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Factors Influencing Organic Carbon Recycling And Burial In Skagerrak Sediments, H. Ståhl, A. Tengberg, J. Brunnegård, E. Bjørnbom, T. L. Forbes, A. B. Josefson, H. G. Kaberi, I. M. Karle Hassellöv, F. Olsgard, P. Roos, P. O. J. Hall Jan 2004

Factors Influencing Organic Carbon Recycling And Burial In Skagerrak Sediments, H. Ståhl, A. Tengberg, J. Brunnegård, E. Bjørnbom, T. L. Forbes, A. B. Josefson, H. G. Kaberi, I. M. Karle Hassellöv, F. Olsgard, P. Roos, P. O. J. Hall

Journal of Marine Research

Different factors influencing recycling and burial rates of organic carbon (OC) were investigated in the continental margin sediments of the Skagerrak (NE North Sea). Two different areas, one in the southern and one in the northeastern part of the Skagerrak were visited shortly after a spring bloom (March 1999) and in late summer (August 2000). Results suggested that: (1) Organic carbon oxidation rates (Cox) (2.2–18 mmol C m-2d-11) were generally larger than the O2 uptake rates (1.9 –25 mmol m-2d-1). Both rates were measured in situ using a benthic …

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Decision Process For Identification Of Estuarine Benthic Impairments, Roberto J. Llansó, Jon H. Volstad, Daniel M. Dauer Nov 2003

Decision Process For Identification Of Estuarine Benthic Impairments, Roberto J. Llansó, Jon H. Volstad, Daniel M. Dauer

Benthic Applications

To meet the requirements of the Clean Water Act, the States of Maryland and Virginia are in the process of developing biological criteria for evaluating estuarine waters. The Chesapeake Bay Benthic Index of Biotic Integrity (B-IBI) is the basis for these biological criteria. As an initial step, a Workgroup developed an interim framework for the application of the B-IBI to the States’ water quality inventory report (305b report) and list of impaired waters (303d list). The Workgroup included representatives of the Maryland Department of the Environment (MDE), Maryland Department of Natural Resources (MDNR), Virginia Department of Environmental Quality (DEQ), USEPA …

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Global Patterns Of Dissolved N, P And Si In Large Rivers, R. Eugene Turner, Nancy N. Rabalais, D. Justic', Q. Dortch Jul 2003

Global Patterns Of Dissolved N, P And Si In Large Rivers, R. Eugene Turner, Nancy N. Rabalais, D. Justic', Q. Dortch

Faculty Publications

The concentration of dissolved inorganic nitrogen (DIN), dissolved nitrate-N, Total-N (TN), dissolved inorganic phosphate (DIP), total phosphorus (TP), dissolved silicate-Si (DSi) and their ratios in the world's largest rivers are examined using a global data base that includes 37% of the earth's watershed area and half its population. These data were compared to water quality in 42 subbasins of the relatively well-monitored Mississippi River basin (MRB) and of 82 small watersheds of the United States. The average total nitrogen concentration varies over three orders of magnitude among both world river watersheds and the MRB, and is primarily dependent on variations …

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Interpreting Wind-Driven Southern Ocean Variability In A Stochastic Framework, Philip Sura, Sarah T. Gille Jan 2003

Interpreting Wind-Driven Southern Ocean Variability In A Stochastic Framework, Philip Sura, Sarah T. Gille

Journal of Marine Research

A stochastic model is derived from wind stress and bottom pressure gauge data to examine the response of the Antarctic Circumpolar Current (ACC) transport to wind stress forcing. A general method is used to estimate the drift and diffusion coefficients of a continuous stationary Markovian system. As a first approximation, the response of the ACC to wind stress forcing can be described by a multivariate Ornstein-Uhlenbeck process: Gaussian red noise wind stress drives the evolution of the ACC transport, which is damped by a linear drag term. The model indicates that about 30(±10)% of ACC variability is directly driven by …

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A Generic Length-Scale Equation For Geophysical Turbulence Models, L. Umlauf, H. Burchard Jan 2003

