Oceanography Commons^™

Diapycnal Mixing And Mass Transfer In Western Boundary Currents, Jose Luis Pelegri Llopart

OES Theses and Dissertations

The distribution of nutrient flux in five sections across the Gulf Stream (from the Florida Straits of 35°W) is characterized by an intense core, centered at the depth of the 26.8 σ_t isopycnal surface. This 'Nutrient Stream' transports nutrients of O(10³ kmol s^-1} of nitrate and proportional amounts of other nutrients. Water mass and nutrient balances of nine isopycnal layers reveal significant diapycnal mixing between upper-thermocline and surface waters in the sector of the Stream between the Florida Straits and the Mid-Atlantic Bight. A two-box model of the nutrient-depleted surface layers (σ_t < 26.8) and the nutrient-rich thermocline layers (26.8< σ_t < 27.5) shows upward one-way transfer and two-way exchange, both at a a rate at about 1.m²s …

Distribution Of Foraminifera And Pollen In Coastal Depositional Environments Of The Southern Delmarva Peninsula, Virginia, U.S.A., Han Jun Woo

OES Theses and Dissertations

The coastal zone of the southern Delmarva Peninsula exhibits a wide variety of barrier island system subenvironments. This study investigates whether 20 a priori subenvironments can be distinguished from each other on the basis of abiotic environmental variables, pollen assemblages, living foraminiferal populations, and total (living plus dead) foraminiferal assemblages.

The physical data collected from the coastal zone were subjected to canonical variate analysis which discriminated 83% of the stations in 19 groups. These groups were clustered into two internally overlapping sets which represented the inside and outside of the inlet.

Twenty-two pollen types were found in low-energy marsh and …

Development And Standardization Of A Short-Term Assay For Evaluating Polluted Estuarine And Coastal Environments: The Medaka Embryo-Larval Assay, Michael Frederick Helmstetter

OES Theses and Dissertations

The eggs of the Japanese medaka (Oryzias latipes) were employed in a number of studies to develop a routine, standardized assay which can assess the acute and sublethal impacts of individual toxicants and complex mixtures. The eggs of this Cyprinodont minnow were topically treated with each toxicant or mixture dissolved in membrane permeable dimethylsulfoxide (DMSO) solvent. Nine chemicals were initially evaluated with two, pentachlorophenol (PCP) and tributyltin chloride (TBTCl), subsequently selected for extensive evaluations of salinity tolerance and the accuracy of the topical exposure method for representing a typical immersion exposure. The amount of material actually penetrating the eggs was …

Processes Affecting The Behavior Of Redox-Sensitive Elements In Chesapeake Bay, Maria Lourdes San Diego-Mcglone

OES Theses and Dissertations

Several processes can affect variations in the chemical composition of an estuary, including (1) biogeochemical reactions in the water column, (2) advective transport, and (3) diffusion from underlying sediments.

The purpose of the study was to establish whether estuarine redox reactions are controlled by a complex interaction of processes 1 to 3. Short-term and long-term studies were conducted in Chesapeake Bay. Redox species involved in redox cycling include oxygen, iron, manganese, hydrogen sulfide, nitrogen species, arsenic and antimony species, while phosphate is indirectly involved in redox cycles. Silicate was used as a non-redox tracer.

For the short-term study, a Lagrangian …

The Effects Of Two Polycyclic Aromatic Hydrocarbons Benzo[A]Pyrene And Naphthalene On Reproductive Success Embryological Development Larval Physiology And Mortality Of The Mud Crab Rhithropanopeus Harisii (Gould), Gregory V. White

OES Theses and Dissertations

Polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap) and benzo[a]pyrene (B[a]P) are common in the water column and sediments of estuarine and coastal areas. The mud crab Rhithropanopeus harrisii was exposed to varying concentrations of Nap or B[a]P to determine the effects on reproductive success, embryological development, larval physiology and mortality. Nap and B[a]P decreased hatching success and prolonged embryological development. Both pollutants produced high abnormality frequencies for egg exposed larvae. Molt frequency and respiratory rates of larvae from non-exposed eggs were more chronically affected by these pollutants than were egg exposed larvae. The EC₅₀ concentrations were determined for …

Trace Metals And Pyrite In Sediments Of Chesapeake Bay, Robert S. Kluckhohn

OES Theses and Dissertations

The formation and cycling of iron sulfides within anoxic sediments can affect the cycling of trace metals. The sediments at station CB-27 (near Annapolis, Maryland) in Chesapeake Bay were rich in FeS (39% of TS), low in greigite (3.6% of TS), and has a relatively constant pyrite concentration (50 - 60% of TS) with depth. The percent composition of total metals in pyrite were 25.7% cu, 11.8% Zn, 15.8% Fe, and non-detectable to 2.1% Cd. At Station CB- 28 (near the Choptank River), the sediments were low in FeS (1.7% of TS), richer in greigite (up to 14% of TS), …

