National Science Foundation
Title: (Collaborative Research) Cycling of peptides and peptide hydrolysis products in marine and estuarine systems.
Collaborators: Cindy Lee (Stony Brook University), Zhanfei Liu (ODU), Patrick Hatcher (ODU)
In many marine and estuarine systems, nitrogen is thought to limit growth and production. Although inorganic nitrogen species can be used up quickly during primary production, dissolved organic nitrogen compounds (DON) are rarely depleted and can dominate the N pool in a variety of aquatic systems. While we are beginning to understand the importance of dissolved organic matter (DOM) as a nutrient in marine ecosystems, we understand little about the processes that affect the character of the DOM pool, its biochemical composition, and the turnover of particular components of this increasingly important nutrient pool in nature. Protein hydrolysis and subsequent peptide production appear to link degradation of particulate organic material and production of free amino acids in the marine environment. Proteinaceous material dominates the DON pool in the euphotic zone where N is recycled rapidly.
The current model of protein degradation in aquatic environments assumes that hydrolysis of proteinaceous compounds yields peptides (amino acid sequences with molecular weight <6000 Da) and free amino acids. Hydrolysis of biopolymers is thought to be a rate-limiting step in microbial uptake of dissolved and particulate organic matter in many aquatic environments. Although larger organisms can consume protein and hydrolyze it internally, marine microbes can only take up small compounds, so they must initially hydrolyze proteins and peptides to smaller substrates outside the cell. Molecules larger than approximately 600 Da (about the size of a dipeptide) cannot be transported across microbial cell membranes. Extracellular hydrolysis occurs by ecto- or extracellular enzymes. These hydrolytic enzymes (and most other cell surface enzymes) have not been characterized or sequenced in the ocean, although numerous studies have detected proteolytic activity in both seawater and sediments.
Our overarching goal is to understand the biological and chemical basis for the observed amino acid pool in the environment. Specifically, does peptide hydrolysis control the composition of the DCAA pool, and does biological uptake of dipeptides lead to the observed composition of the residual low molecular weight (LMW) free and combined amino acid pools. To this end, we hypothesize that dipeptides are the primary product of peptide hydrolysis in nature. Because dipeptides are rapidly consumed, the LMW DOM pool is dominated by recalcitrant products of peptide hydrolysis. We also hypothesize that a variety of phytoplankton and bacteria are capable of hydrolyzing peptides and taking up the primary products of peptide hydrolysis, dipeptides, and that they can do so under relevant environmental conditions. Many of our current ideas about the roles of bacteria and phytoplankton in production and degradation may need re-evaluation to take into account these previously unrecognized pathways.
National Science Foundation
Title: (Collaborative Research) CO2 control of oceanic nitrogen fixation and carbon flow through diazotrophs.
Collaborators: Dave Hutchins (University of Southern California), Mark Warner (University of Delaware)
The importance of marine N2 fixation to present ocean productivity and global nutrient and carbon biogeochemistry is now universally recognized. Marine N2 fixation rates and oceanic N inventories are also thought to have varied over geological time due to climate variability and change. However, almost nothing is known about the responses of dominant N2 fixers in the ocean such as Trichodesmium and unicellular N2 fixing cyanobacteria to past, present and future global atmospheric CO2 regimes. Our preliminary data demonstrate that N2 and CO2 fixation rates, growth rates, and elemental ratios of Atlantic and Pacific Trichodesmium isolates are controlled by the ambient CO2 concentration at which they are grown. At projected year 2100 pCO2 (750 ppm), N2 fixation rates of both strains increased 35-100%, with simultaneous increases in C fixation rates and cellular N:P and C:P ratios. Surprisingly, these increases in N2 and C fixation due to elevated CO2 were of similar relative magnitude regardless of the growth temperature or P availability. Thus, the influence of CO2 appears to be independent of other common growth-limiting factors.
