Physical Sciences and Mathematics Commons^™

Data Assimilation Experiments In The Gulf Stream Region: How Useful Are Satellite-Derived Surface Data For Nowcasting The Subsurface Fields?, Tal Ezer, George L. Mellor

CCPO Publications

Satellite-derived surface data have become an important source of information for studies of the Gulf Stream system. The question of just how useful these datasets are for nowcasting the subsurface thermal fields, however, remains to be fully explored. Three types of surface data-sea surface temperature (SST), sea surface height (SSH), and Gulf Stream position (GSP)-are used here in a series of data assimilation experiments to test their usefulness when assimilated into a realistic primitive equation model. The U.S. Navy's analysis fields from the Optimal Thermal Interpolation System are used to simulate the surface data and to evaluate nowcast errors. Correlation …

Tidally Driven Residual Circulation In Shallow Estuaries With Lateral Depth Variation, Chunyan Li, James O'Donnell

CCPO Publications

Tidally driven residual circulation in shallow estuaries with lateral depth variation has been studied analytically using a two-dimensional, depth-averaged model. The solution is presented for a v-shaped channel. Exchange flow is found to be correlated with the topography. The magnitude of this exchange flow depends mainly on four parameters: the ratio between the minimum depth on the shoal and the maximum depth in the channel, the ratio between the tidal amplitude at the mouth and the mean depth, the ratio between the length of the estuary and the tidal wave length, and the ratio between the tidal timescale and the …

Vertical Profiles Of Bromoform In Snow, Sea Ice, And Seawater In The Canadian Arctic, William T. Sturges, Glenn F. Cota, Paul T. Buckley

CCPO Publications

Bromoform (CHBr₃) was measured in vertical profiles from the snow surface through the snowpack, sea ice, and water column to the seafloor at Resolute Bay, Canada, in the sprig of 1992. Elevated concentrations of bromoform were observed in both the ice (32-266 ng L^-1 by liquid water volume) and seawater (~ 20 ng L^-1 ) at the ice-water interface, associated with bromoform emission from ice microalgae. A surprising finding was a second horizon of high bromoform concentrations (336-367 ng L^-1) in sea ice at the snow-ice interface. Chlorophyll and salinity were also elevated in …

Circulation, Vol. 5, No. 1, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Fall 1997 issue of CCPO Circulation featuring article "CCPO, ODU, and Internet2"

Simulations Of The Atlantic Ocean With A Free Surface Sigma Coordinate Ocean Model, Tal Ezer, George L. Mellor

CCPO Publications

A sigma coordinate, free surface numerical model with turbulence dynamics has been implemented for the Atlantic Ocean and the Greenland Sea, from 80°S to 80°N. It is driven at the surface by monthly mean sea surface temperature and wind stress climatologies and is executed for 30 years. This is the first time that a model of this type, previously used mostly for coastal and regional simulations, has been implemented for the entire Atlantic Ocean and run for a long period of time. The model horizontal circulation, thermohaline overturning circulation, and meridional heat fluxes are described; the results are compared with …

Circulation, Vol. 4, No. 4, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Summer 1997 issue of CCPO Circulation featuring article "HF Radar: Is It Ready for Prime Time"

Resuspension And Transport Of Fine Sediments By Waves, Chiang C. Mei, She-Jun Fan, Kang-Ren Jin

OES Faculty Publications

Although waves are the primary cause of sediment resuspension in the nearshore zone, in existing theoretical models, long-scale currents induced by the mean wind are often taken to be the only agent for the diffusion and convection of resuspended sediments. We present here theoretical examples where waves play a direct role in all aspects of sediment transport. Details are given for the simple case where only waves are present; the wave-induced current and diffusivity are shown to be no less important than similar factors in the wind-driven current. Hence, in a comprehensive model, one should include not only the current …

Systematics Of The Freshwater Amphipod Genus Crangonyx (Crangonyctidae) In North America, Jun Zhang

