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Dynamics And Distribution Of Natural And Human-Caused Hypoxia, N. N. Rabalais, Robert J. Diaz, L.A. Levin, R.E. Turner, D. Gilbert, J. Zhang 2010 Virginia Institute of Marine Science

Dynamics And Distribution Of Natural And Human-Caused Hypoxia, N. N. Rabalais, Robert J. Diaz, L.A. Levin, R.E. Turner, D. Gilbert, J. Zhang

VIMS Articles

Water masses can become undersaturated with oxygen when natural processes alone or in combination with anthropogenic processes produce enough organic carbon that is aerobically decomposed faster than the rate of oxygen re-aeration. The dominant natural processes usually involved are photosynthetic carbon production and microbial respiration. The re-supply rate is indirectly related to its isolation from the surface layer. Hypoxic water masses (< 2 mg L-1, or approximately 30% saturation) can form, therefore, under 'natural' conditions, and are more likely to occur in marine systems when the water residence time is extended, water exchange and ventilation are minimal, stratification occurs, and where carbon production and export to the bottom layer are relatively high. Hypoxia has occurred through geological time and naturally occurs in oxygen minimum zones, deep basins, eastern boundary upwelling systems, and fjords. Hypoxia development and continuation in many areas of the world's coastal ocean is accelerated by human activities, especially where nutrient loading increased in the Anthropocene. This higher loading set in motion a cascading set of events related to eutrophication. The formation of hypoxic areas has been exacerbated by any combination of interactions that increase primary production and accumulation of organic carbon leading to increased respiratory demand for oxygen below a seasonal or permanent pycnocline. Nutrient loading is likely to increase further as population growth and resource intensification rises, especially with increased dependency on crops using fertilizers, burning of fossil fuels, urbanization, and waste water generation. It is likely that the occurrence and persistence of hypoxia will be even more widespread and have more impacts than presently observed. Global climate change will further complicate the causative factors in both natural and human-caused hypoxia. The likelihood of strengthened stratification alone, from increased surface water temperature as the global climate warms, is sufficient to worsen hypoxia where it currently exists and facilitate its formation in additional waters. Increased precipitation that increases freshwater discharge and flux of nutrients will result in increased primary production in the receiving waters up to a point. The interplay of increased nutrients and stratification where they occur will aggravate and accelerate hypoxia. Changes in wind fields may expand oxygen minimum zones onto more continental shelf areas. On the other hand, not all regions will experience increased precipitation, some oceanic water temperatures may decrease as currents shift, and frequency and severity of tropical storms may increase and temporarily disrupt hypoxia more often. The consequences of global warming and climate change are effectively uncontrollable at least in the near term. On the other hand, the consequences of eutrophication-induced hypoxia can be reversed if long-term, broad-scale, and persistent efforts to reduce substantial nutrient loads are developed and implemented. In the face of globally expanding hypoxia, there is a need for water and resource managers to act now to reduce nutrient loads to maintain, at least, the current status.


Molecular Identification, Phylogeny And Geographic Distribution Of Brazilian Mangrove Oysters (Crassostrea), Aline Grasielle Costa de Melo, Kimberly S. Reece 2010 et al

Molecular Identification, Phylogeny And Geographic Distribution Of Brazilian Mangrove Oysters (Crassostrea), Aline Grasielle Costa De Melo, Kimberly S. Reece

VIMS Articles

Oysters (Ostreidae) manifest a high degree of phenotypic plasticity, whereby morphology is of limited value for species identification and taxonomy. By using molecular data, the aim was to genetically characterize the species of Crassostrea occurring along the Brazilian coast, and phylogenetically relate these to other Crassostrea from different parts of the world. Sequencing of the partial cytochrome oxidase c subunit I gene (COI), revealed a total of three species of Crassostrea at 16 locations along the Brazilian coast. C. gasar was found from Curuca (Para state) to Santos (Sao Paulo state), and C. rhizophorae from Fortim (Ceara state) to Florianopolis ...