Equally important, Trichodesmium growth and N2 fixation were completely halted at low pCO2 levels (150 ppm), suggesting that diazotrophy by this genus may have been marginal at best at last glacial maximum pCO2 levels of ~190 ppm. Genetic evidence indicates that Trichodesmium diazotrophy is subject to CO2 control because this cyanobacterium lacks high-affinity dissolved inorganic carbon transport capabilities. These findings may force a re-evaluation of the hypothesized role of past marine N2 fixation in glacial/interglacial climate changes, as well as consideration of the potential for increased ocean diazotrophy and altered nutrient and carbon cycling in the future high-CO2 ocean.
We propose an interdisciplinary project to examine the relationship between ocean N2 fixing cyanobacteria and changing pCO2. A combined field and laboratory approach will incorporate in situ measurements with experimental manipulations using natural and cultured populations of Trichodesmium and unicellular N2 fixers over range of pCO2 spanning glacial era to future concentrations (150-1500 ppm). We will also examine how effects of pCO2 on N2 and C fixation and elemental stoichiometry are moderated by the availability of other potentially growth-limiting variables such as Fe, P, temperature, and light. We plan to obtain a detailed picture of the full range of responses of important oceanic diazotrophs to changing pCO2, including growth rates, N2 and CO2 fixation, cellular elemental ratios, fixed N release, photosynthetic physiology, and expression of key genes involved in carbon and nitrogen acquisition at both the transcript and protein level.
This research has the potential to revolutionize our understanding of controls on N2 fixation in the ocean. Many of our current ideas about the interactions between oceanic N2 fixation, atmospheric CO2, nutrient biogeochemistry, ocean productivity, and global climate change may need revision to take into account previously unrecognized feedback mechanisms between atmospheric composition and diazotrophs. Our findings could thus have major implications for human society, and its increasing dependence on ocean resources in an uncertain future. This project will take the first vital steps towards understanding how a biogeochemically-critical process, the fixation of N2 in the ocean, may respond to our rapidly changing world during the century to come.
National Oceanographic and Atmospheric Administration
Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) Program
Title: ECOHAB: Karenia Nutrient Dynamics in the Eastern Gulf of Mexico.
Collaborators: Cindy Heil (FWRI), Debbie Bronk (VIMS), Judy O’Neil (UMCES), Kellie Dixon (Mote), Gary Hitchcock (Univ. Miami), Gary Kirkpatrick (Mote), John J. Walsh (USF), Robert Weisberg (USF).
The nutrient sources that support and regulate environmentally and economically destructive Karenia brevis blooms in the eastern Gulf of Mexico remain enigmatic. K. brevis blooms in Florida (FL) are annually predictable, have severe economic and environmental impacts, and are closely monitored and so are an ideal system to examine the complexity of nutrient interactions with harmful algal blooms (HABs) throughout entire bloom cycles (initiation and development, maintenance, and decline). To examine how nutrients regulate K. brevis blooms, the following two hypotheses will be tested: 1) multiple nutrient sources and forms support K. brevis blooms, with the relative contribution of each source depending upon bloom physiological state, bloom environment (e.g., lagoonal, lower estuarine, coastal, offshore), and location along a latitudinal gradient and 2) K. brevis is a mixotroph with a flexible metabolism whose limiting growth factors and metabolic preferences vary with the environment. We propose a workplan that will combine biological, chemical and physical measurements with modeling efforts to examine how K. brevis is able to sustain high biomass blooms in oligotrophic environments for extended periods.
This project brings together a multidisciplinary team with extensive expertise on nutrients, HABs, K. brevis, and the southwest Florida (SWF) environment to identify, quantify and model nutrient inputs and cycling over the entire range of K. brevis bloom stages and environments. Efforts will combine a retrospective analysis of the 2001 bloom with targeted laboratory studies, comparative field studies across environments and bloom stages, identification and quantification of multiple nutrient sources, measurement of physical flows and three-dimensional coupled biophysical modeling of near and offshore K. brevis blooms and environments.
