Physical Sciences and Mathematics | Open Access Articles

Characterization Of Pfiesteria Ichthyocidal Activity, Andrew S. Gordon, Harold G. Marshall, Sandra E. Shumway, Kathryn J. Coyne, Alan J. Lewitus, Michael A. Mallin, Parke A. Rublee

Biological Sciences Faculty Publications

Letter to the Editor regarding article: Drgon, T., et al. 2005. Characterization of ichthyocidal activity of Pfiesteria piscicida: Dependence on the dinospore cell density. Appl. Environ. Microbiol. 71:519–529

Go to article

Natural And Synthetic Viniferins Associated With The Grapevine Disease Young Vine Decline, David Michael Mcginnis

Chemistry & Biochemistry Theses & Dissertations

Grapevine disease has been thc subject of intense research amongst viticulturists over the last few decades, especially during the 1990's. There has been discoveries that suggest grapevine disease is commonly caused by fungal pathogens. One of the most common fungi that the vine may become infected by is known as Botrytis cinerea. B. cinerea is capable of attacking the grapevine which in turn will lead to bunch rot in the grape clusters. This disease has been researched in great detail during the past several years and is one of only few microorganisms that have actually been identified. Phaeoacremrmium chnlmydospnrum …

Go to article

Phytoplankton Development Within Tidal Freshwater Regions Of Two Virginia Rivers, Harold G. Marshall, Lubomira Burchardt

Virginia Journal of Science

Phytoplankton composition and the range of seasonal patterns of abundance are presented for the tidal freshwater regions in two Virginia rivers based on data accumulated monthly from 1986 through 1999. Diatoms dominated the flora during spring, summer, and fall, whereas, other taxonomic categories were more representative when the river flow rates decreased, allowing for a more stable water system and increased residency time within this tidal region during summer and early fall. This summer/fall period was associated with increased water temperatures, higher productivity rates and chlorophyll levels, increased total phytoplankton abundance and species diversity. The major components of the summer …

Go to article

Interannual Variation Of Stratification In Lower Chesapeake Bay, Christopher S. Katzenmiller

OES Theses and Dissertations

Stratification in the water column can prove to be an important indicator to the state of the water column and ecosystem. The focus of this research is to evaluate trends in stratification in the Lower Chesapeake Bay. Detailed analysis was performed on a 14 year data set to study interannual variation in the region of study. Potential energy anomaly was used to quantify stratification. Potential energy anomaly is the amount of energy required to mix a water column. It is determined from the vertical density structure of density. Potential energy anomaly is the departure of potential energy from climate conditions. …

Go to article

Can Otolith Elemental Signatures Record The Capture Site Of Patagonian Toothfish (Dissostichus Eleginoides), A Fully Marine Fish In The Southern Ocean?, J. R. Ashford, C. M. Jones, E. Hofmann, I. Everson, C. Moreno, G. Duhamel, R. Williams

CCPO Publications

Otolith chemistry has been successfully used to reconstruct the environmental history experienced by estuarine-dependent teleost fish, including movement between estuaries and coastal areas. However, application has been more limited in species exposed exclusively to oceanic waters, where gradients in physical and chemical properties are less extreme. To test whether otolith elemental signatures record spatial information in an oceanic species, we sampled otoliths from Patagonian toothfish (Dissostichus eleginoides) and used an inductively coupled plasma mass spectrometer (ICP-MS) coupled to a laser ablation system to target the outer otolith edges corresponding to the period immediately before capture. Using multivariate analysis …

Go to article

The Role Of Feeding Behavior In Sustaining Copepod Populations In The Tropical Ocean, J. D. Wiggert, A. G. E. Haskell, G.-A. Paffenhofer, E. E. Hofmann, J. M. Klinck

