Physical Sciences and Mathematics Commons^™

Salt Fluxes At The Chesapeake Bay Entrance, Ruth Lane

OES Theses and Dissertations

Underway measurements of salinity and flow profiles were used to compute salt fluxes at the mouth of the Chesapeake Bay in spring and summer. Waters were sampled along a cross-bay transect over four tidal cycles in 1997: at the end of April, during neap tides, and in mid-July, during spring tides. Data were interpolated onto a uniform grid along the transect area. A least squares regression with semidiurnal and diurnal harmonics was fit on both salinity and flow at each point of the grid to separate tidal from non-tidal influences. The results of the least squares fit were used to …

Limb Regeneration After Multiple Autotomy And Coxae Removal In The Blue Crab Callinectes Sapidus, Jennifer Ambler

OES Theses and Dissertations

This study investigated limb regeneration in the juvenile blue crab, Callinectes sapidus, specifically the role of the coxa and pedal nerve innervation of the regenerative limb bud over time. The coxa is a leg segment that has been defined as the source of positional, cellular, and neuronal information needed for limb regeneration in brachyuran crabs. This study indicates that removal of coxae under regenerative and non-regenerative conditions did not deter limb regeneration. The coxa is not the exclusive location of limb regenerative information since limbs re-grew with normal positional and functional arrangement in 86% of crabs showing regeneration at removal …

Mixed Layer Dynamics Along The Seward Line In The Northern Gulf Of Alaska, Nandita Sarkar

OES Theses and Dissertations

The northern Gulf of Alaska marine ecosystem is very productive with a "nutrient paradox". Primary producers require light and nutrients for photosynthesis. A primary source of nutrients is the deep ocean, while light is available in a relatively shallow layer in the upper ocean. In most productive parts of the world oceans, nutrients are brought to surface waters by upwelling. However, in the northern Gulf of Alaska, the winds are generally downwelling inducing and the mechanism(s) by which nutrients are brought to the euphotic zone are not known. One mechanism that might bring nutrients into the euphotic zone is the …

Annual And Interannual Variability In The Wind Field And The Hydrography Along The Seward Line In The Northern Gulf Of Alaska, Isaac Schroeder

OES Theses and Dissertations

The Northeast Pacific GLOBEC (GLOBal ocean Ecosystems dynamics) program (October 1997 to December 2004) collected hydrographic data along the Seward Line that stretches from the inner shelf (GAM 59.8°N, 149.5°W) and extends over 200 km beyond the continental slope (GAK13 58.1°N, 147.8°W). The complexity of the interannual hydrographic variability in this area stems from the interacting influences of local forcing such as winds, coastal freshwater discharge, eddies, fronts and remote forcing like El Niño-Southern Oscillation. Until now, the influence of winds on the system has been calculated using coarse resolution upwelling index data or spatially sparse buoy data. The coarse …

The Sensitivity Of The Southwest Monsoon Phytoplankton Bloom To Variations In Aeolian Iron Deposition Over The Arabian Sea, Jerry D. Wiggert, Raghu G. Murtugudde

CCPO Publications

[1] A coupled, 3-D biophysical ocean general circulation model is used to investigate how aeolian iron deposition affects the Arabian Sea ecosystem. Two separate aeolian iron deposition fields, derived from the GISS and GOCART atmospheric transport models, have been applied as surface boundary conditions. The model results exhibit widespread biogeochemical sensitivity to the choice of deposition field. With GOCART deposition, SW Monsoon phytoplankton blooms in the western and central Arabian Sea are enhanced and exhibit greater realism. The central Arabian Sea bloom is supported by supplemental input of horizontally advected iron from a pool that undergoes a yearlong progression that …

Interactions Between Phytoplankton And Bacteria In The Uptake Of Organic Compounds, Andrea Michel Rocha

