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Public Beach Assessment Report Gloucester Point Public Beach, Gloucester County, Virginia, Donna A. Milligan, C. Scott Hardaway Jr., George R. Thomas

Reports

Gloucester Point Public Beach is located at the southern end of Gloucester County, Virginia on the York River. It is a southeastward facing shoreline about 960 ft long and it is part of a larger stretch of moderately low shore between Sarah Creek and the George P. Coleman Bridge. While no shoreline improvement projects have taken place at the public beach, shore protection projects updrift and including the Virginia Institute of Marine Science (VIMS) affect it. In 1983, erosion along the shoreline at VIMS just updrift of the public beach led to the installation of a riprap revetment in front …

Modeling Nutrient And Plankton Processes In The California Coastal Transition Zone: 3. Lagrangian Drifters, J. R. Moisan, Eileen E. Hofmann

CCPO Publications

Two types of numerical Lagrangian drifter experiments were conducted, using a set of increasingly complex and sophisticated models, to investigate the processes associated with the plankton distributions in the California coastal transition zone (CTZ). The first experiment used a one-dimensional (1-D; vertical) time-dependent physical-bio-optical model, which contained a nine-component food web. Vertical velocities, along the track of simulated Lagrangian drifters, derived from a three-dimensional (3-D), primitive equation circulation model developed to simulate the flow observed within the CTZ; were used to parameterize the upwelling and downwelling processes. The second experiment used 880 simulated Lagrangian drifters from a 3-D primitive equation …

Modeling Nutrient And Plankton Processes In The California Coastal Transition Zone: 1. A Time- And Depth-Dependent Model, J. R. Moisan, Eileen E. Hofmann

CCPO Publications

A time- and depth-dependent, physical-bio-optical model was developed for the California coastal transition zone (CTZ) with the overall objective of understanding and quantifying the processes that contribute to the vertical and temporal development of nutrient and plankton distributions in the CTZ. The model food web components included silicate, nitrate, ammonium, two phytoplankton size fractions, copepods, doliolids, euphausiids, and a detritus pool. The wavelength-dependent subsurface irradiance field was attenuated by sea water and phytoplankton pigments. The one-dimensional (1-D) model adequately simulated the development and maintenance of a subsurface chlorophyll maximum in different regions within the CTZ. An analysis of the individual …

Modeling Nutrient And Plankton Processes In The California Coastal Transition Zone: 2. A Three-Dimensional Physical-Bio-Optical Model, J. R. Moisan, Eileen E. Hofmann, D. B. Haidvogel

CCPO Publications

A three-dimensional (3-D) primitive equation model, developed to simulate the circulation features (filaments) observed in the California coastal transition zone (CTZ), was coupled to a nine-component food web model and a bio-optical model. The simulated flow fields from a 3-D primitive equation model are used to advect the constituents of the food web model, which include silicate, nitrate, ammonium, two phytoplankton size fractions, copepods, doliolids, euphausiids, and a detritus pool. The bio-optical model simulates the wavelength-dependent attenuation of the subsurface irradiance field. The overall objective of this modeling study was to understand and quantify the processes that contribute to the …

Seasonal And Inter-Annual Patterns Of Sediment-Water Nutrient And Oxygen Fluxes In Mobile Bay, Alabama (Usa): Regulating Factors And Ecological Significance., Jean L. Cowan, Jonathan Pennock, Walter R. Boynton

School of Marine Science and Ocean Engineering

Sediment oxygen and nutrient fluxes were measured monthly for 2 yr in Mobile Bay, Alabama, USA. Rates of sediment oxygen consumption (0.1 to 1.25 gO₂ m^-2 d^-1), ammonium flux (-22 to 181 µmol m^-2 h^-1), nitrate flux (-14 to 67 µmol m^-2 h^-1), phosphate flux (-2 to 20.4 µmol m^-2 h^-1), and dissolved silicate flux (-15 to 342 µmol m^-2 h^-1) were moderate to high compared to values for other estuaries. A step-wise regression analysis revealed that dissolved oxygen concentration and temperature in bottom-waters …

Nutrients And Chlorophyll At The Shelf Break Off The Southeastern United States During The Genesis Of Atlantic Lows Experiment: Winter 1986, L. P. Atkinson, J. L. Miller, T. N. Lee, W. M. Dunstan

CCPO Publications

The outer shelf and upper slope off Charleston, South Carolina, were the site of oceanographic and meteorological measurements during the winter of 1986. The purpose of the study was to test ideas about front formation, heat transport, and stratification during cold air outbreaks. An ancillary part of the study was the observation of nutrients and chlorophyll concentrations. The observations extended across the shelf and sometimes crossed the Gulf Stream front. The results show slightly elevated nitrate concentrations in outer shelf waters (1 - 2 μM NO₃) with chlorophyll concentrations in the 1 - 1.8 μg L^-1 range. …

Effects Of Climate Change On Hypoxia In Coastal Waters: A Doubled Co2 Scenario For The Northern Gulf Of Mexico, Dubravko Justic, Nancy N. Rabalais, R. Eugene Turner