Fate Of Macroalgae In Benthic Systems: Carbon And Nitrogen Cycling Within The Microbial Community, Amber K. Hardison, Elizabeth A. Canuel, Iris C. Anderson, Bart Veuger 2010 Virginia Institute of Marine Science

Fate Of Macroalgae In Benthic Systems: Carbon And Nitrogen Cycling Within The Microbial Community, Amber K. Hardison, Elizabeth A. Canuel, Iris C. Anderson, Bart Veuger

VIMS Articles

High nutrient loading to coastal bays is often accompanied by the presence of bloom-forming macroalgae, which take up and sequester large amounts of C and N while growing. This pool is temporary, however, as nuisance macroalgae exhibit a bloom and die-off cycle, influencing the biogeochemical functioning of these systems in unknown ways. The objective of this study was to trace the C and N from senescing macroalgae into relevant sediment pools. A macroalgal die-off event was simulated by the addition of freeze-dried macroalgae (Gracilaria spp.), pre-labeled with stable isotopes (C-13 and N-15), to sediment mesocosms. The isotopes were traced into ...


Net Removal Of Nitrogen Through Ingestion Of Phytoplankton By Atlantic Menhaden Brevoortia Tyrannus In Chesapeake Bay, Patrick D. Lynch, Mark J. Brush, Elizabeth D. Condon, Robert J. Latour 2010 Virginia Institute of Marine Science

Net Removal Of Nitrogen Through Ingestion Of Phytoplankton By Atlantic Menhaden Brevoortia Tyrannus In Chesapeake Bay, Patrick D. Lynch, Mark J. Brush, Elizabeth D. Condon, Robert J. Latour

VIMS Articles

As filter-feeding planktivores, Atlantic menhaden Brevoortia tyrannus have the potential to influence water quality through ingestion of phytoplankton and assimilation of resultant nutrients. To evaluate the influence of young-of-the-year (YOY) and age-1+ menhaden in Chesapeake Bay, rates of phytoplankton (chl a) ingestion and total dissolved nitrogen (TDN) excretion were measured experimentally across varying phytoplankton concentrations. Ingestion rates of YOY menhaden increased (0.03 to 185 mu g chl a fish(-1) min(-1)) in response to increasing phytoplankton concentration (4.98 to 198.22 mu g chl a l(-1)), while age-1+ menhaden exhibited virtually no ingestion of the phytoplankton ...


Growth, Reproductive Condition, And Digestive Tubule Atrophy Of Pacific Oyster Crassostrea Gigas In Gamakman Bay Off The Southern Coast Of Korea, DH Kang, Fu-Lin E. Chu, HS Yang, CH Lee, CH Lee, HB Koh, KS Choi 2010 Virginia Institute of Marine Science

Growth, Reproductive Condition, And Digestive Tubule Atrophy Of Pacific Oyster Crassostrea Gigas In Gamakman Bay Off The Southern Coast Of Korea, Dh Kang, Fu-Lin E. Chu, Hs Yang, Ch Lee, Ch Lee, Hb Koh, Ks Choi

VIMS Articles

Spat of Pacific oysters (Crassostrea gigas) were collected from Gamakman Bay, Korea, and raised in a spat hardening facility located in the low intertidal zone of the bay for a "hardening/stunting" period of 10 mo. Seasonal changes in growth, reproductive condition, and digestive tubule atrophy (DTA) of these "hardened/stunted" oysters were monitored for more than a year after transplanting to a suspended longline system in a grow-out area in the bay. After transplantation, the hardened/stunted oysters showed a logarithmic increase in shell size for the first 4 mo, from June to October, and growth remained stable from ...


