreadsheet, database, graphics, statistics, and word-processing programs. The IDAS program facilitates the documentation of analyses by keeping a log of the data that are processed, the files that are generated, and the program settings used to process the data. Though the IDAS program was developed to process NAWQA Program invertebrate data downloaded from Bio-TDB, the Edit Data module includes tools that can be used to convert non-NAWQA data into Bio-TDB format. Consequently, the data manipulation, analysis, and export procedures provided by the IDAS program can be used to process data generated outside of the NAWQA Program.

Techniques and Methods↗

Physical, chemical, and biological characteristics of Sturgeon Lake, Goodhue County, Minnesota, 2003-04

The U.S. Geological Survey, in cooperation with the Prairie Island Indian Community and the Minnesota Department of Natural Resources, conducted a study of Sturgeon Lake (a backwater lake in Navigation Pool 3 of the Mississippi River) during 2003-04 to describe the physical, chemical, and biological characteristics of the lake. Riparian and shoreline areas surrounding Sturgeon Lake consist primarily of deciduous tree and shrub cover with minimal amounts of commercial or residential land use. Woody debris and aquatic vegetation are the major types of physical habitat suitable for fish and invertebrates. Among 10 bottom-sediment sampling sites, 24 organic wastewater compounds, 1 organochlorine pesticide metabolite (p,p’DDE), and total polychlorinated biphenyls (PCBs) were detected in the bottom sediments of Sturgeon Lake. The most prevalent class of compounds detected were polyaromatic hydrocarbons. Other classes of compounds detected include sterols, disinfectants, plastic components, alkylphenols, and fragrances. Three compounds detected (bisphenol A, benzo[a]pyrene, and triclosan) are considered endocrine disrupting compounds. Twenty-one and 49 invertebrate taxa were identified from 10 bottom-sediment and 6 woody-debris/vegetation samples, respectively. Most of the taxa were Diptera in the family Chironomidae. The most common invertebrate in terms of density in bottom-sediment samples was the burrowing mayfly ( Hexagenia sp.). Trichoptera in the families Hydropsychidae or Polycentropodidae were common in most of the woody-debris samples. The presence of the Hexagenia larvae in samples indicates that the bottom sediments are stable and that dissolved oxygen concentrations in the lake do not drop to acute or sub-lethal anoxic conditions. Backwater lakes such as Sturgeon Lake are important areas of habitat for aquatic organisms along the Mississippi River, and this report provides baseline physical, chemical, and biological information that resource managers can compare with future investigations.

Minnesota↗

Vectors of invasions in freshwater invertebrates and fishes

Without human assistance, the terrestrial environment and oceans represent barriers to the dispersal of freshwater aquatic organisms. The ability to overcome such barriers depends on the existence of anthropogenic vectors that can transport live organisms to new areas, and the species’ biology to survive the transportation and transplantation into the new environment (Johnson et al., 2006).

Book chapter↗

Development of a Monitoring Protocol to Detect Ecological Change in the Intertidal Zone of Sitka National Historical Park, Alaska

A pilot study to develop and test a probability-based intertidal monitoring protocol for Sitka National Historical Park was conducted from 1999 to 2003. In 1999, the basic design, with a focus on sampling the whole of the designated intertidal was created, and sampling was conducted for sessile species and large mobile invertebrates by point-intercept sampling of vertical transects and band surveys along transects, respectively. In 2002 and 2003, the same types of sampling were conducted, but quadrat sampling for small mobile invertebrates was added and then modified. This project has produced basic data on the presence, abundance, and spatial distribution of substrates and intertidal biota. Additionally, statistical power analyses conducted on the biological data have allowed assessment of the ability of the sampling to detect trends in the abundance of the predominant species. Current sampling has an 80 percent probability to detect +10 percent annual changes in abundance of all targeted species with an a = 0.05; the ability to detect -10 percent trends is not as uniformly high. Various options are discussed for decreasing the spatial variance of the data. The information presented provides a basis for discussion of the major questions being asked, how the sampling design might be reconfigured to be consistent in approach, and how the intertidal monitoring should interface with other potential intertidal monitoring.