Effective HAB management and regulatory interventions are stymied by the lack of an integrated understanding of how nutrients, particularly organic nutrients, regulate blooms temporally and spatially. The proposed effort, focused on environmentally and economically destructive K. brevis blooms, will provide data necessary to identify regulatory alternatives and will couple results with a public outreach approach individually targeting 1) resource managers and decision makers and 2) stakeholders and the general public via symposiums and workshops, newsletters, public seminars and websites.
National Science Foundation
Title: Collaborative Research: Resistance of peptide degradation products in seawater.
Collaborators: Cindy Lee (Stony Brook University), Zhanfei Liu and Patrick Hatcher (ODU).
Protein hydrolysis and subsequent peptide production appear to be the links between degradation of particulate organic material, proteins, and production of free amino acids in the marine environment. They are important components of dissolved organic matter in the marine environment because they represent the bulk of cellular material and microbes concentrate biological nutrients, turn over on short timescales, and are highly labile. Proteinaceous material dominates the nitrogen in the euphotic zone where N is cycled and recycled rapidly and nitrogen in amino acids from acid-hydrolyzable proteinaceous material accounts for about 50% of PON in the water column. Peptides and proteins account for 5–20% of dissolved organic nitrogen and 3–4% of dissolved organic carbon (DOC) in seawater , more recent ref from DOM book 2002). Among the degradative processes occurring on particles, hydrolysis of proteins and peptides seems to be particularly important.
Hydrolysis of biopolymers is thought to be a rate-limiting step in microbial uptake of dissolved and particulate organic matter in many aquatic environments. Although larger organisms can consume protein and hydrolyze it internally, marine microbes can only take up small compounds, so they must initially hydrolyze proteins and peptides to smaller substrates outside the cell. Molecules larger than approximately 600 Da (about the size of a dipeptide) cannot be transported across microbial cell-membranes. Extracellular hydrolysis occurs by ecto- or extracellular enzymes. These hydrolytic enzymes (and most other cell surface enzymes) have not been characterized or sequenced in the ocean, although numerous studies have detected proteolytic activity in both seawater and sediments.
Our overarching goal is to understand the biological and chemical basis for the observed amino acid pool in the environment. Specifically, does peptide hydrolysis control the composition of the DCAA pool and does biological uptake of dipeptides result in the composition of the residual LMW free and combined amino acid pools. To this end, we hypothesize that dipeptides are the primary product of peptide hydrolysis in nature. Because these are rapidly consumed, the LMW DOM pool is dominated by recalcitrant products of peptide hydrolysis. We also hypothesize that a variety of phytoplankton and bacteria are capable of hydrolyzing peptides and taking up the primary products of peptide hydrolysis, dipeptides, and that they can do so under relevant environmental conditions.
Fish and Wildlife Research Institute
Red Tide Control and Mitigation Grant Program
Title: Nutrient Controls Contributing to Karenia Brevis Blooms in the Gulf of Mexico
Collobator: Jason Lenes (USF)
The red tide dinoflagellate, Karenia brevis, has been responsible for fish kills, manatee deaths, shellfish closings, and countless economic losses to fisheries and tourism in the state of Florida for over 50 years. In Florida, red tides appear to be increasing in their intensity and duration. Further, these phenomena appear to be complicated by multiple sites of initiation. In the absence of a single or even multiple causative links between environmental conditions (physical, chemical, and biological) and blooms, it is impossible to adopt policies or mitigation strategies for preventing or alleviating the severity of red tides on the West Florida Shelf or anywhere.
This project assesses the biogeochemical significance of the downstream shift of nutrient ratios in mitigating K.brevis. We propose that shifting the relative supply of silica versus other plant nutrients offers a biochemical control point in which populations of non-siliceous phytoplankton, such as dinoflagellates, can be driven to faster growing and more beneficial organisms, such as diatoms. The same nutrient conditions that support dinoflagellates would also promote growth of potential prey items that contribute to the nutrient success of K. brevis via phagotrophy. Therefore, changes in the nutrient regime not only drive a shift in phytoplankton type by direct competition, but by mitigation K. brevis prey items.
