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Effects Of Porewater Hydrogen Sulfide On The Feeding Activity Of The Subsurface Deposit-Feeding Polychaete, Clymenella Torquata, Leidy, Charlotte M. Fuller

Journal of Marine Research

The effects of porewater hydrogen sulfide concentrations on the feeding and tube-building activity of the subsurface, deposit-feeding polychaete, Clymenella torquata were experimentally determined in the laboratory. Porewater hydrogen sulfide concentrations were manipulated by injecting a buffered, isotonic sodium sulfide solution into the experimental chambers. Fecal material was collected and weighed and tube-building activity was monitored daily. Fecal production was negatively correlated with porewater hydrogen sulfide concentration during experiments conducted in June and July. Hydrogen sulfide concentrations greater than 1000 μM in June and 700 μM in July resulted in reduced fecal production. Fecal production was not correlated with porewater hydrogen …

Particle Bioturbation In Massachusetts Bay: Preliminary Results Using A New Deliberate Tracer Technique, Robert A. Wheatcroft, Ilhan Olmez, Francais X. Pink

Journal of Marine Research

To better understand temporal and particle size-dependent bioturbation processes, we conducted a study of sediment mixing in Massachusetts Bay using a newly developed deliberate tracer technique. Sediments from a 32-m, fine-grained site were collected and the 38–62 (“silt”) and 63–125 (“sand”) μm fractions isolated. These particle-size fractions were labeled with two different noble metals (Au: silt & Ag: sand) using a thermal diffusion technique. Mixtures of the tracers were spread onto the seafloor in April and July 1992 by divers and were tube-cored (3 replicates) ˜ 80 d later in each case. Vertical profiles of the tracers were measured at …

A Linear Homogeneous Model For Topographic Control Of The Antarctic Circumpolar Current, Liping Wang

Journal of Marine Research

The results from the homogeneous channel model discussed by Wang and Huang (1994) is extended to a model whose geometry consists of a zonal channel and two partial meridional barriers along each boundary at the same longitude. Both the model transport and especially the model circulation are significantly affected by the presence of the two meridional barriers. There is a critical height of the ridge between the two partial meridional barriers, above which all geostrophic contours in the channel are blocked. In the case with a subcritically high ridge, the Sverdrup balance does not apply and there is no finite …

Carbon And Nitrogen Isotope Ratios In Bowhead Whales (Balaena Mysticetus) And Their Zooplankton Prey As Indicators Of Feeding Strategy And Environmental Change., Kimberly Ann Vinette

Marine Biology

This study details regional, seasonal and inter-annual differences in $\delta\sp{13}$C and $\delta\sp{15}$N of zooplankton in the Bering and Chukchi Seas. These isotopic variations were correlated with inter-annual and long-term variations in $\delta\sp{13}$C and $\delta\sp{15}$N of bowhead whale baleen.

Statistical analyses indicate significant $\sp{13}$C-enrichment in Bering/Chukchi seas zooplankton relative to Beaufort Sea zooplankton, supporting the observed trends of $\sp{13}$C-depletion at higher latitudes and enrichment at lower latitudes. Bering/Chukchi seas zooplankton show a weak trend in $\sp{13}$C-depletion between 1987-1990, possibly due to inter-annual environmental changes affecting phytoplankton $\delta\sp{13}$C. The $\delta\sp{13}$C of baleen produced in fall/winter months is inversely correlated to sea surface …

The North Atlantic Circulation: Combining Simplified Dynamics With Hydrographic Data, Philip S. Bogden, Russ E. Davis, Rick Salmon

Journal of Marine Research

We estimate the time-averaged velocity field in the North Atlantic from observations of density, wind stress and bottom topography. The flow is assumed geostrophic, with prescribed Ekman pumping at the surface, and no normal component at the bottom. These data and dynamics determine velocity to within an arbitrary function of (Coriolis parameter)/(ocean depth), which we call the “dynamical free mode.” The free mode is selected to minimize mixing of potential density at mid-depth. This tracer-conservation criterion serves as a relatively weak constraint on the calculation. Estimates of vertical velocity are particularly sensitive to variations in the free mode and to …

Rates And Possible Mechanism Of Light-Dependent Degradation Of Pigments In Detritus Derived From Phytoplankton, James R. Nelson

Journal of Marine Research

Rates of degradation of phytoplankton chlorophylls and carotenoids under visible light exposure were determined in laboratory experiments. Killed phytoplankton cells and copepod fecal pellets were used as sources of pigments. Chlorophylls, pheopigments and carotenoids were analyzed by HPLC. Experiments included aerated and N₂ bubbled treatments (light and dark), and in one experiment, killed phytoplankton cells were aged in darkness for 5 days in the presence of an active bacterial population prior to exposure to light. Pigment bleaching in solution was also examined. Pigment degradation was light- and oxygen-dependent and showed apparent first-order kinetics with respect to light exposure. The …