Scientific Investigations Report↗

Aquatic assemblages and their relation to temperature variables of least-disturbed streams in the Salmon River basin, central Idaho, 2001

In the late 1990s, Idaho’s established stream temperature criteria for the protection of coldwater biota and salmonid spawning were considered inadequate because the criteria did not agree with observed biological conditions in many instances and did not allow for variability in environmental condition or species diversity across a broad area such as the entire State of Idaho. In 2001, benthic invertebrate and fish assemblages in 34 least-disturbed streams in the Salmon River Basin, central Idaho, were evaluated in relation to stream temperature and other environmental variables. The Salmon River Basin retains watersheds that are minimally affected by human activities. These “natural” stream conditions provide a basis for deriving attainable stream temperatures that can be used to set new, and revise existing, water-quality criteria for stream habitats affected by human activities. During July through September 2001, data were collected to document the thermal regime of least-disturbed streams, characterize the distribution of aquatic biota at streams representing a gradient of temperature, and describe the relations between environmental variables and benthic invertebrate and fish assemblages. Nine stream temperature metrics were compared with the U.S. Environmental Protection Agency’s criterion of 10 ° C (degrees Celsius) for bull trout spawning and juvenile rearing. The maximum weekly-maximum temperature at all 33 sites where temperature data were available exceeded this criterion. The maximum daily-maximum temperature (MDMT) at 30 of the sites exceeded the Idaho Department of Environmental Quality (IDEQ) criterion of 13.0 ° C for the protection of salmonid spawning; and the maximum daily-average temperature at all 33 sites exceeded the 9.0 ° C criterion for the protection of salmonid spawning. The thermal regime at most sites did not exceed the IDEQ criteria for the protection of coldwater biota. Nine environmental variables—water-surface gradient, discharge, wetted channel width, width:depth ratio, aspect, total seasonal thermal input, open canopy, riparian canopy density, and elevation were selected for correlation with the nine stream temperature metrics. Elevation showed the strongest inverse correlation with the stream temperature metrics. Two hundred and one benthic invertebrate taxa from the 34 sampling sites were identified. The most abundant taxa were Baetis tricaudatus , Oligochaeta, Tvetenia bavarica gr., Acari, Rhithrogena , Cinygmula , Heterlimnius , Micropsectra , Eukiefferiella devonica gr., Drunella doddsi , and Cricotopus . Of the 201 benthic invertebrate taxa collected during this study, 57 taxa (present at a minimum of 5 sampling sites) were significantly correlated with one or more of the stream temperature metrics. Among the invertebrate taxa collected, 32 were identified as coldwater taxa. Of the coldwater taxa collected, Zapada oregonensis gr. showed the strongest inverse correlation with the stream temperature metrics and was collected at sites where maximum weekly-maximum temperature (based on date of sample and 6 days prior) ranged from 11.3 ° to 18.5 °C. Ten species of fish in the families Salmonidae, Cottidae, and Cyprinidae were collected. Two species (bull trout and chinook salmon) listed as threatened under the U.S. Fish and Wildlife Service Endangered Species Act were collected. Among all species, bull trout showed the strongest inverse correlation between relative fish abundance and stream temperature. Bull trout and juvenile bull trout densities were inversely correlated with stream temperature. The probability of occurrence of juvenile bull trout was significantly correlated with MDMT on the basis of results from a logistic regression model developed during this study. However, this model differed from a similar model developed by the U.S. Forest Service on the basis of regional data collected in the Pacific Northwest. The regression model based on data collected during this study showed higher probabilities of occurrence of bull trout at colder stream temperatures (10 ° to 15 ° C) and lower probabilities of occurrence at warmer stream temperatures (16 ° to 21 ° C) than did the model based on regional data. The model comparisons suggest that regional or local differences need to be considered when deriving stream temperature criteria.

