Physical Sciences and Mathematics Commons^™

Salinity History Of Coastal Marshes Reconstructed From Diatom Remains, Michael L. Parsons, Quay Dortch, R. Eugene Turner, Nancy N. Rabalais

Faculty Publications

Sediment cores were collected from three Louisiana coastal marsh ponds, dated with radioisotopes, and analyzed for diatom remains to determine if long-term salinity changes were evident in the sediment record. A diatom-based salinity index formulated from a statistical comparison of available salinity data and changing diatom assemblages demonstrated that diatom remains appear to preserve salinity signals in coastal brackish and salt marsh environments. The salinity index was applied to sediment cores spanning the late 1600s to the 1990s and provided a more complete record of salinity than field data, which were temporally and spatially incomplete. The salinity reconstructions indicated that …

Internal Waves Revealed By Synthetic Aperture Radar (Sar) Imagery In The Vicinity Of The Eastern Cretan Arc Straits (Eastern Mediterranean), Adonis Velegrakis, E. Oikonomou, A. Theocharis, M Collins, H Kontoyannis, V Papadopoulos, George Voulgaris, T. Wells, E. Balopoulos

George Voulgaris

Internal waves have been detected on ERS-1 SAR images obtained during late summer over the eastern Cretan Straits, an area characterised by complex regional physiography, bottom topography, flow regime and stratification patterns of the upper part of the water column. Analysis of the imaged characteristics of the internal waves has revealed a strong diversity in form, propagation direction and type of sea surface modulation, which indicates various mechanisms of generation. Analysis of the currents recorded over the area shows that, although semi-diurnal tidal currents are present, these are of low magnitude in comparison with the overall flow and, therefore, tidal …

Fall 1999, Nsu Oceanographic Center

Currents

No abstract provided.

What Does It Take To Become A Marine Scientist?, Virginia Institute Of Marine Science

Reports

Note: This material may not meet current educational standards and is presented as part of the Institute's historical publications.

Report On Spectral Wave Modeling : Extended Study Of The Effects Of Sand Mining On The Wave Regime At Sandbridge, Virginia - Comparison Of Results Using A Phase-Revolving And A Phase-Averaging Spectral Wave Model (Ref/Dif S And Swan), John D. Boon, Sung Chan Kim

Reports

In an earlier report (Boon, 1998), findings were presented from a wave modeling study whose purpose was to investigate the effects of sand mining on the nearshore wave regime at Sandbridge, Virginia (Fig . 1). Using a phase-resolving spectral wave model, REF/DIF S (Kirby and Ozkan, 1992), a representative set of hypothetical storm waves was propagated across a 20 km section of the inner shelf from approximately the 20 m depth contour offshore to the 11 m depth contour inshore . Subsequent simulations were then made that tested local effects of shoaling and refraction on wave heights within a fine-scale …

Summer 1999, Nsu Oceanographic Center

Currents

No abstract provided.

The Impact Of Accelerating Land-Use Change On The N-Cycle Of Tropical Aquatic Ecosystems: Current Conditions And Projected Changes, J. A. Downing, M. Mcclain, R. Twilley, J. M. Melack, J. Elser, Nancy N. Rabalais, W. M. Lewis Jr., R. Eugene Turner, J. Corredor, D. Soto, A. Yanez Arancibia, J. A. Kopaska, R. W. Howarth

Faculty Publications

Published data and analyses from temperate and tropical aquatic systems are used to summarize knowledge about the potential impact of land-use alteration on the nitrogen biogeochemistry of tropical aquatic ecosystems, identify important patterns and recommend key needs for research. The tropical N-cycle is traced from pre-disturbance conditions through the phases of disturbance, highlighting major differences between tropical and temperate systems that might influence development strategies in the tropics. Analyses suggest that tropical freshwaters are more frequently N-limited than temperate zones, while tropical marine systems may show more frequent P limitation. These analyses indicate that disturbances to pristine tropical lands will …

Nitrate Reductase Activity, Nitrate Uptake And Iodine Speciation In The Marine Environment, Chin-Chang Hung

OES Theses and Dissertations

The present method for the determination of new production (NP) by measuring the uptake of added ¹⁵NO₃^– suffers from a number of limitations. In an attempt to improve this situation, this research examined the possibility of estimating ¹⁵NO₃– uptake by measuring the activity of nitrate reductase (NRA). In addition, because it has long been suspected that the biological reduction of IO₃^– to I^– may be mediated by nitrate reductase (NR), this research investigated the ability of NR to catalyze the reduction of iodate to iodide.

