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At least 1,153 records · Page 64Linked to original sources
USGS2010

Influence of drought conditions on brown trout biomass and size structure in the Black Hills, South Dakota

We evaluated the influence of drought conditions on the biomass of brown trout Salmo trutta in Spearfish Creek, upper Rapid Creek, and lower Rapid Creek in the Black Hills of western South Dakota. Stream discharge, mean summer water temperature, the biomass of juvenile and adult brown trout, and brown trout size structure were compared between two time periods: early (2000–2002) and late drought (2005–2007). Mean summer water temperatures were similar between the early- and late-drought periods in Spearfish Creek (12.4°C versus 11.5°C), lower Rapid Creek (19.2°C versus 19.3°C), and upper Rapid Creek (9.8°C in both periods). In contrast, mean annual discharge differed significantly between the two time periods in Spearfish Creek (1.95 versus 1.50 m 3 /s), lower Rapid Creek (2.01 versus 0.94 m 3 /s), and upper Rapid Creek (1.41 versus 0.84 m 3 /s). The mean biomass of adult brown trout in all three stream sections was significantly higher in the early-drought than in the late-drought period (238 versus 69 kg/ha in Spearfish Creek, 272 versus 91 kg/ha in lower Rapid Creek, and 159 versus 32 kg/ha in upper Rapid Creek). The biomass of juvenile brown trout was similar (43 versus 23 kg/ha) in Spearfish Creek in the two periods, declined from 136 to 45 kg/ha in lower Rapid Creek, and increased from 14 to 73 kg/ha in upper Rapid Creek. Size structure did not differ between the early- and late-drought periods in lower Rapid and Spearfish creeks, but it did in upper Rapid Creek. In addition to drought conditions, factors such as angler harvest, fish movements, and the nuisance algal species Didymosphenia geminata are discussed as possible contributors to the observed changes in brown trout biomass and size structure in Black Hills streams.

South Dakota↗
USGS2010

A digital underwater video camera system for aquatic research in regulated rivers

We designed a digital underwater video camera system to monitor nesting centrarchid behavior in the Tallapoosa River, Alabama, 20 km below a peaking hydropower dam with a highly variable flow regime. Major components of the system included a digital video recorder, multiple underwater cameras, and specially fabricated substrate stakes. The innovative design of the substrate stakes allowed us to effectively observe nesting redbreast sunfish Lepomis auritus in a highly regulated river. Substrate stakes, which were constructed for the specific substratum complex (i.e., sand, gravel, and cobble) identified at our study site, were able to withstand a discharge level of approximately 300 m 3 /s and allowed us to simultaneously record 10 active nests before and during water releases from the dam. We believe our technique will be valuable for other researchers that work in regulated rivers to quantify behavior of aquatic fauna in response to a discharge disturbance.

Alabama↗
USGS2006

Comparison of methods used to diagnose generalized inflammatory disease in manatees (Trichechus manatus latirostris)

Manatees ( Trichechus manatus latirostris ) are afflicted with inflammatory and infectious disease secondary to human interaction, such as boat strike and entanglement, as well as &ldquo;cold stress syndrome&rdquo; and pneumonia. White-blood-cell count and fever, primary indicators of systemic inflammation in most species, are insensitive in diagnosing inflammatory disease in manatees. Acute phase-response proteins, such as haptoglobin and serum amyloid A, have proven to be sensitive measures of inflammation/infection in domestic large animal species. This study assessed diagnosis of generalized inflammatory disease by different methods including total white-blood-cell count, albumin: globulin ratio, gel electrophoresis analysis, C-reactive protein, alpha 1 acid glycoprotein, haptoglobin, fibrinogen, and serum amyloid A. Samples were collected from 71 apparently healthy and 27 diseased animals during diagnostic medical examination. Serum amyloid A, measured by ELISA, followed by albumin:globulin ratio, measured by plasma gel electrophoresis, were most sensitive in diagnosing inflammatory disease, with diagnostic sensitivity and specificity of approximately 90%. The reference interval for serum amyloid A is <10&ndash;50 &mu;g/ml with an equivocal interval of 51&ndash;70 &mu;g/ml. The reference interval for albumin:globulin ratio by plasma gel electrophoresis is 0.7&ndash;1.1. Albumin: globulin ratio, calculated using biochemical techniques, was not accurate due to overestimation of albumin by bromcresol green dye-binding methodology. Albumin:globulin ratio, measured by serum gel electrophoresis, has a low sensitivity of 15% due to the lack of fibrinogen in the sample. Haptoglobin, measured by hemoglobin titration, had a reference interval of 0.4&ndash;2.4 mg/ml, a diagnostic sensitivity of 60%, and a diagnostic specificity of 93%. The haptoglobin assay is significantly affected by hemolysis. Fibrinogen, measured by heat precipitation, has a reference interval of 100&ndash;400 mg/dl, a diagnostic sensitivity of 40%, and a diagnostic specificity of 95%.