Biological Sciences Theses & Dissertations

The systematics of the amphipod genus Crangonyx of North America (north of Mexico) is revised, based on available collections (ca. 2240) and literature dealing with the genus. A grand total of 42 North America species of Crangonyx are recognized in the present study, 24 of them new to science. All species are described or redescribed and figured, utilizing external morphological features. Keys to both species groups and individual species are given. Phylogenetic trees are built using computer programs (PAUP, Hennig86, MacClade) based on 26 characters. Wagner parsimony produced 18 parsimonious trees and Fitch parsimony produced 45 trees. The consensus tree …

Circulation, Vol. 4, No. 3, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Spring 1997 issue of CCPO Circulation featuring article "Fostering Oceanographic Collaboration in Cameroon"

Ecology Of The Early Life History Of The Caribbean Spiny Lobster, Panulirus Argus: Recruitment, Predation, And Habitat Requirements, Charles A. Acosta

Biological Sciences Theses & Dissertations

Recruitment variability of the early life history stages of marine benthic organisms can have profound consequences on population dynamics. I studied factors affecting recruitment success of postlarvae and early juveniles of the Caribbean spiny lobster. I examined patterns in postlarval supply, investigated wind forcing as a potential transport mechanism for recruiting postlarvae, and quantified predation on postlarvae in south Florida, USA. In an eight-year time series, spiny lobster postlarval supply occurred year-round between the new and first quarter lunar phases. The major annual peak occurred around March corresponding to spawning activity ten months earlier, and a smaller non-seasonal peak occurred …

Microzooplankton Dynamics In Lower Chesapeake Bay And Its Major Tributaries, Gyung Soo Park

Biological Sciences Theses & Dissertations

This study identified the temporal and spatial variability of microzooplankton density and biomass at 14 stations located within Chesapeake Bay and four rivers. Microzooplankton are defined as those heterotrophic organisms which range from 20 to 200 $\mu$m in size, and in this study were mainly composed of copepod nauplii, rotifers, and ciliates. Ciliates were the most abundant microzooplankton, comprising more than 90% of the total density, with copepod nauplii representing approximately 50% of the total microzooplankton biomass (carbon content). Rotifers contributed less than 5% for both density and biomass of the total microzooplankton.

Maximum ciliate abundance occurred from spring to …

Influence Of Physics On The Distribution Of Ichthyoplankton Across The Chesapeake Bay Plume, Christian S. Reiss

OES Theses and Dissertations

Most marine fish have retained pelagic larval stages that are spawned away from juvenile habitats. Physical and biological processes on a number of scales may affect larval survival. Mesoscale features like estuarine or riverine plumes and fronts are thought to affect larval survival by transporting larvae to juvenile habitats or by retaining larvae in favorable developmental habitats. It is likely that these features are major contributors in the regulation of shelf-spawned estuarine-dependent taxa.

This study examined how physical oceanographic features affected the spatial distribution of ichthyoplankton across the Chesapeake Bay Plume. Larval surveys were conducted across the shelf and within …

A Modeling Study Of The Effects Of Size- And Depth-Dependent Predation On Larval Survival, Margaret M. Dekshenieks, Eileen E. Hofmann, John M. Klinck, Eric N. Powell

CCPO Publications

The form of the predation pressure experienced by larval stages of marine invertebrates is largely unknown. However, it is believed that the type, timing and rate of larval predation are critical in determining recruitment to adult populations. In this study, a time and depth-dependent model of the growth and behavior of larvae of the Eastern oyster, Crassostrea virginica, was used to investigate the effects of different forms of size-and depth-dependent predation on larval survivorship. The simulated larval survival for a cohort experiencing size-dependent predation showed that the greatest percent of the cohort survived to competent settlement size when the …

Factors Affecting The Recruitment Of Juvenile Caribbean Spiny Lobsters Dwelling In Macroalgae, Mark J. Butler Iv, William F. Herrnkind, John H. Hunt

Biological Sciences Faculty Publications

In south Florida, Caribbean spiny lobsters (Panulirus argus) settle and spend their first few months in macroalgae or seagrass. After a few months, these ''algal-phase'' juveniles emerge from vegetation and, as ''postalgal-phase'' juveniles, seek refuge in crevices, often dwelling in groups. The importance of crevice shelters in determining the abundance of postalgal-phase juvenile spiny lobsters has been studied but we know little about the processes affecting lobster distribution and survival during their cryptic algal-dwelling phase. We found that postlarval supply varied independently of changes in the structure of macroalgal settlement habitat. For this reason, postlarval supply alone can not reliably …

