Digital Commons Network^™

Aquaculture Governance: Five Engagement Arenas For Sustainability Transformation, Darien D. Mizuta, Stefan Partelow

VIMS Articles

A greater focus on governance is needed to facilitate effective and substantive progress toward sustainability transformations in the aquaculture sector. Concerted governance efforts can help move the sector beyond fragmented technical questions associated with intensification and expansion, social and environmental impacts, and toward system-based approaches that address interconnected sustainability issues. Through a review and expert-elicitation process, we identify five engagement arenas to advance a governance agenda for aquaculture sustainability transformation: (1) setting sustainability transformation goals, (2) cross-sectoral linkages, (3) land–water–sea connectivity, (4) knowledge and innovation, and (5) value chains. We then outline the roles different actors and modes of …

Formation Of Oil-Particle-Aggregates: Numerical Model Formulation And Calibration, Linlin Cui, Courtney K. Harris, Danielle R.N. Tarpley

VIMS Articles

When oil spills occur in turbid waters, the oil droplets and mineral grains can combine to form oil-particle aggregates (OPAs). The formation of OPAs impacts the vertical transport of both the oil and the mineral grains; especially increasing deposition of oil to the seabed. Though the coastal oceans can be very turbid, to date, few numerical ocean models have accounted for aggregation processes that form OPAs. However, interactions between oil and mineral aggregates may be represented using techniques developed to account for sediment aggregation. As part of Consortium for Simulation of Oil Microbial Interactions in the Ocean (CSOMIO), we modified …

Experimental Tree Mortality Does Not Induce Marsh Transgression In A Chesapeake Bay Low-Lying Coastal Forest, David C. Walters, Joel A. Carr, (...), Matthew L. Kirwan, Et Al

VIMS Articles

Transgression into adjacent uplands is an important global response of coastal wetlands to accelerated rates of sea level rise. “Ghost forests” mark a signature characteristic of marsh transgression on the landscape, as changes in tidal inundation and salinity cause bordering upland tree mortality, increase light availability, and the emergence of tidal marsh species due to reduced competition. To investigate these mechanisms of the marsh migration process, we conducted a field experiment to simulate a natural disturbance event (e.g., storm-induced flooding) by inducing the death of established trees (coastal loblolly pine, Pinus taeda) at the marsh-upland forest ecotone. After this simulated …

On The Human Appropriation Of Wetland Primary Production, James E. Cloern, Samuel M. Safran, Lydia Smith Vaughn, (...), Elizabeth A. Canuel, J.Letitia Grenier

VIMS Articles

Humans are changing the Earth's surface at an accelerating pace, with significant consequences for ecosystems and their biodiversity. Landscape transformation has far-reaching implications including reduced net primary production (NPP) available to support ecosystems, reduced energy supplies to consumers, and disruption of ecosystem services such as carbon storage. Anthropogenic activities have reduced global NPP available to terrestrial ecosystems by nearly 25%, but the loss of NPP from wetland ecosystems is unknown. We used a simple approach to estimate aquatic NPP from measured habitat areas and habitat-specific areal productivity in the largest wetland complex on the USA west coast, comparing historical and …

A Machine‐Learning‐Based Model For Water Quality In Coastal Waters, Taking Dissolved Oxygen And Hypoxia In Chesapeake Bay As An Example, Xin Yu, Jian Shen, Jiabi Du

VIMS Articles

Hypoxia is a big concern in coastal waters as it affects ecosystem health, fishery yield, and marine water resources. Accurately modeling coastal hypoxia is still very challenging even with the most advanced numerical models. A data‐driven model for coastal water quality is proposed in this study and is applied to predict the temporal‐spatial variations of dissolved oxygen (DO) and hypoxic condition in Chesapeake Bay, the largest estuary in the United States with mean summer hypoxic zone extending about 150 km along its main axis. The proposed model has three major components including empirical orthogonal functions analysis, automatic selection of forcing …

Validating An Operational Flood Forecast Model Using Citizen Science In Hampton Roads, Va, Usa, Jon Derek Loftis, Molly Mitchell, Daniel Schatt, David R. Forrest, Harry V. Wang, David Mayfield, William A. Stiles

