Virginia journal of science最新文献

{"title":"Breeding birds of Virginia","authors":"B. Watts","doi":"10.25778/31DC-JZ42","DOIUrl":"https://doi.org/10.25778/31DC-JZ42","url":null,"abstract":"Virginia supports a diverse community of breeding birds that has been the focus of investigation for more than 400 years. The avifauna reflects the latitudinal position of the state and the fact that the border extends from the Atlantic Ocean to the Appalachian Mountains. A total of 224 species have been recorded breeding in Virginia, 214 of which are extant. Twenty species have colonized the state since 1900 including 14 since 1950. Of all extant species, 102 (48%) are considered common at least somewhere in the state and 64 (30%) are rare to very rare. Diversity varies by physiographic region with 179 (83%), 168 (78%) and 141 (66%) in the Coastal Plain, Mountains and Piedmont, respectively. Two significant landscape features make significant contributions to the state-wide diversity including tidal waters along the coast and isolated spruce-fir forests of the Appalachians that represent Pleistocene-era relicts. In all, nearly 25% of the state-wide avifauna is either wholly or nearly confined to tidal water and 10% is confined to “sky island” refugia. Since 1978, 25 species of birds throughout Virginia have been identified as requiring immediate conservation action. A retrospective assessment shows that 5 of these species including osprey (Pandion haliaetus), bald eagle (Haliaeetus leucocephalus), peregrine falcon (Falco peregrinus), brown pelican (Pelecanus occidentalis) and piping plover (Charadrius melodus) have recovered to or beyond historic numbers. Three species including Bewick’s wren (Thryomanes bewickii), Bachman’s sparrow (Peucaea aestivalis) and upland sandpiper (Bartramia longicauda) have been lost from the state and the black rail (Laterallus jamaicensis), loggerhead shrike (Lanius ludovicianus) and Henslow’s sparrow (Ammodramus henslowii ) are in imminent danger of extirpation. Several species including the peregrine falcon, piping plover, Wilson’s plover (Charadrius wilsonia) and red-cockaded woodpecker (Picoides borealis) are the focus of intensive monitoring and management programs. The underlying causes of imperilment remain unclear for several species of concern, limiting our ability to development effective conservation strategies. 1 Corresponding author: bdwatts@wm.edu Virginia Journal of Science, Vol. 66, No. 3, 2015 http://digitalcommons.odu.edu/vjs/vol66/iss3 224 VIRGINIA JOURNAL OF SCIENCE INTRODUCTION The ornithological record in Virginia stretches back more than four centuries. From the time of settlement at Jamestown in 1607, residents of Virginia and visitors to the state reported on the birds they encountered or were told about by Native Americans. William Strachey who lived in the settlement from 1610 to 1612 remarked at length on the birds he observed (Strachey 1849). Contemporaries including Captain John Smith, Raphe Hamor, and Edward Topsell describe many species including the waterfowl on the Chesapeake Bay, cardinals, mockingbirds and ruby-throated hummingbirds (Smith 1612, Hamor 1615, Christy 1933). Later in","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84630301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Survey of the Ectoparasites of the Invasive Small Indian Mongoose (Herpestes auropunctatus [Carnivora: Herpestidae]) on St. John, U.S. Virgin Islands","authors":"Kelsey L. Townsend, Karen E. Powers","doi":"10.25778/EPA3-MP85","DOIUrl":"https://doi.org/10.25778/EPA3-MP85","url":null,"abstract":"In March 2012, live trapping surveys were conducted for invasive small Indian mongoose (Herpestes auropunctatus) on St. John, U.S. Virgin Islands. Forty mongoose were sampled (31%, 9&) for ectoparasites, and cat fleas (Ctenocephalides felis) were discovered on 17 individuals. There was no difference in the number of ectoparasites per mongoose across age classifications (r = 0.109, P = 0.579). However, males had more cat fleas than females, even when mass was taken into account (males are generally heavier). Future behavioral studies may explain these sex differences. Although management suggestions from this research are limited, these data contribute to an understanding of ectoparasite distributions on these invasive mongoose in the Caribbean. INTRODUCTION The small Indian mongoose (Herpestes auropunctatus) is a 120-1000-gram carnivore, feeding opportunistically on all major vertebrate groups, invertebrates, and occasionally, plants (Lewis et al. 2011). Although uncertainty exists about the extent of its geographic range, this mongoose is believed to be native to the Middle East, India, and Myanmar (Veron et al. 2007). The uncertainty lies in its confusion with a sympatric mongoose, the Javan or small Asian mongoose (H. javanicus), for which H. auropunctatus had been treated as a conspecific. Indeed, nearly all literature published prior to 2007 assumed that the mongoose released onto Hawaiian and Caribbean islands was H. javanicus. However, Veron et