CCPO Publications

A fundamental question regarding marine copepods is how the many species coexist and persist in the oligotrophic environment (i.e. Hutchinson’s paradox). This question is addressed with a stochastic, object-oriented Lagrangian model that explicitly simulates the distinct foraging behaviors of three prominent tropical species: Clausocalanus furcatus, Paracalanus aculeatus and Oithona plumifera. The model also individually tracks all prey cells. Each particle’s motion combines sinking, turbulent diffusion and active swimming when applicable. The model successfully simulates observed size partitioned carbon uptake rates. Based on the model results, the wide-ranging translational ambit employed by C. furcatus is best suited for the acquisition …

Go to article

The Architecture Of A Proteomic Network In The Yeast, Emad Ramadan, Christopher Osgood, Alex Pothern

Biological Sciences Faculty Publications

We describe an approach to clustering the yeast protein-protein inter-action network in order to identify functional modules, groups of proteins forming multi-protein complexes accomplishing various functions in the cell. We have developed a clustering method that accounts for the small-world nature of the network. The algorithm makes use of the concept of k-cores in a graph, and employs recursive spectral clustering to compute the functional modules. The computed clusters are annotated using their protein memberships into known multi-protein complexes in the yeast. We also dissect the protein interaction network into a global subnetwork of hub proteins (connected to several clusters), …

Go to article

Iron In The Sargasso Sea (Bermuda Atlantic Time-Series Study Region) During Summer: Eolian Imprint, Spatiotemporal Variability, And Ecological Implications, Peter N. Sedwick, T. M. Church, A. R. Bowie, C. M. Marsay, S. J. Ussher, K. M. Achilles, P. J. Lethaby, R. J. Johnson, M. M. Sarin, D. J. Mcgillicuddy

OES Faculty Publications

We report iron measurements for water column and aerosol samples collected in the Sargasso Sea during July-August 2003 (summer 2003) and April-May 2004 (spring 2004). Our data reveal a large seasonal change in the dissolved iron (dFe) concentration of surface waters in the Bermuda Atlantic Time-series Study region, from ∼1-2nM in summer 2003, when aerosol iron concentrations were high (mean 10 nmol/m^-3), to ∼0.1-0.2nM in spring 2004, when aerosol iron concentrations were low (mean 0.64 nmol/m^-3). During summer 2003, we observed an increase of ∼0.6nM in surface water dFe concentrations over 13 days, presumably due to …

Go to article

Comparison Of Phytoplankton And Autotrophic Picoplankton Populations Over A 24-Hour Period From A Pond's Surface And Subsurface Waters, Harold G. Marshall, Lubomira Burchardt, Elżbieta Wilk-Woźniak

Biological Sciences Faculty Publications

Phytoplankton abundance and composition relationships within the surface layer changed over short time periods (4-6 hours) in comparison with more constant associations at 2 cm below the surface. Both strata had a diverse algal flora (>50 taxa), but no distinct neuston assemblage characterized the surface layer algal composition over the 24-hour study. The similarity between the two strata indicated the floral composition of the surface layer came from the water column algae below the surface. Chlorophytes, diatoms, cyanobacteria, and cryptophytes represented the most abundant algal categories for both strata with a total mean phytoplankton abundance of 3,566 cells ml …

Go to article

Simulations Of Nanopore Formation And Phosphatidylserine Externalization In Lipid Membranes Subjected To A High-Intensity, Ultrashort Electric Pulse, Q. Hu, R. P. Joshi, K. H. Schoenbach

Bioelectrics Publications

A combined MD simulator and time dependent Laplace solver are used to analyze the electrically driven phosphatidylserine externalization process in cells. Time dependent details of nanopore formation at cell membranes in response to a high-intensity (100kV∕cm), ultrashort (10ns) electric pulse are also probed. Our results show that nanosized pores could typically be formed within about 5ns. These predictions are in very good agreement with recent experimental data. It is also demonstrated that defect formation and PS externalization in membranes should begin on the anode side. Finally, the simulations confirm that PS externalization is a nanopore facilitated event, rather than the …

Go to article

Effects Of Human Disturbances On The Behavior Of Wintering Ducks, Melissa L. Pease, Robert K. Rose, Mark J. Butler

