Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Oceans

Discipline
Institution
Publication Year
Publication
Publication Type

Articles 601 - 630 of 2515

Full-Text Articles in Entire DC Network

Potential Vorticity “Crises”, Adverse Pressure Gradients, And Western Boundary Current Separation, Andrew E. Kiss Jan 2002

Potential Vorticity “Crises”, Adverse Pressure Gradients, And Western Boundary Current Separation, Andrew E. Kiss

Journal of Marine Research

The vorticity dynamics involved in western boundary current separation are investigated in a depth-averaged barotropic single-gyre circulation forced by a spatially uniform wind stress curl in a circular basin on a beta-plane. The mechanism of separation is of interest in this simple model because it lacks most of the features (such as a change in sign of the wind stress curl, collision with another western boundary current, outcropping of isopycnals or an abrupt change in bottom topography or boundary shape) often associated with boundary current separation. It has been suggested that a "crisis" due to insufficient recovery of potential vorticity …

Go to article

Tidal Motion Enhancement Around Islands, Zygmunt Kowalik, Aleksey V. Marchenko Jan 2002

Tidal Motion Enhancement Around Islands, Zygmunt Kowalik, Aleksey V. Marchenko

Journal of Marine Research

Tidally-generated, trapped motions can significantly enhance and modify sea level and currents in the island proximity. The analytical solution for incident waves interacting with a cylindrical island with a circular sill has been constructed to investigate this phenomenon. To derive solutions for the scattering problems simple Sverdrup and Kelvin waves are used as incident waves. The amplification of the signal along the island perimeter has shown to be a function of frequency, relative dimensions of the island and the circular sill surrounding the island, relative sill depth, and the bottom friction. Although the incident diurnal tide may be amplified through …

Go to article

Intermingling Of Two Pseudocalanus Species On Georges Bank, D. J. Mcgillicuddy Jr., A. Bucklin Jan 2002

Intermingling Of Two Pseudocalanus Species On Georges Bank, D. J. Mcgillicuddy Jr., A. Bucklin

Journal of Marine Research

Physical and biological controls on the springtime distributions of Pseudocalanus moultoni and P. newmani on Georges Bank are examined by assimilating observations into a coupled physical-biological model. Monthly snapshots of abundance are derived from U.S. GLOBEC Georges Bank broad-scale surveys during 1997. The forward problem is posed as an advection-diffusion-reaction equation for the copepod concentration. The adjoint method of data assimilation is used to invert for the biological sources and sinks implied by the observed changes in abundance between surveys and the flow during the intervening period. Based on this analysis, the two species appear to have distinct population centers …

Go to article

The Effects Of Buffer And Temperature Feedback On The Oceanic Uptake Of Co2, Chuixiang Yi, Peng Gong, Ming Xu, Ye Qi Mar 2001

The Effects Of Buffer And Temperature Feedback On The Oceanic Uptake Of Co2, Chuixiang Yi, Peng Gong, Ming Xu, Ye Qi

Publications and Research

The feedback between climate and carbon cycle systems is critical to the prediction of future CO2 concentration in the atmosphere and the capacity of the oceans to take up CO2 from the atmosphere. We calculated the magnitudes of the potential feedback between the increase of atmospheric CO2 concentration, the carbonate chemistry of the oceans (via a buffer factor), and the global temperature. We find that the magnitude of the buffer feedback depends strongly on the level of the dissolved inorganic carbon (DIC) in the oceans and increases rapidly with the increase of the atmospheric CO …

Go to article

On The Insensitivity Of The Wind-Driven Circulation To Bottom Topography, David P. Marshall, James C. Stephens Jan 2001

On The Insensitivity Of The Wind-Driven Circulation To Bottom Topography, David P. Marshall, James C. Stephens