OES Theses and Dissertations

The most common methods for estimating bacterial productivity are [³H]-leucine and [³H]-thymidine incorporation. Uptake of these compounds has been attributed primarily to bacteria; however, because dissolved organic nitrogen may be an important N source for some phytoplankton, the use of these compounds to estimate bacterial productivity needs to be reexamined. In order to ascertain whether phytoplankton could compete with bacteria on relevant timescales and thereby bias bacterial productivity estimates in estuaries, I examined the ability of cultured phytoplankton and size-fractionated natural populations to take up leucine and thymidine in systems seasonally dominated by phytoplankton mixotrophs. In …

The Observation, Modeling, And Retrieval Of Bio-Optical Properties For Coastal Waters Of The Southern Chesapeake Bay, Xiaoju Pan

OES Theses and Dissertations

The primary purpose of this study was to develop an inverse method to retrieve the inherent optical properties (IOPs) and biogeochemical parameters (e.g. chlorophyll a concentration and salinity) appropriate to monitor the water quality and biogeochemical processes from remote sensing of the coastal waters in the southern Chesapeake Bay and coastal Mid-Atlantic Bight region (MAB) dominated by Case 2 waters. For this purpose, knowledge of the relationship between remote sensing reflectance (R_rs) and IOPs and the effect from bottom reflectance on R_rs, is required.

A substantial investigation of IOPs has been conducted for the coastal …

Simulations Of Phytoplankton Species And Carbon Production In The Equatorial Pacific Ocean 2. Effects Of Physical And Biogeochemical Processes, Baris Salihoglu, Eileen E. Hofmann

CCPO Publications

A one-dimensional multi-component lower trophic level ecosystem model that includes detailed algal physiology is used to investigate the response of phytoplankton community and carbon production and export to variations in physical and biochemical processes in the Cold Tongue region of the equatorial Pacific Ocean at ON, 140W. Results show that high-frequency variability in vertical advection and temperature is an important mechanism driving the carbon export. Filtering out low frequency physical forcing results in a 30% increase in primary production and dominance of high-light adapted Prochlorococcus and autotrophic eukaryotes. Sensitivity studies show that iron availability is the primary control on carbon …

Nearshore Surface Temperatures In Antofagasta Bay (Chile) And Adjacent Upwelling Centers, A. Piñones, J. C. Castilla, R. Guiñez, J. L. Largier

CCPO Publications

Several years of sea surface temperature data (1997-2003) for the coast of Antofagasta Bay-a semi-enclosed bay in northern Chile-were analyzed in order to further exploring the nature of a warm-water retention pattern inside the bay. Based on time series techniques, we were able to confirm the persistence of warm water in the bay. This warm feature was found immediately downwind of the upwelling center at Jorgillo Point, where temperatures averaged 2-3 degrees C more than at the exposed upwelling sites outside and the bay. Temporal and spatial patterns in sea surface temperature were determined and showed being well associated with …

Assessment Of Skill And Portability In Regional Marine Biogeochemical Models: Role Of Multiple Planktonic Groups, Marjorie A. M. Friedrichs, Jeffery A. Dusenberry, Laurence A. Anderson, Robert A. Armstrong, Fei Chai, James R. Christian, Scott C. Doney, John Dunne, Masahiko Fujii, Jerry D. Wiggert

CCPO Publications

[1] Application of biogeochemical models to the study of marine ecosystems is pervasive, yet objective quantification of these models' performance is rare. Here, 12 lower trophic level models of varying complexity are objectively assessed in two distinct regions (equatorial Pacific and Arabian Sea). Each model was run within an identical one-dimensional physical framework. A consistent variational adjoint implementation assimilating chlorophyll-a, nitrate, export, and primary productivity was applied and the same metrics were used to assess model skill. Experiments were performed in which data were assimilated from each site individually and from both sites simultaneously. A cross-validation experiment was also conducted …

Baroclinic Effects And Tides On The Cape Hatteras Continental Shelf, Dana K. Savidge, Catherine R. Edwards, Mark Santana