The Role Of Longshore Sediment Transport In The Loss Of Fill Material From An Estuarine Groin System, R. Neville Reynolds

OES Theses and Dissertations

The influence of shoreline structures on longshore sediment transport and the evolution of a stable beach planform was investigated at Willoughby Spit, Virginia following the placement of 410,590 cubic meters of beach fill within a groin system. Shoreline changes and wave conditions in a single groin compartment, and the growth rate of a downdrift terminal spit were monitored during 1985 and 1986. Short term fluctuations in the shoreline position within the groin compartment suggested an episodic westerly movement of sediment through the groin system. Primary sediment moving events were associated with northerly winds which produced waves up to 50 cm …

A Comparison Of Metals In Several Ahermatypic Corals And Surficial Sediments: Mobile Pinnacles And Hoffa Reef, Northcentral Gulf Of Mexico, Kathryn M. Conko

OES Theses and Dissertations

Metal concentrations in marine sediment and carbonate secreting invertebrates are representative of surrounding environmental chemistry. Aluminum, Ba Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr, and Zn were measured in carbonate and terrigenous phases of the $<$63 um fraction of sediment samples from two locations in the northcentral Gulf of Mexico. Enrichment factors indicate that Al, Ba, Cu, Cr, Mg, Mn, and Ni are all slightly depleted in these sediments relative to crustal abundances. Discriminant function analyses shows that the concentrations of five elements differ between locations.

Ahermatypic coral (106 specimens) from five genera collected from the study sites were analyzed for Cd, Cu, Cr, Pb, Zn, Mn, Sr, Ba, Fe, Ca and Mg. Eight elements vary between some genera, Al and Ba also vary in concentration in corals between either location. All elements except Sr are significantly depleted in the coral with respect to Ca in the …

Middle Eocene Foraminifera From The Piney Point Formation Of The Virginia And Maryland Coastal Plain, Megan S. Jones

OES Theses and Dissertations

This study examines the foraminiferal fauna, both benthic and planktonic, of the outcropping (45 samples) and subsurface (31 samples) middle Eocene Piney Point Formation in Virginia and Maryland. The primary objective of this study is to further refine the depositional history of the Salisbury Embayment which is represented by the middle Eocene Piney Point Formation. Ninety-six species of benthic and planktonic foraminifera were identified in this study. Of these, several are characteristic of the middle Eocene: Asterigerina texana, Hanzawaia danvillensis, Ceratobulimina exima, Cibicides westi, Chiloguembelitria columbiana, C. stavensis, Testacarinata inconspicua and Pseudohastigerina wilcoxensislmicra. While these were relatively abundant, diagnostic middle …

The Effects Of Variable Parameters On The Behavior Of Initial Wind Waves, Glen Harvey Wheless

OES Theses and Dissertations

The generation mechanism of short wind waves is generally thought to be a viscous instability at the air-sea interface. The short, regular waves arising from a sudden wind on a still water surface have a dispersion relation which is characteristic of gravity-capillary waves. The effects of variable surface tension, viscosity and shear flow parameters on the behavior of these waves were studied.

A numerical hydrodynamic stability analysis of a coupled laminar shear flow was accomplished by integrating a transformed version of the Orr-Sommerfeld equation, subject to the boundary conditions at a two-fluid interface. Unbounded growth problems usually encountered in a …

Nonlinear Solutions To A Two-Layer Quasi-Geostrophic Model Of The Gulf Stream, Eiichi Oka

OES Theses and Dissertations

The Gulf Stream shows a large meander off Cape Hatteras. This is driven by an energy conversion process known as baroclinic instability and observations suggest that nonlinearity is an important part in this process. In order to understand the fundamental role of nonlinearity in baroclinic instability, an inviscid 2-layer quasi-geostrophic model is studied.

The linear solution is obtained by methods of normal mode and Fourier-Laplace transforms. It is found that the set corresponding to the continuous spectrum is null and the set corresponding to the discrete spectrum is complete.