Journal of Marine Research

An analytical model is developed for the wind-driven circulation in a continuously stratified ocean overlying variable bottom topography. In the ocean interior we adopt a linear relation between potential vorticity, density and Montgomery potential, resulting in Welander's solution for an adiabatic internal thermocline. The horizontal structure of the circulation is described by a characteristic equation, obtained by imposing a boundary condition of no-normal flow at the sea floor and a prescribed vertical velocity through the base of the surface Ekman layer. The characteristics, which determine the extent to which bottom topography "steers" the circulation within the upper ocean, are dominated …

Go to article

Absorbed Mn2+ And Mn Redox Cycling In Iberian Continental Margin Sediments (Northeast Atlantic Ocean), Claar Van Der Zee, Wim Van Raaphorst, Eric Epping Jan 2001

Absorbed Mn2+ And Mn Redox Cycling In Iberian Continental Margin Sediments (Northeast Atlantic Ocean), Claar Van Der Zee, Wim Van Raaphorst, Eric Epping

Journal of Marine Research

Although Mn2+ sorption has been investigated extensively in the laboratory, the role of Mn2+ sorption in natural marine sediments remains speculative. Our objectives were to study (1) the role of Mn2+ sorption in the redox cycling of Mn, (2) to quantify Mn cycling and (3) to identify its rate-determining factors at the Iberian margin. Profiles of pore water Mn2+, adsorbed Mn2+ and solid phase Mn were measured together with benthic oxygen fluxes along three transects across the margin from the shelf to the deep sea as well as in the Nazeré Canyon. In the …

Go to article

Annual To Interannual Variations Of Ƒco2 In The Northwestern Mediterranean Sea: Results From Hourly Measurements Made By Carioca Buoys, 1995–1997, E. M. Hood, L. Merlivat Jan 2001

Annual To Interannual Variations Of Ƒco2 In The Northwestern Mediterranean Sea: Results From Hourly Measurements Made By Carioca Buoys, 1995–1997, E. M. Hood, L. Merlivat

Journal of Marine Research

A time series of fCO2, SST, and fluorescence data was collected between 1995 and 1997 by a CARIOCA buoy moored at the DyFAMed station (Dynamique des Flux Atmospheriques en Mediterranée) located in the northwestern Mediterranean Sea. On seasonal timescales, the spring phytoplankton bloom decreases the surface water fCO2 to approximately 290 µatm, followed by summer heating and a strong increase in fCO2 to a maximum of approximately 510 µatm. While the ΔfCO2 shows strong variations on seasonal timescales, the annual average air-sea disequilibrium is only 2 µatm. Temperature-normalized fCO …

Go to article

North Pacific Internal Tides From The Aleutian Ridge: Altimeter Observations And Modeling, Patrick F. Cummins, Josef Y. Cherniawsky, Michael G. G. Foreman Jan 2001

North Pacific Internal Tides From The Aleutian Ridge: Altimeter Observations And Modeling, Patrick F. Cummins, Josef Y. Cherniawsky, Michael G. G. Foreman

Journal of Marine Research

Internal tides radiating into the North Pacific from the Aleutian Ridge near Amukta Pass are examined using 7 years of Topex/Poseidon altimeter data. The observations show coherent southward phase propagation at the M2 frequency over a distance of at least 1100 km into the central Pacific. Barotropic and baroclinic models are applied to study this internal tidal signal. Results from the barotropic model show that the strongest cross-slope volume and energy fluxes occur in the vicinity of Amukta Pass, helping to establish this region as an important site for baroclinic energy conversion along the eastern half of the ridge. …

Go to article

Internal And Interfacial Tides: Beam Scattering And Local Generation Of Solitary Waves, Theo Gerkema Jan 2001

Internal And Interfacial Tides: Beam Scattering And Local Generation Of Solitary Waves, Theo Gerkema

Journal of Marine Research

Analytical solutions of a linear internal-tide generation problem are presented for a stratification that involves both an interface (thermocline) and a lower layer of constant stratification. It is shown that an internal tidal beam scatters strongly at a moderately developed thermocline but much less at a thermocline that is either very weak or very strong. This scattering goes along with a local wave activity at the thermocline as well as with a downward leaking from the thermocline. It is argued that these processes offer a clue to explaining observations in the Bay of Biscay of 'local generation' of internal soliton …