Journal of Zoo and Wildlife Medicine↗
USGS2008

Variability in triactinomyxon production from Tubifex tubifex populations from the same mitochondrial DNA lineage infected with Myxobolus cerebralis, the causative agent of whirling disease in salmonids

Myxobolus cerebralis, the causative agent of whirling disease, infects both salmonid fish and an aquatic oligochaete, Tubifex tubifex. Although M. cerebralis has been detected in river drainages throughout the United States, disease severity among wild fish populations has been highly variable. Tubifex tubifex populations have been genetically characterized using sequences from the 16S mitochondrial DNA (mtDNA) gene, the 18S ribosomal RNA gene, the internal transcribed spacer region 1 (ITS1), and randomly amplified polymorphic DNA (RAPD). Our earlier work indicated that large differences in compatibility between the parasite and populations of T. tubifex may play a substantial role in the distribution of whirling disease and resulting mortality in different watersheds. In the present study, we examined 4 laboratory populations of T. tubifex belonging to 16S mtDNA lineage III and 1 population belonging to 16S mtDNA lineage I for triactinomyxon (TAM) production after infection with M. cerebralis myxospores. All 4 16S mtDNA lineage III populations produced TAMs, but statistically significant differences in TAM production were observed. Most individuals in the 16S mtDNA lineage III-infected populations produced TAMs. The 16S mtDNA lineage I population produced few TAMs. Further genetic characterization of the 16S mtDNA lineage III populations with RAPD markers indicated that populations producing similar levels of TAMs had more genetic similarity. ?? American Society of Parasitologists 2008.

Journal of Parasitology↗
USGS2005

A new Sunwaptan (Late Cambrian) trilobite fauna from the Upper Mississippi Valley

A single bed at the base of the Jordan Sandstone in a road cut at Arcadia, Wisconsin, yielded an undescribed Late Sunwaptan (Saukia Zone) trilobite fauna that includes at least four species from the families Dikelocephalidae Miller, 1889 and Eurekiidae Hupe??, 1953. Arcadiaspis bispinata n. gen. and sp. is a distinctive eurekiid that is characterized by paired occipital and thoracic axial spines, long genal spines, and a nonspinose pygidial margin. Other genera present are the dikelocephalids, Dikelocephalus Owen, 1852 and Calvinella Walcott, 1914, and the eurekiid, Eurekia Walcott, 1916. Type material of Calvinella spiniger (Hall, 1863) is illustrated photographically for the first time. A new eurekiid species, Corbinia burkhalteri from the Fort Sill Formation, Oklahoma, is also described.

Journal of Paleontology↗
USGS2002

An evaluation of population index and estimation techniques for tadpoles in desert pools

Using visual (VI) and dip net indices (DI) and double-observer (DOE), removal (RE), and neutral red dye capture-recapture (CRE) estimates, we counted, estimated, and censused Couch's spadefoot ( Scaphiopus couchii ) and canyon treefrog ( Hyla arenicolor ) tadpole populations in Big Bend National Park, Texas. Initial dye experiments helped us determine appropriate dye concentrations and exposure times to use in mesocosm and field trials. The mesocosm study revealed higher tadpole detection rates, more accurate population estimates, and lower coefficients of variation among pools compared to those from the field study. In both mesocosm and field studies, CRE was the best method for estimating tadpole populations, followed by DOE and RE. In the field, RE, DI, and VI often underestimated populations in pools with higher tadpole numbers. DI improved with increased sampling. Larger pools supported larger tadpole populations, and tadpole detection rates in general decreased with increasing pool volume and surface area. Hence, pool size influenced bias in tadpole sampling. Across all techniques, tadpole detection rates differed among pools, indicating that sampling bias was inherent and techniques did not consistently sample the same proportion of tadpoles in each pool. Estimating bias (i.e., calculating detection rates) therefore was essential in assessing tadpole abundance. Unlike VI and DOE, DI, RE, and CRE could be used in turbid waters in which tadpoles are not visible. The tadpole population estimates we used accommodated differences in detection probabilities in simple desert pool environments but may not work in more complex habitats.