al. (2007) confirmed with mtDNA analyses that H. auropunctatus and H. javanicus were two distinct species, and Bennett et al. (2011), definitively determined through mtDNA barcoding that mongoose currently inhabiting Hawaiian and Caribbean islands were H. auropunctatus. Current address: Dept. of Environmental Studies, Univ. of Illinois at Springfield, 1 Springfield, IL 62703 Corresponding author:kpowers4@radford.edu 2 Virginia Journal of Science, Vol. 65, No. 3, 2014 http://digitalcommons.odu.edu/vjs/vol65/iss3 152 VIRGINIA JOURNAL OF SCIENCE The small Indian mongoose was originally introduced in the late 1800s (likely the 1870s) to control the invasive black rat (Rattus rattus) population on St. John, St. Croix, and other nearby Caribbean islands (Nellis and Everard 1983; Horst et al. 2001). The primary diet of mongoose in this region is not the black rat but instead includes native species on the U.S. Virgin Islands (USVI) such as eggs of the brown pelican (Pelicanus occidentalis) and the green sea turtle (Chelonia mydas; Seaman and Randall 1962), and, more commonly, lizards, amphibians, ground-nesting birds, and invertebrates (Nellis 1989; Lewis et al. 2011). Besides hawks (on some islands), the small Indian mongoose has no other natural predators in the USVI, and wildlife managers lack the time, effort, and funds to eradicate the species from the islands (Nellis and Everard 1983). However, as a method of managing for rare breeding birds or reptiles, localized, seasonal removal efforts can be fai","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86559287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phytoplankton in Virginia Lakes and Reservoirs: Part II","authors":"H. Marshall","doi":"10.25778/FQ7V-MT85","DOIUrl":"https://doi.org/10.25778/FQ7V-MT85","url":null,"abstract":"Phytoplankton composition from 16 Virginia lakes and reservoirs are discussed with emphasis on the dominant taxa, algal bloom producers, and potentially harmful species at these locations. This is a companion study to the more comprehensive publication regarding Virginia freshwater phytoplankton by Marshall (2013).","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89599974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Comparison of Techniques Measuring Stress in Birds","authors":"D. A. O'Dell, Michael A Carlo, A. Kimmitt, Ellen Bikowski, K. Morris, Andrew S. Dolby","doi":"10.25778/5H4Z-5938","DOIUrl":"https://doi.org/10.25778/5H4Z-5938","url":null,"abstract":"Free-living birds are subjected to both external and internal stresses which can affect their health, activity, and reproductive success. To study stress in free living birds, they must be captured in nets and handled by the researcher to take blood samples for commonly used measures of stress, an activity which itself can induce stress and confound results. This study compares the effects of handling time on three different measures of stress: levels of the stress hormone corticosterone (CORT), levels of Heat Shock Protein 60 (HSP 60) and the ratio of heterophils to lymphocytes (H/L ratio) in tufted titmouse (Baeolophus bicolor) captured at feeders between December and January (2011-2013) in Fredericksburg, VA. Blood samples collected between two and 15 minutes from 12 birds were assayed for levels of CORT and HSP and from 24 birds for H/L ratios. Relationships were examined between these stress indicators and handling time, body mass and body condition. CORT was significantly correlated with handling time (p<0.01), which reinforces existing evidence of CORT’s sensitivity to the way subjects are handled immediately prior to blood collection. HSP or H/L ratios were not affected by handling time, suggesting that they may be preferable indicators of stress in free living birds under some circumstances. INTRODUCTION Free-living birds face a variety of internal and external sources of stress, which may affect physiological function and reduce fitness. Acute stress results from a specific stressful event, such as an attack by a predator or sudden storms, whereas chronic stress results from prolonged exposure to biologically challenging conditions, such as exposure to extreme temperatures (Vleck et al. 2000), periods of limited food availability (Herring et al. 2011), and anthropogenic pressures such as pollution, habitat disturbance (Arriero et al. 2008; Busch and Hayward 2009), and from prolonged psychosocial stressors (Cyr et al. 2007; Cyr and Romano 2007; Landys et al. 2011). To Corresponding author: dodell@umw.edu 1 Virginia Journal of Science, Vol. 65, No. 3, 2014 http://digitalcommons.odu.edu/vjs/vol65/iss3 134 VIRGINIA JOURNAL OF SCIENCE cope with such stressors, birds and other animals have a protective physiological stress response that allows them to withstand immediate threats to their homeostatic balance. When this response is elevated chronically, however, it can become biologically costly and have negative impacts on birds’ fitness by weakening the immune system (Dabbert et al. 1997), which could increase susceptibility to