Small-Scale Settlement Patterns Of The Oyster Crassostrea Virginica On A Constructed Intertidal Reef, Ian K. Bartol, Roger Mann

Biological Sciences Faculty Publications

The construction of three-dimensional, intertidal reefs resembling those widely present during colonial times in the Chesapeake Bay, but now absent due to years of overharvesting, may provide a more ecologically advantageous environment for oyster settlement and subsequent survival than present subtidal, two-dimensional habitats. We examined settlement processes on a constructed, 210 x 30 m intertidal reef composed of oyster shell. The reef was destructively and non-destructively sampled weekly throughout the summer and fall at tidal heights ranging from 30 cm above to 90 cm below mean low water (MLW) and at two substrate levels (reef surface and 10 cm below …

Detection Of Harmful Algal Blooms Using Photopigments And Absorption Signatures: A Case Study Of The Florida Red Tide Dinoflagellate, Gymnodinium Breve, David F. Millie, Oscar M. Schofield, Gary J. Kirkpatrick, Geir Johnson, Patricia A. Tester, Btyan T. Vintard

OES Faculty Publications

The utility of photopigments and absorption signatures to detect and enumerate the red tide dinoflagellate, Gymnodinium breve, was evaluated in laboratory cultures and in natural assemblages. The carotenoid, gyroxanthindiester, was an adequate biomarker for G. breve biomass; water‐column concentrations corresponded with cell standing crops and chlorophyll a concentrations during bloom events in Sarasota Bay, Florida. Unlike other carotenoids, the relative abundance of gyroxanthin‐diester did not change throughout a range of physiological states in culture and the gyroxanthin‐diester: chlorophyll a ratio exhibited little variability in a natural assemblage during bloom senescence. Stepwise discriminant analysis indicated that wavelengths indicative of in vivo …

Regulation Of Algal Blooms In Antarctic Shelf Waters By The Release Of Iron From Melting Sea Ice, Peter N. Sedwick, Giacomo R. Ditullio

OES Faculty Publications

During summer 1995-96, we measured iron in the water column and conducted iron-enrichment bottle-incubation experiments at a station in the central Ross Sea (76°30'S, 170°40'W), first, in the presence of melting sea ice, and 17 days later, in ice-free conditions. We observed a striking temporal change in mixed-layer dissolved iron concentrations at this station, from 0.72-2.3 nM with sea ice present, to 0.16-0.17 nM in ice-free conditions. These changes were accompanied doubling of algal (diatom) biomass. Our incubation experiments suggest that conditions were iron-replete in the presence of sea ice, and iron-deficient in the absence of sea ice. We surmise …

Yield-Per-Recruit Analysis And Management Strategies For Atlantic Croaker, Micropogonias Undulatus, In The Middle Atlantic Bight, Luiz R. Barbieri, Mark E. Chittenden, Cynthia M. Jones

OES Faculty Publications

The effect of different fishing mortality (F) and natural mortality (M), and age at first capture (t(c)) on yield-per-recruit of Atlantic croaker, Micropogonias undulatus, in the lower Chesapeake Bay and North Carolina were evaluated with the Beverton-Holt model. Independent of the level of M (0.20-0.35) or F (0.01-2.0) used in simulations, yield-per-recruit values for Chesapeake Bay were consistently higher at t((c)) = 1 and decreased continuously with increases in t(c) (2-5). Although maximum yield-per-recruit always occurred at the maximum level off (F=2.0), marginal increases in yield beyond F = 0.50-0.75 were negligible. Current F (F(CUR)) is estimated to be …

Age And Growth Of Larval And Juvenile Atlantic Croaker, Micropogonias Undulatus, From The Middle Atlantic Bight And Estuarine Waters Of Virginia, Stephen W. Nixon, Cynthia M. Jones