Biological Sciences Faculty Publications

Human activity causes wintering waterfowl to expend energy to avoid humans at a time in their annual cycle when energy conservation is important to survival, migration, and breeding reserves. Understanding the effects of recreational activities on waterfowl is important to managing natural resource areas where migratory birds depend on wetland habitat for resting and feeding. We investigated responses of 7 species of dabbling ducks to 5 different experimental human activities, (a pedestrian, a bicyclist, a truck traveling at 2 different speeds, and an electric passenger tram). Responses of ducks depended on type of disturbance, species, and distance from disturbances. Most …

Go to article

A Review Of Phytoplankton Composition Within Chesapeake Bay And Its Tidal Estuaries, Harold G. Marshall, Lubomira Burchardt, Richard Lacouture

Biological Sciences Faculty Publications

Based on a continuous 20-year data base ofmonthly sampling in Chesapeake Bay and tidal regions of its major tributaries, 1454 phytoplankton taxa have been identified in these waters. They represent a diverse assemblage of species with a dominant diatom flora throughout the year, in addition to large seasonal representation by chlorophytes, cyanobacteria, cryptophytes and dinoflagellates. Included among this flora were 34 potential harmful or toxin producing species. The phytoplankton compositions associated with the seasonal successional patterns are discussed, in addition to characterizing the dominant floral relationships, with comparison to early composition records within the Bay. Several of the present day …

Go to article

Effect Of Humic Substance Photodegradation On Bacterial Growth And Respiration In Lake Water, Alexandre M. Anesio, William Granéli, George R. Aiken, David J. Kieber, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

This study addresses how humic substance (HS) chemical composition and photoreactivity affect bacterial growth, respiration, and growth efficiency (BGE) in lake water. Aqueous solutions of HSs from diverse aquatic environments representing different dissolved organic matter sources (autochthonous and allochthonous) were exposed to artificial solar UV radiation. These solutions were added to lake water passed through a 0.7-μm pore-size filter (containing grazer-free lake bacteria) followed by dark incubation for 5, 43, and 65 h. For the 5-h incubation, several irradiated HSs inhibited bacterial carbon production (BCP) and this inhibition was highly correlated with H₂O₂ photoproduction. The H_{2 …}

Go to article

Phytoplankton Development Within Tidal Freshwater Regions Of Two Virginia Rivers, Usa, Harold G. Marshall, Lubomira Burchardt

Biological Sciences Faculty Publications

Phytoplankton composition and the range of seasonal patterns of abundance are presented for the tidal freshwater regions in two Virginia rivers based on data accumulated monthly from 1986 through 1999. Diatoms dominated the flora during spring, summer, and fall, whereas, other taxonomic categories were more representative when the river flow rates decreased, allowing for a more stable water system and increased residency time within this tidal region during summer and early fall. This summer/fall period was associated with increased water temperatures, higher productivity rates and chlorophyll levels, increased total phytoplankton abundance and species diversity. The major components of the summer …

Go to article

Feeding Ecology Of Juvenile Spiny Lobster, Panulirus Interruptus, On The Pacific Coast Of Baja California Sur, Mexico, Verónica Castañeda‐Fernández‐De‐Lara, Elisa Serviere‐Zaragoza, Sergio Hernández‐Vázquez, Mark J. Butler Iv

Biological Sciences Faculty Publications

Many aspects of the early life history of the red lobster Panulirus interruptus are little known, including the relationship between habitat structure, food resource availability, and nutrition of juveniles. We investigated the spatial and temporal differences in food intake, diet composition, and nutritional condition of juveniles at two sites along the Pacific coast of the Baja California Peninsula (Mexico) with contrasting oceanographic and biological conditions. One site (Arvin) is located inside a protected bay, Bahia Tortugas, where the waters are cooler and temperate seagrasses and macroalgae are the dominant benthic flora. The second site (Queen) in Bahia Sebastian Vizcaino was …

Go to article

Population Dynamics Of Oryzomys Palustris And Microtus Pennsylvanicus In Virginia Tidal Marshes, Christopher P. Bloch, Robert K. Rose