An improved method for the determination …

Seawifs Satellite Ocean Color Data From The Southern Ocean, Jk Moore, Mr Abbott, Rg Richman, Walker O. Smith Jr., Et Al

VIMS Articles

SeaWiFS estimates of surface chlorophyll concentrations are reported for the region of the U.S. JGOFS study in the Southern Ocean (similar to 170 degrees W, 60 degrees S). Elevated chlorophyll was observed at the Southern Ocean fronts, near the edge of the seasonal ice sheet, and above the Pacific-Antarctic Ridge. The elevated chlorophyll levels associated with the Pacific-Antarctic Ridge are surprising since even the crest of the ridge is at depths > 2000 m. This elevated phytoplankton biomass is likely the result of mesoscale physical-biological interactions where the Antarctic Circumpolar Current (ACC) encounters the ridge. Four cruises surveyed this region between …

Characterization Of Hypoxia: Topic 1 Report For The Integrated Assessment On Hypoxia In The Gulf Of Mexico, Nancy N. Rabalais, R. Eugene Turner, Dubravko Justic, Quay Dortch, William J. Wiseman

Faculty Publications

No abstract provided.

Poc Production And Export In The Indian Ocean Sector Of The Southern Ocean: A Us-China Collaborative Research Program, Cynthia H. Pilskaln, Fei Chai

University of Maine Office of Research Administration: Grant Reports

This proposed work is a study of the biological production and export flux of biogenic matter in response to ventilation of intermediate and deep water masses within the Polar Front zone. It is a collaborative work between the University of Maine and the Chinese Antarctic Research Expedition (CHINARE). The shipboard work is proposed for the Chinese antarctic resupply vessel off Prydz Bay in the Indian Ocean sector. In the austral Spring, this region experiences phytoplankton blooms that are thought to be the result of nutrient transport by the ventilation of intermediate and deep water masses. On an annual basis, it …

Nutrient Enhanced Coastal Ocean Productivity In The Northern Gulf Of Mexico, William J. Wiseman Jr., Michael J. Dagg, Nancy N. Rabalais, Terry E. Whitledge

Faculty Publications

No abstract provided.

Spring 1999, Nsu Oceanographic Center

Currents

No abstract provided.

Production Of Copper-Complexing Ligands In Response To Elevated Concentrations Of Copper In Marine Synechococcus Spp., Arunsri Chatkaeomorakot Brown

Theses and Dissertations in Biomedical Sciences

Synechococcus spp. (marine cyanobacteria) are extremely sensitive to copper toxicity and can produce high-affinity ligands of unknown structure which form complexes with free cupric ion. These ligands may contribute to the biological control of the levels of free cupric ions in surface seawater. Synechococcus spp. are known to produce metallothioneins (MT) in response to cadmium and zinc stress. In the present study the hypothesis that marine Synechococcus produce MT in response to copper was tested. Three marine Synechococcus spp. i.e., PCC 7001, PCC 73109, and PCC 7003, were exposed to different concentrations of CUSO 4 for various time periods. Size …

Benthic Community Analysis Of Hog Island Bay, Virginia, David James Lewis

Biological Sciences Theses & Dissertations

The benthic infaunal macroinvertebrate communities of Hog Island Bay of the Virginia Eastern Shore were quantitatively sampled at 30 locations on August 31 and September 1, 1995. The primary objectives of this study were: (1) to characterize the subtidal macroinfaunal benthic communities of Hog Island Bay, (2) to examine relationships between abiotic factors and the macroinfaunal communities and (3) to characterize the environmental condition of the system using the Benthic Index of Biotic Integrity (B-IBI) (Weisburg et al. 1997) and the EMAP Benthic Index for the Virginian Province (Strobel et al. 1995).

