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Small-Scale Settlement Patterns Of The Oyster Crassostrea Virginica On A Constructed Intertidal Reef, Ian K. Bartol, Roger Mann

Biological Sciences Faculty Publications

The construction of three-dimensional, intertidal reefs resembling those widely present during colonial times in the Chesapeake Bay, but now absent due to years of overharvesting, may provide a more ecologically advantageous environment for oyster settlement and subsequent survival than present subtidal, two-dimensional habitats. We examined settlement processes on a constructed, 210 x 30 m intertidal reef composed of oyster shell. The reef was destructively and non-destructively sampled weekly throughout the summer and fall at tidal heights ranging from 30 cm above to 90 cm below mean low water (MLW) and at two substrate levels (reef surface and 10 cm below …

Detection Of Harmful Algal Blooms Using Photopigments And Absorption Signatures: A Case Study Of The Florida Red Tide Dinoflagellate, Gymnodinium Breve, David F. Millie, Oscar M. Schofield, Gary J. Kirkpatrick, Geir Johnson, Patricia A. Tester, Btyan T. Vintard

OES Faculty Publications

The utility of photopigments and absorption signatures to detect and enumerate the red tide dinoflagellate, Gymnodinium breve, was evaluated in laboratory cultures and in natural assemblages. The carotenoid, gyroxanthindiester, was an adequate biomarker for G. breve biomass; water‐column concentrations corresponded with cell standing crops and chlorophyll a concentrations during bloom events in Sarasota Bay, Florida. Unlike other carotenoids, the relative abundance of gyroxanthin‐diester did not change throughout a range of physiological states in culture and the gyroxanthin‐diester: chlorophyll a ratio exhibited little variability in a natural assemblage during bloom senescence. Stepwise discriminant analysis indicated that wavelengths indicative of in vivo …

Fluxes Of Copper-Complexing Ligands From Estuarine Sediments, Stephen A. Skrabal, John R. Donat, David J. Burdige

OES Faculty Publications

Most studies of the organic complexation of Cu in natural waters have focused on distributions and processes in the water column, where a significant fraction of Cu-complexing ligands may be biologically produced. We present direct evidence for a flux of Cu-complexing ligands from estuarine sediments, demonstrating that sediments are a significant, yet previously unrecognized source of the ligands. Fluxes of Cu-complexing ligands from Chesapeake Bay sediments range from 300 to 1,200 nmol m^-2 d^-1, exceeding fluxes of total dissolved Cu by 3->40-fold, suggesting that any Cu fluxing from the sediments is likely to be organically complexed. …

Regulation Of Algal Blooms In Antarctic Shelf Waters By The Release Of Iron From Melting Sea Ice, Peter N. Sedwick, Giacomo R. Ditullio

OES Faculty Publications

During summer 1995-96, we measured iron in the water column and conducted iron-enrichment bottle-incubation experiments at a station in the central Ross Sea (76°30'S, 170°40'W), first, in the presence of melting sea ice, and 17 days later, in ice-free conditions. We observed a striking temporal change in mixed-layer dissolved iron concentrations at this station, from 0.72-2.3 nM with sea ice present, to 0.16-0.17 nM in ice-free conditions. These changes were accompanied doubling of algal (diatom) biomass. Our incubation experiments suggest that conditions were iron-replete in the presence of sea ice, and iron-deficient in the absence of sea ice. We surmise …

Yield-Per-Recruit Analysis And Management Strategies For Atlantic Croaker, Micropogonias Undulatus, In The Middle Atlantic Bight, Luiz R. Barbieri, Mark E. Chittenden, Cynthia M. Jones

OES Faculty Publications

The effect of different fishing mortality (F) and natural mortality (M), and age at first capture (t(c)) on yield-per-recruit of Atlantic croaker, Micropogonias undulatus, in the lower Chesapeake Bay and North Carolina were evaluated with the Beverton-Holt model. Independent of the level of M (0.20-0.35) or F (0.01-2.0) used in simulations, yield-per-recruit values for Chesapeake Bay were consistently higher at t((c)) = 1 and decreased continuously with increases in t(c) (2-5). Although maximum yield-per-recruit always occurred at the maximum level off (F=2.0), marginal increases in yield beyond F = 0.50-0.75 were negligible. Current F (F(CUR)) is estimated to be …