Go to article

The Impact Of Model Configuration In Studies Of Buoyant Coastal Discharge, Richard W. Garvine Jan 2001

The Impact Of Model Configuration In Studies Of Buoyant Coastal Discharge, Richard W. Garvine

Journal of Marine Research

Observations and model studies of large-scale buoyant plumes show three major types for the horizontal distribution of density. Type 1 represents the typical coastal freshwater plume of observations. The buoyant discharge turns right in the northern hemisphere (toward downshelf) under earth rotation at its source. Type 2 is common in many numerical model studies. Most of the buoyant water at the inlet turns left (upshelf) along the coast to form a continuously growing intrusion. Type 3 turns right but exhibits a massive anticyclonic bulge which grows with time; its coastal current is weak and carries a small fraction of the …

Go to article

The Evolution And Energetics Of Large Amplitude Nonlinear Internal Waves On The Portuguese Shelf, D. R. G. Jeans, T. J. Sherwin Jan 2001

The Evolution And Energetics Of Large Amplitude Nonlinear Internal Waves On The Portuguese Shelf, D. R. G. Jeans, T. J. Sherwin

Journal of Marine Research

Intensive in-situ observations of nonlinear internal waves on the Portuguese shelf were made in August 1994, including measurements of the same wavepacket at three locations as it propagated on-shelf. The waves were characterized by sudden isotherm depressions of up to 45 m lasting 10-35 minutes, accompanied by current surges of up to 0.45 m s-1 and shears of up to 0.7 m s-1 over 60 m. The waves propagated away from the shelf break with an estimated phase speed of 0.57 m s-1. The amplitude of the waves was comparable to the theoretical maximum. The kinetic …

Go to article

Barotropic Instabilities Of The Agulhas Current System And Their Relation To Ring Formation, Henk A. Dijkstra, Wilhelmus P. M. De Ruijter Jan 2001

Barotropic Instabilities Of The Agulhas Current System And Their Relation To Ring Formation, Henk A. Dijkstra, Wilhelmus P. M. De Ruijter

Journal of Marine Research

Recent work has shown that different steady retroflection regimes, a viscous and an inertial regime, exist for the Agulhas Current system in an idealized geometry. In this paper, instabilities of the barotropic steady flows are considered by solving the linear stability problem numerically. Barotropic instabilities occur as so-called Hopf bifurcations in the viscous regime, with corresponding patterns related to Rossby basin modes. Depending on the value of the reduced gravity parameter, these instabilities may introduce intermonthly to interannual variability into the retroflection region. Finite amplitude development of these instabilities display 'ring-like' localized anomaly patterns which travel around the tip of …

Go to article

On The Summer Mesoscale Variability Of The Black Sea, Şükrü T. Beşiktepe, Carlos J. Lozano, Allan R. Robinson Jan 2001

On The Summer Mesoscale Variability Of The Black Sea, Şükrü T. Beşiktepe, Carlos J. Lozano, Allan R. Robinson

Journal of Marine Research

The evolution of the Black Sea temperature, salinity and circulation, from large scale to mesoscale, is studied using a data-driven primitive equation simulation. The data are drawn from (i) a basin-wide hydrographic survey, CoMSBlack'92, obtained in the Summer of 1992; (ii) wind stress derived from wind analyses of the Sevastopol MSIA/URHI Office; (iii) climatological heat fluxes; and (iv) climatological river outflows. The primitive equation model is from the Harvard Ocean Prediction System. The simulation is used to examine the evolution of the circulation at mesoscale resolution, its dominant variabilities and dependencies in the summer period. The large-scale upper layer circulation …

Go to article

The Origin Of Low-Frequency Variability Of Double-Gyre Wind-Driven Flows, Janine J. Nauw, Henk A. Dijkstra Jan 2001

The Origin Of Low-Frequency Variability Of Double-Gyre Wind-Driven Flows, Janine J. Nauw, Henk A. Dijkstra