The ecological condition of Hog Island Bay appears …

Three Dimensional Hydrodynamic-Sedimentation Modeling Study : Hampton Roads Crossing, Lower James River, Virginia, John D. Boon, Harry V. Wang, S. C. Kim, Albert Y. Kuo, G. M. Sisson

Reports

A three-dimensional hydrodynamic-sedimentation computer model, HYSED-3D, was used to evaluate the effect of bridge-tunnel infrastructure for a proposed highway crossing of Hampton Roads on the physical characteristics (tides, currents, circulation, salinity, and sedimentation) of the James River estuary in Virginia. Model-represented infrastructure included tunnel islands and bridges on pilings connecting the islands to interstate highways in Newport News, Hampton, Norfolk, and Portsmouth, Virginia. Combinations of these elements occur in each of three proposed crossing routes designated Alternative 1 (Hampton-Norfolk), Alternative 2 (Hampton-Norfolk, Norfolk-Portsmouth), and Alternative 9 (Newport News-Portsmouth-Norfolk). Simulation comparisons were made between the existing waterways and infrastructure in Hampton …

Holocene Climate In Coastal Peru: Potential Implications For Climate Dynamics During The Hypsithermal Period, James D. Wright

University of Maine Office of Research Administration: Grant Reports

This pilot study will analyze stable isotopes in planktic foraminifera in sediment cores off the coast of Peru for the Holocene interval. In many regions of the world the early Holocene is believed to have been a time of warmer-than modern temperatures. Data derived from Peruvian middens give conflicting evidence as to whether this period was somewhat warmer or cooler than today. The foraminiferal data should provide a record of sea surface temperatures and seasonal upwelling along coastal Peru throughout the Holocene, including the period of human coastal settlement.

1999 Gloucester Point Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans

Miscellaneous

These calendars are produced monthly using David Evans' Tidecal.

Analyzing Mean Transport Equations Of Turbulence And Linear Disturbances In Decaying Flows, W. D. Thacker, T. B. Gatski, C. E. Grosch

CCPO Publications

The decay of laminar disturbances and turbulence in mean shear-free flows is studied. In laminar flows, such disturbances are linear superpositions of modes governed by the Orr-Sommerfeld equation. In turbulent flows, disturbances are described through transport equations for representative mean quantities. The link between a description based on a deterministic evolution equation and a probability-based mean transport equation is established. Because an uncertainty in initial conditions exists in the laminar as well as the turbulent regime, a probability distribution must be defined even in the laminar case. Using this probability distribution, it is shown that the exponential decay of the …

An Iron-Based Ecosystem Model Of The Central Equatorial Pacific, Carrie L. Leonard, Charles R. Mcclain, Ragu Murtugudde, Eileen E. Hofmann, Lawrence W. Harding Jr.

CCPO Publications

The central and eastern equatorial Pacific region is characterized by lower than expected phytoplankton biomass and primary production given the relatively high ambient nitrate concentrations. These unusual conditions have spawned several field programs and laboratory experiments to determine why this high nitrate-low chlorophyll pattern persists in this region. To synthesize the results from these field programs, as well as providing additional evidence in support of the iron hypothesis, we developed a one-dimensional, nine-component ecosystem model of 0 degrees N 140 degrees W. The model components include two phytoplankton size fractions, two zooplankton size fractions, two detrital size fractions, dissolved iron, …

Frontogenesis In The North Pacific Oceanic Frontal Zones--A Numerical Simulation, Michael S. Dinniman, Michele M. Rienecker

CCPO Publications

A primitive equation model [Geophysical Fluid Dynamics Laboratory's (GFDL's) MOM 2] with one degree horizontal resolution is used to simulate the seasonal cycle of frontogenesis in the subarctic frontal zone (SAFZ) and the subtropical frontal zone (STFZ) of the North Pacific Ocean. The SAFZ in the model contains deep (greater than 500 m in some places) regions with seasonally varying high gradients in temperature and salinity. The gradients generally weaken toward the east. The STFZ consists of a relatively shallow (less than 200 m in most places) region of high gradient in temperature that disappears in the summer/fall. The high …

Decadal Variabilities Of The Upper Layers Of The Subtropical North Atlantic: An Ocean Model Study, Tal Ezer

