Physical Sciences and Mathematics Commons^™

Flow Kinematics And Dynamics Of The Gulf Stream From Composite Imagery, Caitlin Patrice Mullen

OES Theses and Dissertations

A unique set of contemporaneous satellite-tracked drifters and five-day composite satellite images of the North Atlantic is studied in order to infer the near-surface flow kinematics and dynamics of the Gulf Stream. Using fractal and spectral analyses, two kinematic models, and a potential vorticity model, detailed comparisons are made between these data sets.

Fractal and spectral analyses show that the data set is not fractal, there is no geographic variability, and there is not a strong fractal scaling link between the drifter trajectories and composite temperature fronts as had been postulated by several investigators. These results indicate considerably more work …

Benthic Community Responses To Hypoxic Conditions In The Lower Rappahannock River, Virginia, Mary Elaine Smith

Biological Sciences Theses & Dissertations

The effects of seasonal low dissolved oxygen conditions upon benthic macroinvertebrate communities were studied in the lower Rappahannock River, a tributary of the Chesapeake Bay. Benthic communities were sampled during March, June, August, and September 1993 at five equidistant depths (5, 10, 15, 20, and 25 m) extending upwards from the deepwater Virginia Benthic Biological Monitoring Station LE3.4 located in the deep basin just inside the mouth of the Rappahannock River. Infaunal species diversity, richness, biomass, and density were measured along with the vertical depth distribution of organisms within the sediment. Significant sediment differences were found between the shallowest, 5 …

On The Low-Frequency Current And Temperature Fluctuations Along The Shelf Break In The South Atlantic Bight, Sunny Yu Wu

OES Theses and Dissertations

Current and temperature data collected along the shelf edge in the South Atlantic Bight were analyzed using a spectral analysis technique. The power spectra of both alongshore currents and temperatures (upon removal of seasonal trends) in the mid- to lower water column suggest a significant energy peak at 28 days. The spatial characteristics of the fluctuations around this period band were determined using the frequency domain empirical orthogonal function (EOF) analysis applied to the concurrent current and temperature records. Consistent results were obtained from the upstream side of the Charleston Bump. Around the 28-day period, temperature seems to have little …

Iodate Transformation By Marine Phytoplankton, Ajcharaporn Udomkit

OES Theses and Dissertations

The speciation and distribution of iodine in the oceans are partly under biological control. Phytoplankton are suspected to mediate the transformation of iodate to iodide via reduction by the enzyme nitrate reductase. However, there has been no direct evidence to support this hypothesis.

The influence of phytoplankton on the speciation of iodine was examined with emphasis on the transformation of iodate to iodide. Six cultures of marine phytoplankton: Skeletonema costatum, Dunaliella tertiolecta, Amphidinium carterae, Tetraselmis levis, Emiliania huxleyi, and Synechococcus sp. , have been examined for their ability to take up and reduce iodate under a reduced nitrate environment. In …

Modeling Oyster Populations Ii. Adult Size And Reproductive Effort, E. E. Hofmann, J. M. Klinck, E. N. Powell, S. Boyles, M. Ellis

CCPO Publications

A time-dependent model of energy flow in post-settlement oyster populations is used to examine the factors that influence adult size and reproductive effort in a particular habitat, Galveston Bay, Texas, and in habitats that extend from Laguna Madre, Texas to Chesapeake Bay. The simulated populations show that adult size and reproductive effort are determined by the allocation of net production to somatic or reproductive tissue development and the rate of food acquisition, both of which are temperature dependent. For similar food conditions, increased temperature reduces the allocation of net production to somatic tissue and increases the rate of food acquisition. …

Modeling Oyster Populations. Iv. Rates Of Mortality, Population Crashes, And Management, E. N. Powell, J. M. Klinck, E. E. Hofmann, S. M. Ray

CCPO Publications

A time-dependent energy-flow model was used to examine how mortality affects oyster populations over the latitudinal gradient from Galveston Bay, Texas, to Chesapeake Bay, Virginia. Simulations using different mortality rates showed that mortality is required for market-site oysters to be a component of the population's size-frequency distribution; otherwise a population of stunted individuals results. As mortality extends into the juvenile sizes, the population's size frequency shifts toward the larger sizes. In many cases adults increase despite a decrease in overall population abundance. Simulations, in which the timing of mortality varied, showed that oyster populations are more susceptible to population declines …

The Pressure Gradient Conundrum Of Sigma Coordinate Ocean Models, George L. Mellor, Tal Ezer, Lie-Yauw Oey

CCPO Publications

It is shown that the differencing scheme cited here, though conventional, is not hydrostatically inconsistent; the sigma coordinate, pressure gradient error decreases with the square of the vertical and horizontal grid size. Furthermore, it is shown that the pressure gradient error is advectively eliminated after a long time integration. At the other extreme, it is shown that diagnostic calculations of the North Atlantic Ocean using rather coarse resolution, and where the temperature and salinity and the pressure gradient error are held constant, do not exhibit significant differences when compared to a calculation where horizontal pressure gradients are computed on z-level …