The Annual Variation Of Water Mass Structure In The Gulf Of Maine: 1986-1987, W. S. Brown, J. D. Irish

Journal of Marine Research

The annual variation in the structure and disposition of the principal water masses in the Gulf of Maine has been investigated with a set of water property observations using five shipboard surveys and four moored arrays with data telemetry. The time series observations document the cooling-induced destratification of the upper water column during autumn and the subsequent mixed-layer deepening in the western Gulf—primarily in Wilkinson Basin— during winter 1987. Unusually large amounts of fresher Scotian Shelf Water inflow inhibited winter 1987 vertical mixing in the eastern Gulf relative to the deep mixing in and around Wilkinson Basin in the western …

The Importance Of The Scotia Sea On The Outflow Of Weddell Sea Deep Water, Ricardo A. Locarnini, Thomas Whitworth Iii, Worth D. Nowlin Jr.

Journal of Marine Research

Weddell Sea Deep Water influences the thermohaline circulation of the world ocean directly as a component of the deep western boundary current in the South Atlantic Ocean and indirectly by cooling and freshening Circumpolar Deep Water. Because it is filled with recently ventilated Weddell Sea Deep Water, the Scotia Sea is important to both influences. The main component of the abyssal waters renewing most of the world oceans via deep boundary currents is the Circumpolar Deep Water of the Antarctic Circumpolar Current. Weddell Sea Deep Water is recognized as the main source of cold, fresh waters to Circumpolar Deep Water, …

On The Role Of Large Bubbles In Air-Sea Gas Exchange And Supersaturation In The Ocean, Ralph F. Keeling

Journal of Marine Research

A parameterization of bubble-induced gas exchange is presented in which the bubble contribution to gas exchange is expressed in terms of separate transfer velocities for ingassing (K_bⁱⁿ) and outgassing (K_b^out). The difference between the ingassing and outgassing velocities (K_bⁱⁿ − K_b^out) is further separated into two components, the first caused by the injection of small bubbles into the water, the second caused by gas exchange across the surface of hydrostatically compressed larger bubbles. It is argued that both K_b^out and the exchange contribution to …

The Ecology Of Larger Microzooplankton In The Weddell-Scotia Confluence Area: Horizontal And Vertical Distribution Patterns, Viviana A. Alder, Demetrio Boltovskoy

Journal of Marine Research

The distribution of microzooplankton > 15 μm (large dinoflagellates, foraminifers, radiolarians, tintinnids, microcrustaceans and various invertebrate larvae) was studied in samples retrieved from 10 to 400 m in two overlapping transects along 49W, between 57S and 61°30′S (27 Nov.–12 Dec. 1988, and 27 Dec. 1988–4 Jan. 1989). Dinoflagellates and tintinnids concentrated at 50–90 m (10–400 m weighted averages, dinoflagellates: 103 ind./I, 131 mg C/m²; tintinnids: 9.7 ind./I, 53 mg C/m²). Copepod nauplii had a more variable vertical pattern with maximum numbers at 100–200 m (10–400 m av.: 2.6 ind./I, 27 mg C/m²). Foraminifers and radiolarians …

Benthic Fluxes And Nitrogen Cycling In Sediments Of The Continental Margin Of The Eastern North Pacific, Allan H. Devol, John P. Christensen

Journal of Marine Research

The exchange of O₂, N₂, NO₃⁻, NH₄⁺, Si(OH)₄, and PO₄⁻³ between the sediments and the overlying water (benthic flux) was determined at 18 locations on the Washington State continental margin using an in situ benthic tripod. Oxygen consumption by the sediments ranged from 21.2 pmole cm⁻² s⁻¹ on the shelf to 2.85 pmole cm⁻² s⁻¹ on the slope. Nitrogen gas fluxes were from the sediments to the overlying water. They varied 5.5 to 1.2 pmole-N cm⁻² s^{−1 …}

An Analytic Model Of Tidal Circulation In A Narrow Estuary, X. H. Wang, P. D. Craig

Journal of Marine Research

A simple model of open coastal dynamics is adapted to provide an analytic solution of the vertical and axial structure of tidal currents in an estuary. Applied to the Hey River estuary in northern Queensland, the model provides an accurate representation of the four major tidal constituents. By best-fit analysis of the model results to data from three current meters, the vertical eddy viscosity for the estuary is estimated as 2.8 × 10⁻³ m²s⁻¹, and the linear friction coefficient as 8 × 10⁻⁴ ms⁻¹. Bottom boundary considerations indicate that the data are …

