Physical Sciences and Mathematics Commons^™

Spatial And Temporal Variability In Net Community Metabolism In The Middle Atlantic Bight, Georges Bank, And Gulf Of Maine: Observations Of Net Heterotrophic Phases In The Highly Productive Coastal Zone, Cory James Staryk

OES Theses and Dissertations

Net community metabolism (NCM), the balance between primary production and community respiration, was measured during two cruises, June 2011 and August 2012, in the Middle Atlantic Bight, Georges Bank and Gulf of Maine. Net heterotrophy was observed in Georges Bank and Gulf of Maine during the June 2011 cruise. During the August 2012 cruise, net heterotrophy was observed in the Middle Atlantic Bight and net autotrophy was observed in Georges Bank and the Gulf of Maine. Dark community respiration increased (DCR) with biomass and temperature. Gross community production (GCP) also increased with Chl a, bicarbonate uptake, and temperature. Net …

Implications Of Climate Change For Cyanobacteria Over The Western Florida Shelf In The Gulf Of Mexico, Ivy Mara Ozmon

OES Theses and Dissertations

Concentrations of atmospheric CO₂ are expected to double by year 2100 as a result of anthropogenic activities. Under elevated CO₂ conditions, cyanobacteria may reallocate energy from active accumulation and transport of dissolved inorganic carbon (C) required for photosynthesis to other growth processes. Stimulation of cyanobacterial production on the Western Florida Shelf in the Gulf of Mexico (GOM) could lead to improved nutritional status for the toxic, mixotrophic dinoflagellate Karenia brevis that utilizes newly fixed N₂ from co-occurring diazotrophic cyanobacteria and consumes unicellular cyanobacteria via grazing for growth. Culture studies performed by other researchers on the climate induced …

Phosphorus Cycling In Tropical Carbonate Sediment-Seagrass Systems, Zachary Howerton

OES Theses and Dissertations

This thesis presents two studies focusing on phosphorus cycling in calcium carbonate sediments inhabited by seagrasses. Phosphorus is a major limiting nutrient for primary productivity in these sediments as well as in the overlying waters. In large part this is due to removal of phosphate from solution by adsorption and precipitation reactions.

In chapter II, the relationship between the size of the sedimentary phosphorus pool and the abundance of seagrass on the Great Bahama Bank, as well as the relationship between phosphorus content and grain size in the sediments, were examined to better understand the biogeochemistry of carbonate sediments and …

Response Of Natural Estuarine Algal Communities To Nitrogen Additions, Christopher Schweitzer

OES Theses and Dissertations

Coastal eutrophication resulting from nutrient over-enrichment plagues coastal waterways worldwide. In addition to dissolved inorganic N, many marine microbes, including phytoplankton, have the capacity to use certain dissolved organic nitrogen (DON) compounds. However, while we know that many specific DON compounds are labile, the bulk of the DON pool in nature is uncharacterized. The bioavailability of DON to estuarine microbes currently remains unclear.

It is becoming evident that natural phytoplankton assemblages in estuarine waters are capable of using both inorganic and organic N compounds for growth, both of which are present in anthropogenic point and non-point source discharges. Methods for …

The Biogeochemistry Of Iodine In Seawater, Lingsu Zhang

OES Theses and Dissertations

Iodate and iodide are the two major species of iodine in seawater. In comparison to iodate, iodide is thermodynamically unstable in oxic seawater. The conversion (or reduction) of iodate to iodide may be mediated via biological activities. Since biological activities vary with the season, the conversion of iodate to iodide may also vary seasonally. The conversion (or oxidation) of iodide to iodate is thermodynamically feasible, but the mechanism is poorly known. Hydrogen peroxide, which is ubiquitous in surface seawater, may oxidize iodide to iodate.

Water samples were collected in the middle and lower Chesapeake Bay in different seasons between 1990 …