Management Of The Piankatank River, Virginia, In Support Of Oyster (Crassostrea Virginica, Gmelin 1791) Fishery Repletion, Juliana M. Harding, Roger L. Mann, Melissa Southworth, James A. Wesson 2010 Virginia Institute of Marine Science

Management Of The Piankatank River, Virginia, In Support Of Oyster (Crassostrea Virginica, Gmelin 1791) Fishery Repletion, Juliana M. Harding, Roger L. Mann, Melissa Southworth, James A. Wesson

VIMS Articles

The Piankatank River is a trap-type estuary on the western shore of Chesapeake Bay that has been managed for seed oyster production since 1963. Market oyster production in the river is minimal. Repletion efforts include shell planting and seed removal. We describe sequential changes in population demographics and habitat in relation to repletion activities on eight Piankatank River public oyster reefs from 1998 through 2009. Two reef groups (northern and southern) may be distinguished by density (oysters/m(2)), biomass (e dry tissue weight), and shell volume (L/m(2)) data. Age-at-length relationships were estimated from demographic data using a ...


A Comparison Of Crassostrea Virginica And C. Ariakensis In Chesapeake Bay: Does Oyster Species Affect Habitat Function?, HD Harwell, PR Kingsley-Smith, M. Lisa Kellogg, Standish K. Allen Jr., DW Meritt, Kennedy Paynter, Mark Luckenbach 2010 Virginia Institute of Marine Science

A Comparison Of Crassostrea Virginica And C. Ariakensis In Chesapeake Bay: Does Oyster Species Affect Habitat Function?, Hd Harwell, Pr Kingsley-Smith, M. Lisa Kellogg, Standish K. Allen Jr., Dw Meritt, Kennedy Paynter, Mark Luckenbach

VIMS Articles

We examined the possibility that a nonnative oyster species would provide an ecologically functional equivalent of the native oyster species if introduced into the Chesapeake Bay. Habitat complexity and associated benthic communities of experimental triploid Crassostrea virginica and Crassostrea ariakensis reefs were investigated at 4 sites of varying salinity, tidal regime, water depth, predation intensity, and disease pressure in the Chesapeake Bay region (Maryland and Virginia). Four experimental treatments were established at each site: C. virginica, C. ariakensis, 50:50 of C. virginica and C. ariakensis, and shell only. Abundance, biomass, species richness, evenness, dominance, and diversity of reef-associated fauna ...


Oyster (Crassostrea Virginica, Gmelin 1791) Population Dynamics On Public Reefs In The Great Wicomico River, Virginia, Usa, Melissa Southworth, Juliana M. Harding, James A. Wesson, Roger L. Mann 2010 Virginia Institute of Marine Science

Oyster (Crassostrea Virginica, Gmelin 1791) Population Dynamics On Public Reefs In The Great Wicomico River, Virginia, Usa, Melissa Southworth, Juliana M. Harding, James A. Wesson, Roger L. Mann

VIMS Articles

We describe oyster population trends in the Great Wicomico River, VA, from 2000 through 2009 using quantitative fishery independent survey data collected using a stratified random design. The seven public reefs examined cover a total of 2.8 X 10(5) m(2) and vary in individual size from 1.36 X 10(4) to 7.16 X 10(4) m(2). The river is functionally divided by a sand spit into upriver and downriver regions. Oyster densities on the upriver reefs were typically an order of magnitude higher than densities on the downriver reefs within the same time period ...


Oceanic Heterotrophic Bacterial Nutrition By Semilabile Dom As Revealed By Data Assimilative Modeling, YW Luo, MAM Friedrichs, SC Doney, MJ Church, HW Ducklow 2010 Virginia Institute of Marine Science

Oceanic Heterotrophic Bacterial Nutrition By Semilabile Dom As Revealed By Data Assimilative Modeling, Yw Luo, Mam Friedrichs, Sc Doney, Mj Church, Hw Ducklow

VIMS Articles

Previous studies have focused on the role of labile dissolved organic matter (DOM) (defined as turnover time of similar to 1 d) in supporting heterotrophic bacterial production, but have mostly neglected semilabile DOM (defined as turnover time of similar to 100 to 1000 d) as a potential substrate for heterotrophic bacterial growth. To test the hypothesis that semilabile DOM supports substantial amounts of heterotrophic bacterial production in the open ocean, we constructed a 1-dimensional epipelagic ecosystem model and applied it to 3 open ocean sites: the Arabian Sea, Equatorial Pacific and Station ALOHA in the North Pacific Subtropical Gyre. The ...