VIMS Articles

Changes in the eustatic sea level have enhanced the impact of inundation events in the coastal zone, ranging in significance from tropical storm surges to pervasive nuisance flooding events. The increased frequency of these inundation events has stimulated the production of interactive web-map tracking tools to cope with changes in our changing coastal environment. Tidewatch Maps, developed by the Virginia Institute of Marine Science (VIMS), is an effective example of an emerging street-level inundation mapping tool. Leveraging the Semi-implicit Cross-scale Hydro-science Integrated System Model (SCHISM) as the engine, Tidewatch operationally disseminates 36-h inundation forecast maps with a 12-h update frequency. …

Sea-Level Driven Land Conversion And The Formation Of Ghost Forests, Matthew L. Kirwan, Keryn B. Gedan

VIMS Articles

Ghost forests created by the submergence of low-lying land are one of the most striking indicators of climate change along the Atlantic coast of North America. Although dead trees at the margin of estuaries were described as early as 1910, recent research has led to new recognition that the submergence of terrestrial land is geographically widespread, ecologically and economically important, and globally relevant to the survival of coastal wetlands in the face of rapid sea level rise. This emerging understanding has in turn generated widespread interest in the physical and ecological mechanisms influencing the extent and pace of upland to …

Citizen-Science For The Future: Advisory Case Studies From Around The Globe, C Simoniello, J Jencks, Fm Lauro, Jon Derek Loftis, K Deja, David R. Forrest, Et At

VIMS Articles

The democratization of ocean observation has the potential to add millions of observations every day. Though not a solution for all ocean monitoring needs, citizen scientists offer compelling examples showcasing their ability to augment and enhance traditional research and monitoring. Information they are providing is increasing the spatial and temporal frequency and duration of sampling, reducing time and labor costs for academic and government monitoring programs, providing hands-on STEM learning related to real-world issues and increasing public awareness and support for the scientific process. Examples provided here demonstrate the wide range of people who are already dramatically reducing gaps in …

A Data-Driven Modeling Approach For Simulating Algal Blooms In The Tidal Freshwater Of James River In Response To Riverine Nutrient Loading, Jian Shen, Qubin Qin, Ya Wang, Mac Sisson

VIMS Articles

Algal blooms often occur in the tidal freshwater (TF) of the James River estuary, a tributary of the Chesapeake Bay. The timing of algal blooms correlates highly to a summer low-flow period when residence time is long and nutrients are available. Because of complex interactions between physical transport and algal dynamics, it is challenging to predict interannual variations of bloom correctly using a complex eutrophication model without having ahigh-resolution model gridto resolve complexgeometryand anaccurate estimate of nutrientloading to drive the model. In this study, an approach using long-term observational data (from 1990 to 2013) and the Support vector machine (LS-SVM) …

Overcoming Early Career Barriers To Interdisciplinary Climate Change Research, Christopher J. Hein, John E. Ten Hoeve, Sathya Gopalakrishnan, Et Al

VIMS Articles

Climate-change impacts are among the most serious and complex challenges facing society, affecting both natural and social systems. Addressing these requires a new paradigm of interdisciplinary collaboration which incorporates tools, techniques, and insights from across the social, natural, and engineering sciences. Yet, a wide range of intrinsic and extrinsic hurdles need to be overcome to conduct successful, integrated interdisciplinary research. The results of a bibliometric analysis and survey of early to mid-career scientists from 56 countries who were involved with the interdisciplinary DISsertations initiative for the advancement of Climate Change ReSearch (DISCCRS) emphasize the particular challenges faced by early career …

Future Response Of Global Coastal Wetlands To Sea-Level Rise, M. Schuerch, T. Spencer, S. Temmerman, Matthew L. Kirwan, Et Al

VIMS Articles

The response of coastal wetlands to sea-level rise during the twenty-first century remains uncertain. Global-scale projections suggest that between 20 and 90 per cent (for low and high sea-level rise scenarios, respectively) of the present-day coastal wetland area will be lost, which will in turn result in the loss of biodiversity and highly valued ecosystem services(1-3). These projections do not necessarily take into account all essential geomorphological(4-7) and socio-economic system feedbacks(8). Here we present an integrated global modelling approach that considers both the ability of coastal wetlands to build up vertically by sediment accretion, and the accommodation space, namely, the …

A Synergistic Approach For Evaluating Climate Model Output For Ecological Applications, Rochelle Cavanaugh, Ej Murphy, Et Al, Walker O. Smith Jr., Et Al

VIMS Articles

Increasing concern about the impacts of climate change on ecosystems is prompting ecologists and ecosystem managers to seek reliable projections of physical drivers of change. The use of global climate models in ecology is growing, although drawing ecologically meaningful conclusions can be problematic. The expertise required to access and interpret output from climate and earth system models is hampering progress in utilizing them most effectively to determine the wider implications of climate change. To address this issue, we present a joint approach between climate scientists and ecologists that explores key challenges and opportunities for progress. As an exemplar, our focus …