Idaho↗

Handbook of acute toxicity of chemicals to fish and aquatic invertebrates : summaries of toxicity tests conducted at Columbia National Fisheries Research Laboratory, 1965-78

Acute toxicity is a major subject of research at Columbia National Fisheries Research Laboratory for evaluating the impact of toxic chemicals on fishery resources. The Laboratory has played a leading role in developing research technology for toxicity testing and data interpretation. In 1965-78, more than 400 chemicals were tested against a variety of invertebrates and fish species representative of both cold- and warm-water climates. The use of acute toxicity tests for assessing the potential hazard of chemical contaminants to aquatic organisms is well documented (Boyd 1957; Henderson et al. 1960; Sanders and Cope 1966; Macek and McAllister 1970). Static acute toxicity tests provide rapid and (within limits) reproducible concentration-response curves for estimating toxic effects of chemicals on aquatic organisms. These tests provide a database for determining relative toxicity of a large number of chemicals to a variety of species and for estimating acute effects of chemical spills on natural aquatic systems; they also assist in determining priority and design of additional toxicity studies. Acute toxicity tests usually provide estimates of the exposure concentration causing 50% mortality (LC50) to test organisms during a specified period of time. For certain invertebrates, the effective concentration is based on immobilization, or some other identifiable endpoint, rather than on lethality. The application of the LC50 has gained acceptance among toxicologists and is generally the most highly rated test for assessing potential adverse effects of chemical contaminants to aquatic life (Brungs and Mount 1978; American Institute for Biological Sciences 1978 a ). The literature contains numerous papers dealing with the acute toxicity of chemicals to freshwater organisms. However, there is a tremendous need for a concise compendium of toxicity data covering a large variety of chemicals and test species. This Handbook is a compilation of a large volume of acute toxicity data from the Columbia Laboratory and its field laboratories. It presents definitive acute toxicity data on 271 chemicals tested against a variety of freshwater invertebrates and fishes. The chemicals represent all major groups of pesticides, as well as numerous industrial chemicals. This compilation should serve as a useful database for the many agencies and organizations dealing with research and management programs concerned with the impact of chemicals on aquatic resources. The Columbia Laboratory has played a major role in developing currently used standard methodology for static acute toxicity testing. The use of standardized methodology greatly reduces variation in results. The data presented here have been carefully scrutinized to eliminate tests that failed to follow acceptable procedures. Handling of test organisms and procedures for static toxicity tests followed those described by Lennon and Walker (1964) and Macek and McAllister (1970), and conform well with those recommended by Brauhn and Schoettger (1975) and the Committee on Methods for Toxicity Tests with Aquatic Organisms (1975). The species of fish and invertebrates that were tested are listed in phylogenetic order in Tables 1 and 2. Fish were obtained from Federal and State hatcheries as either eggs or fry. Original stocks of invertebrates were collected and cultured from wild populations with no known source of contamination; these populations were replenished regularly. The invertebrates were cultured in the Laboratory by methods similar to those described by Sanders and Cope (1966). Test chemicals usually consisted of technical or analytical grade samples of known purity. Formulations of the chemicals were also tested when available. When purity of test chemicals was known, all calculated concentrations were based on percent active ingredients. Stock solutions were prepared immediately before each test, with commercial grade acetone as the carrier solvent. Occasionally, ethanol or dimethyl-formamide was substituted. Solvent concentrations did not exceed 0.5 mL/L in final dilution water. Test water (dilution water) was reconstituted from deionized water of at least 10 6 ohms resistivity by the addition of appropriate reagent grade chemicals (Marking 1969). Water was buffered to maintain a pH of 7.2 to 7.5, an alkalinity of 30 to 35 mg/L, and a hardness of 40 to 50 mg/L as CaCO 3 . Test water was mixed thoroughly and aerated before transfer into test chambers. Fish were acclimated to dilution water by gradually changing the water in acclimated tanks from 100% well water to 100% reconstituted water over a 1- to 3-day period at the desired testing temperature. Invertebrates were acclimated from well water to dilution water over a 4- to 6-h period. Toxicity tests were conducted under static conditions without aeration, and the organisms were not fed during acclimation or testing. Temperature of test solutions was maintained within ± 1°C of that required for a given test. Toxicity tests with fish were conducted in 18.9-liter (5-gal) wide-mouthed jars containing 15 liters of test solution. Fingerling fish weighing 0.2 to 1.5 g were tested at each concentration. Caution was taken not to exceed 0.8 g of test organisms per liter of solution. Duplicate test chambers were used to accommodate larger fish. Test chambers varied in size for invertebrates, depending on the species used; volume of test solution ranged from 0.25 to 4 liters. At least 10 organisms were exposed to each concentration for all definitive tests. At least six concentrations were used per toxicity test. The tests began upon initial exposure to the toxicant and continued for 96 h. Immobilization tests with invertebrates were conducted for only 48 h. The number of dead or affected organisms in each test chamber were recorded and the dead organisms were removed every 24 h; general observations on the condition of test organisms were also recorded at these times. Toxicity data were analyzed by a statistical method described by Litchfield and Wilcoxon (1949) to determine LC50 (theoretical estimate of the concentration lethal to 50% of the test animals) and 95% confidence intervals. This method is recommended by the American Public Health Association (1971) and by Sprague (1969) for determining median lethal concentrations. The procedure is easily modified for computing a single LC50 when replicate tests are performed.

