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Dynamics And Distribution Of Natural And Human-Caused Hypoxia, N. N. Rabalais, R. 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, R. 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.


Copepod Carcasses, Mortality And Population Dynamics In The Tributaries Of The Lower Chesapeake Bay, David Thomas. Elliott 2010 College of William and Mary - Virginia Institute of Marine Science

Copepod Carcasses, Mortality And Population Dynamics In The Tributaries Of The Lower Chesapeake Bay, David Thomas. Elliott

Dissertations, Theses, and Masters Projects

Several studies have documented the occurrence of substantial numbers of zooplankton carcasses in marine field samples. However, the potential effect of carcasses on conclusions resting on zooplankton abundance estimates, and the reasons for carcass occurrence have been largely disregarded. Many field studies do not account for the presence of carcasses in their sampling methodology. Zooplankton carcasses in situ are significant for several reasons. as concentrated particles of organic matter in the water column, zooplankton carcasses can be important vehicles for organic matter transport and hotspots of microbial abundance and activity. If dead animals are treated alive, carcasses could bias the …


Habitat Utilization And Dive Characterization Of Blue Marlin (Makaira Nigricans) And White Marlin (Kajikia Albida) In The Western Atlantic Ocean, Daniel J. Dutton 2010 College of William and Mary - Virginia Institute of Marine Science

Habitat Utilization And Dive Characterization Of Blue Marlin (Makaira Nigricans) And White Marlin (Kajikia Albida) In The Western Atlantic Ocean, Daniel J. Dutton

Dissertations, Theses, and Masters Projects

Blue marlin Makaira nigricans and white marlin Kajikia albida (formerly Tetrapturus albidus) are overfished in the Atlantic Ocean, with the vast majority of fishing mortality resulting from the pelagic longline fishery that targets tunas (Thunnus spp.) and swordfish Xiphias gladius. Time series of catch-per-unit-effort (CPUE) data have been fundamental to assessments of blue marlin and white marlin stocks, but these time series have been affected by a shift over time in pelagic longline fishing practices from shallow to deeper sets. One method for adjusting CPUE data for changes in fishing practices is a habitat-based standardization that modifies fishing effort in …


Habitat Complexity And Habitat Function Of Native (Crassostrea Virginica) And Non-Native (C. Ariakensis) Oysters In The Chesapeake Bay Region, Heather D. Harwell 2010 College of William and Mary - Virginia Institute of Marine Science

Habitat Complexity And Habitat Function Of Native (Crassostrea Virginica) And Non-Native (C. Ariakensis) Oysters In The Chesapeake Bay Region, Heather D. Harwell

Dissertations, Theses, and Masters Projects

Complex oyster reefs created by the Eastern oyster, Crassostrea virginica, though once prominent features of the Chesapeake Bay region, have become relatively scarce in comparison to historic descriptions. This decline, caused by a combination of overfishing, disease, habitat destruction and pollution, this decline continues despite substantial restoration efforts that have spanned decades. In response to this decline, the states of Virginia and Maryland considered the intentional introduction of the non-native Suminoe oyster, C. ariakensis. Previous studies questioned the reef-building capability of this Crassostrea species, which may affect its habitat function. Through a combination of field and mesocosm studies, I examined …


The Behavioral Response Of Harbor Seals To Seasonal Prey Pulses Of Spawning Pacific Herring, Austen C. Thomas 2010 Western Washington University

The Behavioral Response Of Harbor Seals To Seasonal Prey Pulses Of Spawning Pacific Herring, Austen C. Thomas

WWU Graduate School Collection

The Pacific harbor seal (Phoca vitulina) is a noteworthy omission from the list of predators that aggregate at herring spawning sites, despite strong suggestive evidence that they are likely to respond to herring pulses. Working with the hypothesis that spawning herring aggregations are seasonally important prey for harbor seals, we tested several predictions using an analysis of harbor seal prey remains, GPS telemetry, and satellite-linked time/depth recorder data. Contrary to predictions, herring in harbor seal diet was comprised of 77% juveniles and 23% adults in the spawn season, versus 33% juveniles and 67% adults in the post-spawn season. Seal diving …