This research will manipulate the relative supply of nutrient elements (N and Si) in water collected from areas identified as points of red tide initiation. The results of the lab and field studies will be used to develop 1-d and 3-d biogeochemical models to help determine where the manipulation of nutrient ratios could best deter the growth and accumulation of red tides. These experiments will reveal not only a better understanding of the complex processes governing the growth and maintenance of red tide blooms in the eastern Gulf of Mexico, but also provide a biochemical point in which the ratios and types of nutrients available to the blooms can be altered to mitigate and control the areal extent of the blooms. We believe this strategy provides a non-evasive means to lessen the size and duration of red tides on the West Florida Shelf by shifting the phytoplankton species to more ecologically beneficial organisms.
National Science Foundation
Title: Collaborative Research: Assessing the Bioavailability of effluent organic nitrogen (EON) along a freshwater to saltwater continuum.”
Collaborators: Nancy G. Love (University of Michigan), Debbie Bronk and Elizabeth Canuel (VIMS), and Patrick Hatcher (ODU).
The National Coastal Condition Report II classified 79% of the estuaries assessed as threatened or impaired with eutrophication listed as one of the main problems. A key issue in dealing with estuarine eutrophication is the substantial differences in the cycling of nitrogen (N) and phosphorus (P) along the length of an estuary. While freshwater end-members tend toward P limitation, marine end-members tend toward N limitation leading to preferential downstream transport of N relative to P. Consequently, dramatic reductions in P loading since the 1980s resulted in significant improvements in freshwater systems but often did not improve or even exacerbated effects at the marine end. Eutrophication is an especially pressing problem in Chesapeake Bay where, despite years of effort, the restoration process has not met its goals. Continued water quality problems led to the signing of the Chesapeake Bay 2000 agreement which mandated a 48% reduction (from 1985 levels) in N loads from point sources to the Bay and its tributaries. That agreement has resulted in increasingly stringent effluent discharge limits for total N by wastewater utilities that are projected to cost over $1 billion in capital costs.
Effluent from wastewater treatment plants includes inorganic and organic N. Currently, the organic N in effluent, which we term EON, is believed to be largely unavailable biologically and so it is not believed to be detrimental to the environment if released. However, quantitative data on EON bioavailability is lacking and there is currently no standard method to accurately assess EON bioavailability to any system (STAC 2007). Any method that is developed to determine EON bioavailability must take into account a number of variables. It must account for uptake in the proximate receiving waters (typically freshwater) and well as the estuarine and saline waters down stream. It must be sensitive to changing microbial ecology and environmental conditions along the estuarine gradient, including changes in salinity and the generation of photodegradation products. We propose to use a combination of bioavailability, photochemical release and salinity release assays and chemical characterization to quantify the percentage of EON (bulk, high and low molecular weight) derived from a range of waste streams that is bioavailable along an estuarine gradient. If a sizable fraction of EON is determined to be non-bioavailable by the robust assessment methods proposed here, then perhaps the cost of N removal by utilities can be substantially reduced.
This project originated when four of the investigators were asked to serve on a committee set up to advise the Chesapeake Bay Program on organic N in effluent. We each approached the problem from a different perspective but all rapidly concluded that this issue was woefully understudied. It was also apparent that to interface engineering capabilities with desired ecological endpoints, the engineering and aquatic science communities must work together to understand how technology impacts the quality and composition of effluent and ultimately the fate of this material in the environment. Here we propose a first step – to determine which fractions of EON are bioavailable or photochemically labile in estuarine waters. The data we propose to collect is essential to our longer-term goal of establishing a standard method to distinguish between bioavailable and refractory EON – a goal with great societal and economic importance. These data will also be useful to identify and target treatment technologies that can effectively remove components that are most harmful to the receiving stream.