The nonlinear solution is expanded in terms of the complete set …

The Temporal And Spatial Distribution Of Blue Crab Larvae On The Mid-Atlantic Bight Adjacent To The Chesapeake Bay, 1982-1983, Lyle Michael Varnell

OES Theses and Dissertations

Recruitment processes are important information for the management of commercially and recreationally exploited marine species. Recruitment processes of the Chesapeake Bay's most important commercial and recreational species, the blue crab, are unknown, due in part to the lack of knowledge of the processes directly preceeding recruitment.

The present study was undertaken to investigate and explain the movement and developmental patterns of blue crab larvae while offshore. Interannual and intraseasonal variations of these patterns were also examined.

Sampling occurred from May to November during 1982 and 1983. Larvae were collected at three depths (neuston layer (upper 10 cm), one meter and …

Picoplankton/Phytoplankton Dynamics In Hampton Roads, Virginia, Leslie E. Dorworth

OES Theses and Dissertations

The biomass distribution of the three main size components of the phytoplankton (net, nano, and picoplankton) was examined in the lower Chesapeake Bay. Work was done at two stations during the spring and neap tidal cycles when freshwater flow into the bay was at its seasonal minimum and maximum. Emphasis was placed on how the picoplankton ( < 2.0 μm, > 0.2 μm) reacted during the sampling period.

Picoplankton made up approximately 13% of the total biomass, during the observed time period, at the more oceanic station. The picoplankton fraction contributed up to 16% of the total biomass at the estuarine station. From this …

Population Variation In The Mitochondrial-Dna Of Two Marine Organisms: The Hard Shell Clam Mercenaria Spp. And The Killifish, Fundulus Heteroclitus, Bonnie Lynn Brown

OES Theses and Dissertations

The two major topics are covered in this dissertation: the integration of molecular genetic tools with applied aquacultural research and short-term evolutionary dynamics. The first study investigated the extent of geographic differentiation of native clam stocks along the U.S. east and Gulf coasts. Clam mitochondrial DNA (mtDNA) demonstrated size polymorphism (16.5-19.0 kb) and restriction site heteroplasmy. Size heteroplasmic individuals occurred at a frequencies of 0-89% in clam populations. Restriction site heteroplasmy occurred in 12% of the 317 individuals assayed. Results of the study indicated that although harbouring a wealth of genetic variation, clams from northern regions were similar and lacked …

Survival And Reproduction Of The Freshwater Grass Shrimp Palaemonetes Paludosus (Gibbes 1850) (Decapoda:Palaemonidae), In Saline Water, Brian Thomas Lowe

OES Theses and Dissertations

To determine the effects of salinity on adult and larval survival, egg deposition, egg hatching and metamorphosis, shrimp were held in the laboratory and exposed to treatment salinities ranging from O to 35 ppt. Tests on adult survival indicate a 96 hour LC-50 between 30 and 35 ppt. Longer term tests on adult survival showed high mortality in salinities greater than 15 ppt. Shrimp became ovigerous in salinities of O - 20 ppt with egg hatching and metamorphosis limited to O - 5 ppt. Starved- larvae hatched from field captured ovigerous females in O ppt were able to metamorphose in …

Nutrient Cycling In Bordenstake Bay Sediments: A Backbarrier Lagoon, Mark J. Herrenkohl

OES Theses and Dissertations

Six sets of sediment cores were collected over a one year period (June 1986 to July 1987) to examine nutrient cycling in Bordenstake Bay, a back barrier lagoon on Virginia's Eastern Shore Peninsula. The sampling times were chosen to examine any seasonal effects (e.g., temperature changes) which may affect the rates of metabolism in these sediments.

The sedimentation rate in Bordenstake Bay is 0.76 ± 0.21 cm/yr, leading to the annual deposition of 7. 05 moles of carbon, 0.46 moles of nitrogen, and 0.15 moles of phosphorus, per square meter of the sediment surface. The remineralization of organic matter in …

Distribution Of Suspended Particulate Matter, Patuxent River Estuary, Maryland, Christopher W. Frye

OES Theses and Dissertations

Physical processes which may affect estuarine circulation in a coastal plain estuary were monitored to determine their relative importance on temporal and spatial variability of the concentration, composition, and particle-size of suspended particulate matter (SPM) in Patuxent River estuary, MD, during 1985-86. Discharge rates from Patuxent River determined the character of fresh and estuarine water mixing, and magnitude of SPM concentration in the upper estuary. The mixing zone between fresh and estuarine water, defined as 0 - 1.5 °‰, and turbidity maximum were geographically separated during most of the study period. This suggests that two-layer circulation may be less important …

Economic Considerations For Artificial Reef Development In Coastal Virginia, Dean Thomas Devereaux

OES Theses and Dissertations

The contingent valuation method, recommended by the U. S. Water Resources Council, was used to estimate the economic value of sport fishing and diving at the Chesapeake Light Tower Artificial Reef. The study is based on a random sample of 170 anglers and 33 divers who participated in telephone, personell and mail-in surveys in 1985 and 1986.

