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Articles 1 - 4 of 4
Full-Text Articles in Terrestrial and Aquatic Ecology
Modeling Phytoplankton Community Response To Nutrient Loading And Climate Change In A Shallow Temperate Estuary, Sara Aimee Blachman
Modeling Phytoplankton Community Response To Nutrient Loading And Climate Change In A Shallow Temperate Estuary, Sara Aimee Blachman
Dissertations, Theses, and Masters Projects
Phytoplankton account for at least half of all primary production in estuarine waters and are at the center of biogeochemical cycles and material budgets. Environmental managers use water column chlorophyll-a (chl-a) concentrations as a basic water quality indictor, as the problems of eutrophication and hypoxia are intrinsically linked to excessive phytoplankton growth. Evidence suggests that the distribution and frequency of harmful algal blooms may be increasing worldwide. For the most part, phytoplankton communities follow a standard seasonal pattern, with specific groups dominating the assemblage during the time of year when environmental conditions correspond to their requisites for growth. However, climate …
The Effects Of Pollution On Benthic Communities Of The Tidal James River, Virginia, Robert J. Diaz
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 …
Nitrogen Fixation In Virginia Salt Marshes And The Effects Of Chronic Oil Pollution On Nitrogen Fixation In The Mobjack Bay Marshes, Alyce Diane Thomson
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 …
Heavy Metal Concentrations In The Clam Rangia Cuneata From The Rappahannock And James Rivers, Robert Emile Croonenberghs
Heavy Metal Concentrations In The Clam Rangia Cuneata From The Rappahannock And James Rivers, Robert Emile Croonenberghs
Dissertations, Theses, and Masters Projects
This project investigated the feasibility of using the brackish water clam Rangia cuneata as a heavy metal pollution indicator, and further investigated the state of heavy metal pollution in the James River. Rangia cuneata were sampled in the fall of 1972 from the Rappahannock and James Rivers , and meats were analyzed by atomic absorption spectrophotometry for wet weight concentrations of copper, zinc, cadmium and lead. Levels of copper and zinc in Rangia cuneata were shown to be unaffected by clam size, spawning differences, salinity or distance upriver, and substrate grain size. Heavy metal concentrations in the oxidized channel sediments, …