Age And Growth Of Larval And Juvenile Atlantic Croaker, Micropogonias Undulatus, From The Middle Atlantic Bight And Estuarine Waters Of Virginia, Stephen W. Nixon, Cynthia M. Jones

OES Faculty Publications

Sagittal otoliths were used to determine age and growth of 605 larval and juvenile Atlantic croaker, Micropogonias undulatus, collected in the Middle Atlantic Bight and estuarine waters of Virginia. This study is the first to use age-based analysis for young Atlantic croaker collected in this region. A Laird-Gompertz model (r2=0.95) was used to describe the growth of Atlantic croaker up to 65 mm standard length (SL) and 142 days (t): SL((t)) = 2.657 exp (4.656 [1-exp (-0.0081t)]); where SL((t)) = standard length at day t. Spatial and temporal patterns in the size and age of Atlantic croaker showed a …

Response Of Otolith Microchemistry To Environmental Variations Experienced By Larval And Juvenile Atlantic Croaker (Micropogonias Undulatus), Simon R. Thorrold, Cynthia M. Jones, Steven E. Campana

OES Faculty Publications

Minor and trace elements incorporated into otoliths during growth may permanently record environmental conditions experienced by fishes. To determine the validity of this approach, we used laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to assay sectioned otoliths from juvenile Atlantic croaker (Micropogonias undulatus) collected from each of three sites in the Neuse River, North Carolina, and the Elizabeth River, Virginia. Elemental concentrations at the center of the otoliths did not differ between locations, although both Mg : Ca and Ba : Ca were significantly higher at the edge of otoliths from the Neuse River than from the …

Destruction Of Chloropigments In Copepod Guts, A. B. Bochdansky, D. Deibel

OES Faculty Publications

In a recent account regarding the destruction of chloropigments within the guts of copepods, Head & Harris (1996) (H&H) presented valuable data on pigment destruction in copepods. However, in one of their main conclusions, the authors invoked 2 enzyme pools to explain the pattern of pigment destruction: one directly derived from copepods, the other one produced by the ingested algae. If this conclusion is correct, it would have tremendous impact on the interpretation of data collected by the gut pigment technique. Estimating ingestion rates of copepods in the field would be very difficult, if not impossible, if pigment destruction was …

Watershed Prioritization, David G. Parker, Rod Williams, Hubert D. Scott

Arkansas Water Resources Center Technical Reports

The overall objective of this two-year study was to evaluate the water quality in the thirty-seven sub-basin watersheds in the Illinois River in Arkansas and to arrive at a watershed prioritization list to use in targeting non-point source activities. A water quality monitoring program was conducted with sampling in all thirty-seven sub-basins during both storm and base flow events and more intensive sampling in eight representative sub-basins during stOffil events. Each sub-basin was sampled seasonally during low flow (base-flow) conditions and during high flow storm (storm flow) conditions. In addition to the regular sampling, the intensive sub-basins were sampled approximately …

Investigation Of Ba, Bao, Sr And Sro Pulsed Laser-Induced Vapor Plumes In N2, O2, Microwave Discharged O2, And Vacuum At Low Laser Fluence, David L. Byers

Theses and Dissertations

Ba, BaO, Sr and SrO were ablated by 248 nm laser pulses at fluences ranging from 270 mJ-/cm² to 575 mJ-/cm² in vacuum and in 25 mtorr atmospheres of N2, O2 and microwave-discharged O₂. The spectral emissions of these plumes were compared for indications of ionization due to Ba or Sr collisions with each gas. The addition of a background gas increased the ion and neutral signature across the spectrum. SrO band emission was observed at 16,600-16,900/cm and possible BaO band emissions were observed in the 18,250-18,400/cm, 19,000-19700/cm and 19,800-20,000/cm regions. A screened plate ion probe …

Analysis Of Multimode Low-Probability-Of-Intercept (Lpi) Communications With Atmospheric Effects, Ala Ghordlo

Theses and Dissertations

This research expanded Low Probability of Intercept (LPI) communications analysis in two areas. First, multimode communication was included to account for ground to ground and air to ground links in addition to the standard air to air links traditionally used in LPI analysis. The propagation equations for the three modes of interest were derived and included in LPI analytic models in the form of a mode quality factor to account for multimode LPI scenarios. This new quality factor was used in studying several communication and interception link combinations. Variations due to differences between the communication and interception modes were presented …

Performance Analysis Of A Hartman Wavefront Sensor Used For Sensing Atmospheric Turbulence Statistics, Toby D. Reeves