Journal of Herpetology↗
USGS2012

Body condition of Morelet’s Crocodiles ( Crocodylus moreletii ) from northern Belize

Body condition factors have been used as an indicator of health and well-being of crocodilians. We evaluated body condition of Morelet's Crocodiles ( Crocodylus moreletii ) in northern Belize in relation to biotic (size, sex, and habitat) and abiotic (location, water level, and air temperature) factors. We also tested the hypothesis that high water levels and warm temperatures combine or interact to result in a decrease in body condition. Size class, temperature, and water level explained 20% of the variability in condition of Morelet's Crocodiles in this study. We found that adult crocodiles had higher condition scores than juveniles/subadults but that sex, habitat, and site had no effect. We confirmed our hypothesis that warm temperatures and high water levels interact to decrease body condition. We related body condition of Morelet's Crocodiles to natural fluctuations in air temperatures and water levels in northern Belize, providing baseline conditions for population and ecosystem monitoring.

Journal of Herpetology↗
USGS2013

Potential effects of sea-level rise on coastal wetlands in southeastern Louisiana

Coastal Louisiana wetlands contain about 37% of the estuarine herbaceous marshes in the conterminous United States. The long-term stability of coastal wetlands is often a function of a wetland's ability to maintain elevation equilibrium with mean sea level through processes such as primary production and sediment accretion. However, Louisiana has sustained more coastal wetland loss than all other states in the continental United States combined due to a combination of natural and anthropogenic factors, including sea-level rise. This study investigates the potential impact of current and accelerating sea-level rise rates on key coastal wetland habitats in southeastern Louisiana using the Sea Level Affecting Marshes Model (SLAMM). Model calibration was conducted using a 1956–2007 observation period and hindcasting results predicted 35% versus observed 39% total marsh loss. Multiple sea-level-rise scenarios were then simulated for the period of 2007–2100. Results indicate a range of potential wetland losses by 2100, from an additional 2,188.97 km 2 (218,897 ha, 9% of the 2007 wetland area) under the lowest sea-level-rise scenario (0.34 m), to a potential loss of 5,875.27 km 2 (587,527 ha, 24% of the 2007 wetland area) in the highest sea-level-rise scenario (1.9 m). Model results suggest that one area of particular concern is the potential vulnerability of the region's baldcypress-water tupelo ( Taxodium distichum-Nyssa aquatica ) swamp habitat, much of which is projected to become permanently flooded (affecting regeneration) under all modeled scenarios for sea-level rise. These findings will aid in the development of ecosystem management plans that support the processes and conditions that result in sustainable coastal ecosystems.

Louisiana↗
USGS2013

Marsh collapse thresholds for coastal Louisiana estimated using elevation and vegetation index data

Forecasting marsh collapse in coastal Louisiana as a result of changes in sea-level rise, subsidence, and accretion deficits necessitates an understanding of thresholds beyond which inundation stress impedes marsh survival. The variability in thresholds at which different marsh types cease to occur (i.e., marsh collapse) is not well understood. We utilized remotely sensed imagery, field data, and elevation data to help gain insight into the relationships between vegetation health and inundation. A Normalized Difference Vegetation Index (NDVI) dataset was calculated using remotely sensed data at peak biomass (August) and used as a proxy for vegetation health and productivity. Statistics were calculated for NDVI values by marsh type for intermediate, brackish, and saline marsh in coastal Louisiana. Marsh-type specific NDVI values of 1.5 and 2 standard deviations below the mean were used as upper and lower limits to identify conditions indicative of collapse. As marshes seldom occur beyond these values, they are believed to represent a range within which marsh collapse is likely to occur. Inundation depth was selected as the primary candidate for evaluation of marsh collapse thresholds. Elevation relative to mean water level (MWL) was calculated by subtracting MWL from an elevation dataset compiled from multiple data types including light detection and ranging (lidar) and bathymetry. A polynomial cubic regression was used to examine a random subset of pixels to determine the relationship between elevation (relative to MWL) and NDVI. The marsh collapse uncertainty range values were found by locating the intercept of the regression line with the 1.5 and 2 standard deviations below the mean NDVI value for each marsh type. Results indicate marsh collapse uncertainty ranges of 30.7–35.8 cm below MWL for intermediate marsh, 20–25.6 cm below MWL for brackish marsh, and 16.9–23.5 cm below MWL for saline marsh. These values are thought to represent the ranges of inundation depths within which marsh collapse is probable.