disease, and compromising growth and reproduction (Sapolsky et al. 2000). Thus, stress levels can indicate the general physiological condition of birds and point to possible environmental perturbations. Biomarkers such as the glucocorticoid corticosterone (CORT), heterophil/lymphocyte ratios (H/L), and heat shock proteins (HSPs) have all been used as tools to assess chronic or long-term stress in wild populations. Thes","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73160085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phytoplankton in Virginia Lakes and Reservoirs","authors":"H. Marshall","doi":"10.25778/F2RH-ZD44","DOIUrl":"https://doi.org/10.25778/F2RH-ZD44","url":null,"abstract":"This study involves a phytoplankton summer/autumn survey in 46 Virginia lakes and reservoirs during 2010-2012. A total of 307 taxa were identified which included several filamentous and colonial cyanabacteria in bloom concentrations. With the exception of one natural lake, the other sites sampled represent impoundments created decades ago, with the majority presently classified as mesoor eutrophic. Among the cyanobacteria were 6 known toxin producers (Anabaena circinalis, Anabaena spiroides, Aphanizomenon flos-aquae, Cylindrospermopsis raciborskii, Limnothrix redekei, and Microcystis aeruginosa). The study characterizes phytoplankton populations in these aging freshwater habitats taken from a large number of sites over a broad geographical extent in Virginia. The results portend future concerns for increased presence of less favorable algal populations in Virginia lakes and reservoirs, including an increased occurrence of algal blooms, and presence of potential harmful species.","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88575170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First Record of Pond Sliders (Trachemys scripta scripta and T. s. elegans) at Fredericksburg, Virginia with Observations on Population Size, Age and Growth","authors":"Werner Wieland, Yoshinori Takeda","doi":"10.25778/33P9-MA73","DOIUrl":"https://doi.org/10.25778/33P9-MA73","url":null,"abstract":"We conducted a turtle mark-recapture program within a 160 m stretch of the Fredericksburg Canal with standard, baited hoop nets from May to July 2012 to determine if a population of the introduced Red-eared Slider (Trachemys scripta elegans) and Yellow-bellied Slider (Trachemys s. scripta) are established in this area. We captured and marked nine Red-eared Sliders (1 male, 8 females) and estimated a population size of 23 individuals. Most were reproductively mature. The established population in the canal may be a source of introduction into the Rappahannock River.","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77347156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Population Dynamics of Two Rodents in Two Coastal Marshes in Virginia","authors":"R. K. Rose, J. March","doi":"10.25778/QSQ8-ED95","DOIUrl":"https://doi.org/10.25778/QSQ8-ED95","url":null,"abstract":"The communities of small mammals were evaluated for 13 months with capture-mark-recapture methods in two Spartina-Juncus marshes of the Atlantic coast in Northampton County, Virginia. Small mammals were trapped for three days each month using live traps placed on floats on two study grids. Two rodents were numerically dominant (~90% of small mammals) there: marsh rice rat, Oryzomys palustris, and meadow vole, Microtus pennsylvanicus. Monthly estimates of population density were greater for rice rats (peak: 45/ha) than for those of meadow voles (peak: 30/ha). Survival rates were generally low, especially for rice rats, indicating highly vagile populations. Both species had greatest breeding activity in spring and autumn, with lower rates in summer and winter. Sex ratios favored males in rice rats but were unity in meadow voles. Although marsh rice rats, being semi-aquatic and capable swimmers, are more highly adapted to living in flooded marsh environments, meadow voles can thrive there too. INTRODUCTION Two species of rodent, marsh rice rat, Oryzomys palustris, and meadow vole, Microtus pennsylvanicus, are dominant in the marshes of the coast and the nearby barrier islands in eastern Virginia (Bloch and Rose 2005, Cranford and Maly 1990, Dueser et al. 1979). These species have been frequently studied elsewhere, but rarely together because the meadow vole is a boreal species near its southern limit in eastern Virginia and Oryzomys, a tropical genus, is widespread only from coastal Delaware southward. Early studies reporting the presence of the marsh rice rat in Virginia tidal marshes include Goldman (1918) on Wreck and Smith islands and Bailey (1946) on Wallops Island. Later, Paradiso and Handley (1965) found rice rats and meadow voles as the dominant marsh rodents in their survey of the small mammal fauna of the northernmost barrier island, Assateague Island. But the most complete survey of tidal marsh and island mammals was conducted in the mid-1970s by Dueser et al. (1979), who trapped on 11 islands; nine had marsh rice rats but only three islands