Resource Publication↗

Relation of periphyton and benthic invertebrate communities to environmental factors and land use at selected sites in part of the upper Mississippi River basin, 1996-98

The Upper Mississippi River Basin is one of the hydrologic systems selected for study by the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey. NAWQA utilizes a multi-disciplinary approach to explain factors that affect water quality. Part of the NAWQA design addresses the relation of land use and environmental factors to periphyton and benthic invertebrate communities in streams. This report focuses on a 122,000 square kilometer area of the Mississippi River Basin, including the Twin Cities metropolitan area (TCMA). The northeastern part of the study area is forested, the southwestern part is agricultural, and the central part is transitional between forest and agriculture. Sampling sites were selected based on a process that identified small streams in predominantly forested, agricultural, and urban settings, and large river sites on the Mississippi River and major tributaries. Periphyton and benthic invertebrate communities were evaluated at each site. Compared to the forested site, periphyton density and biovolume in small streams generally increased as nutrient concentrations associated with urban and agricultural land use increased. Periphyton communities varied within agricultural and urban streams, indicating that physical and chemical factors other than land use also affect periphyton communities. Benthic invertebrate communities also are affected by land use and associated stream habitat. There were few intolerant taxa (Ephemeroptera and Plecoptera) in urban streams, potentially due to high streamflow variability and contaminants from runoff. Ephemeroptera taxa richness was greatest in the agricultural streams. The most abundant Ephemeroptera taxa were those tolerant to high concentrations of suspended sediment. Richness of Plecoptera and Trichoptera taxa were greatest in the forested stream. Biological communities in the St. Croix and Minnesota River generally reflected relatively homogeneous land uses. Biological communities in the Mississippi River reflected changes in water quality and physical habitat as the Minnesota and St. Croix Rivers join the Mississippi River. Periphyton density and biovolume, and the relative abundance of blue-green algae density increased in the Mississippi River at the confluence compared to the Minnesota and St. Croix Rivers. Relative abundance of benthic invertebrate taxa richness and diversity generally decreased downstream in the large rivers as urban and agricultural land use become more prevalent. Impoundments and dredging of the Mississippi River in and downstream from the TCMA exacerbate effects of increasing river size to produce a more lake-like system.

Iowa, Minnesota, North Dakota, South Dakota, Wisco↗

Comparison of watershed disturbance predictive models for stream benthic macroinvertebrates for three distinct ecoregions in western US