Net Removal Of Nitrogen Through Ingestion Of Phytoplankton By Atlantic Menhaden Brevoortia Tyrannus In Chesapeake Bay, PD Lynch, MJ Brush, ED Condon, RJ Latour 2010 Virginia Institute of Marine Science

Net Removal Of Nitrogen Through Ingestion Of Phytoplankton By Atlantic Menhaden Brevoortia Tyrannus In Chesapeake Bay, Pd Lynch, Mj Brush, Ed Condon, Rj Latour

VIMS Articles

As filter-feeding planktivores, Atlantic menhaden Brevoortia tyrannus have the potential to influence water quality through ingestion of phytoplankton and assimilation of resultant nutrients. To evaluate the influence of young-of-the-year (YOY) and age-1+ menhaden in Chesapeake Bay, rates of phytoplankton (chl a) ingestion and total dissolved nitrogen (TDN) excretion were measured experimentally across varying phytoplankton concentrations. Ingestion rates of YOY menhaden increased (0.03 to 3.85 µg chl a fish–1 min–1) in response to increasing phytoplankton concentration (4.98 to 198.22 µg chl a l–1), while age-1+ menhaden exhibited virtually no ingestion of the phytoplankton offered ...


Do Different Levels Of Fishing Pressure, Through Spatial Management, Influence Communities And Ecological Interactions In Seagrass Meadows In South Western Australia?, Karina Inostroza 2010 Edith Cowan University

Do Different Levels Of Fishing Pressure, Through Spatial Management, Influence Communities And Ecological Interactions In Seagrass Meadows In South Western Australia?, Karina Inostroza

Theses : Honours

Marine Protected Areas (MPAs) are internationally recognised as a significant spatial management and cost-effective strategy to restore and conserve the marine ecosystems structure and function from human impact. MPAs have been declared with the aim to address a single or a set of management objectives in response to anthropogenic threats, such as fishing, which can have repercussions on biodiversity through indirect interactions or top-down control within an ecosystem or across ecosystems where consumers migrate to forage. However, this indirect impact of fishing remains poorly understood, and as a consequence, the effectiveness of MP As in conserving those ecological processes and ...


Constructing A Fish Metabolic Network Model, Shuzhao Li, Alexander Pozhitkov, Rachel A. Ryan, Charles Steve Manning, Nancy J. Brown-Peterson, Marius Brouwer 2010 University of Southern Mississippi

Constructing A Fish Metabolic Network Model, Shuzhao Li, Alexander Pozhitkov, Rachel A. Ryan, Charles Steve Manning, Nancy J. Brown-Peterson, Marius Brouwer

Faculty Publications

We report the construction of a genome-wide fish metabolic network model, MetaFishNet, and its application to analyzing high throughput gene expression data. This model is a stepping stone to broader applications of fish systems biology, for example by guiding study design through comparison with human metabolism and the integration of multiple data types. MetaFishNet resources, including a pathway enrichment analysis tool, are accessible at http://metafishnet.appspot.com.


First Report Of Viral Pathogens Wssv And Ihhnv In Argentine Crustaceans, Sergio R. Martorelli, Robin M. Overstreet, Jean A. Jovonovich 2010 Centro de Estudios Parasitológicos y Vectores

First Report Of Viral Pathogens Wssv And Ihhnv In Argentine Crustaceans, Sergio R. Martorelli, Robin M. Overstreet, Jean A. Jovonovich

Faculty Publications

The pathogenic penaeid shrimp viruses white spot syndrome virus (WSSV) and infectious hypodermal and hematopoietic necrosis virus (IHHNV) are reported for the first time from Argentina. They both occurred in wild crustaceans in Bahia Blanca Estuary, with WSSV detected by polymerase chain reaction (PCR) or real time quantitative PCR (qPCR) methods as infecting samples as high as 56% of the penaeid Artemesia longinaris Bate, 1888, 67% of the grapsoid Cyrtograpsus angulatus Dana, 1851, and 40% of the introduced palaemonid Palaemon macrodactylus Rathbun, 1902. The highest detected copy number was 39,600 copies/mu g DNA. IHHNV was tested for using ...