Faculty Publications

Projections of general circulation models suggest that freshwater discharge from the Mississippi River to the coastal ocean will increase 20% if atmospheric CO2 concentration doubles. This result is likely to affect water column stability, surface productivity, and global oxygen cycling in the northern Gulf of Mexico, which is the site of the largest (up to 16,500 km2) and most severe hypoxic zone (liter‒1) in the western Atlantic Ocean. We use a coupled physical-biological two-box model to investigate potential effects of climate change on seasonal oxygen cycling and hypoxia in river-dominated coastal waters. The model was developed and calibrated using comprehensive …

Nutrient Changes In The Mississippi River And System Responses On The Adjacent Continental Shelf, Nancy N. Rabalais, R. Eugene Turner, Dubravko Justic, Quay Dortch, William J. Wiseman, Barun Sen Gupta

Faculty Publications

The Mississippi River system ranks among the world's top 10 rivers in freshwater and sediment inputs to the coastal ocean. The river contributes 90% of the freshwater loading to the Gulf of Mexico, and terminates amidst one of the United States' most productive fisheries regions and the location of the largest zone of hypoxia, in the western Atlantic Ocean. Significant increases in riverine nutrient concentrations and loadings of nitrate and phosphorus and decreases in silicate have occurred this century, and have accelerated since 1950. Consequently, major alterations have occurred in the probable nutrient limitation and overall stoichiometric nutrient balance in …

1996 Gloucester Point Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans

Miscellaneous

These calendars are produced monthly using David Evans' Tidecal.

Circulation Near Submarine Canyons: A Modeling Study, John M. Klinck

CCPO Publications

Circulation near a submarine canyon is analyzed with a numerical model. Previous theoretical work indicated that stratification controlled the interaction of coastal flow with canyons, specifically, the ratio of canyon width to the internal radius of deformation. A wide canyon was thought to merely steer the flow, while a narrow canyon would create substantial cross-shelf exchange. Four cases are analyzed considering two directions of alongshore flow and two choices of initial stratification. The weakly stratified case has an internal radius about equal to the canyon width, while the strongly stratified case has one about 3 times the canyon width. The …

Modeling The Vertical Distribution Of Oyster Larvae In Response To Environmental Conditions, Margaret M. Dekshenieks, Eileen E. Hofmann, John M. Klinck, Eric N. Powell

CCPO Publications

A size-structured, time and vertically-dependent model was used to investigate the effects of water column structure on the distribution of larvae of the oyster Crassostrea virginica. Formulations used to model larval growth and behavior are based upon laboratory studies. Simulated vertical larval distributions obtained for conditions representative of a well-mixed, partially stratified and strongly stratified water column illustrate the effect that salinity and temperature gradients have on moderating larval swimming and hence on larvae vertical location. For well-mixed conditions, smaller larvae are dispersed throughout most of the water column. For strongly stratified conditions, the smaller-sized larvae cluster within the …

1996 Hampton Roads Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans

Miscellaneous

These calendars are produced monthly using David Evans' Tidecal.

Linking Sediment Transport And Stratigraphy On The Continental Shelf, Patrica Wiberg, David Cacchione, Richard Sternberg, L. Donelson Wright

VIMS Articles

The goal of the shelf sediment dynamics component of STRATAFORM is to link sediment transport processes active on the continental shelfto the formation and preservation of event beds inshelf sediment deposits. An approach combining
shelf sediment-transport models with high-resolution measurements of water-column and bed properties over periods from several months to several
years allows us to make quantitative estimates of bed modification caused by sediment resuspension during episodic transport events.

Temporal And Spatial Patterns In The Ross Sea: Phytoplankton Biomass, Elemental Composition, Productivity And Growth Rates, Walker O. Smith Jr., David Nelson, Giacomo R. Ditullio, Amy R. Leventer

VIMS Articles

The temporal and spatial patterns of phytoplankton biomass, productivity, and particulate matter composition in the Ross Sea were assessed during cruises in January 1990 and February 1992. Biomass and primary productivity in the southern Ross Sea were greatest during mid-January, with surface chlorophyll concentrations, particulate organic carbon levels, and integrated primary productivity averaging 4.9 Ixg L 'l, 0.54 mg L-•, and 2.63 g C m"• d '•, respectively. Comparable mean concentrations and rates for February were 1.1 Ixg L 'l, 0.29 mg L 'l, and 0.78 g C m '•- d '• (decreases of 76, 46, and 70%, respectively), indicative …

Linking Sediment Transport And Stratigraphy On The Continental Shelf, Pl Wilberg, Da Cacchione, Rw Sternberg, L. Donelson Wright

VIMS Articles

The goal of the shelf sediment dynamics component of STRATAFORM is to link sediment transport processes active on the continental shelf to the formation and preservation of event beds in shelf sediment deposits. An approach combining shelf sediment-transport models with high-resolution measurements of water-column and bed properties over periods from several months to several years allows us to make quantitative estimates of bed modification caused by sediment resuspension during episodic transport events. These modifications include erosion and deposition of bed material, formation of graded storm beds, and changes in small-scale bed surface morphology. The characteristics of the resulting “event bed” …

Organic Matter Accumulation, Sulfate Reduction, And Methanogenesis In Pliocene–Pleistocene Turbidites On The Iberia Abyssal Plain, P. A. Meyers, Timothy J. Shaw

Faculty Publications

No abstract provided.