The National Aeronautic and Space Administration
Title: The Impacts of Climate Variability on Primary Productivity and Carbon Distributions in the Middle Atlantic Bight and Gulf of Maine
Collaborators: Antonio Mannino (NASA Goddard), John O’Reilly (NOAA NEFSC), David Lary (UMBC JCET – GSFC), and Kimberly Hyde (NOAA NEFSC)
CliVEC
Observations from MODIS and SeaWiFS between 1997-2012 and measurements from the extensive field campaign proposed here will be used to examine how inter-annual and decadal-scale climate variability affect primary productivity and organic carbon distributions along the continental margin of the U.S. East coast. Estimates of daily primary productivity (PP) will be computed using the Ocean Productivity from Absorption of Light (OPAL) model (Marra et al. 2007). OPAL vertically resolves phytoplankton absorption of photosynthetically active radiation and relates the chlorophyll-specific absorption coefficient to sea-surface temperature (SST), where SST is a proxy for seasonal changes in the phytoplankton community. OPAL will be validated with new field measurements of PP including dissolved organic carbon production. Field measurements of particulate (POC) and dissolved organic carbon (DOC) and the absorption coefficients of phytoplankton (aph) and colored dissolved organic matter (aCDOM) will allow us to extend the validation range (temporally and spatially) for our coastal algorithms (Mannino et al. 2008; Pan et al. submitted) and reduce the uncertainties in satellite-derived estimates of OPAL PP, POC, DOC, aph and aCDOM. Furthermore, we will apply our extensive field data to derive region-independent ocean color algorithms for PP, POC, DOC aCDOM and aph using a neural network approach. We will rigorously validate and compare band-ratio multivariate neural network algorithms. The U.S. Middle Atlantic Bight (MAB), George’s Bank (GB) and Gulf of Maine (GoM) stand at the crossroads between major ocean circulation features – the Gulf Stream and Labrador slope-sea and shelf currents – and are influenced by highly variable river discharge, summer upwelling, warm core rings, and intense seasonal stratification. Our work will focus on the impacts of variable river discharge, SST, wind stress and large-scale climate indices on primary production, and POC and DOC distributions. These processes are not unique to the MAB and GoM. Consequently, the results from the proposed activity can be applied to understanding how inter-annual and long-term variability in climate patterns can impact the carbon cycle of continental margins throughout the globe.
Virginia Sea Grant
Title: Bioavailability of effluent organic nitrogen in Virginia coastal waters
Collaborator: Deborah A. Bronk (VIMS)
EON
The Chesapeake Bay restoration goals laid out in the Chesapeake Bay Agreement have not been met despite 25 years of targeted, but voluntary, management activities. As a result, total maximum daily loads (TMDL) for nitrogen (N) and phosphorus (P) are being set for the entire watershed and are scheduled to be implemented in 2010. An important point source of nutrients to the watershed is wastewater treatment plants. Nutrient removal within wastewater treatment plants is limited by available technologies and/or funds to implement best available technologies to further reduce loads as will be required in the impending regulatory framework. Because dissolved inorganic nitrogen (DIN) is easier to remove than dissolved organic N (DON), as N removal gets more effective, the residual N in treated effluent is increasingly dominated by DON. In most freshwater systems where treated effluent is discharged, DON is thought to be unavailable to many microbes, particularly phytoplankton. It has been suggested that inert N should not count toward a discharger’s permit. In estuarine and marine systems, however, DON can be an important source of N fueling microbial communities including phytoplankton. In fact, it is thought that DON can fuel algal blooms. Consequently, it is paramount that we determine the bioavailability of DON in effluent, which we term effluent ON (EON) to natural communities as they change along a natural salinity gradient as water moves from fresh headwaters into an estuary and ultimately the ocean.
