A Study of Dredging Effects in Hampton Roads, Virginia

The intent of this report is to identify and quantify, in part, the adverse effects associated with the dredging operation itself and those segments of the ecological community which might be adversely affected by the levels of suspended solids and sedimentation attributable to the dredge. It consists of three sections including: a comprehensive review of the major marine resources, their location in and utilization of the Hampton Roads Harbor and vicinity; the turbidity model and physical environment, describing the levels and distribution of suspended sediment and sedimentation and local current patterns; and a review of the effects of increased suspended sediment loads on estuarine organisms and water quality

Wetlands mitigation evaluation vegetation studies : Final report to the city of Norfolk

Coastal wetlands in Virginia represent a finite resource which is beingsubjected to ever increasing development pressures. As a means of reducingthese losses while accomodating necessary economic development, the policyof wetlands mitigation through compensation is increasingly being utilizedby both regulatory agencies and developers. This practice generallyinvolves the grading of an upland area to the appropriate elevation andplanting it with wetlands vegetation to replace a mar sh being lost inanother area. The technology to plant and grow marsh vegetation for this and otherpurposes has been well demonstrated . In as few as two growing seasons theappearance and primary productivity can be very similar to natural marshes,but the length of time necessary for them to become fully functional in anecological sense is unknown (Woodhouse et al, 1974) . This question remainsunanswered and the need still exists to conduct both short and long termstudies of planted marshes to evaluate their success at replacing thewetlands resources being lost to development. These studies need to includenot only the plant community but also the physical environment and the utilization of these areas by invertebrates, fishes, birds, and mammals (Zedler, 1984). In an effort to address some of these questions this portion of the study was designed to 1) compare the vegetative characteristics of a manmade marsh with those of similar natural marshes and 2) investigate the role of elevation and tidal inundation in the development of the marsh

The Marshes of Back Bay, Virginia

An inventory was undertaken to determine the type and extent of the emergent tidal wetlands in Back Bay, which, historically, has ranged from a lunar tidal brackish estuary to a wind tidal freshwater system. The inventory was conducted primarily by boat with visual observations made for each marsh. The configuration and areal extent of each marsh was determined from USGS topographic maps and confirmed with aerial photography where necessary. Approximately 9925 acres of wetlands as defined by the Commonwealth of Virginia were identified within the watershed. These wetlands supported a very diverse flora consisting of over 109 species. The five dominant species accounted for almost 75% of the wetland acreage. They included: cattails, Typha spp., (4004 acres), needlerush, ]uncus roemerianus, (2371 acres), big cordgrass, Spartina cynosuroides, (605 acres), saltmeadow hay, Sp.artina patens, (449 acres) and switchgrass Panicum virgatum, (427 acres). The remainder of the species represented a diverse mixture of brackish plants with a significant component of freshwater species. The emergent tidal wetlands are dominated by plants typically indicative of brackish conditions even though the system now tends toward freshwater conditions under normal circumstances. These brackish species are probably relicts from when Back Bay was directly influenced by the salinity and tides afforded by inlets to the ocean. The brackish communities because of their continued dominance appear to be more adaptable to the periods of freshwater than the freshwater species are to periods of brackish conditions. These historical oscillations between brackish and fresh conditions are probably responsible for much of the plant diversity found. These plant communities are not static either, as evidenced by changes in the coverage of common reed, Phragmites australis, which has increased substantially between this inventory done in 1977 and recent (1990) observations

Multivariate Analyses of Spatiotemporal Water Quality Patterns of Back Bay, Virginia