Biological Sciences Faculty Publications

Oryzomys palustris (marsh rice rat) and Microtus pennsylvanicus (meadow vole) cohabit coastal marshes in the mid-Atlantic US. Both were live-trapped for 23 months at two tidal marsh sites in Virginia to assess their demography near the margins of their distributions. In the presence of dense vegetation, population dynamics of the two species were seasonal and positively correlated, with densities declining through the winter. At the more sparsely vegetated site, densities of both species were lower, and densities of M. pennsylvanicus were negatively correlated with those of O. palustris. Patterns of reproduction differed between the species. O. palustris was reproductively …

Go to article

Do Viruses Affect Fecundity And Survival Of The Copepod Acartia Tonsa Dana?, Lisa A. Drake, Fred C. Dobbs

OES Faculty Publications

Naturally occurring viruses are extremely abundant in aquatic systems, and they infect bacteria, cyanobacteria, prokaryotic and eukaryotic phytoplankton, heterotrophic nanoflagellates, fish and mammals. Viral infections of single-celled organisms have been studied intensively in the past decade, but little is known about the effects of viruses on aquatic metazoans, other than for some economically important species. Because zooplankton assemblages are often dominated in number and biomass by copepods, we used them as model organisms to study the effects of naturally occurring viruses on higher trophic levels. We attempted to induce viral infection in laboratory-reared cultures of the estuarine copepod Acartia tonsa …

Go to article

Demonstration Of Toxicity To Fish And To Mammalian Cells By Pfiesteria Species: Comparison Of Assay Methods And Strains, Joann M. Burkholder, Andrew S. Gordon, Peter D. Moeller, J. Mac Law, Kathryn J. Coyne, Alan J. Lewitus, John S. Ramsdell, Harold G. Marshall, Nora J. Deamer, S. Craig Cary, Jason W. Kempton, Steven L. Morton, Parke A. Rublee

Biological Sciences Faculty Publications

Toxicity and its detection in the dinoflagellate fish predators Pfiesteria piscicida and Pfiesteria shumwayae depend on the strain and the use of reliable assays. Two assays, standardized fish bioassays (SFBs) with juvenile fish and fish microassays (FMAs) with larval fish, were compared for their utility to detect toxic Pfiesteria. The comparison included strains with confirmed toxicity, negative controls (noninducible Pfiesteria strains and a related nontoxic cryptoperidiniopsoid dinoflagellate), and P. shumwayae strain CCMP2089, which previously had been reported as nontoxic. SFBs, standardized by using toxic Pfiesteria (coupled with tests confirming Pfiesteria toxin) and conditions conducive to toxicity expression, reliably detected …

Go to article

Chemistry Of Surface Waters: Distinguishing Fine-Scale Differences In Sea Grass Habitats Of Chesapeake Bay, Emmanis Dorval, Cynthia M. Jones

OES Faculty Publications

We tested the hypothesis that the physical and chemical processes acting in sea grass habitats of the lower Chesapeake Bay are spatially structured and that dissolved elemental chemistry of sea grass-habitat surface waters have their own unique identity. We sampled surface waters from July to September 2001 in five sea grass habitats of the lower bay: Potomac, Rappahannock, York, Island (Tangier-Bloodsworth), and Eastern Shore. Dissolved Mg, Mn, Sr, and Ba concentrations were measured by sector field inductively coupled plasma-mass spectrometry. As expected, Mg, Sr, and Ba exhibited conservative behavior, but Mn exhibited nonconservative behavior along the salinity gradient. Spatial differences …

Go to article

Circulation, Mixing And The Distribution Of Remineralized Nutrients, Larry P. Atkinson, John Huthnance, Jose L. Blanco

CCPO Publications

No abstract provided.