CCPO Publications

Numerical simulations of the Atlantic Ocean during the period 1950 to 1989, using a sigma coordinate, free surface numerical model, show long-term variabilities in the upper ocean subtropical gyre similar to those obtained from observations. The simulations show how westward propagating planetary waves, originated in the eastern North Atlantic, affect interdecadal variabilities of ocean properties such as the Bermuda sea level, the Gulf Stream position and strength, and subsurface temperature anomalies in the western North Atlantic. Special attention is given to the dramatic sea level drop at Bermuda in the early 1970s, which is accompanied by cooling of subsurface layers …

Modification Of No, Po, And No/Po During Flow Across The Bering And Chukchi Shelves: Implications For Use As Arctic Water Mass Tracers, Lee W. Cooper, Glenn F. Cota, Lawrence R. Pomeroy, Jacqueline M. Grebmeier, Terry E. Whitledge

CCPO Publications

The NO and PO tracers (9[NO₃-] + 02 and 135[PO₄-] + 02, respectively,) and their derivative NO/PO have found increasing use in Arctic water mass analyses for identifying the specific basin or shelf areas from which surface waters originate, based upon assumed differences in Pacific- and Atlantic-derived content and basin-to-basin differences within the Arctic. Following shipboard sampling in June-September 1993 and May-June 1994, both north and south of Bering Strait, we have found evidence that Pacific-derived waters flowing north to Bering Strait do not necessarily have any unique NO, PO, or NO/PO identity that would permit …

Warm Water Formation And Escape In The Upper Tropical Atlantic Ocean - 1. A Literature Review, Sang-Ki Lee, G. T. Csanady

CCPO Publications

We review current understanding of the warm water formation and escape process in the tropical Atlantic Ocean and point out the physical aspects of the process not yet fully explored. From this review, we found a need for a simple model capable of describing the first-order heat and mass balance in the tropical Atlantic Ocean. This line of work is continued in part 2 [Lee and Csanady, this issue]. Copyright 1999 by the American Geophysical Union.

A Two-Dimensional Analytic Tidal Model For A Narrow Estuary Of Arbitrary Lateral Depth Variation: The Intratidal Motion, Chunyan Li, Arnoldo Valle-Levinson

CCPO Publications

An innovative method is introduced to solve a two-dimensional, depth-averaged analytic model for narrow estuaries or tidal channels with arbitrary lateral depth variations. The solution is valid if the lateral variation of the amplitude of tidal elevation (\Delta a\) is small, i.e., \Delta a\ much less than a, where a is the amplitude of the tidal elevation. This assumption is supported by a 60-day observation of elevation in the James River Estuary using pressure sensors at both sides of a cross section of the estuary. The error introduced by the solution is of the order of \Delta a\/a, which has …

1999 Hampton Roads Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans

Miscellaneous

These calendars are produced monthly using David Evans' Tidecal.

1999 Wachapreague Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans

Miscellaneous

These calendars are produced monthly using David Evans' Tidecal.

Winter 1999, Nsu Oceanographic Center

Currents

No abstract provided.

Protease Inhibitors Of The Eastern Oyster, Crassostrea Virginica, And Their Relationship To The Protozoan Pathogen, Perkinsus Marinus, Jacques L. Oliver

Dissertations, Theses, and Masters Projects

No abstract provided.

The Cause And Consequence Of Ontogenetic Changes In Social Aggregation In New Zealand Spiny Lobsters, Mark J. Butler Iv, Alistair B. Macdiarmid, John D. Booth

Biological Sciences Faculty Publications

Ontogenetic changes in the behavior, spatial distribution, or habitat use of a species are presumably adaptations to ecological forces that differ in their effect on various life stages. The New Zealand rock lobster Jasus edwardsii is one of several species of spiny lobster that exhibits dramatic ontogenetic shifts in sociality and spatial distribution, and we tested whether such changes are adaptive. We first surveyed several natural populations of J. edwardsii to document size-specific differences in aggregation. To determine if chemical cues discharged by conspecifics promote aggregation of certain ontogenetic stages, we tested the responsiveness of lobsters of 3 ontogenetic stages …