Theses and Dissertations

Atmospheric turbulence parameters, such as Fried's coherence diameter, the outer scale of turbulence, and the turbulence power law, are related to the wavefront slope structure function (SSF). The SSF is defined as the second moment of the wavefront slope difference as a function of both time and position. Knowledge of the SSF allows turbulence parameters to be estimated. Hartmann wavefront sensor (H-WFS) slope measurements composed of both signal and noise, allow the SSF to be estimated by computing a mean square difference of H-WFS slope measurements. The quality of the SSF estimate is quantified by the signal-to-noise ratio (SNR) of …

Deconvolution From Wavefront Sensing Using Optimal Wavefront Estimators, Scott R. Maethner

Theses and Dissertations

A cost effective method to improve the space surveillance mission performance of United States Air Force (USAF) ground-based telescopes is investigated and improved. A minimum variance wavefront estimation technique is used to improve Deconvolution from Wavefront Sensing (DWFS), a method to mitigate the effects of atmospheric turbulence on imaging systems that does not require expensive adaptive optics. Both least-squares and minimum variance wavefront phase estimation techniques are investigated, using both Gaussian and Zernike polynomial elementary functions. Imaging simulations and established performance metrics are used to evaluate these wavefront estimation techniques for a one-meter optical telescope. Performance metrics include the average …

Species Composition, Abundance, And Vertical Distribution Of The Stomiid (Pisces: Stomiiformes) Fish Assemblage Of The Gulf Of Mexico, Tracey Sutton, T. L. Hopkins

Marine & Environmental Sciences Faculty Articles

Species composition, abundance, and vertical distribution of the stomiid fish assemblage were investigated in the eastern Gulf of Mexico, a low-latitude, oligotrophic oceanic ecosystem. Seventy-two described species, representing 18 genera, and one undescribed species were identified from 1155 trawl samples. With an additional 10 species reported elsewhere, the stomiid species number now known equals 83, making the Stomiidae the most diverse fish family in the Gulf of Mexico. The assemblage was dominated by three species,Photostomias guernei, Chauliodus sloani and Stomias affinis. These species, as well as four other common species, exhibited an asynchronous diel vertical migration pattern (450–900 …

Directory Of Water Related Courses Offered At Colleges And Universites In Arkansas, Kenneth F. Steele

Arkansas Water Resources Center Technical Reports

This publication lists the water and water-related courses at several universities and colleges in Arkansas as reported during the Fall of 1996. It Is anticipated that users of this directory will extend beyond college students, and will include professionals seeking continuing education, and professors desiring to exchange information on courses. This directory is not an "absolute" source of water and water-related courses because all of the higher learning institutions in Arkansas are not listed, and, secondly, because the definition of "water and water-related" varies from institution to institution. None-the-less this directory provides a very valuable and impressive reference on water …

Observation Of Spatial Variability Of Diurnal Thermocline And Rain-Formed Halocline In The Western Pacific Warm Pool, Alexander Soloviev, Roger Lukas

Marine & Environmental Sciences Faculty Articles

High-resolution measurements of temperature and salinity were made in the near-surface layer of the ocean during the Tropical Oceans-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment, using probes mounted on the bow of the R/V Moana Wave. Because of surface waves and pitching of the vessel, the bow probes profiled the near-surface layer of the ocean within depths of 0–4.0 m. In the near-surface layer of the ocean in the western Pacific warm pool, strong variability of temperature and salinity produced by diurnal heating and/or rain was often observed. The contoured density field revealed cases of pronounced spatial variability. The shallow …

Western Australian Salinity Action Plan, Agriculture Western Australia, Department Of Conservation And Land Management, Department Of Environmental Protection, Water And Rivers Commission

Natural resources published reports

Salinity is one of the State's most critical environmental problems, threatening major economic and social consequences. It is preventable and, in the long term, reversible. Complete elimination is not realistic, but we can dramatically reduce its impact.

Salinity is caused by replacing deep-rooted native plants with shallow-rooted crops and pastures. More rainfall passed below the root zone and accumulates as groundwater so that watertables rise. The groundwater mobilises natural salts in the soil as it rises and carries them towards the surface, eventually degrading land and streams.