An investigation employing multivariate statistical techniques was conducted to determine major spatiotemporal patterns in water quality in Back Bay, Virginia. Water quality data collected by the Virginia Water Control Board (VWCB) over the past two decades and recent data collected by the Department of Game and Inland Fisheries and the Back Bay Restoration Foundation were consolidated for statistical analysis. Unfortunately, lack of continuity in sampling regimes prevented the use of many of the site/date/variable combinations in the statistical analyses. Nonetheless, a number of water quality patterns were characterized. Long-term trends could be evaluated for a relatively few parameters (NO2, NH3, TKN, conductivity, DO, and pH) for which an adequate data base existed. Trend analysis of a 16-year data base for Hell Point Creek indicated a significant decrease in ammonia concentrations (-0.011 mg 1-1 yr-1) , possibly related to changes in land use activities in the region. The TKN concentrations in the Bay almost doubled between the 1970\u27s and 1980\u27s (from 1.14 mg/1 to 1.97 mg/1). Indicators of eutrophication such as high daytime dissolved oxygen and pH measurements qualitatively appeared to decrease between 1970\u27s and 1980\u27s throughout the Bay, but lack of spatial and/or temporal continuity in the data sets prevented direct statistical comparisons. Distinct seasonal patterns were characterized: summer conditions were characterized by high temperatures but lower suspended solids load and nutrient concentrations, while the converse was true for winter months. Spring and fall collection periods were intermediate in these characteristics but displayed elevated volatile suspended solids and depressed phosphorus concentrations, possibly due to seasonal phytoplankton blooms. Overall spatial patterns indicated the tributary creeks appeared to be source areas for elevated nitrogen and phosphorus based nutrients, while the main Bay was characterized by a high organic-rich suspended solids load. The tributary of greatest concern was Nawney Creek, which displayed elevated nutrient concentrations and appeared to influence water quality in the proximate Bay region. In summary, two major problems appear to be associated with water quality conditions in Back Bay: elevated levels of nitrogen and phosphorus based nutrient in the tributary creeks and a high suspended solids load of organic-rich particles in the Bay. The full ecological significance of these conditions cannot be determined by the present study. However, consistent and comprehensive monitoring of water quality conditions, such as has been implemented in recent years, should permit observation of long-term trends in environmental conditions in various portions of the Bay. Only in this way can the success of any management or restoration actions be judged

A natural resources survey and habitat evaluation of the Willoughby Disposal Area, U.S. Naval Base, Norfolk, Virginia

The purpose of this study is to determine the living natural resources utilizing the U.S. Navy\u27s dredged material disposal area located adjacent to Willoughby Bay in Norfolk, Virginia and to determine the habitat value of this area to these resources

Investigation and long-term monitoring of Phragmites australis within Virginia\u27s constructed wetland sites : final report

The use of constructed wetlands to replace natural wetlands is becoming pandemic. An investigation using Global Positioning System technology to map the vegetated communities of fifteen of the largest constructed wetlands in Virginia reveals that 80% are colonized by the invasive species, Phragmites australis Trin., and/or aggressive species, Typha spp. Tidally influenced wetlands that have subtidal perimeter ditches have significantly less (p\u3c0.05) P. australis in the wetland interior than those without perimeter ditches. Fractured regression analyses show that 6-years after constructionP. australis invasion can be extensive. Linear regression analysis suggests that, if conditions remain favorable for P. australis colonization, constructed wetlands could be overrun in 40 years

The Use of Night-Vision Equipment to observe Wildlife in Forested Wetlands

Urban forested wetlands and rural forested wetlands were studied to investigate the effectiveness of night-vision image intensifier equipment in the observation of medium-to-large animals and to investigate if surrounding landscape type influences wetland habitat value. Bats, cats, dogs, owls, deer, and humans were easily observed using the night-vision equipment. Differences in species use between the rural and urban forested wetland were observed. Light levels and noise levels were significantly higher (

Use of Dredged Material for Oyster Habitat Creation in Coastal Virginia

Dredging can have a beneficial effect on oyster habitat when the placement of the dredged material is effectively managed to help provide the bottom structure necessary to develop an oyster reef. Construction and maintenance of the Waterway on the Coast of Virginia (WCV) by the U. S. Army Corps of Engineers (Corps) has provided a number of examples of this process, both serendipitous and deliberate. The historical development of reefs that evolved from the random overboard placement of dredged material and the subsequent leasing of these areas for oyster cultivation is reviewed. A monitoring plan for the development of a reef in Swash Bay using maintenance dredging material is also described including pre- and post-dredging hydrographic surveys, surface sediment distributions, and shellfish surveys. After one year, the benthic communities at the recently used placement site, the historical placement site and an unimpacted area in Swash Bay were compared using the Benthic Assessment Method (BAM) to determine short-term impacts. The historical and unimpacted sites had very similar values while the recently used site was somewhat lower. Consequences of continued success in developing oyster reefs in close proximity to a dredged channel are addressed with a suggested management plan that involves rotating the placement among a number of sites. This would allow for the continued maintenance of both the channel and the adjacent oyster reefs.https://scholarworks.wm.edu/vimsbooks/1090/thumbnail.jp