A Generic Length-Scale Equation For Geophysical Turbulence Models, L. Umlauf, H. Burchard

Journal of Marine Research

A generalization of a class of differential length-scale equations typically used in second-order turbulence models for oceanic flows is suggested. Commonly used models, like the k-ε model and the Mellor-Yamada model, can be recovered as special cases of this generic model, and thus can be rationally compared. In addition, a method is proposed that yields a generalized framework for the calibration of the most frequently used class of differential length-scale equations. The generic model, calibrated with this method, exhibits a greater range of applicability than any of the traditional models. Stratified flows, plane mixing layers, and turbulence introduced by …

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Relative Dispersion At The Surface Of The Gulf Of Mexico, J. H. Lacasce, Carter Ohlmann Jan 2003

Relative Dispersion At The Surface Of The Gulf Of Mexico, J. H. Lacasce, Carter Ohlmann

Journal of Marine Research

We examine the relative motion of pairs and triplets of surface drifters in the Gulf of Mexico. The mean square pair separations grow exponentially in time from the smallest resolved scale (1 km) to 40-50 km, with an e-folding time of 2-3 days. Thereafter, the dispersion exhibits a power law dependence on time with an exponent of between 2 and 3 (depending on the measure used) up to scales of several hundred kilometers. The straining is for the most part isotropic, with only weak regional variations. But there are suggestions of anisotropy in the western basin, probably due to boundary …

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Control Of Black Sea Intermediate Water Mass Formation By Dynamics And Topography: Comparison Of Numerical Simulations, Surveys And Satellite Data, Emil V. Stanev, Malcolm J. Bowman, Elissaveta L. Peneva, Joanna V. Staneva Jan 2003

Control Of Black Sea Intermediate Water Mass Formation By Dynamics And Topography: Comparison Of Numerical Simulations, Surveys And Satellite Data, Emil V. Stanev, Malcolm J. Bowman, Elissaveta L. Peneva, Joanna V. Staneva

Journal of Marine Research

The processes of cold intermediate water (CIW) formation in the Black Sea are quantified by analyzing the results of numerical simulations using the Modular Ocean Model (MOM) plus observations obtained from both hydrographic surveys and the TOPEX/POSEIDON altimeter. In the first phase of integration the model is forced with seasonally-variable atmospheric data. After reaching a quasi-periodic state, the integration is continued using forcing data for the period 1991-1994 provided by the United Kingdom Meteorological Office. The performance of the model is assessed in reproducing the dominant physical mechanisms that control the process and rate of CIW formation, viz., circulation, vertical …

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On The Generation Of North Brazil Current Rings, Markus Jochum, Paola Malanotte-Rizzoli Jan 2003

On The Generation Of North Brazil Current Rings, Markus Jochum, Paola Malanotte-Rizzoli

Journal of Marine Research

A high resolution general circulation model (OGCM) is used to investigate the life cycle of North Brazil Current (NBC) rings. The focus of the study is on explaining the generation mechanisms of the rings and their vertical structure. The OGCM is used in a configuration simplified as much as possible but capable of reproducing a realistic mean circulation of the tropical Atlantic. Three numerical experiments are analyzed: no wind; steady wind; seasonally varying winds. With wind forcing, a consistent scenario emerges for the generation of NBC rings. It is shown first that the NECC is barotropically unstable, radiating Rossby waves …

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Relations Between Local, Nonlocal, Discrete And Continuous Models Of Bioturbation, Filip J. R. Meysman, Bernard P. Boudreau, Jack J. Middelburg Jan 2003

Relations Between Local, Nonlocal, Discrete And Continuous Models Of Bioturbation, Filip J. R. Meysman, Bernard P. Boudreau, Jack J. Middelburg