also had meadow voles. Corresponding author: brose@odu.edu 1 Current address: 520 East Main Street, Suite 608, Richmond Virginia 23219 2 Virginia Journal of Science, Vol. 64, No. 1, 2013 http://digitalcommons.odu.edu/vjs/vol64/iss1 18 VIRGINIA JOURNAL OF SCIENCE All studies confirm the numerical dominance of marsh rice rats and, when present, meadow voles in the grassand sedge-dominated tidal marshes. Two studies used regular trapping on study grids to obtain density estimates of small mammals on barrier islands: Adkins (1980) in an Assateague Island marsh and Cranford and Maly (1990), on Wallops Island. Adkins (1980) found modest densities (10-15/ha) of both species in late autumn of two years with few or none of either species during the summer months. Cranford and Maly (1990) reported densities of 25 and 30/ha in two Novembers for rice rats but higher peaks in late winter (45 and 50/ha in March) fo","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72560330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Systematic Ichthyofaunal Surveys in Urban and Non-Urban Watersheds","authors":"E. Maurakis, David V. Grimes, A. Schutt, S. Short","doi":"10.25778/36HJ-6X63","DOIUrl":"https://doi.org/10.25778/36HJ-6X63","url":null,"abstract":"Objectives were to model fish species richness relative to natural and anthropogenic variables in Quantico Creek, a forested undisturbed stream environment, and Cameron Run, a highly disturbed urban stream environment in the lower Piedmont-Fall Line region of the Potomac River watershed. Species richness in all stream orders (e.g. avg. range=2.5-9.65 in 1 -3 orders) st rd of Quantico Creek were significantly higher than those (e.g. avg. range=2.17.6 in 1 -4 orders) of Cameron Run. Fish species richness in Quantico Creek st th watershed can be modeled by eight factors: season, stream order, elevation, river km, stream width and depth, watershed size, and percent of undeveloped land cover; and that in Cameron Run can be modeled with four factors: stream gradient, stream flow, water temperature, and percent undeveloped land cover. Therefore, it cannot be assumed that a model composed of one set of variables that represents species richness for a given watershed can be applied to a nearby watershed. Based on potential impacts of increased population growth and climate change in the area, coupled with a paucity of information on the extent of the use of the lower reaches of Quantico Creek as a spawning area for anadromous fishes, we propose that the national park, Prince William Forest Park, should be included as a freshwater protection area for the Quantico Creek watershed as proposed by the National Park Service for 50 other national parks in the country. Data and models generated in our study can serve as baselines in future comparative studies of mid-Atlantic streams relative to changes in system parameters (e.g. human population, Corresponding author: emaurakis@smv.org * Current address: Science from Scientists, 515 Beacon St., Boston, MA 02215 1 Published by ODU Digital Commons, 2013 134 VIRGINIA JOURNAL OF SCIENCE corresponding anthropogenic effects and climatic change predicted for the mid-Atlantic region).","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79814000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Camera Trap Success Among Carnivores and Prey Animals in Tazewell County, Virginia","authors":"D. Chambers, J. Vance","doi":"10.25778/MXDR-D985","DOIUrl":"https://doi.org/10.25778/MXDR-D985","url":null,"abstract":"Obtaining basic ecological information on occurrence and activity levels in cryptic and elusive species is often difficult. Camera trapping provides a relatively inexpensive opportunity to acquire such data. We used infraredtriggered cameras to assess trap success and activity levels of several species across four consecutive seasons, including: Ursus americanus (black bear), Lynx rufus (bobcat), Canis latrans (coyote), Vulpes vulpes (red fox), Urocyon cinereoargenteus (gray fox), Procyon lotor (raccoon), Odocoileus virginianus (white-tailed deer), Didelphis virginiana (opossum), Sciurus carolinensis (gray squirrel), and Meleagris gallopavo (wild turkey). With a total of 396 trap nights (TN) at one station over the span of four consecutive seasons, overall trap success rate was 86.87 captures per 100 TN. Trap success was highest in wild turkeys (31.57/100 TN), followed by raccoons (15.66/100 TN), gray squirrels (10.86/100 TN), gray foxes (8.59/100 TN), white-tailed deer (8.08/100 TN), opossums (5.56/100 TN), coyotes (1.52/100 TN), red foxes (1.26/100 TN), and bobcats (0.76/100 TN). Overall trap success significantly varied across all target species combined (Kruskal Wallis ChiSquare = 349, d.f. = 10, p < 0.0001). However, trap success did not vary across all seasons for all target species combined (Kruskal Wallis Chi-Square = 0.99, d.f. = 3, p = 0.78). This study is the first to use camera trapping to examine species presence and activity levels in a longitudinal manner for cryptic and elusive species of southwest