Grazing Interactions Between Oxyrrhis Marina And Synechococcus Strains Grown In Single Nitrogen Sources, Virginia. Selz 2010 Western Washington University

Grazing Interactions Between Oxyrrhis Marina And Synechococcus Strains Grown In Single Nitrogen Sources, Virginia. Selz

WWU Graduate School Collection

The goal of this study was to assess the interaction between abiotic and biotic factors on diverse Synechococcus strains isolated from the coastal California Current (CC9311, CC9605, CC9902) and the oceanic Sargasso Sea (WH8102 and mutants: JMS40 and SIO7B). Previous research has demonstrated that abiotic factors, such as nutrient source or concentration, can alter cellular structure and chemistry. These cell characteristics in turn influence biotic factors such as predation by protozoan grazers. Synechococcus strains isolated from coastal and open ocean waters were grown to nitrogen (N) depletion in N-reduced medium. After reaching stationary phase, strains were transferred to media containing ...


Snail Grazing Facilitates Growth Of A Bloom-Forming Alga, Michele Guidone, Carol S. Thornber, Emily Field 2010 Sacred Heart University

Snail Grazing Facilitates Growth Of A Bloom-Forming Alga, Michele Guidone, Carol S. Thornber, Emily Field

Biology Faculty Publications

Herbivory often has a negative effect on plants. However, there is a growing number of examples, primarily in terrestrial ecosystems, where herbivory causes an increase in plant size, growth rate, and/or reproductive output. In marine ecosystems, the positive effects of herbivores on macroalgae are not as well studied, although limited evidence exists for herbivore-induced increases in macroalgal growth rates via 2 mechanisms: nutrient addition via grazer defecation, and epiphyte removal. In this study, we examined the effects of grazing by the mud snail Ilyanassa obsoleta on Ulva lactuca, the dominant bloom-forming macroalga in many New England estuaries. We found ...


Theory Of Island Biogeography On A Microscopic Scale: Organic Aggregates As Islands For Aquatic Pathogens, M. M. Lyons, J. E. Ward, Holly Gaff, R. E. Hicks, J. M. Drake, Fred C. Dobbs 2010 Old Dominion University

Theory Of Island Biogeography On A Microscopic Scale: Organic Aggregates As Islands For Aquatic Pathogens, M. M. Lyons, J. E. Ward, Holly Gaff, R. E. Hicks, J. M. Drake, Fred C. Dobbs

OEAS Faculty Publications

Four predictions of the MacArthur-Wilson theory of island biogeography were evaluated to assess the degree to which detrital-based organic aggregates (e.g. marine snow, organic detritus, and bioflocs) may provide a favorable microhabitat (i.e. an 'island') for bacteria in general, and specifically aquatic pathogens. We demonstrate the theory's relevance for microbial communities in aquatic environments by describing the community metabolic response and functional diversity of individual organic aggregates while documenting the persistence of potential pathogens and fecal indicator bacteria. Our results support the 4 predictions, including a significant species-area relationship, consistency of species richness at equilibrium, non-zero level ...


Benthic Ecology From Space: Optics And Net Primary Production In Seagrass And Benthic Algae Across The Great Bahama Bank, Heidi M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige 2010 Old Dominion University

Benthic Ecology From Space: Optics And Net Primary Production In Seagrass And Benthic Algae Across The Great Bahama Bank, Heidi M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige

OEAS Faculty Publications

Development of repeatable and quantitative tools are necessary for determining the abundance and distribution of different types of benthic habitats, detecting changes to these ecosystems, and determining their role in the global carbon cycle. Here we used ocean color remote sensing techniques to map different major groups of primary producers and estimate net primary productivity (NPP) across Great Bahama Bank (GBB). Field investigations on the northern portion of the GBB in 2004 revealed 3 dominant types of benthic primary producers: seagrass, benthic macroalgae, and microalgae attached to sediment. Laboratory measurements of NPP ranged from barely net autotrophic for grapestone sediment ...