The average user value (consumer surplus) was $21.13, $110,75, and $13.30 for head boat anglers, private boat anglers and sport divers, respectively, who claimed to have used the reef in 1985. Variation in consumer surplus was statistically affected by trip expense, distance from …

Molting In The Mature Female Blue Crab, Callinectes Sapidus, Rathbun, Kirk J. Havens

OES Theses and Dissertations

The present study examines the hypothesis that mature female blue crabs, Callinectes sapidus, do not have a terminal anecdysis. Induced molting via eyestalk ablation, size frequency distributions and gonad and limb regeneration indices from field collected animals are used as indicators of potential post maturity molts.

Eyestalk ablation of mature females resulted in ecdysis approximately 51 days after ablation, indicating a physiological ability if mature females to complete ecdysis. Analysis of size frequency distributions indicates two distinct shifts from smaller to larger females, one in early spring and a second in early fall. While migration of larger females into …

Sulfide In Shelf/Slope Waters Of The Western Atlantic, Christian F. Krahforst

OES Theses and Dissertations

Sulfide in the surface ocean has been recently considered as a source of hydrogen sulfide gas in the marine boundary layer. This "oxic" sulfide may also be important as a ligand in trace metal complexation. In the absence of actual data, the existence of sulfide in the ocean mixed layer remains speculative. The purpose of this study was to develop a sensitive technique (having picomolar detection limits) for the determination of sulfide in seawater, and to investigate the distribution of sulfide in the surface ocean.

In order to assess the abundance and distribution of sulfide in surface waters, samples were …

Sediment Budgets And Shoreline Dynamics Cape Henry, Virginia, Marcia R. Berman

OES Theses and Dissertations

Analysis of 1183 beach profiles from Cape Henry, Virginia indicated that the recession-erosion ''rule" established by the Army Corps of Engineers underestimates the short-term response of the shoreline to changes in sediment volume.

Correlation between bi-weekly backshore volume change and the change in high water line (HWL) position was stronger (0.67 < r < 0.88) than correlation between bi-weekly total volume change and the change in mean low water (MLW) shoreline position (0.33 < r < 0.52). The short-term change in position of MLW is influenced by minor features such as bars. The position of the HWL is controlled by volume change at the backshore.

Correlation between change in HWL and MLW shoreline positions improved from r = 0.01 tor·= 0.67 for intervals of two weeks to two years, respectively. This suggests parallel-shore retreat only may be operable for greater than two-year periods.

Phytoplankton Dynamics In The Very Low Salinity Region Of The James River Estuary, Virginia, U.S.A., Changho Moon

OES Theses and Dissertations

During summer and autumn discharge from the James River estuary, Virginia, was less than 120 _m³sec^-1. There was a peak phytoplankton biomass in the very low salinity region (defined as the location where surface salinity measured less than 0.5$ 0/00) and this peak represented five to ten times greater biomass than adjacent waters. The peak biomass occurred independent of the tidal state and the location of nutrient inputs. It disappeared during winter and spring, and nutrient limitation was not responsible for the low phytoplankton biomass, indicating there were physical, not chemical controlling factors.

The peak biomass …

Analysis Of Phytoplankton And Particle Variability At A Warm Core Ring/Shelf Break Front Using Flow Cytometry, Kimberly G. Davis

OES Theses and Dissertations

Particle variability at a Gulf Stream warm core ring/ shelf break front on 09 Nay 1985 was analyzed. Single particle measurements of fluorescence, perpendicular light scatter, and volume were made using a FACS Analyzer flow cytometer. Advantages and disadvantages of at-sea use of the instrument are described. To evaluate the flow cytometry data, individual particle data were compared with bulk phytoplankton and particle measurements. Abundance and size distributions of fluorescent and non-fluorescent particles indicated a convergence zone at the front while upwelling was likely within the ring perimeter. Variability in fluorescence (approximating chlorophyll A) and cell biovolume exposed regions of …

Processes Which Create And Destroy Stratification In The South Atlantic Bight During Gabex Ii, Rebecca Lynn Lovingood