Age Determination Of The Sixgill Shark From Hard Parts Using A Series Of Traditional And Novel Approaches, S. Jeffrey (Steven Jeffrey) Campbell 2010 Western Washington University

Age Determination Of The Sixgill Shark From Hard Parts Using A Series Of Traditional And Novel Approaches, S. Jeffrey (Steven Jeffrey) Campbell

WWU Graduate School Collection

Necessary to the management of any species of fish is the ability to determine age in individuals. Age information is used to establish growth rates, longevity, age at maturity, and population age structure, and to predict how population demographics will change over time. For most species of fish, reliable aging techniques have been in use since the early 20th century. Most boney fish are aged by counting bands of calcium phosphate hydroxyapatite that form over time in skeletal hard parts such as otoliths, fin-spines, and scales, which can be used as proxies for age in years. Fishes in the Class …


Bacterial Acquisition In Juveniles Of Several Broadcast Spawning Coral Species, Koty H. Sharp, Kim B. Ritchie 2010 Roger Williams University

Bacterial Acquisition In Juveniles Of Several Broadcast Spawning Coral Species, Koty H. Sharp, Kim B. Ritchie

Arts & Sciences Faculty Publications

Coral animals harbor diverse microorganisms in their tissues, including archaea, bacteria, viruses, and zooxanthellae. The extent to which coral-bacterial associations are specific and the mechanisms for their maintenance across generations in the environment are unknown. The high diversity of bacteria in adult coral colonies has made it challenging to identify species-specific patterns. Localization of bacteria in gametes and larvae of corals presents an opportunity for determining when bacterial-coral associations are initiated and whether they are dynamic throughout early development. This study focuses on the early onset of bacterial associations in the mass spawning corals Montastraea annularis, M. franksi, M. faveolata, …


Bryostatins: Biological Context And Biotechnological Prospects, Amaro E. Trindade-Silva, Grace E. Lim-Fong, Koty H. Sharp 2010 Roger Williams University

Bryostatins: Biological Context And Biotechnological Prospects, Amaro E. Trindade-Silva, Grace E. Lim-Fong, Koty H. Sharp

Arts & Sciences Faculty Publications

Coral animals harbor diverse microorganisms in their tissues, including archaea, bacteria, viruses, and Bryostatins are a family of protein kinase C modulators that have potential applications in biomedicine. Found in miniscule quantities in a small marine invertebrate, lack of supply has hampered their development. In recent years, bryostatins have been shown to have potent bioactivity in the central nervous system, an uncultivated marine bacterial symbiont has been shown to be the likely natural source of the bryostatins, the bryostatin biosynthetic genes have been identified and characterized, and bryostatin analogues with promising biological activity have been developed and tested. Challenges in …


Alien Vs. Predator: Effects Of A Native Predator On Two Invasive Oyster Drills And Oysters In Washington State, Emily W. Grason 2010 Western Washington University

Alien Vs. Predator: Effects Of A Native Predator On Two Invasive Oyster Drills And Oysters In Washington State, Emily W. Grason

WWU Graduate School Collection

I investigated the consumptive (CEs) and non-consumptive effects (NCEs) of a native crab predator (the red rock crab, Cancer productus) on a system of two invasive oyster drills (the Atlantic drill, Urosalpinx cinerea, and the Japanese drill, Ocinebrina inornata), a native oyster (the Olympia oyster, Ostrea lurida), and an introduced but commercially valuable oyster (the Pacific oyster, Crassostrea gigas). In the presence of chemical effluent from crabs eating conspecifics, drills increased hiding behavior by 2 to 6 times, and reduced the number of oysters consumed by 50 to 67%. This is consistent with an adaptive behavioral response and has the …


