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Responses of benthic macroinvertebrates along gradients of urban intensity were investigated in nine metropolitan areas across the United States. Invertebrate assemblages in metropolitan areas where forests or shrublands were being converted to urban land were strongly related to urban intensity. In metropolitan areas where agriculture and grazing lands were being converted to urban land, invertebrate assemblages showed much weaker or nonsignificant relations with urban intensity because sites with low urban intensity were already degraded by agriculture. Ordination scores, the number of EPT taxa, and the mean pollution-tolerance value of organisms at a site were the best indicators of changes in assemblage condition. Diversity indices, functional groups, behavior, and dominance metrics were not good indicators of urbanization. Richness metrics were better indicators of urban effects than were abundance metrics, and qualitative samples collected from multiple habitats gave similar results to those of single habitat quantitative samples (riffles or woody snags) in all metropolitan areas. Changes in urban intensity were strongly correlated with a set of landscape variables that was consistent across all metropolitan areas. In contrast, the instream environmental variables that were strongly correlated with urbanization and invertebrate responses varied among metropolitan areas. The natural environmental setting determined the biological, chemical, and physical instream conditions upon which urbanization acts and dictated the differences in responses to urbanization among metropolitan areas. Threshold analysis showed little evidence for an initial period of resistance to urbanization. Instead, assemblages were degraded at very low levels of urbanization, and response rates were either similar across the gradient or higher at low levels of urbanization. Levels of impervious cover that have been suggested as protective of streams (5-10%) were associated with significant assemblage degradation and were not protective.

1. During late spring 1993-1995, the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) sampled 490 wadeable streams in the mid-Atlantic Highlands (MAH) of the U.S. for a variety of physical, chemical and biological indicators of environmental condition. We used the resulting data set to evaluate the importance of differing levels of macroinvertebrate taxonomic resolution in bioassessments by comparing the ability of family versus genus to detect differences among sites classified by type and magnitude of human impact and by stream size. We divided the MAH into two physiographic regions: the Appalachian Plateau where mine drainage (MD) and acidic deposition are major stressors, and the Ridge and Valley where nutrient enrichment is a major stressor. Stream sites were classified into three or four impact classes based on water chemistry and habitat. We used stream order (first to third Strahler order) in each region as a measure of stream size. Ordination, 2 · 2 chi-square and biotic metrics were used to compare the ability of family and genus to detect differences among both stressor and size classes. 2. With one notable exception, there were only a small number of different genera per family (interquartile range ¼ 1-4). Family Chironomidae, however, contained 123 different genera. As a result, significant information loss occurred when this group was only classified to family. The family Chironomidae did not discriminate among the predefined classes but many chironomid genera did: by chi-square analysis, 10 and 28 chironomid genera were significant in discriminating MD and nutrient impacts, respectively. 3. Family and genus data were similar in their ability to distinguish among the coarse impacts (e.g. most severe versus least severe impact classes) for all cases. Though genus data in many cases distinguished the subtler differences (e.g. mixed/moderate impacts versus high or low impacts) better than family, differences in significance levels between family and genus analyses were relatively minor. However, genus data detected differences among stream orders in ordination analyses that were not revealed at the 474 This article is the material of the U.S. Government and can be reproduced by the public at will. family level. In the ordinations, both family and genus levels of analysis responded to similar suites of environmental variables. 4. Our results suggest that identification to the family level is sufficient for many bioassessment purposes. However, identifications to genus do provide more information in genera-rich families like Chironomidae. Genus or finer levels of identification are important for investigating natural history, stream ecology, biodiversity and indicator species. Decisions about the taxonomic level of identification need to be study specific and depend on available resources (cost) and study objectives.