Journal of Marine Research

Bifurcation analysis on flows in a two-layer shallow-water model is used to clarify the dynamical origin of low-frequency variability of the double-gyre wind-driven ocean circulation. In many previous model studies, generic low-frequency variations appear to be associated with distinct regimes, characterized by the level of kinetic energy of the mean flow. From these transient flow computations, the current view is that these regimes, and transitions between them, arise through a complex nonlinear interaction between the mean flow and its high-frequency instabilities (the eddies). On the contrary, we demonstrate here, for a particular (but relevant) case, that the origin of these …

Go to article

Impact Of Sub-Mesoscale Physics On Production And Subduction Of Phytoplankton In An Oligotrophic Regime, Marina Lévy, Patrice Klein, Anne-Marie Treguier Jan 2001

Impact Of Sub-Mesoscale Physics On Production And Subduction Of Phytoplankton In An Oligotrophic Regime, Marina Lévy, Patrice Klein, Anne-Marie Treguier

Journal of Marine Research

Using a protocol of numerical experiments where horizontal resolution is progressively increased, we show that small-scale (or sub-mesoscale) physics has a strong impact on both mesoscale physics and phytoplankton production/subduction. Mesoscale and sub-mesoscale physics result from the nonlinear equilibration of an unstable baroclinic jet. The biogeochemical context is oligotrophy. The explicitly resolved sub-mesoscales, at least smaller than one fifth of the internal Rossby radius of deformation, reinforce the mesoscale eddy field and contribute to double the primary production and phytoplankton subduction budgets. This enhancement is due to the reinforced mesoscale physics and is also achieved by the small-scale frontal dynamics. …

Go to article

A Bifurcation Study Of The Three-Dimensional Thermohaline Ocean Circulation: The Double Hemispheric Case, Wilbert Weijer, Henk A. Dijkstra Jan 2001

A Bifurcation Study Of The Three-Dimensional Thermohaline Ocean Circulation: The Double Hemispheric Case, Wilbert Weijer, Henk A. Dijkstra

Journal of Marine Research

Within a low-resolution primitive-equation model of the three-dimensional ocean circulation, a bifurcation analysis is performed of double-hemispheric basin flows. Main focus is on the connection between results for steady two-dimensional flows in a nonrotating basin and those for three-dimensional flows in a rotating basin. With the use of continuation methods, branches of steady states are followed in parameter space and their linear stability is monitored. There is a close qualitative similarity between the bifurcation structure of steady-state solutions of the two- and three dimensional flows. In both cases, symmetry-breaking pitchfork bifurcations are central in generating a multiple equilibria structure. The …

Go to article

Particle Flux In The Rainbow Hydrothermal Vent Field (Mid-Atlantic Ridge): Dynamics, Mineral And Biological Composition, Alexis Khripounoff, Annick Vangriesheim, Philippe Crassous, Michel Segonzac, Ana Colaço, Daniel Desbruyères, Roxane Barthelemey Jan 2001

Particle Flux In The Rainbow Hydrothermal Vent Field (Mid-Atlantic Ridge): Dynamics, Mineral And Biological Composition, Alexis Khripounoff, Annick Vangriesheim, Philippe Crassous, Michel Segonzac, Ana Colaço, Daniel Desbruyères, Roxane Barthelemey

Journal of Marine Research

In order to provide information about the export and the distribution of hydrothermal particulate material to the surrounding deep ocean, four moorings were deployed in the vicinity of the hydrothermal Rainbow vent field (Mid-Atlantic Ridge, 36°14′N, 2250 m depth). The first mooring was a sediment trap with a current meter deployed at 2 m from a chimney of the Rainbow vent field and 1.5 m above the bottom (a.b.) for 16 days. It represented the reference for the initial composition of particles produced by the vent. The total mean mass particle flux (6.9 g m-2 d-1) was …

Go to article

Mechanism Of Offshore Nutrient Supply In The Western Arabian Sea, Michio Kawamiya Jan 2001

Mechanism Of Offshore Nutrient Supply In The Western Arabian Sea, Michio Kawamiya