Journal of Marine Research

A general framework is proposed that classifies existing bioturbation models according to two dividing lines: discrete/semi-discrete/continuous and local/nonlocal. Based on a common stochastic approach, which models biological reworking of particles as a position jump process, the relationships among the different model classes are exposed and the assumptions underlying each model are explicitly derived. We find that discrete/semi-discrete/continuous formulations are principally equivalent, leaving two basic modeling formalisms: (1) the more inclusive nonlocal exchange formalism and (2) the local biodiffusion model, which is obtained as a special case of the former. Three fundamental criteria determine the applicability of these formalisms, termed the …

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Wave-Induced Boundary Mixing In A Partially Mixed Estuary, Daniel Bourgault, Daniel E. Kelley Jan 2003

Wave-Induced Boundary Mixing In A Partially Mixed Estuary, Daniel Bourgault, Daniel E. Kelley

Journal of Marine Research

We present observations that reveal the existence of horizontally propagating, tidally-driven, high-frequency internal wave (IW) packets in a channel of the partially mixed St. Lawrence Estuary. The packets propagate transversely to the channel axis and collide with the shoaling lateral boundaries. The structure and energy of IWs are diagnosed with a two-dimensional, nonlinear nonhydrostatic model, and the results are compared with weakly nonlinear Korteweg-de-Vries (KdV) theory. The behavior of IWs running into the shoaling lateral boundary is examined in terms of published laboratory and numerical experiments. Our analysis indicates that IWs break on the slope, during which 6% of their …

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Intermediate Water Masses Off South-Southwest Portugal: Chemical Tracers, Graça Cabeçadas, Maria J. Brogueira, Célia Gonçalves Jan 2003

Intermediate Water Masses Off South-Southwest Portugal: Chemical Tracers, Graça Cabeçadas, Maria J. Brogueira, Célia Gonçalves

Journal of Marine Research

Biogeochemical tracers, as dissolved oxygen and nutrients, were measured during several surveys carried out between 1999 and 2001, off south-southwestern Portugal. The dense vertical and horizontal sampling allows the extensions of intermediate water masses present in the region to be resolved. A subsurface minimum salinity water layer, exhibiting values of apparent oxygen utilization (AOU) in the range 40 – 60 μmol/kg and intruding into the study area mainly from the south-southwest, is proposed to be a remnant of the Subarctic Intermediate Water (SAIW). A deeper salinity minimum displaying high concentrations of nutrients and AOU (~100 μmol/kg) and identified as a …

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The Effect Of Fiddler Crab Burrowing On Sediment Mixing And Radionuclide Profiles Along A Topographic Gradient In A Southeastern Salt Marsh, Barbara J. Mccraith, Leonard R. Gardner, David S. Wethey, Willard S. Moore Jan 2003

The Effect Of Fiddler Crab Burrowing On Sediment Mixing And Radionuclide Profiles Along A Topographic Gradient In A Southeastern Salt Marsh, Barbara J. Mccraith, Leonard R. Gardner, David S. Wethey, Willard S. Moore

Journal of Marine Research

Fiddler crabs are one of the principal agents of bioturbation in intertidal salt marshes. The physical, chemical, and biological properties of sediments can be modified by fiddler crab burrowing activity. This study examined the effect of fiddler crab burrowing on sediment reworking and the distributions of 210Pb and 137Cs in salt marsh sediments at North Inlet Estuary, South Carolina. Fiddler crab burrow density, turnover, and volume were measured along a transect from the forest to the creek bank. Burrow density ranged between 40 and 300 burrows m-2 with highest densities at the creek bank. Sediment reworking is …

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Upper Ocean Control On The Solubility Pump Of Co2, Takamitsu Ito, Michael J. Follows Jan 2003

Upper Ocean Control On The Solubility Pump Of Co2, Takamitsu Ito, Michael J. Follows

Journal of Marine Research

We develop and test a theory for the relationship of atmospheric p CO2 and the solubility pump of CO2 in an abiotic ocean. The solubility pump depends on the hydrographic structure of the ocean and the degree of saturation of the waters. The depth of thermocline sets the relative volume of warm and cold waters, which sets the mean solubility of CO2 in the ocean. The degree of saturation depends on the surface residence time of the waters. We develop a theory describing how atmospheric CO2 varies with diapycnal diffusivity and wind stress in a simple, …