Influence Of Reservoir Infill On Coastal Deep Water Hypoxia, Lewis C. Linker, Richard A. Batiuk, Carl F. Cerco, Gary W. Shenk, Richard Tian, Ping Wang, Guido Yactayo

VIMS Articles

Ecological restoration of the Chesapeake through the Chesapeake Bay total maximum daily load (TMDL) requires the reduction of nitrogen, phosphorus, and sediment loads in the Chesapeake watershed because of the tidal water quality impairments and damage to living resources they cause. Within the Chesapeake watershed, the Conowingo Reservoir has been filling in with sediment for almost a century and is now in a state of near‐full capacity called dynamic equilibrium. The development of the Chesapeake TMDL in 2010 was with the assumption that the Conowingo Reservoir was still effectively trapping sediment and nutrients. This is now known not to …

Modeling Storm Surge And Inundation In Washington, Dc, During Hurricane Isabel And The 1936 Potomac River Great Flood, Harry V. Wang, Jon Derek Loftis, David R. Forrest, Wade Smith, Barry Stamey

VIMS Articles

Abstract: Washington, DC, the capital of the U.S., is located along the Upper Tidal Potomac River, where a reliable operational model is needed for making predictions of storm surge and river-induced flooding. We set up a finite volume model using a semi-implicit, Eulerian-Lagrangian scheme on a base grid (200 m) and a special feature of sub-grids (10 m), sourced with high-resolution LiDAR data and bathymetry surveys. The model domain starts at the fall line and extends 120 km downstream to Colonial Beach, VA. The model was used to simulate storm tides during the 2003 Hurricane Isabel. The water level measuring …

The Storm Surge And Sub-Grid Inundation Modeling In New York City During Hurricane Sandy, Harry V. Wang, Jon Derek Loftis, Zhou Liu, David R. Forrest, Yinglong J. Zhang

VIMS Articles

Hurricane Sandy inflicted heavy damage in New York City and the New Jersey coast as the second costliest storm in history. A large-scale, unstructured grid storm tide model, Semi-implicit Eulerian Lagrangian Finite Element (SELFE), was used to hindcast water level variation during Hurricane Sandy in the mid-Atlantic portion of the U.S. East Coast. The model was forced by eight tidal constituents at the model’s open boundary, 1500 km away from the coast, and the wind and pressure fields from atmospheric model Regional Atmospheric Modeling System (RAMS) provided by Weatherflow Inc. The comparisons of the modeled storm tide with the NOAA …

West Antarctic Peninsula: An Ice-Dependent Coastal Marine Ecosystem In Transition, Hugh Ducklow, William R. Fraser, Michael P. Meredith, Sharon E. Stammerjohn, Scott C. Doney, Douglas G. Martinson, Sevrine F. Sailley, Oscar M. Schofield, Deborah K. Steinberg, Hugh Venables, Charles Amsler

VIMS Articles

The extent, duration, and seasonality of sea ice and glacial discharge strongly influence Antarctic marine ecosystems. Most organisms' life cycles in this region are attuned to ice seasonality The annual retreat and melting of sea ice in the austral spring stratifies the upper ocean, triggering large phytoplankton blooms. The magnitude of the blooms is proportional to the winter extent of ice cover, which can act as a barrier to wind mixing. Antarctic krill, one of the most abundant metazoan populations on Earth, consume phytoplankton blooms dominated by large diatoms. Krill, in turn, support a large biomass of predators, including penguins, …

Trichodesmium-Derived Dissolved Organic Matter Is A Source Of Nitrogen Capable Of Supporting The Growth Of Toxic Red Tide Karenia Brevis, Rachel E. Sipler, Deborah A. Bronk, Sybil P. Seitzinger, Ronald J. Lauck, Lora R. Mcguinness, Gary J. Kirkpatrick, Cynthia A. Heil, Lee J. Kerkhof, Oscar M. Schofield

VIMS Articles

Dissolved organic nitrogen (DON) produced by the nitrogen-fixer Trichodesmium sp. has the potential to serve as a nitrogen source for the red tide dinoflagellate Karenia brevis. Dissolved organic matter (DOM) from laboratory cultures of Trichodesmium sp. was isolated, concentrated and then supplied as a nutrient source to K. brevis cells collected from the Gulf of Mexico. K. brevis abundance increased immediately after Trichodesmium sp. cellular exudate (TCE) addition, allowing the population to double within the first 24 h. There was rapid and complete utilization of the TCE DON as well as ~89% of the TCE dissolved organic phosphorus (DOP). Additionally, …

