Life Sciences Commons^™

Effects Of Petroleum Hydrocarbons On Salt Marsh Communities, Carleton H. Hershner Jr.

Dissertations, Theses, and Masters Projects

This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

The effects of petroleum hydrocarbons on salt marsh grasses and gastropods were examined under three different circumstances. In the first study reported, a small pocket marsh was repeatedly dosed with small amounts of a No. 2 fuel oil. The second study investigated the effects of a large accidental spill of No. 6 fuel oil. The third study involved single doses of a fresh and a weathered crude oil on artificially enclosed segments of marsh.

The Effects Of Pollution On Benthic Communities Of The Tidal James River, Virginia, Robert J. Diaz

Dissertations, Theses, and Masters Projects

Benthic communities in the estuarine portion of the James River are controlled mainly by salinity. Pollution effects are localized and difficult to assess because of the rigorous physical environment. Mesohaline and oligohaline communities were very similar to those in other east coast estuaries. except for the dominance of Rangia cuneata in the oligohaline zone. Communities of the tidal freshwater zone are most affected by pollution. In the areas of Richmond and Hopewell, where the major portion of the pollution load enters the river, communities are most severely depressed. Separate multivariate analyses of species distributional patterns, and pollution and physical parameters …

The Effects Of Conditioning The American Oyster (Crassostrea Virginica) With Tetraselmis Suecica And Cornstarch On The Growth, Vigor And Survival Of Its Larvae, Laura Lee Creekman

Dissertations, Theses, and Masters Projects

A comparison of effects of conditioning adult oysters (Crassostrea virginica) with Cornstarch and/or Tetraselmis suecica and raw water were determined on subsequent larval growth, vigor and successful metamorphosis. Possible correlations of lipid content of eggs and larval growth, vigor and metamorphosis was also examined. Results illustrated the effectiveness of Cornstarch when used as a supplemental conditioning agent for producing larvae and spat in greater quantity and of better quality than the other conditioning diets employed. Investigation revealed that lipid content of eggs is an important indicator for larval growth, vigor, set and successful metamorphosis. This dissertation is from the Joint …

Nitrogen Fixation In Virginia Salt Marshes And The Effects Of Chronic Oil Pollution On Nitrogen Fixation In The Mobjack Bay Marshes, Alyce Diane Thomson

Dissertations, Theses, and Masters Projects

N2 fixation rates for several Virginia salt marshes were determined using in situ acetylene-reduction assays. A control and a chronically polluted oil marsh of the mesohaline Mobjack Bay area were sampled over a 1975-76 annual cycle. N2 fixation occurred in all transects which extended from upper mudflat to the Spartina patens zone. An isolated blue-green algal mat exhibited some of the highest N2 fixation rates. Intertidal sediment N2 fixation was patchy, both spatially and seasonally. However average rates (91.45 μg N/m2/h) compared to the estimated N requirement of the graminoid vegetation indicated a significant contribution to the N budget. Vegetation …

The Ecology Of The Marine Cladocera Of Lower Chesapeake Bay, Burton Barker Bryan

Dissertations, Theses, and Masters Projects

A two-year zooplankton survey of lower Chesapeake Bay was conducted from August 1971 to August 1973. Twenty-four stations extending from the Rappahannock River mouth to the Bay entrance were sampled each month, using paired bongo nets with a 202 μm mesh. Marine Cladocera comprised >68% of the total zooplankton during two months of the survey, and were 36-40% by number three other times. The mean abundance over the whole study area of all cladoceran species combined was >62,000 m-3 in August 1971 and was >1000 m-3 on six other occasions. Of the six species of marine Cladocera found, Podon polyphemoides …