Go to article

Biophysical Mechanisms Of Larval Fish Ingress Into Chesapeake Bay, Jonathan A. Hare, Simon Thorrold, Harvey Walsh, Christian Reiss, Arnoldo Valle-Levinson, Cynthia Jones

OES Faculty Publications

Selective tidal stream transport is hypothesized as a dominant mechanism by which larvae of marine animals move through estuarine openings. For larvae moving from the shelf to estuarine habitats, selective tidal stream transport proposes that larvae are higher in the water column during flood tide and lower in the water column during ebb tide. Although a number of studies conclude that selective tidal stream transport is the mechanism responsible for larval ingress, few studies consider alternative mechanisms or consider passive explanations for tidal patterns in larval distributions. We examined the biophysical mechanisms responsible for larval ingress into Chesapeake Bay using …

Go to article

A Unique Seasonal Pattern In Phytoplankton Biomass In Low-Latitude Waters In The South China Sea, Chun-Mao Tseng, George T. F. Wong, I.-I. Lin, C.-R. Wu, K.-K. Liu

OES Faculty Publications

A distinctive seasonal pattern in phytoplankton biomass was observed at the South East Asian Time series Study (SEATS) station (18°N, 116°E) in the northern South China Sea (SCS). Surface chlorophyll-a, depth integrated chlorophyll-a and primary production were elevated to 0.3 mg/m³, ~35 mg/m² and 300 mg-C/m²/d, respectively, in the winter but stayed low, at 0.1 mg/m³, ~15 mg/m² and 110 mg-C/m²/d as commonly found in other low latitude waters, in the rest of the year. Concomitantly, soluble reactive phosphate and nitrate+nitrite in the mixed layer also became …

Go to article

The Effect Of Growth Rate, Phosphorus Concentration, And Temperature On N-2 Fixation, Carbon Fixation, And Nitrogen Release In Continuous Cultures Of Trichodesmium Ims101, Margaret R. Mulholland, Peter W. Bernhardt

OES Faculty Publications

With the use of continuous culture systems, rates of dinitrogen (N₂) and carbon (C) fixation and nitrogen (N)- and C-based doubling times were assessed in Trichodesmium IMS101 growing exponentially at steady state dilution rates of 0.10, 0.20, and 0.33 d^-1 (doubling times of 10, 5, and 3 d - within the range reported for natural populations). Rates of C fixation, N₂ fixation, and N release were examined in replicate culture systems with several techniques. Biomass-specific C uptake varied little with population doubling time, but N₂ fixation and N release varied markedly among treatments. Total daily …

Go to article

Ridding Ships' Ballast Water Of Microorganisms, Fred C. Dobbs, Andrew Rogerson

OES Faculty Publications

( First paragraph) A complex assemblage of microorganisms exists in nearly every aquatic system on earth. In lakes and oceans, every milliliter of water contains about 10² protists (single-celled eukaryotes), 10⁶ bacteria, and 10⁷–10⁹ viruses. Therefore, billions of microorganisms inevitably enter ships’ ballast tanks during normal operations. It has been argued that microorganisms must certainly be frequent invaders of coastal ecosystems, given the high densities of bacteria and viruses in ballast water—10⁸ and 10⁹ organisms per liter, respectively (1)—their potentially high reproductive rates, broad tolerances to physical conditions, and ability to form resting …

Go to article

Full-Text Articles in Physical Sciences and Mathematics

Characterization Of Pfiesteria Ichthyocidal Activity, Andrew S. Gordon, Harold G. Marshall, Sandra E. Shumway, Kathryn J. Coyne, Alan J. Lewitus, Michael A. Mallin, Parke A. Rublee

Biological Sciences Faculty Publications

Natural And Synthetic Viniferins Associated With The Grapevine Disease Young Vine Decline, David Michael Mcginnis

Chemistry & Biochemistry Theses & Dissertations

Phytoplankton Development Within Tidal Freshwater Regions Of Two Virginia Rivers, Harold G. Marshall, Lubomira Burchardt

Virginia Journal of Science

Interannual Variation Of Stratification In Lower Chesapeake Bay, Christopher S. Katzenmiller

OES Theses and Dissertations

Can Otolith Elemental Signatures Record The Capture Site Of Patagonian Toothfish (Dissostichus Eleginoides), A Fully Marine Fish In The Southern Ocean?, J. R. Ashford, C. M. Jones, E. Hofmann, I. Everson, C. Moreno, G. Duhamel, R. Williams