Continuous Assimilation Of Geosat Altimeter Data Into A Three-Dimensional Primitive Equation Gulf Stream Model, Tal Ezer, George L. Mellor

CCPO Publications

A three-dimensional data assimilation scheme is described and tested, using the Geosat altimeter data and a high-resolution, primitive equation, numerical ocean model of the Gulf Stream region. The assimilation scheme is based on an optimal interpolation approach in which data along satellite tracks are continuously interpolated horizontally and vertically into the model grid and assimilated with the model prognostic fields. Preprocessed correlations between surface elevation anomalies and subsurface temperature and salinity anomalies are used to project surface information into the deep ocean; model and data error estimates are used to optimize the assimilation. Analysis fields derived from the Navy's Optimum …

Prediction Of The Stochastic Behavior Of Nonlinear Systems By Deterministic Models As A Classical Time-Passage Probabilistic Problem, L. M. Ivanov, A. D. Kirwan Jr., O. V. Melnichenko

CCPO Publications

Assuming that the behaviour of a nonlinear stochastic system can be described by a Markovian diffusion approximation and that the evolution equations can be reduced to a system of ordinary differential equations, a method for the calculation of prediction time is developed. In this approach, the prediction time depends upon the accuracy of prediction, the intensity of turbulence, the accuracy of the initial conditions, the physics contained in the mathematical model, the measurement errors, and the number of prediction variables. A numerical application to zonal channel flow illustrates the theory. Some possible generalizations of the theory are also discussed.

Surface Flow Structure Of The Gulf Stream From Composite Imagery And Satellite-Tracked Drifters, C. P. Mullen, A. D. Kirwan Jr.

CCPO Publications

A unique set of coutemporaneous satellite-tracked drifters and five-day composite Advanced Very High Resolution Radionmeter (AVHRR) satellite imagery of the North Atlantic has been analyzed to examine the surface flow structure of the Gulf Stream. The study region was divided into two sections, greater than 37 degrees N and less than 37 degrees N, in order to answer the question of geographic variability. Fractal and spectral analyses methods were applied to the data. Fractal analysis of the Lagrangian trajectories showed a fractal dimension of 1.21 +/- 0.02 with a scaling range of 83 - 343 km. The fractal dimension of …

Contribution Of Zooplankton Lipids To The Flux Of Organic Matter In The Northern Adriatic Sea, Mirjana Najdek, Staša Puškarić, Alexander B. Bochdansky

OES Faculty Publications

Analyses of particulate material collected by sediment traps moored at a location in the northern Adriatic Sea in 1991 revealed the presence of zooplankton fatty acids, even though zooplankton and other 'swimmers' killed by the trap's preservative were carefully removed. Laboratory experiments were conducted to (1) prove the existence of zooplankton lipids within fecal pellets, (2) exclude the possibility of incomplete separation of swimmers and other material as eventual contamination with polyunsaturated fatty acids in fecal pellets, (3) evaluate the importance of zooplankton lipids to mass flux and (4) reveal the mechanisms which lead to excretion of undigested organic matter, …

The Biogeochemistry Of Hydrogen Sulfide: Phytoplankton Production In The Surface Ocean, Russell S. Walsh, Gregory A. Cutter, William M. Dunstan, Joel Radford-Knoery, Jennifer T. Elder

OES Faculty Publications

Hydrogen sulfide can exist in oxic waters in the form of a dissolved gas, dissociated ions, dissolved metal sulfide complexes, and particulate metal sulfides. The sum of the dissolved species is termed total dissolved sulfide (TDS). In addition to the hydrolysis of carbonyl sulfide, it has been speculated that phytoplankton may produce TDS. We present results from preliminary culture studies which demonstrate that phytoplankton produce TDS and particulate acid-volatile sulfide (pAVS). The phylogenetic order of TDS + pAVS production (per unit cell volume) for the oceanic species examined is Synechococcus sp. > Emiliania huxleyi ≈ Pyramimonas obovata > Thalassiosira oceanica. Moreover, …

Modeling Daily Production Of Aquatic Macrophytes From Irradiance Measurements: A Comparative Analysis, Richard C. Zimmerman, Alejandro C. Pasini, Randall S. Alberte

OES Faculty Publications

The importance of submerged aquatic macrophytes to coastal ecosystems has generated a need for knowledge of minimum light levels that will support the maintenance and restoration of healthy populations. Our goals were (1) to evaluate the sensitivity to natural, non-sinusoidal fluctuations in irradiance I of analytical integration techniques for calculating daily carbon gain, (2) to evaluate the H_sat (the daily period of I-saturated photosynthesis) model of daily production relative to models based on instantaneous photosynthesis vs irradiance (P vs I) and (3) to provide some guidance for the temporal density of irradiance data required for accurate estimation of …