Louisiana↗
USGS1994

Adsorption and desorption of atrazine and deethylatrazine by low organic carbon geologic materials

The adsorption and desorption of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) and a primary metabolite, deethylatrazine (2-amino-4-chloro-6-isopropylamino-s-triazine; DEA), by low organic C (≤ 3.3 g kg −1 ) materials were measured by batch-equilibrium techniques. The adsorbents were samples of glacial outwash sand, till, and stream sediments. The adsorption of both atrazine and DEA conformed to linear isotherms. The adsorption of atrazine by most of the adsorbents yielded apparent K oc values that were in excess of those based on surface agricultural soils. Adsorption correlated with only the pH of the sand-water suspensions. The desorption of atrazine was hysteretic under the conditions of the measurement. DEA had a lower affinity for the same adsorbents; the mean ratio of K d values of DEA to those of atrazine was 0.37 ± 0.20. DEA adsorption did not correlate with organic C, surface area, clay content of the adsorbents, or with the pH of the suspensions. DEA adsorption, unlike atrazine, tended to be reversible. There was a linear relationship between the adsorption constants of atrazine and those of DEA.

Journal of Environmental Quality↗
USGS2007

Improving the accuracy of sediment-associated constituent concentrations in whole storm water samples by wet-sieving

Sand-sized particles (>63 ??m) in whole storm water samples collected from urban runoff have the potential to produce data with substantial bias and/or poor precision both during sample splitting and laboratory analysis. New techniques were evaluated in an effort to overcome some of the limitations associated with sample splitting and analyzing whole storm water samples containing sand-sized particles. Wet-sieving separates sand-sized particles from a whole storm water sample. Once separated, both the sieved solids and the remaining aqueous (water suspension of particles less than 63 ??m) samples were analyzed for total recoverable metals using a modification of USEPA Method 200.7. The modified version digests the entire sample, rather than an aliquot, of the sample. Using a total recoverable acid digestion on the entire contents of the sieved solid and aqueous samples improved the accuracy of the derived sediment-associated constituent concentrations. Concentration values of sieved solid and aqueous samples can later be summed to determine an event mean concentration. ?? ASA, CSSA, SSSA.

Journal of Environmental Quality↗
USGS2010

The green alga, Cladophora, promotes Escherichia coli growth and contamination of recreational waters in Lake Michigan

A linkage between Cladophora mats and exceedances of recreational water quality criteria has been suggested, but not directly studied. Th is study investigates the spatial and temporal association between Escherichia coli concentrations within and near Cladophora mats at two northwestern Lake Michigan beaches in Door County, Wisconsin. Escherichia coli concentrations in water underlying mats were significantly greater than surrounding water (p < 0.001). Below mat E. coli increased as the stranded mats persisted at the beach swash zone. Water adjacent to Cladophora mats had lower E. coli concentrations, but surpassed EPA swimming criteria the majority of sampling days. A signifi cant positive association was found between E. coli concentrations attached to Cladophora and in underlying water (p < 0.001). The attached E. coli likely acted as a reservoir for populating water underlying the mat. Fecal bacterial pathogens, however, could not be detected by microbiological culture methods either attached to mat biomass or in underlying water. Removal of Cladophora mats from beach areas may improve aesthetic and microbial water quality at affected beaches. These associations and potential natural growth of E. coli in bathing waters call into question the efficacy of using E. coli as a recreational water quality indicator of fecal contaminations. Copyright ?? 2010 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Journal of Environmental Quality↗
USGS2002

Kilometer-scale rapid transport of naphthalene sulfonate tracer in the unsaturated zone at the Idaho National Engineering and Environmental Laboratory