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How Estuaries Work: A Charlotte Harbor Example, Robert H. Weisberg, Lianyuan Zheng Jan 2003

How Estuaries Work: A Charlotte Harbor Example, Robert H. Weisberg, Lianyuan Zheng

Journal of Marine Research

We consider the time-averaged, estuarine circulation through a control volume analysis of its mechanical energy balance; hence the title of our paper: "How estuaries work." The venue is the Charlotte Harbor on Florida's west coast, and the analysis medium is the primitive equation ECOM3D-si model. We are motivated by an estuary classification dilemma. Being that estuarine circulation is buoyancy driven by the horizontal salinity gradient, and that the gradient increases with increasing vertical mixing as the salinity isolines rotate from horizontal to vertical, it follows that an increase in mixing should lead to an increase in circulation. Yet, at some …

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Form, Performance And Trade-Offs In Swimming And Stability Of Armed Larvae, Daniel Grünbaum, Richard R. Strathmann Jan 2003

Form, Performance And Trade-Offs In Swimming And Stability Of Armed Larvae, Daniel Grünbaum, Richard R. Strathmann

Journal of Marine Research

Diverse larval forms swim and feed with ciliary bands on arms or analogous structures. Armed morphologies are varied: numbers, lengths, and orientations of arms differ among species, change through development, and can be plastic in response to physiological or environmental conditions. A hydromechanical model of idealized equal-armed larvae was used to examine functional consequences of these varied arm arrangements for larval swimming performance. With effects of overall size, ciliary tip speed, and viscosity factored out, the model suggested trade-offs between morphological traits conferring high swimming speed and weight-carrying ability in still water (generally few arms and low arm elevations), and …

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Stability Of The Global Ocean Circulation: The Connection Of Equilibria Within A Hierarchy Of Models, Henk A. Dijkstra, Wilbert Weijer Jan 2003

Stability Of The Global Ocean Circulation: The Connection Of Equilibria Within A Hierarchy Of Models, Henk A. Dijkstra, Wilbert Weijer

Journal of Marine Research

We address the problem of the multiple equilibria of the thermohaline circulation in a hierarchy of models. The understanding of the relation between bifurcation diagrams of box models, two-dimensional models and those of a global ocean general circulation model, is facilitated through analysis of the equilibrium solutions of a three-dimensional Atlantic-like sector model with an open southern channel. Using this configuration, the subtle effects of the wind-stress field, the effects of continental asymmetry and the asymmetry in the surface freshwater flux can be systematically studied. The results clarify why there is an asymmetric Atlantic circulation under a near equatorially-symmetric buoyancy …

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The Characteristics Of The Recirculating Bulge Region In Coastal Buoyant Outflows, Greg Avicola, Pablo Huq Jan 2003

The Characteristics Of The Recirculating Bulge Region In Coastal Buoyant Outflows, Greg Avicola, Pablo Huq

Journal of Marine Research

A relatively large recirculating gyre, or bulge (anticyclonic buoyant lens) region attached to the source has been observed to occur in some numerical simulations and in some oceanic outflows. The purpose of this paper is to determine the dynamics of such recirculating bulge regions. Laboratory experiments were conducted for the purpose of examining the characteristics, evolution, and impact of a recirculating bulge in a coastal buoyant outflow. All experiments were performed such that the buoyant layer was thin compared to the total water depth, and the width of the bay exit was approximately equal to the internal Rossby deformation radius …

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Reply To: “Comments On ‘A Generic Length-Scale Equation For Geophysical Turbulence Models’ ”By L. Kantha And S. Carniel, Lars Umlauf, Hans Burchard Jan 2003

Reply To: “Comments On ‘A Generic Length-Scale Equation For Geophysical Turbulence Models’ ”By L. Kantha And S. Carniel, Lars Umlauf, Hans Burchard

Journal of Marine Research

Recently, Kantha and Carniel (2003) commented on some earlier work of Kantha (2003) and Umlauf and Burchard (2003) on the formulation of a generalized length-scale equation in Reynolds stress models for geophysical flows. With the present short note, we respond to their major criticism of the Umlauf and Burchard (2003) generic two-equation model...