Seasonal And Inter-Annual Patterns Of Sediment-Water Nutrient And Oxygen Fluxes In Mobile Bay, Alabama (Usa): Regulating Factors And Ecological Significance., Jean L. Cowan, Jonathan Pennock, Walter R. Boynton

School of Marine Science and Ocean Engineering

Sediment oxygen and nutrient fluxes were measured monthly for 2 yr in Mobile Bay, Alabama, USA. Rates of sediment oxygen consumption (0.1 to 1.25 gO₂ m^-2 d^-1), ammonium flux (-22 to 181 µmol m^-2 h^-1), nitrate flux (-14 to 67 µmol m^-2 h^-1), phosphate flux (-2 to 20.4 µmol m^-2 h^-1), and dissolved silicate flux (-15 to 342 µmol m^-2 h^-1) were moderate to high compared to values for other estuaries. A step-wise regression analysis revealed that dissolved oxygen concentration and temperature in bottom-waters …

Diversity Of Arkansas Water Resources Research, Kenneth F. Steele

Arkansas Water Resources Center Technical Reports

In order to understand, protect, and manage our water resources effectively knowledge is required from many diverse areas of science, engineering, economics, and sociology. These proceedings of the conference on the Diversity of Arkansas Water Resources Research reflect this need and demonstrate how researchers in the state are responding to water issues and problems in Arkansas. The papers in these proceedings are representative of the research in Arkansas, but are only a sample of the work being conducted by universities and government agencies in Arkansas. We are grateful that Arkansas has the expertise available to provide the information necessary to …

Food Security In The Southern African Development Community States, Joshua Chigodora

Drought Network News (1994–2001)

The 1995–96 cereal harvest in the Southern African Development Community (SADC) is the best within the last ten years. Provisional assessments project a regional maize surplus of 2.08 million tons, a 72% increase in production over the previous year’s harvest. Overall cereal production substantially increased in all countries except Tanzania, where the current cereal forecast of 3.73 million tons is a 14% drop from last year’s output of 4.34 million tons. Of special note are the exceptionally large increases in the area planted in cereals in war-ravaged Angola and Mozambique, for the first time in many years. Production trebled in …

Assessing The Impacts Of El Niño And Non-El Niño-Related Droughts Over India, R. H. Kripalani, Ashwini Kulkarni

Drought Network News (1994–2001)

It has now been recognized that the single most important key to the earth’s year-to-year climate variability is the El Niño/Southern Oscillation (ENSO) phenomenon. El Niño episodes directly affect the climate of at least half the planet and in many instances result in heavy loss of life and resources. The global impacts of El Niño events have been summarized in a review article by Bigg (1990), while the role of ENSO in Indian monsoon rainfall variability is given in Krishna Kumar et al. (1995). During the ENSO warm/ cold extremes—i.e., El Niño/La Niña events—the majority of the episodes induce below/above-normal …

Moisture Deficit Index Evaluated For Dry Regions Of India, K. K. Nathan, S. K. Sinha

Drought Network News (1994–2001)

In India, about 70% of the cultivable land is rainfed. This includes areas where crops are rarely affected by drought and areas where crops experience moisture stress and often fail. The regions with the latter characteristics are often called dryland areas and the agriculture so practiced there is known as dryland agriculture. About 35% of the total cultivable land belongs in this category. To determine the magnitude of water deficiency in these regions, the moisture deficit index (MDI) has been evaluated for dryland stations in India. The MDI is usually determined on the basis of annual precipitation and annual potential …

Exploring The Potential For Using Enso Forecasts In The U.S. Corn Belt, Jennifer G. Phillips, Cynthia Rosenzweig, Mark Cane

Drought Network News (1994–2001)

Interannual climate variability poses the greatest risk that farmers face. Until recently, seasonal climate forecasts have been weak and therefore rarely observed by farmers in making management decisions. Farm management is generally based on long-term mean expectations of climate and crop responses to local edaphic conditions. Currently, significant progress is being made in the skill level of predictions of seasonal to interannual climate, primarily because of new understanding of the teleconnections between ocean circulation and atmospheric processes. The El Niño/Southern Oscillation (ENSO) refers to fluctuations in both sea-surface temperatures (SSTs) in the eastern equatorial Pacific and in sea-level pressures in …

Meteorological Drought In Turkey: A Historical Perspective, 1930-–93, Murat Türkes

Drought Network News (1994–2001)

The climate of Turkey, which is mainly characterized by the Mediterranean macro climate, results from the seasonal alternation of frontal depressions with polar air masses and subtropical high pressures with subsiding maritime tropical and continental tropical air masses. Continental tropical airstreams from the northern African and Arabian deserts particularly dominate throughout the summer, by causing long-lasting warm (hot) and dry conditions over Turkey (except the Black Sea region and northeastern Anatolia). Turkey has an area of 779,452 km² and an average elevation of 1,132 m.

