Seasonal Prevalence of Hematodinium sp. Infections of Blue Crabs in Three South Carolina (USA) Rivers     

Kirk J. Parmenter  Patrick A. Vigueira  C. Kaighn Morlok  Jennifer A. Micklewright  Kylie M. Smith  Kimberly S. Paul  Michael J. Childress 《Estuaries and Coasts》2013,36(1):174-191

Blue crab, Callinectes sapidus, commercial landings in the USA have been declining at an alarming rate. In South Carolina, these declines are significantly correlated with years of decreased rainfall and elevated salt marsh salinity. Previous studies suggest that higher salinity increases the risk of infection by Hematodinium sp., a dinoflagellate parasite of blue crabs, C. sapidus. A 4-year survey (June 2008 to March 2012) of blue crabs in the ACE Basin National Estuarine Research Reserve documented (1) the temporal and spatial patterns of Hematodinium sp. infection in relation to salinity, (2) some environmental correlates of disease prevalence, and (3) the characteristics of infected blue crabs. Sampling was conducted four times a year in March, June, September, and December in the South Edisto, Ashepoo, and Combahee rivers beginning in June 2008. Crab hemolymph samples were collected and preserved and DNA was successfully amplified for 2,303 individuals. Hematodinium sp. infection was evaluated by PCR amplification of its 18S rRNA gene and adjacent regions. Prevalence was highest in December 2008 in the Combahee River at sites closest to St. Helena Sound. The spatial and temporal pattern of Hematodinium sp. infection was correlated with several environmental parameters. Infected crabs exhibited differences in carapace shape and body condition compared to uninfected crabs. Overall, these results suggest that blue crabs in regions of higher salinity are at greater risk of infection by Hematodinium sp. and infected individuals exhibit sub-lethal effects of the disease.  相似文献   

Scouring the surface: Ejecta dynamics and the LCROSS impact event     

Brendan Hermalyn  Peter H. Schultz  Mark Shirley  Kimberly Ennico  Anthony Colaprete 《Icarus》2012,218(1):654-665

The Lunar CRater Observation and Sensing Satellite mission (LCROSS) impacted the moon in a permanently shadowed region of Cabeus crater on October 9th 2009, excavating material rich in water ice and volatiles. The thermal and spatial evolution of LCROSS ejecta is essential to interpretation of regolith properties and sources of released volatiles. The unique conditions of the impact, however, made analysis of the data based on canonical ejecta models impossible. Here we present the results of a series of impact experiments performed at the NASA Ames Vertical Gun Range designed to explore the LCROSS event using both high-speed cameras and LCROSS flight backup instruments. The LCROSS impact created a two-component ejecta plume: the usual inverted lampshade “low-angle” curtain, and a high speed, high-angle component. These separate components excavated to different depths in the regolith. Extrapolations from experiments match the visible data and the light curves in the spectrometers. The hollow geometry of the Centaur led to the formation of the high-angle plume, as was evident in the LCROSS visible and infrared measurements of the ejecta. Subsequent ballistic return of the sunlight-warmed ejecta curtain could scour the surface out to many crater radii, possibly liberating loosely bonded surface volatiles (e.g., H₂). Thermal imaging reveals a complex, heterogeneous distribution of heated material after crater formation that is present but unresolved in LCROSS data. This material could potentially serve as an additional source of energy for volatile release.  相似文献   

Alkalinity production as an indicator of failure in steel slag leach beds treating acid mine drainage   总被引：1，自引：0，他引：1  

Natalie A. Kruse  Amy L. Mackey  Jennifer R. Bowman  Kimberly Brewster  R. Guy Riefler 《Environmental Earth Sciences》2012,67(5):1389-1395

Acid mine drainage is a serious environmental problem throughout mining regions of the US and around the world. In Appalachia, reuse of steel slag from steel production as a source of alkalinity for treatment of acid mine drainage has become a common practice. In these systems, dubbed steel slag leach beds, relatively clean surface water is percolated through a bed of steel slag to add large amounts of alkalinity to the water before mixing it with acidic, metalliferous mine water. These beds do not operate consistently and their failure mechanisms are poorly understood. Using the experience of Raccoon Creek watershed in southern Ohio, the alkalinity distribution of the discharge of six steel slag leach beds is compared. Two of these beds are still functional, one has been abandoned and three are operating poorly. The difference in alkalinity distribution between these beds suggests that a carbonate-dominated alkalinity system is an indicator of a poorly performing steel slag leach bed, while a more even distribution between hydroxide, carbonate and bicarbonate may point to more ideal operating conditions. In eight laboratory column experiments, this evidence was then expanded upon by testing different mixed media substrates (differing mixes of steel slag, wood chips and river gravel) to see which provided the most ideal alkalinity distributions. The columns that had steel slag mixed either with wood chips or wood chips and river gravel outperformed the column with slag only in terms of alkalinity distribution, perhaps due to microbial processes or increased hydraulic conductivity without significant added calcium or carbon that could drive calcium carbonate precipitation within the beds and causing them to fail.  相似文献   