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Seasonal To Interannual Upper-Ocean Variability In The Drake Passage, Janet Sprintall Jan 2003

Seasonal To Interannual Upper-Ocean Variability In The Drake Passage, Janet Sprintall

Journal of Marine Research

Year-round monitoring of the upper-ocean temperature variability in Drake Passage has been undertaken since September 1996 through repeat expendable bathythermograph (XBT) surveys. The closely spaced measurements (6-15 km apart) provide the first multi-year time series for examining seasonal to interannual variability in this Southern Ocean choke point. While the temperature sections reveal the seasonal variability in water mass formation of the upper layer, there was no seasonal signal evident below 200 m. Similarly, there was little seasonal cycle evident in the position of the Subantarctic Front, the Polar Front and the Southern Antarctic Circumpolar Current Front associated with the Antarctic …

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The Influence Of Macrofaunal Burrow Spacing And Diffusive Scaling On Sedimentary Nitrification And Denitrification: An Experimental Simulation And Model Approach, Franck Gilbert, Robert C. Aller, Stefan Hulth Jan 2003

The Influence Of Macrofaunal Burrow Spacing And Diffusive Scaling On Sedimentary Nitrification And Denitrification: An Experimental Simulation And Model Approach, Franck Gilbert, Robert C. Aller, Stefan Hulth

Journal of Marine Research

The influence of burrow spacing on sedimentary nitrification and denitrification was simulated experimentally using sediment plugs of different thicknesses immersed in aerated seawater reservoirs. Different plug thicknesses mimic different distances between oxygenated burrow centers and produce similar changes in aerobic-anaerobic reaction balances as a function of diffusive transport scaling. The thicknesses used were roughly equivalent to transport scales (interburrow spacing) that could be produced by burrow abundances of ~400 to 50,000 m-2, depending on burrow lumen radii (e.g., 0.05-1 cm). Following the exposure of anoxic sediment plugs to aerated water, an efficient aerobic nitrification zone was established within …

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Initiation Of A Doubly Diffusive Convection In A Stable Halocline, Melvin E. Stern Jan 2003

Initiation Of A Doubly Diffusive Convection In A Stable Halocline, Melvin E. Stern

Journal of Marine Research

A vertically stable density stratification with temperature gradient Tz < 0, salinity gradient Sz < 0, and with density compensating horizontal T/S gradients is unstable to lateral intrusions because the molecular heat diffusivity is much larger than the salt diffusivity. Previous marginal instability theory is extended to the supercritical regime. The fastest growing vertical wavelength (δz) is obtained in a model of a T/S front with finite lateral width (L*) and lateral salinity variation (ΔS). The value of δz ≈ ΔS/|Sz| varies only slightly with the parameters, and this result is applied to the smallest "step" …

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Variation Of Nonlocal Irrigation In A Subtidal Benthic Community, Stefan Forster, Arzhang Khalili, Jarmila Kitlar Jan 2003

Variation Of Nonlocal Irrigation In A Subtidal Benthic Community, Stefan Forster, Arzhang Khalili, Jarmila Kitlar

Journal of Marine Research

Irrigation, the effect of the pumping activity by benthic infauna on pore water solute distribution and fluxes, may be represented by a nonlocal irrigation function, α (units: 1/time) in the general diagenetic equation. We derived α from the distribution of a solute tracer, bromide, during laboratory incubations of sediment cores containing their natural faunal community. Sediments were sampled on 4 occasions over a period of one year from a site at 30 m depth in the southern North Sea. Fitting an irrigation function exponentially decaying with depth, we arrived at α-values ranging from 25 to >200 yr-1 at the sediment …