This study outlines some spatial and temporal characteristics of Turkey’s rainfall, particularly in terms …

Corals Of The South-West Indian Ocean Iv. The Hard Coral Family Faviidae Gregory, 1900 (Scleractinia: Faviina), Bernhard Riegl

Marine & Environmental Sciences Faculty Reports

This annotated check-list deals with the scleractinian coral family Faviidae in subtropical south-east Africa (the African mainland coast south of the Tropic of Capricorn). Material from the atoll Bassas da India in the Mozambique channel was included. Most species are of wide Indo-Pacific distribution. The faviid fauna of Mozambique was richer (28 species) than the South African fauna (21 species). The fauna of Bassas da India was similar to that on the African mainland coast with four additional species. South-east Africa has a moderately rich faviid fauna compared with other areas in the Indo-Pacific region. Field and laboratory characteristics are …

Modeling Nutrient And Plankton Processes In The California Coastal Transition Zone: 1. A Time- And Depth-Dependent Model, J. R. Moisan, Eileen E. Hofmann

CCPO Publications

A time- and depth-dependent, physical-bio-optical model was developed for the California coastal transition zone (CTZ) with the overall objective of understanding and quantifying the processes that contribute to the vertical and temporal development of nutrient and plankton distributions in the CTZ. The model food web components included silicate, nitrate, ammonium, two phytoplankton size fractions, copepods, doliolids, euphausiids, and a detritus pool. The wavelength-dependent subsurface irradiance field was attenuated by sea water and phytoplankton pigments. The one-dimensional (1-D) model adequately simulated the development and maintenance of a subsurface chlorophyll maximum in different regions within the CTZ. An analysis of the individual …

Circulation, Fall 1996, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Fall 1996 issue of CCPO Circulation featuring article "Antarctic Continental Shelves Are Strange And Unique"

Modeling Nutrient And Plankton Processes In The California Coastal Transition Zone: 3. Lagrangian Drifters, J. R. Moisan, Eileen E. Hofmann

CCPO Publications

Two types of numerical Lagrangian drifter experiments were conducted, using a set of increasingly complex and sophisticated models, to investigate the processes associated with the plankton distributions in the California coastal transition zone (CTZ). The first experiment used a one-dimensional (1-D; vertical) time-dependent physical-bio-optical model, which contained a nine-component food web. Vertical velocities, along the track of simulated Lagrangian drifters, derived from a three-dimensional (3-D), primitive equation circulation model developed to simulate the flow observed within the CTZ; were used to parameterize the upwelling and downwelling processes. The second experiment used 880 simulated Lagrangian drifters from a 3-D primitive equation …

Modeling Nutrient And Plankton Processes In The California Coastal Transition Zone: 2. A Three-Dimensional Physical-Bio-Optical Model, J. R. Moisan, Eileen E. Hofmann, D. B. Haidvogel

CCPO Publications

A three-dimensional (3-D) primitive equation model, developed to simulate the circulation features (filaments) observed in the California coastal transition zone (CTZ), was coupled to a nine-component food web model and a bio-optical model. The simulated flow fields from a 3-D primitive equation model are used to advect the constituents of the food web model, which include silicate, nitrate, ammonium, two phytoplankton size fractions, copepods, doliolids, euphausiids, and a detritus pool. The bio-optical model simulates the wavelength-dependent attenuation of the subsurface irradiance field. The overall objective of this modeling study was to understand and quantify the processes that contribute to the …

In-Situ Far-Field Calibration Of Multibeam Sonar Arrays For Precise Backscatter Imagery, Larry Fusillo, Christian De Moustier, John H. Satriano, Stanley Zietz

Center for Coastal and Ocean Mapping

Calibration of large hull-mounted sonar transducer arrays is usually done by measuring the performance of individual components in a test tank. Multiple transducer element beam patterns are superimposed and combined with window attenuation and other partial measurements to give an approximation of the total beam pattern. This process often ignores or fails to accurately model factors such as mounting hardware, array misalignment, reflections from the hull structure and other real world absorbers, reflectors and attenuators which can have significant effect on the actual beam pattern. This paper describes an application of a novel technique for in-situ measurement of the far-field …