Multivariable Statistical Regression Models Of The Areal Extent Of Hypoxia Over The Texas-Louisiana Continental Shelf, David R. Forrest, Rochelle Hetland, Sf Dimarco

VIMS Articles

Observations of the areal extent of seasonal hypoxia over the Texas-Louisiana continental shelf from 1985 to 2010 are correlated with a variety of physical and biogeochemical forcing mechanisms. Significant correlation is found between hypoxic area and both nitrogen load (r(2) = 0.24) and east-west wind speed (r(2) = 0.16). There is also a significant increasing trend in the areal extent of hypoxia in time; a linearly increasing trend over the entire record (r(2) = 0.17), a step increase in area for the years 1994 and beyond (r(2) = 0.21), and a step increase for 1993 and beyond (r(2) = 0.29) …

Nitrogen Fixation And Release Of Fixed Nitrogen By Trichodesmium Spp. In The Gulf Of Mexico, Margaret R. Mulholland, Peter W. Bernhardt, Cynthia A. Heil, Deborah A. Bronk, Judith M. O'Neil

VIMS Articles

During a 3‐yr study in the Gulf of Mexico, we measured dinitrogen (N2) fixation and nitrogen (N) release by Trichodesmium and compared these rates with water column N demand and the estimated N necessary to support blooms of Karenia brevis, a toxic dinoflagellate that severely affects the West Florida shelf. Net and gross N2 fixation rates were compared in simultaneous incubations using δ15N2 uptake and acetylene reduction, respectively. The difference between net and gross N2 fixation is assumed to be an approximation of the rate of N release. Results demonstrate that Trichodesmium in the Gulf of Mexico are fixing …

Assessing Sources And Ages Of Organic Matter Supporting River And Estuarine Bacterial Production: A Multiple-Isotope (D14c, D13c, And D15n) Approach, S. Leigh Mccallister, James E. Bauer, J Cherrier, Hugh W. Ducklow

VIMS Articles

We used radiocarbon (D14C) and stable isotopic (d13C, d15N) signatures of bacterial nucleic acids to estimate the sources and ages of organic matter (OM) assimilated by bacteria in the Hudson River and York River estuary. Dualisotope plots of D14C and d13C coupled with a three-source mixing model resolved the major OM sources supporting bacterial biomass production (BBP). However, overlap in the stable isotopic (d13C and d15N) values of potential source end members (i.e., terrestrial, freshwater phytoplankton, and marsh-derived) prohibited unequivocal source assignments for certain samples. In freshwater regions of the York, terrigenous material of relatively recent origin (i.e., decadal in …

Photochemical Production Of Dissolved Inorganic Nitrogen And Primary Amines From Dissolved Organic Nitrogen In Waters Of Two Estuaries And Adjacent Surficial Groundwaters, Dj Koopmans, Da Bronk

VIMS Articles

Recent studies have shown that in a number of humic-rich surface waters in North America, NH4+ is released when dissolved organic matter (DOM) is exposed to sunlight. However, photochemical NH4+ production has not been observed in all surface waters, and factors that contribute to it are not well understood. We hypothesized that the presence or absence of NH4+ photoproduction may be affected by the light exposure history of DOM, The present study was undertaken to determine whether DOM from surficial groundwaters, with minimal light exposure history, would produce labile nitrogen (N) photoproducts more consistently, In this study, estuarine surface waters …

Dynamic Bacterial And Viral Response To An Algal Bloom At Subzero Temperatures, Patricia L. Yager, Tara L. Connelly, Behzad Mortazavi, K. Eric Wommack, Nasreen Bano, James E. Bauer, Stephen Opsahl, James T. Hollibaugh

VIMS Articles

New evidence suggests that cold‐loving (psychrophilic) bacteria may be a dynamic component of the episodic bloom events of high‐latitude ecosystems. Here we report the results of an unusually early springtime study of pelagic microbial activity in the coastal Alaskan Arctic. Heterotrophic bacterioplankton clearly responded to an algal bloom by doubling cell size, increasing the fraction of actively respiring cells (up to an unprecedented 84% metabolically active using redox dye CTC), shifting substrate‐uptake capabilities from kinetic parameters better adapted to lower substrate concentrations to those more suited for higher concentrations, and more than doubling cell abundance. Community composition (determined by polymerase …