Journal of Marine Research

The mechanism to maintain the high surface chlorophyll in the western Arabian Sea during the southwest monsoon (SWM) season is studied with an eddy-permitting, biological-physical coupled model. Using a set of artificial tracers, it is revealed that horizontal transport of nutrient subsequent to the coastal upwelling is by far more important than the open ocean upwelling due to the Ekman pumping. The horizontal transport can be classified into three processes, the Ekman transport, transport by the large-scale circulation and that by the mesoscale currents. In the model, the first has only a minor effect within the area of high chlorophyll …

Go to article

The Role Of Colonization In Establishing Patterns Of Community Composition And Diversity In Shallow-Water Sedimentary Communities, Paul V. R. Snelgrove, J. Frederick Grassle, Judith P. Grassle, Rosemarie F. Petrecca, Karen I. Stocks Jan 2001

The Role Of Colonization In Establishing Patterns Of Community Composition And Diversity In Shallow-Water Sedimentary Communities, Paul V. R. Snelgrove, J. Frederick Grassle, Judith P. Grassle, Rosemarie F. Petrecca, Karen I. Stocks

Journal of Marine Research

To determine whether pattern and diversity in benthic sedimentary communities are set primarily at colonization or by post-settlement biological interactions, we collected faunal cores and conducted reciprocal sediment transplant experiments at a sandy and a muddy site at 12 m depth, ~3 km apart off New Jersey. Multivariate analyses of cores collected at these sites in September 1994 indicated differences in the taxa determining local pattern, with the bivalve Spisula solidissima and the polychaete Polygordius sp. being dominant at the sandy site, and oligochaetes, several polychaete species and the bivalve Nucula annulata dominant at the muddy site. Individual cores from …

Go to article

Phytoplankton Seasonal Distribution From Seawifs Data In The Agulhas Current System, E. Machu, V. Garçon Jan 2001

Phytoplankton Seasonal Distribution From Seawifs Data In The Agulhas Current System, E. Machu, V. Garçon

Journal of Marine Research

The interocean conduit for warm Indian Ocean water into the Atlantic Ocean is the Agulhas system which plays an important role in maintaining the global thermohaline circulation. The frontal system formed by the Agulhas Return Current (ARC) and the Subtropical Convergence (STC) is also a region of intense mesoscale activity presenting enhanced levels of biological production and chlorophyll a. We jointly analyzed three different satellite data sets to relate the remotely sensed distribution of phytoplankton (SeaWiFS ocean color data) to the dynamical environment (Topex/Poséidon-ERS sea level anomalies-SLA- and sea-surface temperature-SST-) to gain insight into the seasonal behavior of the …

Go to article

A Data Assimilative Marine Ecosystem Model Of The Central Equatorial Pacific: Numerical Twin Experiments, Marjorie A. M. Friedrichs Jan 2001

A Data Assimilative Marine Ecosystem Model Of The Central Equatorial Pacific: Numerical Twin Experiments, Marjorie A. M. Friedrichs

Journal of Marine Research

A five-component, data assimilative marine ecosystem model is developed for the high-nutrient low-chlorophyll region of the central equatorial Pacific (0N, 140W). Identical twin experiments, in which model-generated synthetic 'data' are assimilated into the model, are employed to determine the feasibility of improving simulation skill by assimilating in situ cruise data (plankton, nutrients and primary production) and remotely-sensed ocean color data. Simple data assimilative schemes such as data insertion or nudging may be insufficient for lower trophic level marine ecosystem models, since they require long time-series of daily to weekly plankton and nutrient data as well as adequate knowledge of the …

Go to article

Central Equatorial Pacific Zonal Currents. I: The Sverdrup Balance, Nonlinearity And Tropical Instability Waves. Annual Mean Dynamics, D. E. Harrison, R. D. Romea, S. H. Hankin Jan 2001

Central Equatorial Pacific Zonal Currents. I: The Sverdrup Balance, Nonlinearity And Tropical Instability Waves. Annual Mean Dynamics, D. E. Harrison, R. D. Romea, S. H. Hankin