CCPO Publications

Seasonal variability has been identified on the shelf near Cape Hatteras in the semidiurnal and diurnal frequency bands. Large summertime semidiurnal currents appear to be an M2 internal tide whose propagation shoreward is supported by strong Middle Atlantic Bight (MAB) seasonal stratification. At the southern limit of the MAB, strong MAB stratification gives way to weaker seasonal stratification in the South Atlantic Bight (SAB), and the M2 internal tide propagates shoreward less effectively. Strong diurnal variability appears in K1 and O1 components in summer, achieving magnitudes as large as the M2. The diurnal components are typically much smaller than M2 …

Bottom-Up Forcing And The Decline Of Steller Sea Lions (Eumetopias Jubatus) In Alaska: Assessing The Ocean Climate Hypothesis, Andrew W. Trites, Arthur J. Miller, Michael A. Alexander, Steven J. Bograd, John A. Calder, Antonietta Capotondi, Kenneth O. Coyle, Emanuele Di Lorenzo, Bruce P. Finney, Edward J. Gregr, Chester E. Grosch, Thomas C. Royer

CCPO Publications

Declines of Steller sea lion ( Eumetopias jubatus) populations in the Aleutian Islands and Gulf of Alaska could be a consequence of physical oceanographic changes associated with the 1976–77 climate regime shift. Changes in ocean climate are hypothesized to have affected the quantity, quality, and accessibility of prey, which in turn may have affected the rates of birth and death of sea lions. Recent studies of the spatial and temporal variations in the ocean climate system of the North Pacific support this hypothesis. Ocean climate changes appear to have created adaptive opportunities for various species that are preyed upon …

Simulations Of Phytoplankton Species And Carbon Production In The Equatorial Pacific Ocean 1. Model Configuration And Ecosystem Dynamics, Baris Salihoglu, Eileen E. Hofmann

OES Faculty Publications

The primary objective of this research is to investigate phytoplankton community response to variations in physical forcing and biological processes in the Cold Tongue region of the equatorial Pacific Ocean at 0N, 140W. This research objective was addressed using a one-dimensional multicomponent lower trophic level ecosystem model that includes detailed algal physiology, such as spectrally-dependent photosynthetic processes and iron limitation on algal growth. The ecosystem model is forced by a one-year (1992) time series of spectrally-dependent light, temperature, and water column mixing obtained from a Tropical Atmosphere-Ocean (TAO) Array mooring. Autotrophic growth is represented by five algal groups, which have …

Application Of Maldis-Ms To Identification Of Phytoplankton In Ballast Water, Dana Woodruff, Karen L. Wahl, Nancy B. Valentine, Fred Dobbs

OES Faculty Publications

Non-native invasive species are increasingly evident in marine and estuarine environments, largely because of the intake and release of ballast water from sea vessels. Innovative methods are needed to quickly and accurately detect and speciate non-native and/or harmful phytoplankton in ballast water. Recent advances in ionization techniques such as matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) have allowed detection of intact biomolecules within ballast samples. Statistically-based algorithms are used to discern "fingerprints" of phytoplankton species and to discern individual species from mixtures. MALDI-MS is particularly attractive for field applications because of the speed of analysis, minimal liquids/consumables required, and femtomole (10-15) …

Grazing Impacts Of Diverse Zooplankton Taxa On Thin Layers, Alexander Bochdansky

OES Faculty Publications

The US Navy needs to know how distributions and abundances of light-scattering and sound-scattering organisms in the ocean vary in space and time, particularly in the vertical dimension. Recent field observations have shown that many biological properties may vary substantially over small e.g. centimeter scales, commonly referred to as thin layers e.g. Cowles et al. 1998, 1999, Hanson Donaghay 1998, Holliday et al. 1999, Dekshenieks et al. 2001, Alldredge et al. 2002, Rines et al. 2002. Our previous ONR-funded research has allowed us to begin to understand how zooplankton interact with thin layers and how they can take advantage of …

Using Principles Of Momentum Conservation To Develop A Coastal Storm Impulse Scale (Cosi), Chris Adam Klentzman