Release Rates Of Trace Elements And Protein From Decomposing Planktonic Debris. 1. Phytoplankton Debris, Byeong-Gweon Lee, Nicholas S. Fisher

Journal of Marine Research

The release rates of Ag, Am, Cd, Ce, Co, Pb, Se and Zn from decomposing diatom cells were determined using gamma-emitting radiotracers; rates were compared with C and protein loss rates over time. Additionally, experiments were designed to evaluate various artifacts involved in the experimental use of radioisotopes, handling of biogenic debris, and the use of poisons. The release rates of C at 18°C exponentially decreased with time from 17.5% d⁻¹ at 1 d to 2.7% d⁻¹ at 6 d; those of protein slowed from 9.2% d⁻¹ at 1 d to 2.0% d⁻¹ at 6 d. …

Potential Carbon Sources For The Head-Down Deposit-Feeding Polychaete Heteromastus Filiformis, Lisa M. Clough, Glenn R. Lopez

Journal of Marine Research

In this study we investigated potential carbon sources for the capitellid polychaete, Heteromastus filiformis. It is a head-down deposit feeder ingesting sediment from at least 15 cm below the sediment-water interface. This orientation appears to minimize the worm's ability to acquire food and oxygen and maximize its exposure to sulfide. The food sources we examined were metabolically active bacteria, benthic algae, detritus and chemoautotrophic bacteria. Carbon retention efficiencies from metabolically active bacteria, benthic algae and detritus by H. filiformis were 26%, 8% and 4% respectively. These values are relatively low compared to other deposit feeding species suggesting that H. …

Prochlorococcus And Synechococcus: A Comparative Study Of Their Optical Properties In Relation To Their Size And Pigmentation, André Morel, Yu-Hwan Ahn, Frédéric Partensky, Daniel Vaulot, Hervé Claustre

Journal of Marine Research

Three unialgal strains of Prochlorococcus and four of Synechococcus were grown in batch culture at low irradiances. The spectral values of light absorption, scattering and backscattering of intact cells in suspension were determined, together with cell counts, size distribution and pigment composition (via HPLC). The spectral efficiency factors Q_a, Q_b, Q_bb for light absorption, scattering and backscattering respectively, were derived, as well as the corresponding chlorophyll-specific coefficients a*, b* and b_b*. The pigment used when normalizing is “true” chlorophyll a for Synechococcus, and divinyl-chlorophyll a for Prochlorococcus. In correspondence …

Effects Of Poisons And Preservatives On The Fluxes And Elemental Compositions Of Sediment Trap Materials, John I. Hedges, Cindy Lee, Stuart G. Wakeham, Peter J. Hernes, Michael L. Peterson

Journal of Marine Research

Bulk particle fluxes and organic elemental compositions were compared among sediment traps treated with different poisons and preservatives. The traps (3:1 open cylinders) were deployed for 1–2 months at 30 and 60 m depths in a coastal marine environment. The tested treatments included mercuric chloride, mixed antibiotics, sodium azide, formalin, chloroform, and salt, along with untreated controls. Fluxes of bulk particulate material and weight percentages of organic carbon measured for differently treated traps deployed simultaneously at the same depth both varied by an average of ±8% of the mean value. Great numbers of large (>850 μm) zooplankton swimmers were …

Effects Of Poisons And Preservatives On The Composition Of Organic Matter In A Sediment Trap Experiment, Stuart G. Wakeham, John I. Hedges, Cindy Lee, Tamara K. Pease

Journal of Marine Research

Fluxes and molecular compositions of a group of major biochemical classes (lipids, lignin, pigments, amino acids, and carbohydrates) were compared among sediment traps treated with different poisons and preservatives and deployed for 1–2 months in a coastal marine environment. Fluxes and compositions of biochemicals were significantly more variable than bulk particle fluxes and elemental compositions. This observation was attributed to a greater influence of dead zooplankton “swimmers” in treated traps rather than differences in microbial decomposition due to the various treatments. Molecular compositions, especially of lipids, confirm the influence of zooplankton swimmers on the biochemical composition of the particulate material …

Deep Circulation In The Tropical North Atlantic, Marjorie A. M. Friedrichs, Melinda M. Hall

Journal of Marine Research

A transatlantic CTD/ADCP (Conductivity, Temperature, Depth/Acoustic Doppler Current Profiler) section along 11N, taken in March 1989, has been used to compute geostrophic velocities; geostrophic transport is required to balance in situ values of the Ekman and shallow boundary current transports. The horizontal flow structure is described for eight layers, with particular emphasis on deep and bottom waters (four layers below  = 4.7°C). In the shallow layers, total North Brazil Current (NBC) transport agrees with other observations previously made in the month of March, while net northward flow of these layers across the western basin is also consistent with recent …