As part of the U.S. Geological Survey's National Water-Quality Assessment Program, fish were collected from 24 selected stream sites in the Willamette Basin during 1993-1995 to determine the composition of the fish assemblages and their relation to the chemical and physical environment. Variance in fish relative abundance was greater among all sites than among spatially distinct reaches within a site (spatial variation) or among multiple sampled years at a site (temporal variation). Therefore, data from a single reach in an individual year was considered to be a reliable estimator of the fish assemblage structure at a site when the data were normalized by percent relative abundance. Multivariate classification and ordination were used to examine patterns in environmental variables and fish relative abundance over differing spatial scales (among versus within ecoregions). Across all ecoregions (all sites), fish assemblages were primarily structured along environmental gradients of water temperature and stream gradient (coldwater, high-gradient forested sites versus warmwater, low-gradient Willamette Valley sites); this pattern superseded patterns that were ecoregion specific. Water temperature, dissolved oxygen, and physical habitat (e.g., riparian canopy and percent riffles) were associated with patterns of fish assemblages across all ecoregions; however, pesticide and total phosphorus concentrations were more important than physical habitat within the Willamette Valley ecoregion. Consideration of stream site stratification (e.g., stream size, ecoregion, and stream gradient), identification of fish to species level (particularly the sculpin family), and detailed measurement of habitat, diurnal dissolved oxygen, and water temperature were critical in evaluating the composition of fish assemblages in relation to land use. In general, these low-gradient valley streams typical of other agricultural regions had poor riparian systems and showed increases in water temperature, nutrients, and fine grain sediments that were associated with degradation in the native fish assemblages. There was an association of high abundances of introduced species and high percent external abnormalities in medium-sized river sites of mixed land use and high abundances of tolerant species in small streams of predominantly agricultural land use.

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For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprodTo order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. Tables Executive SummaryThis document describes the concept, organization, and application of a hierarchical ecosystem classification that integrates saline and tidal freshwater reaches of estuaries in order to characterize the ecosystems of large flood plain rivers that are strongly influenced by riverine and estuarine hydrology. We illustrate the classification by applying it to the Columbia River estuary (Oregon-Washington, USA), a system that extends about 233 river kilometers (rkm) inland from the Pacific Ocean. More than three-quarters of this length is tidal freshwater. The Columbia River Estuary Ecosystem Classification ("Classification") is based on six hierarchical levels, progressing from the coarsest, regional scale to the finest, localized scale: (1) Ecosystem Province; (2) Ecoregion; (3) Hydrogeomorphic Reach; (4) Ecosystem Complex; (5) Geomorphic Catena; and (6) Primary Cover Class. We define and map Levels 1-3 for the entire Columbia River estuary with existing geospatial datasets, and provide examples of Levels 4-6 for one hydrogeomorphic reach. In particular, three levels of the Classification capture the scales and categories of ecosystem structure and processes that are most tractable to estuarine research, monitoring, and management. These three levels are the (1) eight hydrogeomorphic reaches that embody the formative geologic and tectonic processes that created the existing estuarine landscape and encompass the influence of the resulting physiography on interactions between fluvial and tidal hydrology and geomorphology across 230 kilometers (km) of estuary, (2) more than 15 ecosystem complexes composed of broad landforms created predominantly by geologic processes during the Holocene, and (3) more than 25 geomorphic catenae embedded within ecosystem complexes that represent distinct geomorphic landforms, structures, ecosystems, and habitats, and components of the estuarine landscape most likely to change over short time periods. 2 IntroductionWe describe the rationale, conceptual basis, and application of a hierarchical ecosystem classification for large-river, flood-plain estuaries, and provide examples from the application of this controlling factor approach for the Columbia River estuary (Oregon-Washington, USA). A number of estuarine, delta and river-flood plain classifications based on ...

Pharmaceutical contaminants are growing aquatic-health concerns and largely attributed to wastewater treatment facility (WWTF) discharges. Five biweekly water samples from 59 small Piedmont (United States) streams were analyzed for 108 pharmaceuticals and degradates using high-performance liquid chromatography and tandem mass spectrometry. The antidiabetic metformin was detected in 89% of samples and at 97% of sites. At least one pharmaceutical was detected at every site (median of 6, maximum of 45), and several were detected at ≥10% of sites at concentrations reported to affect multiple aquatic end points. Maximal cumulative (all detected compounds) concentrations per site ranged from 17 to 16000 ng L −1 . Watershed urbanization, water table depth, soil thickness, and WWTF metrics correlated significantly with in-stream pharmaceutical contamination. Comparable pharmaceutical concentrations and detections at sites with and without permitted wastewater discharges demonstrate the importance of non-WWTF sources and the need for broad-scale mitigation. The results highlight a fundamental biochemical link between global human-health crises like diabetes and aquatic ecosystem health.