155 research outputs found

    Shallow Water Fish Communities and Coastal Development Stressors in the Lynnhaven River

    Get PDF
    Coastal development pressures in the Mid-Atlantic have been attributed to significant negative impacts to aquatic ecosystems. The Lynnhaven River watershed, located in the southernmost extent of the Chesapeake Bay and encompassing Virginia Beach, is an example of a shallow-water tidal system under intense development pressure that is confronted with multiple and often conflicting coastal management issues. Rapid development in and around the City of Virginia Beach over the past few decades has led to the loss of natural buffers and habitat (e.g. oyster, wetlands and seagrasses), increased sedimentation, and degraded water quality. The Lynnhaven Ecosystem Restoration Project, led by U.S Army Corps of Engineers, is an effort to collaborate with State and federal partners over a 5-year period to identify and implement the most effective strategies for improving water quality, restoring oysters and seagrasses, and managing siltation. Limited quantitative information exists on the nekton assemblages utilizing shallow water habitats, such as tidal creeks, within the Lynnhaven River restoration area. To document nekton composition, and to investigate potential effects of development stressors, such as dredging and shoreline modification, three sets of paired dredged and undredged tidal creeks were surveyed in the Western Branch of the Lynnhaven River. Fish communities were sampled with multiple gear types once per month for three months (August, September, October, 2006). Abundance, average length and weight, diversity, and fish community indices were estimated for each creek and time period, and dredged compared with undredged systems for resemblance in fish composition and abundance. Tidal creeks within Lynnhaven Bay support diverse and similar fish communities. Slight differences in community structure among creeks may be attributable to the location and size of watersheds. The effects of dredging were not apparent in fish community responses measured as abundance, biomass, diversity, and fish community indices. However, anthropogenic effects may be obscured in the shortterm by the background variability of physical and water quality features of Lynnhaven Bay estuary, and long-term or cumulative effects are not quantifiable due to the dearth of historic information on fish communities. Available historic information may indicate a shift in fish community structure that could be associated with coastal development pressures, such as shoreline alteration and habitat loss of wetlands and oyster reefs. Accordingly, restoration and preservation of critical nursery habitats may augment fish productivity in Lynnhaven Bay

    Ecosystem Approaches to Aquatic Health Assessment: Linking Subtidal Habitat Quality, Shoreline Condition and Estuarine Fish Communities

    Get PDF
    In the Chesapeake Bay, there is currently no comprehensive assessment of aquatic habitat heterogeneity or understanding of the effects of multiple stressors on the viability of these habitats. To assess the use of side-scan sonar technology with specially designed classification software, QTC SIDEVIEW developed by Quester Tangent Corporation as a tool to define subtidal nearshore habitat, two representative watersheds of the Chesapeake Bay were surveyed. Relationships between subtidal habitat and shoreline condition as well as linkages of habitat condition to fish community indices were assessed. Side-scan technology had the ability to image habitat at a resolution of less than 1 meter. Automated seabed classification shows promise as a delineation tool for broad seabed habitat classes. In the James River, relationships between shoreline condition and fish community indices were observed, while no association with bottom type was reflected in the data possibly due to the limited availability of vertical structure in this system. Observed relationships and habitat mapping protocols have the potential to be extrapolated to additional watersheds in the coastal plain, and become tools for future development of habitat indices and ecosystem management

    Targeted “Hotspot” Removal of Derelict Blue Crab Traps (VA, MD)

    Get PDF
    In the winter of 2019/2020, five commercial watermen spent a cumulative total of 120 removal days on the water and collected 971 derelict blue crab traps which contained 985 blue crabs, 239 fish (oyster toad fish, black sea bass, flounder, pig fish, striped bass, speckled trout, perch, butterfish), 31 diamond back terrapin (a listed “species of concern”), and one duck. A majority of the traps removed were metal as opposed to vinyl coated (83% and 17%, respectively). Bycatch was present in 43% (346) of metal traps and 44% (72) of vinyl coated traps removed. On average, the instantaneous capture rates were similar for both trap types with an average of 1.0 crab captured per trap and 0.25 fish captured per trap. In addition, 10 abandoned eel traps were removed which contained 2 blue crabs, 3 fish, and 1eel

    Architecture of a Silicon Strip Beam Position Monitor

    Full text link
    A collaboration between Fermilab and the Institute for High Energy Physics (IHEP), Beijing, has developed a beam position monitor for the IHEP test beam facility. This telescope is based on 5 stations of silicon strip detectors having a pitch of 60 microns. The total active area of each layer of the detector is about 12x10 cm2. Readout of the strips is provided through the use of VA1` ASICs mounted on custom hybrid printed circuit boards and interfaced to Adapter Cards via copper-over-kapton flexible circuits. The Adapter Cards amplify and level-shift the signal for input to the Fermilab CAPTAN data acquisition nodes for data readout and channel configuration. These nodes deliver readout and temperature data from triggered events to an analysis computer over gigabit Ethernet links.Comment: Submitted to TWEPP 201

    The D0 Run IIb Luminosity Measurement

    Full text link
    An assessment of the recorded integrated luminosity is presented for data collected with the D0 detector at the Fermilab Tevatron Collider from June 2006 to September 2011 (Run IIb). In addition, a measurement of the effective cross section for inelastic interactions, also referred to as the luminosity constant, is reported. This measurement incorporates new features that lead to a substantial improvement in the precision of the result. A luminosity constant of \sigma_{LM} = 48.3\pm1.9\pm0.6 mb is obtained, where the first uncertainty is due to the accuracy of the inelastic cross section used by both CDF and D0, and the second uncertainty is due to D0 sources. The recorded luminosity for the highest E_T jet trigger is L_rec = 9.2 \pm 0.4 fb^{-1}, with a relative uncertainty of 4.3%.Comment: 20 pages, 23 figure
    corecore