Assessment Of Genetic Diversity Of Seagrass Populations Using Dna Fingerprinting: Implications For Population Stability And Management, Randall S. Alberte, Gregory K. Suba, Gabriele Procaccini, Richard C. Zimmerman, Steven R. Fain

OES Faculty Publications

Populations of the temperate seagrass, Zostera marina L. (eelgrass), often exist as discontinuous beds in estuaries, harbors, and bays where they can reproduce sexually or vegetatively through clonal propagation. We examined the genetic structure of three geographically and morphologically distinct populations from central California (Elkhorn Slough, Tomales Bay, and Del Monte Beach), using multilocus restriction fragment length polymorphisms (DNA fingerprints). Within-population genetic similarity (S_w) values for the three eelgrass populations ranged from 0.44 to 0.68. The Tomales Bay population located in an undisturbed, littoral site possessed a within-population genetic similarity (S_w = 0.44) that was significantly lower …

A Comparison Of A Validated Otolith Method To Age Weakfish, Cynoscion Regalis, With The Traditional Scale Method, Susan K. Lowerre-Barbieri, Mark E. Chittenden Jr., Cynthia M. Jones

OES Faculty Publications

Otoliths, scales, dorsal spines, and pectoral-fin rays were compared to ascertain the best hardpart for determining the age of weakfish, Cynoscion regalis. Each showed concentric marks, which could be interpreted as annuli. Sectioned otoliths, however, consistently showed the clearest marks, had 100% agreement between and within readers, and were validated by the marginal increment method for ages 1-5. This validated method of ageing weakfish was then compared with the traditionally used scale method. The scale method was less precise, as demonstrated by lower percent agreement, and generally assigned younger ages for fish older than age 6 (as determined by …

Biogeochemical Control Of Phosphorus Cycling And Primary Production In Lake Michigan, R. S. Walsh, Gregory A. Cutter, W. M. Dunstan, J. Radford-Knoery, J. T. Elder

OES Faculty Publications

A 3-yr study in Lake Michigan has shown a 27 mmol P m^-2 increase in the mass of total P (TP) in the water during spring when the lake is mixed from surface to sediment. This value is an order of magnitude greater than the annual P input from external sources. TP changed in concert with increases in chlorophyll a and organic N and decreases in nitrate and soluble Si. The concentration of soluble reactive PO_4^-3 (SRP) remained relatively constant throughout the study. We hypothesize that the SRP concentration is maintained by a chemical equilibrium with calcium-phosphate …

The Oceanographer's Toolkit: Oceanatlas And Atlast, Larry P. Atkinson

CCPO Publications

Most of us spend a great deal of time looking at data, visualizing it in our mind, and interpreting it for others. I am sure we all have also often realized how much time we spend on the unproductive part of these tasks. How often have you said, “I could have done this faster by hand!” I looked at two free software packages, OceanAtlas (OA) and Atlast, with success, but I wondered what longtime users thought of them. OceanAtlas is for the Mac and Atlast for the PC. Both have extensive data visualization capability and both come with large datasets: …

Population-Dynamics Of Juvenile Caribbean Spiny Lobster, Panulirus-Argus, In Florida Bay, Florida, David Forcucci, Mark J. Butler Iv, John H. Hunt

Biological Sciences Faculty Publications

Despite a wealth of information on the growth and population dynamics of sub-adult and adult Caribbean spiny lobsters (Panulirus argus), there is far less information about younger juveniles under natural conditions. Here we describe growth and population dynamics of juvenile spiny lobsters (12-68 mm carapace length, CL) that we have studied for 14 months (October 1988-December 1989) using mark-recapture techniques in a hardbottom community in Florida Bay, Florida. We also monitored the supply of postlarvae into the region in 1988 and 1989 using Witham-type surface collectors in an effort to link peak periods of settlement of postlarvae with subsequent cohorts …

The Dinoflagellate Flora Of The Late Oligocene - Early Miocene Old Church Formation Mid-Atlantic Coastal Plain, Alan P. Hoffmeister

OES Theses and Dissertations

The Old Church Formation contains the only presently known exposed Oligocene sediments in the North American mid-Atlantic Coastal Plain. Some ambiguity concerning the exact age of the Old Church Formation exists because it may include both Oligocene and Miocene sediments. Two outcrops and four cores containing the Old Church Formation were examined for dinoflagellates to determine the composition of the dinoflagellate flora in the Old Church Formation, the age of the Old Church Formation as indicated by this flora, general depositional environment of the Old Church Formation and correlative relationships of the Old Church Formation with other Coastal Plain units. …