Journal of Marine Research

Several recent observational studies of central Pacific equatorial current dynamics have suggested that, in the vertical integral between the surface and the thermocline, the linear equatorial Sverdrup balance holds. However, in a high vertical resolution ocean general circulation model, we find that nonlinearity is an order (1) element of the local and the vertically integrated balances on and near the equator at 140W. Although this OGCM has been used in many studies of the tropical Pacific, its equatorial zonal momentum equation balances have never been described in detail and compared with observations. We describe the annual mean balances here, identify …

Go to article

The Impact Of Model-Error Correlation On Regional Data Assimilative Models And Their Observational Arrays, Philip S. Bogden Jan 2001

The Impact Of Model-Error Correlation On Regional Data Assimilative Models And Their Observational Arrays, Philip S. Bogden

Journal of Marine Research

Data assimilative models often minimize a penalty functional that measures model adjustment and model-data misfit. The penalty functional builds assumptions about model error into the analysis. Usually, errors from different parts of the model (e.g., dynamics and boundary conditions) are presumed to be uncorrelated. This is clearly not a valid assumption in regional models where uncertain large-scale forcing affects open-ocean boundary conditions. In this study, calculations with a regional wind-driven inverse model provide a specific example where model error from uncertain wind stress is correlated with model error from uncertain open boundary conditions. This physically realistic scenario motivates development of …

Go to article

The Near-Surface Velocity And Potential Vorticity Structure Of The Gulf Stream, T. Rossby, H. M. Zhang Jan 2001

The Near-Surface Velocity And Potential Vorticity Structure Of The Gulf Stream, T. Rossby, H. M. Zhang

Journal of Marine Research

Using Acoustic Doppler Current Profiler and XBT data between 1992 and 1999 from a container vessel that crosses the Gulf Stream twice weekly near 70W, we examine the near-surface velocity, thermal and vorticity structure of the current. These data come from an ongoing sampling program that has as its overall objective to measure the currents between New York and Bermuda to provide a high-quality database for studies of variability and long-term trends in the region. These Gulf Stream sections, when averaged in natural or stream coordinates, exhibit a remarkable double-exponential structure. The scale-widths of the lateral shear north and south …

Go to article

Effects Of Topography On The Beta-Drift Of A Baroclinic Vortex, Georgi Sutyrin Jan 2001

Effects Of Topography On The Beta-Drift Of A Baroclinic Vortex, Georgi Sutyrin

Journal of Marine Research

The propagation of compact, surface-intensified vortices over a topographic slope on the beta-plane is studied in the framework of a two-layer model. A perturbation theory is derived for a circular vortex in the upper layer with the lower layer at rest as a basic state. An integral momentum balance for the upper layer is used to obtain expressions for the velocity of the vortex center assuming the flow is quasi-stationary to leading order. This approach allows the calculation of the lower-layer flow pattern as a function of the interface shape and the slope orientation. The essential part of the lower-layer …

Go to article

Modeling Water Column Structure And Suspended Particulate Matter On The Middle Atlantic Continental Shelf During The Passages Of Hurricanes Edouard And Hortense, Alejandro J. Souza, Tommy D. Dickey, Grace C. Chang Jan 2001

Modeling Water Column Structure And Suspended Particulate Matter On The Middle Atlantic Continental Shelf During The Passages Of Hurricanes Edouard And Hortense, Alejandro J. Souza, Tommy D. Dickey, Grace C. Chang

Journal of Marine Research

The present contribution is motivated by the desire to elucidate the processes that contributed to the evolution of observed thermal structure and resuspension of particulate matter during and after the passages of two hurricanes, Edouard and Hortense, within a two-week period in late-summer 1996. A unique set of high temporal frequency measurements of the vertical structures of physical and optical properties was obtained at a mooring site near the Middle Atlantic Bight continental shelf-break (70 m water depth). These data provided insight and initial conditions for the physical model used for this study. The model accounted for wind and bottom …

Go to article

Particle Trapping In A Stratified Flood-Dominated Estuary, Robert J. Chant, Allan W. Stoner Jan 2001