User's Manual For The Environmental Fluid Dynamics Computer Code, John M. Hamrick

Reports

No abstract provided.

The Implications Of Turbidite-Driven Redox Changes In Sediments Of The Iberia Abyssal Plain, Timothy J. Shaw, P. A. Meyers

Faculty Publications

No abstract provided.

Hydrodynamics Of Sediment Suspensions In The Littoral Zone Of The Lower York River - Phase I, John D. Boon

Reports

Motivation for this study derives from a need to know more about processes governing sediment suspension within the shallow waters of the littoral zone (depths< 2m) in coastal estuaries. These are regions in which bottom sediment, in the absence of vegetative cover and depending on grain sizes present, has the potential to be actively eroded and entrained in the water column by wind waves and/or currents. Suspended sediment has the further potential to impact water quality and promote eutrophication through nutrient enrichment processes (Kemp et al., 1983; Orth and Moore, 1983). High sediment loadings also lead to light reduction in the photic zone which can impact the growth or survival of submerged aquatic vegetation (De Groot and de Jonge, 1990).

A Coupled, Non-Linear, Steady State Model For Early Diagenetic Processes In Pelagic Sediments, Surya P. Dhakar, David J. Burdige

OES Faculty Publications

A steady state, coupled, non-linear model has been developed for early diagenetic processes in pelagic and hemi-pelagic marine sediments. Model results show that the occurrence of oxic and sub-oxic diagenetic processes is significantly affected by variations in parameters such as the sedimentation rate, bioturbation coefficient, sediment porosity, and organic matter flux to the sediments. Increases in the sedimentation rate or the bioturbation coefficient increase organic matter oxidation by sub-oxic processes, whereas an increase in sediment porosity decreases organic matter oxidation by sub-oxic processes. Sediment data from three contrasting MANOP sites are fit reasonably well with the model. The resulting best-fit …

Effect Of Light/Dark Transition On Carbon Translocation In Eelgrass Zostera Marina Seedlings, Richard C. Zimmerman, Randall S. Alberte

OES Faculty Publications

Carbon translocation in the marine macrophyte Zostera marina L. (eelgrass) was investigated to elucidate the impact of light/dark transitions on sucrose partitioning between roots and shoots. After exposure of leaves to C-14-bicarbonate, the level of C-14-labelled photoassimilates increased monotonically in both leaves and fully aerobic roots of plants maintained in the light. Accumulation of C-14 in roots and leaves ceased abruptly when plants were transferred to darkness that induced root anaerobiosis even though C-14 levels remained high in the dark-exposed leaves. Thus, translocation of C-14 photoassimilates from shoots to roots was inhibited when roots became anoxic. Anoxia induced by light …

Biogenic Matter Diagenesis On The Sea Floor: A Comparison Between Two Continental Margin Transects, William M. Berelson, Jim Mcmanus, Kenneth H. Coale, Kenneth S. Johnson, Tammy Kilgore, David J. Burdige, Cynthia Pilskaln

OES Faculty Publications

Benthic chamber measurements of the reactants and products involved with biogenic matter diagenesis (oxygen, ammonium, nitrate, silicate, phosphate, TCO₂, alkalinity) were used to define fluxes of these solutes into and out of the sediments off southern and central California. Onshore to offshore transects indicate many similarities in benthic fluxes between these regions. The pattern of benthic organic carbon oxidation as a function of water depth, combined with published sediment trap records, suggest that the supply of organic carbon from vertical rain can just meet the sedimentary carbon oxidation + burial demand for the central California region between the …

Hydrodynamics Of Sediment Suspensions In The Littoral Zone Of The Lower York River - Phase Ii, John D. Boon

Reports

This report covers the second year (Phase II) of a two-year study. An earlier contract report (Boon,1996) was submitted in January, 1996, to the Virginia Coastal Resources Management Program covering the first year (Phase I) results of a wave , current and suspended sediment monitoring study conducted at the mouth of the York River (Figure 1).

The purpose of the monitoring study , as originally planned , was to investigate processes governing sediment suspension within the shallow waters of the littoral zone (depths< 2m) in coastal estuaries. These are regions in which bottom sediment, in the absence of vegetative cover and depending on sediment grain sizes present, has the potential to be actively eroded and entrained in the water column by wind waves and/or currents. Suspended sediment has the further potential to impact water quality and promote eutrophication through nutrient enrichment processes (Kemp et al., 1983; Orth and Moore, 1983). High sediment loadings also lead to light reduction in the photic zone which can impact the growth or survival of submerged aquatic vegetation (De Groot and de Jonge, 1990) .