The Fundamental Challenge in Measuring Sprawl: Which Land Should Be Considered?*     

Harold Wolman  George Galster  Royce Hanson  Michael Ratcliffe  Kimberly Furdell  Andrea Sarzynski 《The Professional geographer》2005,57(1):94-105

Lack of agreement on how to define and measure sprawl has hampered development of policy related to its causes and consequences. We question previous work for two reasons: the use of study areas that overbound or underbound sprawl landscapes, and the failure to account for land unavailable for development. We formulate “extended urban areas,” based on housing density and commuting patterns and argue that they represent a preferable geographic basis for measuring sprawl. We operationalize with satellite imagery a way for measuring land unavailable for development in these areas. We then compute five measures of urban development using the National Land Cover Data Base and decennial census data to assess the extent of sprawl in the extended urban areas of Atlanta, Baltimore, Boston, Los Angeles, and Washington. Our sensitivity analyses reveal that the measurement of sprawl critically depends on which land area forms the basis of the analysis, and, to a lesser degree, how one accounts for land unavailable for development.  相似文献   

Ecological Signatures of Anthropogenically Altered Tidal Exchange in Estuarine Ecosystems     

Amy F. Ritter  Kerstin Wasson  Steve I. Lonhart  Rikke K. Preisler  Andrea Woolfolk  Katie A. Griffith  Sarah Connors  Kimberly W. Heiman 《Estuaries and Coasts》2008,31(3):554-571

One of the most conspicuous anthropogenic disturbances to estuaries worldwide has been the alteration of freshwater and tidal influence through the construction of water control structures (dikes, tide gates, culverts). Few studies have rigorously compared the responses of differing groups of organisms that serve as contrasting conservation targets to such anthropogenic disturbances in estuarine ecosystems. Elkhorn Slough in central California includes a spectrum of tidally restricted habitats behind water control structures and habitats experiencing full tidal exchange. To assess community composition for several different taxa in habitats with varying tidal exchange, we employed a variety of field approaches and synthesized results from several different studies. Overall, we found that communities at sites with moderately restricted tidal exchange were fairly similar to those with full tidal exchange, but those with extremely restricted tidal exchange were markedly different from other categories. These differences in community composition are likely the result of several factors, including restricted movement due to physical barriers, differences in water quality characteristics, and differences in habitat structure. Indeed, in this study, we found that water quality characteristics strongly vary with tidal restriction and may strongly influence patterns of species presence or absence. We also found that different conservation targets showed contrasting responses to variation in tidal exchange. Full exchange appears to favor native oysters, commercially valuable flatfish, migratory shorebirds, and site-level biodiversity. Minimal tidal exchange due to water control structures supports a suite of estuarine endemics (including the tidewater goby and California brackish snail) not represented elsewhere and minimizes invasions by non-native marine species. Altogether, our results suggest that total estuary-wide biodiversity may be enhanced with a mosaic of tidal exchange regimes.  相似文献   

Acoustically estimated size distribution of sperm whales (Physeter macrocephalus) off the east coast of New Zealand     

Giacomo Giorli  Kimberly T. Goetz 《新西兰海洋与淡水研究杂志》2020,54(2):177-188

ABSTRACT

The length-frequency distribution of sperm whales (Physeter macrocephalus) was studied on the east coast of NZ using passive acoustic recorders moored offshore of Kaikoura, Cape Palliser and Castlepoint. Sperm whale’s echolocation signals are unique among odontocete species. Their clicks are composed by multiple pulses resulting from the sound transmission within the whale head. The total length of the whales can be estimated by measuring the time delay between these pulses. A total of 997 length measurements were obtained from click trains using cepstral analysis (mean?=?14.6?m; min?=?9.6?m; max?=?18.3?m; std?=?1?m). The size-frequency distributions at all three locations were similar, although animals smaller than 12?m were not present offshore of Kaikoura. Animals of various sizes appeared to be present all year round, with no apparent seasonality in the occurrence of any size class.  相似文献   