Particle Trapping In A Stratified Flood-Dominated Estuary, Robert J. Chant, Allan W. Stoner

Journal of Marine Research

Observations in the Navesink River estuary in northern New Jersey demonstrate that buoyancy augments the particle trapping tendencies of flood-dominated systems because these estuaries heighten tidal period asymmetries in stratification. During the long and slow ebb which typifies flood-dominated systems, a positive feedback between tidal straining and weak vertical mixing stratifies the estuary. In contrast, during flood, turbulence generated by the stronger tidal currents augments overstraining of the density field and the water column becomes well mixed. The tidal period asymmetries in stratification have profound effects on the vertical structure and transport of suspended matter. During ebb, weak vertical mixing …

Go to article

Performance Of Cages As Large Animal-Exclusion Devices In The Deep Sea, James E. Eckman, David Thistle, William C. Burnett, Gordon L. J. Paterson, Charles Y. Robertson, P. John D. Lambshead Jan 2001

Performance Of Cages As Large Animal-Exclusion Devices In The Deep Sea, James E. Eckman, David Thistle, William C. Burnett, Gordon L. J. Paterson, Charles Y. Robertson, P. John D. Lambshead

Journal of Marine Research

Sedimentary, deep-sea communities include megafaunal animals (e.g., sea cucumbers, brittle stars, crabs) and demersal fishes, collectively termed the large, motile epifauna (LME). Individuals of the LME are common, and their biomass approximates that of the macrofauna. Based on analogies with shallow-water animals, they are likely to be sources of mortality for the infauna and to create spatial and temporal heterogeneity in the community. Given present theories of deep-sea community organization, such effects could be important. Unfortunately, this hypothesis has not been tested because of the difficulty of conducting experiments in the deep sea and because tools for manipulating the LME …

Go to article

Assessing The Dispersal And Exchange Of Brachyuran Larvae Between Regions Of San Diego Bay, California And Nearshore Coastal Habitats Using Elemental Fingerprinting, Claudio Dibacco, D. Bart Chadwick Jan 2001

Assessing The Dispersal And Exchange Of Brachyuran Larvae Between Regions Of San Diego Bay, California And Nearshore Coastal Habitats Using Elemental Fingerprinting, Claudio Dibacco, D. Bart Chadwick

Journal of Marine Research

Marine benthic invertebrate populations found in estuarine or coastal habitats often exchange larvae. However, the dynamics of larval exchange are poorly understood because of difficulties in (1) making synoptic assessments of horizontal and vertical larval distribution patterns over large areas for extended periods of time and (2) determining the origins of field-sampled larvae. This study examines how temporal changes in the vertical and horizontal distribution of crab larvae (i.e., Pachygrapsus crassipes and Lophopanopeus spp.) affect larval transport. Larval concentration and water velocity data were collected concurrently and were used to estimate larval exchange between regions of San Diego Bay (SDB) …

Go to article

A Particle Introduction Experiment In Santa Catalina Basin Sediments: Testing The Age-Dependent Mixing Hypothesis, William L. Fornes, David J. Demaster, Craig R. Smith Jan 2001

A Particle Introduction Experiment In Santa Catalina Basin Sediments: Testing The Age-Dependent Mixing Hypothesis, William L. Fornes, David J. Demaster, Craig R. Smith

Journal of Marine Research

The occurrence of "age-dependent mixing," a process by which recently deposited, food-rich particles undergo more intense bioturbation than older, food-poor particles, could dramatically alter patterns of organic-matter diagenesis in deep-sea sediments. To explicitly test for age-dependent mixing, an in-situ particle introduction experiment was conducted on the bathyal Santa Catalina Basin floor. Mixtures of radioisotope-tagged particles representing a food quality gradient were dispersed in small amounts on the seafloor and sampled over periods of 0 to 594 days. Introduced particle types were all similar in size and included fresh diatoms ("young" particles), surface sediments ("intermediate-age" particles), and particles from 30-cm deep …

Go to article

First Prev Next Last