Virginia. INTRODUCTION Camera trapping is an excellent non-invasive tool for identifying cryptic or elusive species (Yasuda, 2004; Rowcliffe et al. 2008). While this approach to elusive species identification is not a recent revelation in ecological methodologies (e.g., Chapman, 1927), camera trap usage has picked up momentum in recent years (Karanth and Nichols, 1998). In fact, published papers utilizing some degree of camera trapping have seen an estimated 50% annual growth over the past decade (Rowcliffe and Carbone, Corresponding author: David L. Chambers chambersdl@longwood.edu 130 VIRGINIA JOURNAL OF SCIENCE 2008). Much of this growth can be attributed to increased technological and analytical advances that allow ecologists to determine population densities, dispersal behaviors, and relative abundance – all from a distance (Karanth and Nichols, 2000; Kelly et al. 2012). Trap success is one common index of activity level that can be obtained using camera trap data. Trap success calculated per species can provide insight into species presence or, at a more interactive scale, potential species interactions among predators/prey (Kelly and Holub, 2008), despite recent debate about its use as an index of abundance (Anderson, 2003; O’Brien et al., 2003). Regardless of debate, it is impractical to ignore the importance of understanding predator/prey dynamics particularly in the wake of increasing anthropogenic disturbances that are alteri","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75125199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Centennial Record of Paleosalinity Change in the Tidal Reaches of the Potomac and Rappahannock Rivers, Tributaries to Chesapeake Bay","authors":"N. Tibert, L. Walker, W. Patterson, J. B. Hubeny, Emma Jones, Olivia R. Cooper","doi":"10.25778/8Q18-AY59","DOIUrl":"https://doi.org/10.25778/8Q18-AY59","url":null,"abstract":"Gravity and push cores from the Potomac and Rappahannock Rivers (Virginia Tidewater) were collected from central and proximal estuarine zones with known seasonal salinity stratification. The lowermost microfossil associations in the cores comprise alternating ostracode populations of Cyprideis salebrosa and Cytheromorpha. This microfossil association gives way to an oligohaline association dominated by the freshwater ostracode Darwinula stevensoni. Stable oxygen isotope values (ä O) of Rapphannock Cyprideis salebrosa are 18 highly variable ranging between -6.6 to -3.2‰ VPDB. ä O values for 18 Potomac Cytheromorpha fuscata range from -8.2 to -3.2‰ VPDB. Positive excursions in ä O values are synchronous with population peaks for both 18 Cyprideis and Cytheromorpha indicative of increased marine influence and/or higher salinities. Microfossil paleoecology coupled with oxygen isotope values record a marked shift towards gradual freshening and deterioration of the salinity structure in the tidal tributaries during the mid-to late 19 century. th We attribute these trends to both decadal climate trends and aggressive land use practices in the Chesapeake Bay watershed during the late 19 to middle th 20th centuries. INTRODUCTION Estuaries are physically, chemically, and biologically complex environments at the convergence of continental and marine processes. In the Chesapeake Bay, the recent combination of anthropogenic watershed modification and sea-level rise are forcing mechanisms that have potentially influenced mixing of fresh and marine waters in the tidal reaches of the major tributaries (Colman and Bratton 2003; Boon 2012). To test this hypothesis, sediment cores were collected from the proximal and central reaches Corresponding author: Neil E. Tibert, ntibert@umw.edu Virginia Journal of Science, Vol. 63, No. 3, 2012 http://digitalcommons.odu.edu/vjs/vol63/iss3 112 VIRGINIA JOURNAL OF SCIENCE of the Potomac and Rappahannock estuaries for microfossil and stable isotopic analyses. Paleosalinity indicators were established on the basis of ostracode paleoecology (population abundances and pore morphometrics) and oxygen isotope values (ä O). The paleosalinity trends were considered in the context of sedimentation 18 history based on Cs dating, organic matter concentrations, and magnetic 137 susceptibility of collected cores. Cumulative results of these analyses indicate that salinity gradients in both estuaries have changed markedly since the beginning of the 19 century which is suggestive of anthropogenic influence on estuarine processes in th the Chesapeake Bay. BACKGROUND Geographic Location The Chesapeake Bay is the largest estuarine system in the United States that is located between Virginia and Maryland on the Atlantic Coastal Plain (Colman and Mixon 1988). This study focuses on the upper tidal reaches of the Potomac and Rappahannock Rivers where they transition from estuarine-to fluvial conditions (Fig. 1). Sediment cores were collected near th","PeriodicalId":23516,"journal":{"name":"Virginia journal of science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78057890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}