The successful use of macroinvertebrates as indicators of stream condition in bioassessments has led to heightened interest throughout the scientific community in the prediction of stream condition. For example, predictive models are increasingly being developed that use measures of watershed disturbance, including urban and agricultural land-use, as explanatory variables to predict various metrics of biological condition such as richness, tolerance, percent predators, index of biotic integrity, functional species traits, or even ordination axes scores. Our primary intent was to determine if effective models could be developed using watershed characteristics of disturbance to predict macroinvertebrate metrics among disparate and widely separated ecoregions. We aggregated macroinvertebrate data from universities and state and federal agencies in order to assemble stream data sets of high enough density appropriate for modeling in three distinct ecoregions in Oregon and California. Extensive review and quality assurance of macroinvertebrate sampling protocols, laboratory subsample counts and taxonomic resolution was completed to assure data comparability. We used widely available digital coverages of land-use and land-cover data summarized at the watershed and riparian scale as explanatory variables to predict macroinvertebrate metrics commonly used by state resource managers to assess stream condition. The “best” multiple linear regression models from each region required only two or three explanatory variables to model macroinvertebrate metrics and explained 41–74% of the variation. In each region the best model contained some measure of urban and/or agricultural land-use, yet often the model was improved by including a natural explanatory variable such as mean annual precipitation or mean watershed slope. Two macroinvertebrate metrics were common among all three regions, the metric that summarizes the richness of tolerant macroinvertebrates (RICHTOL) and some form of EPT (Ephemeroptera, Plecoptera, and Trichoptera) richness. Best models were developed for the same two invertebrate metrics even though the geographic regions reflect distinct differences in precipitation, geology, elevation, slope, population density, and land-use. With further development, models like these can be used to elicit better causal linkages to stream biological attributes or condition and can be used by researchers or managers to predict biological indicators of stream condition at unsampled sites.

Ecological Indicators↗

Water-quality assessment of Rattlesnake Creek watershed, Ohio

Chemical and biological water quality in Rattlesnake Creek basin, Ohio, are evaluated. The data include field and laboratory data for eight sites during August 1976- August 1977 and summaries of earlier (1972-76) data. Streamflow was below normal during the study period. Basin waters types were calcium bicarbonate or calcium magnesium bicarbonate. Specific conductance ranged from 405 to 1,300 micromhos per centimeter. High concentrations of sodium (110-140 milligrams per liter) , nitrogen (24 milligrams per liter as N), and phosphorus (7.8 milligrams per liter as P) were observed during low flows downstream from domestic sewage facilities. Nonpoint sources contributed high concentrations of nitrate-nitrogen to all streams during the high flows of winter and spring. Dissolved-oxygen concentrations in the upper basin ranged from 3.2 to 18.4 milligrams per liter. Mean saturation values of dissolved oxygen were at or near 100 percent in the lower basin. Stream pH exceeded 8.4 when dissolved-oxygen saturation was above 120 percent. Bacteria and invertebrate data suggest that moderate pollution from cultural sources may exist in the upper basin. Water quality was poorest in the sluggish flows of the upper basin but improved downstream. Increases in flow velocity and stream aeration rates, dilution, and biological activity contributed to the downstream recovery. Except for' high nitrogen concentrations, water quality was best in the lower basin.

Ohio↗

Biological, habitat, and water quality conditions in the upper Merced River drainage, Yosemite National Park, California, 1993-1996

Four studies were done in the upper Merced River drainage in Yosemite National Park and nearby areas from 1993 to 1996. First, monitoring studies of benthic algae, benthic invertebrates, fish, and habitat were undertaken at sites near Happy Isles and Pohono bridges from 1993 to 1995 as part of the National Water-Quality Assessment Program of the U.S. Geological Survey. Second, an ecological survey of benthic algae, benthic invertebrates, fish, and habitat was done in the upper Merced River drainage in 1994. Third, a special study of benthic algae, habitat, and water quality was done in the reach of the Merced River within Yosemite Valley to deter-mine whether human activities were having measurable effects on the ecosystem. Fourth, baseline data on benthic algae, benthic invertebrates, and habitat were collected in 1996 at four sites, two of which were undergoing extensive streambank restoration activities. Comparisons of the baseline data with future collections could be used to assess the effects of streambank restoration on aquatic biota. The general conclusion from these studies is that water quality in the upper Merced River was very good from 1993-1996, despite high levels of human activities in some areas. Fish communities did not appear to be a useful indicator of habitat and water quality because of low species richness and the apparent importance of physical barriers in determining species distributions. Measurements of fish densities and size-distributions might be useful, but would be logistically difficult. Benthic algae and benthic invertebrates do appear to be useful in monitoring environmental conditions. Benthic algae may be more sensitive than benthic invertebrates to small environmental differences within years. Benthic algae were also more responsive than benthic invertebrates to differences in discharge between years. Thus, benthic invertebrates may be more useful in comparing environmental conditions between years, independent of discharge conditions.

Water-Resources Investigations Report↗