Do Small, Patchy, Constructed Intertidal Oyster Reefs Reduce Salt Marsh Erosion As Well As Natural Reefs?, Alix G. Stricklin, Mark S. Peterson, John D. Lopez, Christopher A. May, Christina F. Mohrman, Mark S. Woodrey 2010 University of Southern Mississippi

Do Small, Patchy, Constructed Intertidal Oyster Reefs Reduce Salt Marsh Erosion As Well As Natural Reefs?, Alix G. Stricklin, Mark S. Peterson, John D. Lopez, Christopher A. May, Christina F. Mohrman, Mark S. Woodrey

Gulf and Caribbean Research

One ecological service that oyster reefs provide is stabilization of shorelines through reduced wave energy and erosion from boat traffic, storms, and predominant wind direction. Additionally, increasing sedimentation can enhance the growth of emergent marsh vegetation which further stabilizes unconsolidated sediments. A 21 mo study of constructed (with only 30-35% coverage) and natural oyster reefs in 3 bayous in the Grand Bay National Estuarine Research Reserve (NERR) suggested constructed reefs benefit this retrograding deltaic ecosystem. The marsh edge adjacent to all constructed reefs was less eroded (mean = 0.043 m) than edges adjacent to natural reefs (mean = 0.728 m), …


State Of The River Report For The Lower St. Johns River Basin, Florida: Water Quality, Fisheries, Aquatic Life, And Contaminants 2010, Environmental Protection Board, City of Jacksonville, University of North Florida, Jacksonville University 2010 University of North Florida

State Of The River Report For The Lower St. Johns River Basin, Florida: Water Quality, Fisheries, Aquatic Life, And Contaminants 2010, Environmental Protection Board, City Of Jacksonville, University Of North Florida, Jacksonville University

State of the River Report

No abstract provided.


Tidal Amplification Of Seabed Light, D. G. Bowers, John M. Brubaker 2010 Bangor University

Tidal Amplification Of Seabed Light, D. G. Bowers, John M. Brubaker

VIMS Articles

Because solar irradiance decreases approximately exponentially with depth in the sea, the increase in irradiance at the seabed from mid to low tide is greater than the decrease from mid to high tide. Summed over a day, this can lead to a net amplification of seabed irradiance in tidal waters compared to nontidal waters with the same mean depth and transparency. In this paper, this effect is quantified by numerical and analytical integration of the Lambert-Beer equation to derive the ratio of daily total seabed irradiance with and without a tide. Greatest amplification occurs in turbid water with large tidal …


Autotrophic Picoplankton In Mesozooplankton Guts: Evidence Of Aggregate Feeding In The Mesopelagic Zone And Export Of Small Phytoplankton, S. E. Wilson, D. K. Steinberg 2010 Virginia Institute of Marine Science

Autotrophic Picoplankton In Mesozooplankton Guts: Evidence Of Aggregate Feeding In The Mesopelagic Zone And Export Of Small Phytoplankton, S. E. Wilson, D. K. Steinberg

VIMS Articles

Zooplankton play a key role in affecting the efficiency by which organic matter is exported to depth. Mesozooplankton consumption of detrital aggregates has been hypothesized as a mechanism for enhancing the export of picoplankton from surface layers. We analyzed the gut contents of mesopelagic copepods and ostracods using light and epifluorescence microscopy to determine if cyanobacteria and eukaryotic phytoplankton too small to be ingested individually were present. Hind-guts were dissected from multiple species collected in discrete depth intervals between 0 and 1000 m during the day and night, at contrasting sites in the subtropical (Hawaii Ocean Time-series site ALOHA) and …


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 quadratic model. Observed mortality …


Buoyancy Regulation In Phaeocystis Globosa Scherffel Colonies, Xiaodong Wang, Kam W. Tang 2010 Virginia Institute of Marine Science

Buoyancy Regulation In Phaeocystis Globosa Scherffel Colonies, Xiaodong Wang, Kam W. Tang