OES Faculty Publications

Sagittal otoliths were used to determine age and growth of 605 larval and juvenile Atlantic croaker, Micropogonias undulatus, collected in the Middle Atlantic Bight and estuarine waters of Virginia. This study is the first to use age-based analysis for young Atlantic croaker collected in this region. A Laird-Gompertz model (r2=0.95) was used to describe the growth of Atlantic croaker up to 65 mm standard length (SL) and 142 days (t): SL((t)) = 2.657 exp (4.656 [1-exp (-0.0081t)]); where SL((t)) = standard length at day t. Spatial and temporal patterns in the size and age of Atlantic croaker showed a …

Destruction Of Chloropigments In Copepod Guts, A. B. Bochdansky, D. Deibel

OES Faculty Publications

In a recent account regarding the destruction of chloropigments within the guts of copepods, Head & Harris (1996) (H&H) presented valuable data on pigment destruction in copepods. However, in one of their main conclusions, the authors invoked 2 enzyme pools to explain the pattern of pigment destruction: one directly derived from copepods, the other one produced by the ingested algae. If this conclusion is correct, it would have tremendous impact on the interpretation of data collected by the gut pigment technique. Estimating ingestion rates of copepods in the field would be very difficult, if not impossible, if pigment destruction was …

Fluxes Of Copper-Complexing Ligands From Estuarine Sediments, Stephen A. Skrabal, John R. Donat, David J. Burdige

OES Faculty Publications

Most studies of the organic complexation of Cu in natural waters have focused on distributions and processes in the water column, where a significant fraction of Cu-complexing ligands may be biologically produced. We present direct evidence for a flux of Cu-complexing ligands from estuarine sediments, demonstrating that sediments are a significant, yet previously unrecognized source of the ligands. Fluxes of Cu-complexing ligands from Chesapeake Bay sediments range from 300 to 1,200 nmol m^-2 d^-1, exceeding fluxes of total dissolved Cu by 3->40-fold, suggesting that any Cu fluxing from the sediments is likely to be organically complexed. …

Response Of Otolith Microchemistry To Environmental Variations Experienced By Larval And Juvenile Atlantic Croaker (Micropogonias Undulatus), Simon R. Thorrold, Cynthia M. Jones, Steven E. Campana

OES Faculty Publications

Minor and trace elements incorporated into otoliths during growth may permanently record environmental conditions experienced by fishes. To determine the validity of this approach, we used laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to assay sectioned otoliths from juvenile Atlantic croaker (Micropogonias undulatus) collected from each of three sites in the Neuse River, North Carolina, and the Elizabeth River, Virginia. Elemental concentrations at the center of the otoliths did not differ between locations, although both Mg : Ca and Ba : Ca were significantly higher at the edge of otoliths from the Neuse River than from the …

Distribution Of Free Marine Viruses Of Lower Chesapeake Bay And Their Effects On Life-History Parameters Of The Estuarine Copepod Acartia Tonsa Dana, Lisa A. Drake

OES Theses and Dissertations

Naturally occurring viruses are very abundant in fresh, estuarine, and marine waters, with densities on the order of 10⁵-10⁸ viruses ml^-1. Research has focused on virus effects on bacteria, cyanobacteria, and phytoplankton, as well as mechanisms of virus production and decay. However, little is known about the distribution of viruses in benthic environments or virus effects on organisms in higher trophic levels.

To determine the distribution of virus-like particles (VLPs) and bacteria in the lower Chesapeake Bay, vertical profiles of VLPs and bacteria were determined through the water column and 15-25 cm into the sediment …

Modeling Plankton Community Structure Under Environmental Forcing On The Southeastern United States Continental Shelf, Andrew Glenn Edward Haskell

OES Theses and Dissertations

A system of coupled ordinary differential equations was developed to investigate the time-dependent behavior of phytoplankton, copepod, and doliolid populations associated with upwelling features on the outer southeastern U.S. continental shelf. Model equations describe the interactions of nitrate, ammonium, two phytoplankton size fractions, five copepod developmental stages, doliolids, and a detrital pool. Model dynamics are based primarily upon data obtained from field and laboratory experiments made for southeastern U.S. continental shelf plankton populations. Numerous simulations were performed to investigate the effects of environmental variability on the temporal distribution of the structure of resident plankton populations. Variations on a reference simulation, …