Civil & Environmental Engineering Theses & Dissertations

Coastal engineers have long recognized the need for a storm classification system that combines wave conditions, storm surge, and the length of time for the storm event. A new classification system has been developed that is based on the conservation of total horizontal momentum. This research concentrated on developing the theory and then applying that theory for a 10-year period of data from the Army Corps of Engineers Field Research Facility (FRF) in Duck, North Carolina. When fully developed, the Coastal Storm Impulse scale (COSI) may be applied to all previous Hurricane and Northeaster storm events along a coast and …

Impact Of Anthropogenic Combustion Emissions On The Fractional Solubility Of Aeroosol Iron: Evidence From The Sargasso Sea, Peter N. Sedwick, Edward R. Sholkovitz, Thomas M. Church

OES Faculty Publications

We report empirical estimates of the fractional solubility of aerosol iron over the Sargasso Sea during periods characterized by high concentrations of Saharan dust (summer 2003) and by low concentrations of aerosols in North American/maritime North Atlantic air masses (spring 2004 and early summer 2004). We observed a strong inverse relationship between the operational solubility of aerosol iron (defined using a flow-through deionized-water leaching protocol) and the total concentration of aerosol iron, whereby the operational solubility of aerosol iron was elevated when total aerosol iron loadings were low. This relationship is consistent with source-dependent differences in the solubility characteristics of …

Response Of Eelgrass Zostera Marina To Co2 Enrichment: Possible Impacts Of Climate Change And Potential For Remediation Of Coastal Habitats, Sherry L. Palacios, Richard C. Zimmerman

OES Faculty Publications

Projected increases in dissolved aqueous concentrations of carbon dioxide [CO_2(aq)] may have significant impacts on photosynthesis Of CO₂-limited organisms such as seagrasses. Short-term CO_2(aq) enrichment increases photosynthetic rates and reduces light requirements for growth and survival of individual eelgrass Zostera marina L. shoots growing in the laboratory under artificial light regimes for at least 45 d. This study examined the effects of long-term CO_2(aq) enrichment on the performance of eelgrass growing under natural light-replete (33% surface irradiance) and light-limited (5% surface irradiance) conditions for a period of 1 yr. Eelgrass shoots were grown at …

Otolith Chemistry Reflects Frontal Systems In The Antarctic Circumpolar Current, J. R. Ashford, A. I. Arkhipkin, C. M. Jones

OES Faculty Publications

Pronounced environmental trends across fronts suggest that the otolith chemistry of oceanic fish can resolve zones on either side, promoting application to population questions at similar spatial scales. Trace and minor elements laid down immediately prior to capture - along the edges of otoliths from Patagonian toothfish Dissostichus eleginoides - discriminated frontal zones in the Antarctic Circumpolar Current in the Southwestern Atlantic Ocean. Mean values differentiated sampling areas by up to 2.6 standard deviations, suggesting: (1) otolith Mg/Ca enrichment related to fish activity around the Burdwood Bank; (2) Mn/Ca enrichment associated with South America; (3) Sr/Ca linked to the presence …

Co2 Control Of Trichodesmium N-2 Fixation, Photosynthesis, Growth Rates, And Elemental Ratios: Implications For Past, Present, And Future Ocean Biogeochemistry, D. A. Hutchins, F.-X. Fu, Y. Zhang, M. E. Warner, Y. Feng, K. Portune, P. W. Bernhardt, M. R. Mulholland

OES Faculty Publications

Diazotrophic marine cyanobacteria in the genus Trichodesmium contribute a large fraction of the new nitrogen entering the oligotrophic oceans, but little is known about how they respond to shifts in global change variables such as carbon dioxide (CO₂) and temperature. We compared Trichodesmium dinitrogen (N₂) and CO₂ fixation rates during steady-state growth under past, current, and future CO₂ scenarios, and at two relevant temperatures. At projected CO₂ levels of year 2100 (76 Pa, 750 ppm), N₂ fixation rates of Pacific and Atlantic isolates increased 35-100%, and CO₂ fixation rates increased 15-128% …