VIMS Articles

Buoyancy of Phaeocystis globosa Scherffel (Prymnesiophyceae) colonies was investigated by measuring the vertical distribution of colonies in quiescent water where convection had been removed. Over 60% of the colonies exhibited negative buoyancy regardless of light condition or growth phase. Positively and neutrally buoyant colonies lost their buoyancy in the dark, but regained buoyancy upon return to the light. Colonies with closer cell packing; i.e., more cells per unit colonial surface area, had greater capability to remain buoyant. Our results suggest that colony buoyancy was not uniform within a P. globosa population, and that biological regulation of colony buoyancy required light …


Observations Of Distribution, Size, And Sex Ratio Of Mature Blue Crabs, Callinectes Sapidus, From A Chesapeake Bay Tributary In Relation To Oyster Habitat And Environmental Factors, JM Harding, R Mann 2010 Virginia Institute of Marine Science

Observations Of Distribution, Size, And Sex Ratio Of Mature Blue Crabs, Callinectes Sapidus, From A Chesapeake Bay Tributary In Relation To Oyster Habitat And Environmental Factors, Jm Harding, R Mann

VIMS Articles

Blue crabs Callinectes sapidus (Rathbun, 1896) > 100 mm carapace width were sampled from a constructed oyster reef (1996 and 1997), a sand bar (1997) and a natural oyster bar (1997) in the Piankatank River, Chesapeake Bay, USA to describe habitat use, sex ratios, and demographics across a gradient of habitat types. Patterns of blue crab catch-per-unit-effort (CPUE), and demographics were similar on the oyster reef in 1996 and 1997. Average annual CPUE on the reef was 6-8 crabs pot(-1) with maximum CPUE of 15 crabs pot(-1). Daylength and water temperature significantly affected reef CPUE with more crabs observed in late …


Oceanic Heterotrophic Bacterial Nutrition By Semilabile Dom As Revealed By Data Assimilative Modeling, YW Luo, M. A.M. 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, M. A.M. 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 …


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. Throughout the system, the highest observed densities were …


Regional Management Units For Marine Turtles: A Novel Framework For Prioritizing Conservation And Research Across Multiple Scales, Bryan P. Wallace, John A. Musick 2010 et al

Regional Management Units For Marine Turtles: A Novel Framework For Prioritizing Conservation And Research Across Multiple Scales, Bryan P. Wallace, John A. Musick

VIMS Articles

Background: Resolving threats to widely distributed marine megafauna requires definition of the geographic distributions of both the threats as well as the population unit(s) of interest. In turn, because individual threats can operate on varying spatial scales, their impacts can affect different segments of a population of the same species. Therefore, integration of multiple tools and techniques - including site-based monitoring, genetic analyses, mark-recapture studies and telemetry - can facilitate robust definitions of population segments at multiple biological and spatial scales to address different management and research challenges. Methodology/Principal Findings: To address these issues for marine turtles, we collated all …


Increased Ocean Carbon Export In The Sargasso Sea Linked To Climate Variability Is Countered By Its Enhanced Mesopelagic Attenuation, M. W. Lomas, Deborah K. Steinberg, T. Dickey, C.A. Carlson, N.B. Nelson, R.H. Condon, N.R. Bates 2010 Virginia Institute of Marine Science

Increased Ocean Carbon Export In The Sargasso Sea Linked To Climate Variability Is Countered By Its Enhanced Mesopelagic Attenuation, M. W. Lomas, Deborah K. Steinberg, T. Dickey, C.A. Carlson, N.B. Nelson, R.H. Condon, N.R. Bates

VIMS Articles

Photosynthetic CO(2) uptake by oceanic phytoplankton and subsequent export of particulate organic carbon (POC) to the ocean interior comprises a globally significant biological carbon pump, controlled in part by the composition of the planktonic community. The strength and efficiency of this pump depends upon the balance of particle production in the euphotic zone and remineralization of those particles in the mesopelagic (defined here as depths between 150 and 300 m), but how these processes respond to climate-driven changes in the physical environment is not completely understood. In the Sargasso Sea, from similar to 1996-2007, we have observed a decade-long > 50% …


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