CCPO Publications

The Role Of Feeding Behavior In Sustaining Copepod Populations In The Tropical Ocean, J. D. Wiggert, A. G. E. Haskell, G.-A. Paffenhofer, E. E. Hofmann, J. M. Klinck

CCPO Publications

The Architecture Of A Proteomic Network In The Yeast, Emad Ramadan, Christopher Osgood, Alex Pothern

Biological Sciences Faculty Publications

OES Faculty Publications

Comparison Of Phytoplankton And Autotrophic Picoplankton Populations Over A 24-Hour Period From A Pond's Surface And Subsurface Waters, Harold G. Marshall, Lubomira Burchardt, Elżbieta Wilk-Woźniak

Biological Sciences Faculty Publications

Simulations Of Nanopore Formation And Phosphatidylserine Externalization In Lipid Membranes Subjected To A High-Intensity, Ultrashort Electric Pulse, Q. Hu, R. P. Joshi, K. H. Schoenbach

Bioelectrics Publications

Effects Of Human Disturbances On The Behavior Of Wintering Ducks, Melissa L. Pease, Robert K. Rose, Mark J. Butler

Biological Sciences Faculty Publications

A Review Of Phytoplankton Composition Within Chesapeake Bay And Its Tidal Estuaries, Harold G. Marshall, Lubomira Burchardt, Richard Lacouture

Biological Sciences Faculty Publications

Effect Of Humic Substance Photodegradation On Bacterial Growth And Respiration In Lake Water, Alexandre M. Anesio, William Granéli, George R. Aiken, David J. Kieber, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

Phytoplankton Development Within Tidal Freshwater Regions Of Two Virginia Rivers, Usa, Harold G. Marshall, Lubomira Burchardt

Biological Sciences Faculty Publications

Feeding Ecology Of Juvenile Spiny Lobster, Panulirus Interruptus, On The Pacific Coast Of Baja California Sur, Mexico, Verónica Castañeda‐Fernández‐De‐Lara, Elisa Serviere‐Zaragoza, Sergio Hernández‐Vázquez, Mark J. Butler Iv

Biological Sciences Faculty Publications

Population Dynamics Of Oryzomys Palustris And Microtus Pennsylvanicus In Virginia Tidal Marshes, Christopher P. Bloch, Robert K. Rose

Biological Sciences Faculty Publications

Do Viruses Affect Fecundity And Survival Of The Copepod Acartia Tonsa Dana?, Lisa A. Drake, Fred C. Dobbs

OES Faculty Publications

Biological Sciences Faculty Publications

Chemistry Of Surface Waters: Distinguishing Fine-Scale Differences In Sea Grass Habitats Of Chesapeake Bay, Emmanis Dorval, Cynthia M. Jones

OES Faculty Publications

Circulation, Mixing And The Distribution Of Remineralized Nutrients, Larry P. Atkinson, John Huthnance, Jose L. Blanco

CCPO Publications

Biophysical Mechanisms Of Larval Fish Ingress Into Chesapeake Bay, Jonathan A. Hare, Simon Thorrold, Harvey Walsh, Christian Reiss, Arnoldo Valle-Levinson, Cynthia Jones

OES Faculty Publications

A Unique Seasonal Pattern In Phytoplankton Biomass In Low-Latitude Waters In The South China Sea, Chun-Mao Tseng, George T. F. Wong, I.-I. Lin, C.-R. Wu, K.-K. Liu

OES Faculty Publications

The Effect Of Growth Rate, Phosphorus Concentration, And Temperature On N-2 Fixation, Carbon Fixation, And Nitrogen Release In Continuous Cultures Of Trichodesmium Ims101, Margaret R. Mulholland, Peter W. Bernhardt

OES Faculty Publications

Ridding Ships' Ballast Water Of Microorganisms, Fred C. Dobbs, Andrew Rogerson

OES Faculty Publications