OES Theses and Dissertations

The stratification present on the South Atlantic Bight (SAB) during the summertime is influenced by creative forces, namely surface heating, precipitation, fresh water runoff and advection of Gulf Stream water, and destructive forces, these being wind, bottom currents, tides, evaporation and cooling. During the summer of 1981 the Georgia Bight Experiment II (GABEX II) was conducted to evaluate the Gulf Stream intrusions on the shelf dynamics. Calculations using potential energy as an indicator of stratification showed that the mixing forces were strong enough to destroy the stratification if the advection of buoyancy is ignored. During this period, however, the potential …

Growth Potential Of Young Black Sea Bass, Centropristis Striata, In Artificial Environments, Joung Won Kim

OES Theses and Dissertations

The growth potential of the commercially important marine finfish, black sea bass (Centropristis striata), was examined for aquaculture under controlled conditions. The effect of food and body weight on growth was evaluated using juveniles and young black sea bass cultured with a natural diet and a commercial diet at various feeding levels.

Growth was affected by type of food, food consumption rate, and fish body weight. For fish having positive weight gain, absolute growth rate (gram/day) increased exponentially as food consumption rate (percent of body weight per day) and/or body weight increased. Instantaneous growth rate (percent of body weight per …

Cross-Shore Sediment Transport In Relation To Waves And Currents In A Groin Compartment, Hyo Jin Kang

OES Theses and Dissertations

In nearshore areas waves are generally irregular, and the irregular wave-induced currents have different peak velocities (magnitude asymmetry) and durations (duration asymmetry) between forward and backward motions. These asymmetries may produce a net cross-shore sediment transport in one direction. The sediment transport mostly occurs as bedload where the waves are non-breaking.

Sediment transport on a sloping bed is also affected by gravity, and accordingly the Shields parameter should be re-evaluated for a grain on a sloping bed. It was also found that the affect of a steady current that interacts nonlinearly with the waves was important for the cross-shore sediment …

The Geochemistry Of Selenium And Sulfur In A Coastal Salt Marsh, David Jay Velinsky

OES Theses and Dissertations

Investigation of the various chemical forms of selenium and sulfur in sediments and pore waters can provide information about various oxidation/reduction processes. Five cores were obtained from the Great Marsh, from April 1985 to June 1986. Sampling times coincided with the seasonal redox cycle known to occur within the marsh system. Sediments were analyzed for various selenium and sulfur phases.

Iron monosulfides and elemental sulfur both display large seasonal changes in concentration and distribution with depth, indicating a coupling with redox conditions. In contrast, the depth distribution of greigite did not show appreciable changes with season. Pyrite underwent large concentration …

A Comparison Of Potential Fishing Methods Associated With Fish Aggregating Devices Off The Northeast Coast Of Puerto Rico, Alan M. Friedlander

OES Theses and Dissertations

Six fish aggregating devices (FADs) were deployed in June and monitored through December 1986. Emphasis was placed on trolling, live-bait handlining and longlining.

There was a significant difference (x2 = 7.815, pCoryphaena hippurus) which made up 64.2% of the catch.

Handlining at night around inshore buoys for one boat yielded 82.7 kg per trip. Pelagic fish comprised 83.9% of the catch, with the majority (81.4%) being kingfish (Scomberomorous cavalla). Catch rates were 50% higher and the species diversity much greater on the FADs versus control during experimental nightfishing, but the difference was not significant.

Longlining resulted in 3.4 …

Laminar Viscous Effects On Longitudinal Dispersion In Tidal Froude Models, Larry H. White

OES Theses and Dissertations

A laboratory investigation was designed to test the ability of a tidal Froude model operated according to the minimum Reynolds number criterion of 1400 to simulate the longitudinal dispersion of its turbulent, laboratory prototype in the absence of depth distortion and density stratification. To examine the model's performance, comparative tracer-dye dispersion tests were conducted in the model and in the prototype to determine spatial and temporal longitudinal dye distributions. Froude similitude of cross-sectional mean tide heights and current velocities was achieved. The minimum Reynolds number criterion did not guarantee turbulent flow throughout all tidal stages, prolonged periods of laminar flow …

A Simple Numerical Model For The Study Of Baroclinic Estuarine Shelf Interactions, Thomas J. Berger

OES Theses and Dissertations

A one and a half layer nonlinear f-plane numerical model was used to study estuarine-shelf interactions. The single active layer covered a domain consisting of a 100 km long by 20 km wide channel discharging onto a 100 km wide by 300 km long shelf. Channel and "western” shelf boundaries were no-slip, "eastern" or oceanic boundary was free-slip and "northern" and "southern" shelf boundaries were open. The channel was forced with a constant inflow velocity spun up from 2 cm s^-1 to 27 cm s^-1over five days. The model initial conditions were a flat interface at …