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The Pacific/Indian Ocean Pressure Difference And Its Influence On The Indonesian Seas Circulation: Part I—The Study With Specified Total Transports, William H. Burnett, Vladimir M. Kamenkovich, Arnold L. Gordon, George L. Mellor Jan 2003

The Pacific/Indian Ocean Pressure Difference And Its Influence On The Indonesian Seas Circulation: Part I—The Study With Specified Total Transports, William H. Burnett, Vladimir M. Kamenkovich, Arnold L. Gordon, George L. Mellor

Journal of Marine Research

The main objective of this paper is to investigate the overall balance of momentum and energy within the Indonesian Seas to better understand the factors that control the total transport of the Indonesian Throughflow. Two models are used in the investigation: a "first-step" heuristic channel model and a more sophisticated "second-step," barotropic numerical model that incorporates high-resolution coastline and bottom topography. The experiments show that the barotropic model develops typical horizontal circulation patterns for the region. An analysis of the overall momentum and energy balances suggests that the total transport of the Indonesian Throughflow does not depend exclusively on the …

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The Pacific/Indian Ocean Pressure Difference And Its Influence On The Indonesian Seas Circulation: Part Ii—The Study With Specified Sea-Surface Heights, Vladimir M. Kamenkovich, William H. Burnett, Arnold L. Gordon, George L. Mellor Jan 2003

The Pacific/Indian Ocean Pressure Difference And Its Influence On The Indonesian Seas Circulation: Part Ii—The Study With Specified Sea-Surface Heights, Vladimir M. Kamenkovich, William H. Burnett, Arnold L. Gordon, George L. Mellor

Journal of Marine Research

In Part II we construct new numerical solutions to further analyze our results in Part I (Burnett et al., 2003), that indicate the lack of a unique relationship between the Pacific/Indian Ocean pressure difference and the total transport of the Indonesian Throughflow (ITF). These new solutions involve perturbations of the sea level relative to the original solutions. We present detailed analyses of the overall momentum and energy balances for these new solutions to stay consistent with the procedures developed in Part I. The results validate our conclusions regarding the lack of a unique relationship between the pressure head and the …

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Comments On “A Generic Length-Scale Equation For Geophysical Turbulence Models” By L. Umlauf And H. Burchard, L. Kantha, S. Carniel Jan 2003

Comments On “A Generic Length-Scale Equation For Geophysical Turbulence Models” By L. Umlauf And H. Burchard, L. Kantha, S. Carniel

Journal of Marine Research

Umlauf and Burchard (2003) present a generic length-scale equation... for use in two-equation models of turbulence. However, because of the traditional form used for the diffusion term, it can be used at present for only negative values of n. We show that a simple modification of the diffusion term is sufficient to insure a more universal generic length-scale equation that is valid for all values of m and n, including positive values of n. We also show that an appropriate combination of exponents m and n will enable the generic length-scale equation to simulate any desired length-scale equation...

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Does The Nonlinearity Of The Equation Of State Impose An Upper Bound On The Buoyancy Frequency?, Trevor J. Mcdougall, John A. Church, David R. Jackett Jan 2003

Does The Nonlinearity Of The Equation Of State Impose An Upper Bound On The Buoyancy Frequency?, Trevor J. Mcdougall, John A. Church, David R. Jackett

Journal of Marine Research

Mixing in the ocean is usually accompanied by a net reduction in volume caused by the nonlinear nature of the equation of state. This contraction-on-mixing at a certain depth implies that the whole water column above this depth slumps a little and so suffers a reduction in gravitational potential energy. Under certain circumstances the gravitational potential energy of the entire water column can decrease as a consequence of mixing activity at a certain depth. We examine Fofonoff's hypothesis that in these circumstances the net reduction of gravitational potential energy of the whole water column causes a local increase in the …

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Simultaneous Data-Based Optimization Of A 1d-Ecosystem Model At Three Locations In The North Atlantic: Part Ii—Standing Stocks And Nitrogen Fluxes, Markus Schartau, Andreas Oschlies Jan 2003