Doc Cycling In A Temperate Estuary: A Mass Balance Approach Using Natural 14c And 13c Isotopes, Peter Raymond, James E. Bauer

VIMS Articles

We measured dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and their corresponding D14C and d13C values in order to study the sources and fates of DOC in the York River Estuary (Virginia, U.S.A.). The D14C and d13C values of DOC and DIC at the freshwater end-member indicate that during periods of moderate to high flow, riverine DOC entering the York was composed of decadal-aged terrestrially organic matter. In nearly all cases, DOC concentrations exceeded conservative mixing lines and were therefore indicative of a net DOC input flux from within the estuary that averaged 1.2 mM L21 d21 . The …

Trophic Effects Of Sponge Feeding Within Lake Baikal's Littoral Zone .2. Sponge Abundance, Diet, Feeding Efficiency, And Carbon Flux, Aj Pile, Mark R. Patterson, M. Savarese, V I. Chernykh, V A. Fialkov

VIMS Articles

Endemic freshwater demosponges in the littoral zone of Lake Baikal, Russia, dominate the benthic biomass, covering 44% of the benthos. We measured in situ sponge abundance and,orating and calculated sponge-mediated Fluxes of picoplankton (plankton <2 mu m) for two common species, Baikalospongia intermedia and Baikalospongia bacillifera. By means of dual-beam how cytometry, we found retention efficiencies ranging from 58 to 99% for four types of picoplankton: heterotrophic bacteria, Synechococcus-type cyanobacteria, autotrophic picoplankton with one chloroplast, and autotrophic picoplankton with two chloroplasts. By using a general model for organism-mediated fluxes, we conservatively estimate that through active suspension feeding, sponges are a sink for 1.97 g C d(-1) m(-1), mostly from procaryotic cell types. Furthermore, grazing by these extensive sponge communities can create a layer of picoplankton-depleted water overlying the benthic community in this unique lake.

Degradation Kinetics Of Aromatic Organic Solutes Introduced Into A Heterogeneous Aquifer, Wg Macintyre, M Boggs, Cp Antworth, Tb Stauffer

VIMS Articles

Degradation rates of benzene, p-xylene, naphthalene, and o-dichlorobenzene have been measured in a heterogeneous, unconfined aquifer during a pulse injection experiment at Columbus Air Force Base, Columbus, Mississippi. Dissolved oxygen in the pulse plume maintained aerobic conditions. Degradation kinetics calculated from the complete field data set were approximately first order with the following rate constants: benzene, 0.0070 d-1; p-xylene, 0.0107 d-1; naphthalene, 0.0064 d-1; and o-dichlorobenzene, 0.0046 d-1. Reaction rates were also calculated from a near-field subset of the data using a model based on the hydrologic characteristics of the aquifer. Shapes of the degradation rate curves were consistent with …

Tracing Kepone Contamination In James Estuary Sediments, Maynard M. Nichols, Norman H. Cutshall

VIMS Articles

The escape of Kepone into the James River estuary, Virginia, for more than nine years produced widespread contamination of the sediments with important ecological consequences. The pollutant extended seaward more than 100 km from its source and contaminated an estimated 31 million tonnes of sediment to depths of more than 60 cm. Kepone spread through the food chain and to every segment of the environment from marshes to the channel floor.

Kepone escaped mainly during high river inflow from a point source in freshwater tributaries. Near the source Kepone is associated with organic material but in the low er estuary …

Enewetak (Eniwetok) Atoll- Aspects Of Nitrogen Cycle On A Coral Reef, K. L. Webb, William D. Dupaul, W. Wiebe, W. Sottile, R. E. Johannes

VIMS Articles

No abstract provided.

Tidal Discharge Asymmetry In A Salt Marsh Drainage System, John D. Boon

VIMS Articles

Tidal discharge and area‐averaged current speed were measured over complete tidal cycles at the entrance to a salt marsh drainage system near Wachapreague, Virginia. A pronounced asymmetry in curves of discharge and current speed through time was observed which can be simulated by a model incorporating semidiurnal tides and “overtides” in conjunction with marsh and channel storage relationships. As a persistent feature in marsh channel flow relationships, the asymmetry, along with an apparent difference in flood and ebb maxima, may have a systematic, long term influence on the net transport of suspended matter entering and leaving natural marshes.