To investigate possible long-range flow paths through the interbedded basalts and sediments of a 200-m-thick unsaturated zone, we applied a chemical tracer to seasonally filled infiltration ponds on the Snake River Plain in Idaho. This site is near the Subsurface Disposal Area for radioactive and other hazardous waste at the Idaho National Engineering and Environmental Laboratory. Within 4 mo, we detected tracer in one of 13 sampled aquifer wells, and in eight of 11 sampled perched-water wells as far as 1.3 km away. These detections show that (i) low-permeability layers in the unsaturated zone divert some flow horizontally, but do not prevent rapid transport to the aquifer; (ii) horizontal convective transport rates within the unsaturated zone may exceed 14 m d −1 , perhaps through essentially saturated basalt fractures, tension cracks, lava tubes, or rubble zones; and (iii) some perched water beneath the Subsurface Disposal Area derives from episodic surface water more than 1 km away. Such rapid and far-reaching flow may be common throughout the Snake River Plain, and possibly occurs in other locations that have a geologically complex unsaturated zone and comparable sources of infiltrating water.

Idaho↗
USGS2007

Research activities at U.S. Government agencies in subsurface reactive transport modeling

The fate of contaminants in the environment is controlled by both chemical reactions and transport phenomena in the subsurface. Our ability to understand the significance of these processes over time requires an accurate conceptual model that incorporates the various mechanisms of coupled chemical and physical processes. Adsorption, desorption, ion exchange, precipitation, dissolution, growth, solid solution, redox, microbial activity, and other processes are often incorporated into reactive transport models for the prediction of contaminant fate and transport. U.S. federal agencies use such models to evaluate contaminant transport and provide guidance to decision makers and regulators for treatment issues. We provide summaries of selected research projects and programs to demonstrate the level of activity in various applications and to present examples of recent advances in subsurface reactive transport modeling.

Vadose Zone Journal↗
USGS2010

Response to Germann's "Comment on 'theory for source-responsive and free-surface film modeling of unsaturated flow'"

Germann's (2010) comment helpfully presents supporting evidence that I have missed, notes items that need clarification or correction, and stimulates discussion of what is needed for improved theory of unsaturated flow. Several points from this comment relate not only to specific features of the content of my paper (Nimmo, 2010), but also to the broader question of what methodology is appropriate for developing an applied earth science. Accordingly, before addressing specific points that Germann identified, I present here some considerations of purpose and background relevant to evaluation of the unsaturated flow model of Nimmo (2010).

Vadose Zone Journal↗
USGS2012

Response to "Comments on 'Theory for source-responsive and free-surface film modeling of unsaturated flow'"

I am grateful to Masciopinto (2012) for raising several issues from my study (Nimmo, 2010) that deserve elaboration or clarification. In this reply, I address these in what I judge to be the order of importance, the main ones being (i) the discrepancy of scales between the two domains that treat preferential and diffuse unsaturated flow, and (ii) the properties that must be evaluated to characterize the medium.

Vadose Zone Journal↗
USGS2016

Quantitative framework for preferential flow initiation and partitioning

A model for preferential flow in macropores is based on the short-range spatial distribution of soil matrix infiltrability. It uses elementary areas at two different scales. One is the traditional representative elementary area (REA), which includes a sufficient heterogeneity to typify larger areas, as for measuring field-scale infiltrability. The other, called an elementary matrix area (EMA), is smaller, but large enough to represent the local infiltrability of soil matrix material, between macropores. When water is applied to the land surface, each EMA absorbs water up to the rate of its matrix infiltrability. Excess water flows into a macropore, becoming preferential flow. The land surface then can be represented by a mesoscale (EMA-scale) distribution of matrix infiltrabilities. Total preferential flow at a given depth is the sum of contributions from all EMAs. Applying the model, one case study with multi-year field measurements of both preferential and diffuse fluxes at a specific depth was used to obtain parameter values by inverse calculation. The results quantify the preferential&ndash;diffuse partition of flow from individual storms that differed in rainfall amount, intensity, antecedent soil water, and other factors. Another case study provided measured values of matrix infiltrability to estimate parameter values for comparison and illustrative predictions. These examples give a self-consistent picture from the combination of parameter values, directions of sensitivities, and magnitudes of differences caused by different variables. One major practical use of this model is to calculate the dependence of preferential flow on climate-related factors, such as varying soil wetness and rainfall intensity.

Vadose Zone Journal↗