Simultaneous Data-Based Optimization Of A 1d-Ecosystem Model At Three Locations In The North Atlantic: Part Ii—Standing Stocks And Nitrogen Fluxes, Markus Schartau, Andreas Oschlies

Journal of Marine Research

This study relates the performance of an optimized one-dimensional ecosystem model to observations at three sites in the North Atlantic Ocean: the Bermuda Atlantic Time Series Study (BATS, 31N 64W), the location of the North Atlantic Bloom Experiment (NABE, 47N 20W), and Ocean Weather Ship INDIA (OWS-INDIA, 59N 19W). The ecosystem model is based on nitrogen and resolves dissolved inorganic nitrogen (N), phytoplankton (P), zooplankton (Z) and detritus (D), therefore called the NPZD-model. Physical forcing, such as temperature and eddy diffusivities are taken from an eddy-permitting general circulation model of the …

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Simultaneous Data-Based Optimization Of A 1d-Ecosystem Model At Three Locations In The North Atlantic: Part I—Method And Parameter Estimates, Markus Schartau, Andreas Oschlies Jan 2003

Simultaneous Data-Based Optimization Of A 1d-Ecosystem Model At Three Locations In The North Atlantic: Part I—Method And Parameter Estimates, Markus Schartau, Andreas Oschlies

Journal of Marine Research

An optimization experiment is performed with a vertically resolved, nitrogen-based ecosystem model, composed of four state variables (NPZD-model): dissolved inorganic nitrogen (N), phytoplankton (P), herbivorous zooplankton (Z) and detritus (D). Parameter values of the NPZD-model are optimized while assimilating observations at three locations in the North Atlantic simultaneously, namely at the sites of the Bermuda Atlantic Time-Series Study (BATS; 31N 64W), of the North Atlantic Bloom Experiment (NABE; 47N 20W), and of Ocean Weather Ship-India (OWS-INDIA; 59N 19W). A method is described for a simultaneous optimization which effectively merges …

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Evaluation Of Excess 234th Activity In Sediments As An Indicator Of Food Quality For Deep-Sea Deposit Feeders, Amanda W. J. Demopoulos, Craig R. Smith, David J. Demaster, William L. Fornes Jan 2003

Evaluation Of Excess 234th Activity In Sediments As An Indicator Of Food Quality For Deep-Sea Deposit Feeders, Amanda W. J. Demopoulos, Craig R. Smith, David J. Demaster, William L. Fornes

Journal of Marine Research

Deep-sea deposit feeders selectively ingest large volumes of sediment. Knowledge of the nature of this selectivity will help to elucidate the limiting nutritional requirements and geochemical impacts of these abundant animals. Shallow-water and theoretical studies suggest that deep-sea deposit feeders should select particles rich in protein, bacterial biomass, and/or chloropigment concentrations. Recent studies indicate that deep-sea megafaunal deposit feeders exhibit strong gut enrichment of excess (xs) 234Th activity, even though 234Thxs lacks nutritional value. To explore the significance of selective ingestion of 234Thxs activity, we evaluated the correlations between 234Thxs activity and three …

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The Role Of Outflow Geometry In The Formation Of The Recirculating Bulge Region In Coastal Buoyant Outflows, Greg Avicola, Pablo Huq Jan 2003

The Role Of Outflow Geometry In The Formation Of The Recirculating Bulge Region In Coastal Buoyant Outflows, Greg Avicola, Pablo Huq

Journal of Marine Research

Density-driven coastal currents are a common feature in the world's coastal oceans. These currents may separate from the coastline due to variations in geometry. Past studies have shown that this separation may produce two distinctly different flow states: a continuation of the coastal current, or a recirculating gyre downshelf of, and attached to, the separation point. Laboratory experiments of coastal buoyant outflows (rotationally dominated, buoyancy driven) were undertaken to examine the role of bay geometry on the evolution of the outflow. Experiments were conducted on a rotating turntable in relatively deep water (such that the buoyant layer depth was much …

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