Virus and Bacteria Transport in a Sandy Aquifer, Cape Cod, MA   总被引：5，自引：0，他引：5  

Roger C. Bales  Shimin Li  Kimberly M. Maguire  Moyasar T. Yahya  Charles P. Gerba  Ronald W. Harvey 《Ground water》1995,33(4):653-661

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Application of a partial least-squares regression model to retrieve chlorophyll-<Emphasis Type="Italic">a</Emphasis> concentrations in coastal waters using hyper-spectral data     

Kimberly Ryan  Khalid Ali 《Ocean Science Journal》2016,51(2):209-221

Coastal and inland waters represent a diverse set of resources that support natural habitats and provide valuable ecosystem services to the human population. Monitoring the quality of these waters is essential to maintaining the resources they provide, and long-term monitoring may offer a better understanding of the relationship between human development and the health of these resource producers. The implementation of conventional monitoring is typically time-intensive and limited in geographic scale. Alternatively, the use of airborne and spaceborne remote sensors provides a synoptic view of water quality with better spatial coverage to more accurately identify dynamic and unique parameters. Concentrations of optically active constituents (OACs) such as suspended sediments and the phytoplankton pigment chlorophylla (CHLa), act as proxies for water quality and can be detected by optical sensors. Traditional remote sensing techniques were developed using multispectral sensors, and employ band ratio algorithms that seek to predict the concentrations of OACs in relation to water quality. In complex coastal waters, overlapping spectral signatures of OACs often confound these algorithms and reduce their predictive capacity. The objective of this study was to develop a dataset to test the predictive capabilities of partial least-squares regression, a multivariate statistical method, for hyperspectral remote sensing and in situ CHLa concentrations. This paper presents the model performance for a dataset developed in Long Bay, a ~160 km arcuate bay that spans the border between North and South Carolina. The model uses multivariate-based statistical modeling to capitalize on the spectral advantage gained by hyperspectral sensors when observing such waters. Following this approach, a multivariate-based monitoring tool for the prediction of CHLa concentrations is presented with a partial least-squares regression (PLSR) method using hyperspectral and laboratory-analyzed field data. The PLSR model was used based on its ability to identify wavelengths that are more sensitive to CHLa relative to other OACs. The model was able to explain 80% of the observed CHLa variability in Long Bay with root mean square error (RMSE) = 2.03 µg/L. This enhanced mode of water quality monitoring has potential to deliver insights to point-sources and problem areas that may contribute to a decline in the water quality of valuable inland and coastal systems.  相似文献   

Comparative Study of Biosorption of Copper(II) by Lipid Extracted and Non‐Extracted Chlorella sorokiniana          下载免费PDF全文

Lisa A. Jones  Kimberly L. Ogden  Fei Jia 《洁净——土壤、空气、水》2015,43(1):73-78

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Geochemistry and hydrology of perched groundwater springs: assessing elevated uranium concentrations at Pigeon Spring relative to nearby Pigeon Mine,Arizona (USA)     

Kimberly R. Beisner  Nicholas V. Paretti  Fred D. Tillman  David L. Naftz  Donald J. Bills  Katie Walton-Day  Tanya J. Gallegos 《Hydrogeology Journal》2017,25(2):539-556

The processes that affect water chemistry as the water flows from recharge areas through breccia-pipe uranium deposits in the Grand Canyon region of the southwestern United States are not well understood. Pigeon Spring had elevated uranium in 1982 (44 μg/L), compared to other perched springs (2.7–18 μg/L), prior to mining operations at the nearby Pigeon Mine. Perched groundwater springs in an area around the Pigeon Mine were sampled between 2009 and 2015 and compared with material from the Pigeon Mine to better understand the geochemistry and hydrology of the area. Two general groups of perched groundwater springs were identified from this study; one group is characterized by calcium sulfate type water, low uranium activity ratio ²³⁴U/²³⁸U (UAR) values, and a mixture of water with some component of modern water, and the other group by calcium-magnesium sulfate type water, higher UAR values, and radiocarbon ages indicating recharge on the order of several thousand years ago. Multivariate statistical principal components analysis of Pigeon Mine and spring samples indicate Cu, Pb, As, Mn, and Cd concentrations distinguished mining-related leachates from perched groundwater springs. The groundwater potentiometric surface indicates that perched groundwater at Pigeon Mine would likely flow toward the northwest away from Pigeon Spring. The geochemical analysis of the water, sediment and rock samples collected from the Snake Gulch area indicate that the elevated uranium at Pigeon Spring is likely related to a natural source of uranium upgradient from the spring and not likely related to the Pigeon Mine.  相似文献