A Seasonal Study Of Dissolved Cobalt In The Ross Sea, Antarctica: Micronutrient Behavior, Absence Of Scavenging, And Relationships With Zd, Cd, And P., M. A. Saito, T. J. Goepfert, A. E. Noble, E. M. Bertrand, Peter N. Sedwick, Giacomo R. DiTullio 2010 Old Dominion University

A Seasonal Study Of Dissolved Cobalt In The Ross Sea, Antarctica: Micronutrient Behavior, Absence Of Scavenging, And Relationships With Zd, Cd, And P., M. A. Saito, T. J. Goepfert, A. E. Noble, E. M. Bertrand, Peter N. Sedwick, Giacomo R. Ditullio

OEAS Faculty Publications

We report the distribution of cobalt (Co) in the Ross Sea polynya during austral summer 2005-2006 and the following austral spring 2006. The vertical distribution of total dissolved Co (dCo) was similar to soluble reactive phosphate (PO(4)(3-)), with dCo and PO(4)(3-) showing a significant correlation throughout the water column (r(2) = 0.87, 164 samples). A strong seasonal signal for dCo was observed, with most spring samples having concentrations ranging from similar to ~ 45-85 pM, whereas summer dCo values were depleted below these levels by biological activity. Surface transect data from the summer cruise revealed concentrations ...


Determination Of Total Dissolved Cobalt In Uv-Irradiated Seawater Using Flow Injection With Chemiluminescence Detection, Rachel U. Shelley, Bernhard Zachhuber, Peter N. Sedwick, Paul J. Worsfold, Maeve C. Lohan 2010 Old Dominion University

Determination Of Total Dissolved Cobalt In Uv-Irradiated Seawater Using Flow Injection With Chemiluminescence Detection, Rachel U. Shelley, Bernhard Zachhuber, Peter N. Sedwick, Paul J. Worsfold, Maeve C. Lohan

OEAS Faculty Publications

A sensitive flow-injection method with chemiluminescence detection (FI-CL) for the determination of dissolved cobalt in open ocean samples, suitable for shipboard use has been developed. To date, FI methods for dissolved cobalt have been used only in coastal and estuarine waters. Therefore, significant modifications to existing methods were required, including (1) the use of a commercially available iminodiacetate (IDA) resin (Toyopearl AF-chelate 650M) in place of resin immobilized 8-hydroxyquinoline for online preconcentration and matrix removal, (2) the introduction of acidified ammonium acetate (pH 4) as a column-conditioning step before sample loading and rinse steps, and most importantly, (3) UV irradiation ...


Modeling The Vertical Distributions Of Downwelling Plane Irradiance And Diffuse Attenuation Coefficient In Optically Deep Waters, X. J. Pan, Richard C. Zimmerman 2010 Old Dominion University

Modeling The Vertical Distributions Of Downwelling Plane Irradiance And Diffuse Attenuation Coefficient In Optically Deep Waters, X. J. Pan, Richard C. Zimmerman

OEAS Faculty Publications

The diffuse attenuation coefficient Kᵈ is critical to understand the vertical distribution of underwater downwelling irradiance (Eᵈ). Theoretically Eᵈ is composed of the direct solar beam and the diffuse sky irradiance. Applying the statistical results from Hydrolight radiative transfer simulations, Kᵈ is expressed into a mathematical equation (named as PZ06) integrated from the contribution of direct solar beam and diffuse sky irradiance with the knowledge of sky and water conditions. The percent root mean square errors (RMSE) for the vertical distribution of Eᵈ(z) under various sky and water conditions between PZ06 and Hydrolight results are typically less than 4 ...


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