Advection And Eddy Mixing In The Mediterranean Salt Tongue, Michael A. Spall, Philip L. Richardson, James Price

Journal of Marine Research

Lagrangian trajectories from the SOFAR float Mediterranean outflow experiment are used to estimate the low frequency variability and mixing in the vicinity of the Mediterranean salt tongue. Two dominant patterns of Lagrangian variability are observed, (1) nearly zonal low frequency motions and (2) wave-like oscillations with northwest to southeast orientation. The zonal motions are found near the core of the salt tongue in the Canary Basin while the oscillations are generally found to the south and east. It is suggested that the zonal motions are the result of baroclinic instability of the large-scale flow. They have zonally enhanced low frequency …

The Splitting Of Eddies Along Boundaries, Chuan Shi, Doron Nof

Journal of Marine Research

This paper addresses the question of what happens to an eddy that is forced “violently” against a boundary by, say, an advective current or another vortex. The detailed temporal evolution of such a collision on an f-plane is examined using a barotropic, as well as a one-and-a-half-layer contour dynamics model with surgery procedures. Both the barotropic eddy and the one-and-a-half-layer eddy initially have two circular potential vorticity fronts: an inner front at which the velocity increases to a maximum from zero at its center, and an outer front (e.g., the edge of the eddy) at which the velocity reduces …

Size-Fractionated 234th In Continental Shelf Waters Off New England: Implications For The Role Of Colloids In Oceanic Trace Metal Scavenging, S. Bradley Moran, Ken O. Buesseler

Journal of Marine Research

Measurements of ²³⁴Th (t_1/2 = 24.1 days) in dissolved, colloidal, and particulate forms have been made to investigate the role of colloids in reactive metal scavenging in the surface waters of Buzzards Bay, over an annual cycle, and in the shelf and slope waters off New England. At-sea sampling involved prefiltering seawater through 0.2 μm filters followed by cross-flow filtration using a 10,000 nominal molecular weight filter to collect colloidal (10,000 NMW-0.2 μm) and dissolved (<10,000 NMW) phases. Total ²³⁴Th activities increase with distance from shore, indicative of enhanced scavenging in the particle-rich nearshore waters. Clearly seen in Buzzards …

Detrital Spectral Absorption: Laboratory Studies Of Visible Light Effects On Phytodetritus Absorption, Bacterial Spectral Signal, And Comparison To Field Measurements, James R. Nelson, Charles Y. Robertson

Journal of Marine Research

Visible light-dependent changes in the visible and near-ultraviolet spectral absorption (250–750 nm) of phytodetritus (killed and disrupted phytoplankton and copepod fecal pellets) were determined in laboratory experiments, as were spectral changes due to the growth of bacteria. Bacteria carbon and nitrogen content were estimated. Results of the laboratory studies are compared to field measurements of particulate spectral absorption in waters from the South Atlantic Bight off the southeastern U.S. The correction for “pathlength amplification” of filtered particulate samples (β) is also examined. Light-dependent changes in the spectral absorption of phytodetritus are principally due to the bleaching of chlorophylls, pheopigments, and …

Enhanced Deposition To Pits: A Local Food Source For Benthos, Patricia L. Yager, Arthur R. M. Nowell, Peter A. Jumars

Journal of Marine Research

Particle deposition experiments using mimics of biogenous negative relief (“pits”) and low-excess-density particles in a small annular flume indicate a significantly enhanced deposition rate (number of particles per time) compared to smooth, flat patches of the same diameter. This study included flow visualizations as well as observations of particle residence times, particle concentrations in the pits, and particle fluxes to the pits from the main flow. Experimental conditions of particle concentration, shear velocity, and particle settling velocity mimicked the dynamic characteristics (low excess density and large size) of organic-rich flocs and flow conditions in the subtidal and deep sea where …

The Stability Of An Axially Symmetric Warm-Core Model Eddy On A Stratified Ocean, John Kroll

Journal of Marine Research

The linear stability of an axially symmetric model of a warm-core eddy over a stratified ocean of infinite depth is investigated using asymptotic techniques for large wavenumber and small Burger number. The development is similar to previous work on the stability of a geostrophic front (Kroll, 1992) and the results found there can be modified and applied to most oceanic eddies. The most important result is that instability occurs in a region confined at the edge of the eddy with maximum width of a fraction of the radius given approximately by the Rossby number for realistic eddies. We expect the …

Release Rates Of Trace Elements And Protein From Decomposing Planktonic Debris. 2. Copepod Carcasses And Sediment Trap Particulate Matter, John R. Reinfelder, Nicholas S. Fisher, Scott W. Fowler, Jean-Louis Teyssié

Journal of Marine Research

In experiments designed to relate the release kinetics of various elements with that of protein from biogenic particles, ^110mAg, ²⁴¹Am, ¹⁰⁹Cd, ⁶⁰Co, ⁷⁵Se and protein were measured over time in radiolabeled copepod carcasses and particles caught in unpoisoned sediment traps (mostly zooplankton fecal pellets and amorphous marine snow). Log-linear release rate constants (k) of ^110mAg, ²⁴¹Am, ¹⁰⁹Cd, and ⁶⁰Co from carcasses ranged from 0.079 d⁻¹ for ⁶⁰Co at 2°C to 0.130 d⁻¹ for ¹⁰⁹Cd at 15°C, and did not vary significantly with temperature. ⁷⁵Se …

Model Of Frontogenesis: Subduction And Upwelling, Dong-Ping Wang

Journal of Marine Research

A high-resolution, three-dimensional, primitive-equation model is used to study frontogenesis. The initial state includes a surface front and geostrophic jet. A small initial disturbance grows rapidly into a steepened backward-breaking wave, characterized by narrow wave trough and broad wave crest. Analysis of the energetics indicates that the unstable waves are generated by baroclinic instability. The wavelength scales as the baroclinic deformation radius, but the growth rate appears to be much faster than found in previous primitive-equation model studies. The predicted downward velocity also is an order of magnitude greater than found in previous model studies. As the amplitude of unstable …

Biological Effects Of Gulf Stream Meandering, Glenn R. Flierl, Cabell S. Davis

Journal of Marine Research

A modeling study was conducted to examine the effects of time-dependent mesoscale meandering of a jet on nutrient—phytoplankton—zooplankton (NPZ) dynamics. The jet was represented as a quasi-geostrophic flow using the method of contour dynamics. Two cases for biology were examined: 1) plankton in a mixed layer of fixed depth and 2) plankton at the base of a mixed layer (i.e., pycnocline) of variable depth. When the mixed layer depth is fixed, nutrient upwelling and dilution of the phytoplankton and zooplankton populations occur along the northward branch of the meander. The additional nutrients and reduced grazing pressure leads to significant enhancement …

Seasonal Contrasts In The Diel Vertical Distribution, Feeding Behavior, And Grazing Impact Of The Copepod Temora Longicornis In Long Island Sound, Hans G. Dam, William T. Peterson

Journal of Marine Research

We studied diel variability in vertical distribution, feeding behavior and grazing impact of female Temora longicornis in Long Island Sound on seven cruises from March to July. T. longicornis usually performed diel vertical migration characterized by deep residence during the day and ascent to near-surface waters at night for variable periods. The pattern of diel migration was independent of either the vertical distribution or relative abundance of chlorophyll in the water column. There was no clear evidence linking the amplitude of vertical migration to food concentration. Rather, the amplitude of migration decreased toward the end of the season probably due …

Cell Merging And The Jet/Downwelling Ratio In Langmuir Circulation, Ming Li, Chris Garrett

Journal of Marine Research

The Craik-Leibovich equations for Langmuir circulation have been integrated numerically to investigate the cell merging process as well as the strength and structure of the cells. We find that pairs of counterrotating vortices cancel each other, leading to a growth in scale of the dominant vortices. However, when there is no external forcing, vortices of opposite sign do not merge irrespective of the vortex size and circulation strength. The merging of Langmuir cells, or rather the cancellation of counterrotating vortices, is thus different from the amalgamation of like-signed vortices in two-dimensional turbulence. The forcing due to the Stokes drift plays …

Coupled Effects Of Vertical Mixing And Benthic Grazing On Phytoplankton Populations In Shallow, Turbid Estuaries, Jeffrey R. Koseff, Jacqueline K. Holen, Stephen G. Monismith, James E. Cloern

Journal of Marine Research

Coastal ocean waters tend to have very different patterns of phytoplankton biomass variability from the open ocean, and the connections between physical variability and phytoplankton bloom dynamics are less well established for these shallow systems. Predictions of biological responses to physical variability in these environments is inherently difficult because the recurrent seasonal patterns of mixing are complicated by aperiodic fluctuations in river discharge and the high-frequency components of tidal variability. We might expect, then, less predictable and more complex bloom dynamics in these shallow coastal systems compared with the open ocean. Given this complex and dynamic physical environment, can we …