The proposed research builds off of two preliminary bioassay experiments conducted by the co-PIs and their extensive experience with DON in marine systems. During spring 2007, we conducted an unfunded preliminary bioassay experiment with effluent organic N (EON) from two wastewater treatment plants, one a limit of technology (LOT) plant and plant that employs biological nutrient removal (BNR). We concentrated the effluent and then challenged natural water samples collected along a salinity gradient (four salinities ranging from 0 to 28) with this material. Results indicate that EON was consumed and that the decrease in EON was greatest in the light treatments. At the same time, chlorophyll a (Chl a) concentrations increased substantially, up to five-fold, in water collected from the higher salinity stations and incubated in the light. This initial study was followed by a second bioassay study funded with Sea Grant Project Development funds. In the second bioassay study we further refined our bioassay approach to streamline the process. The initial findings from the both bioassays studies to date indicate that at least some fraction of EON is bioavailable to natural communities and therefore should be included in discharge allowances from wastewater treatment plants. Most importantly, the preliminary research has led to an important conceptual realization of how future bioassays should be conducted. We outline this approach in the method section below.
This proposal addresses the Virginia Sea Grant Research Focus Area of Healthy Coastal Ecosystems. The research addresses a pressing problem that is currently being faced by treatment plant operators and resource managers within Virginia. Further, the question of the bioavailability of EON and its contribution to coastal eutrophication is not confined to Virginia, but is an emerging issue for the entire Chesapeake Bay region and will ultimately affect the nation.
Virginia Coastal Energy Research Consortium, Commonwealth of Virginia.
Title: Biodiesel production from algae
Collaborators: Patrick Hatcher, Andy Gordon, Harold Marshall and Gary Shafran (ODU)
The overall goal for the ODU effort in biodiesel energy is to conduct research that will lead to the development of improved, cost-effective technology to convert algal biomass to diesel fuel under the conditions present in the state of Virginia. Accordingly, we will address the effort by pursuing three strategies for efficient development of biodiesel from algae. The first is production of biodiesel from indigenous algal populations growing within eutrophied coastal and fresh waters. The second is development of algal biomass within aquaculture systems (algal ponds), some associated with electric power-generating facilities that produce CO2 and can supply heated water for more efficient growth, and others associated with nutrient-rich sewage treatment or agricultural runoff. The third is the development of a conversion reactor where algal biomass can be efficiently transformed to diesel and other usable by-products.
National Oceanographic and Atmospheric Administration
Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) Program
Title: Competitive interactions among organisms that use organic nutrients: The case of Aureococcus anophagefferens and bacteria.
Collaborator: Elizabeth Minor (ODU)
Dissolved organic material (DOM) has been implicated as a causative agent promoting the growth of harmful algal species and initiating blooms in the inland waterways of the Eastern United States. In particular, dissolved organic nitrogen (DON) can be taken up by a number of harmful algal species, and so can out-compete other organisms in organically enriched environments when inorganic N concentrations are low. Because DON also contains C, uptake of this material can also provide a substantial heterotrophic subsidy to autotrophic photosynthesis. During our current ECOHAB project, due to end this year, we have investigated the role of DOM in fueling the growth of the brown tide pelagophyte, Aureococcus anophagefferens. In addition, we have attempted to characterize DOM compounds and relate that to bloom development.
While being able to use DON as an N source may offer a competitive advantage to phytoplankton competing with each other, acquiring nutrients in organic forms may be complicated by competition from bacteria. The objectives of the proposed project are to: continue to identify compounds and compound classes that stimulate the growth of harmful species, determine possible sources of these materials and their importance to the nutrition of harmful species, and determine key nutritional and trophic interactions that enhance the competitive ability of bloom species relative to other phytoplankton species and bacteria. In particular, this project will expand upon the currently funded program by coupling flow cytometric techniques with stable isotope tracer techniques to unequivocally establish pathways of C and N flow from DOM to bacteria and brown tide cells. To accomplish our goals we will continue to sample at the two sites in Chincoteague Bay where we have conducted intensive process studies over the previous year and a half. These sites share similar physical attributes (e.g., circulation and geomorphology) but are separated geographically. At one of these sites (Public Landing, MD), intensive blooms have occurred during the last 4 years. This work will answer basic questions regarding the ability of organic compounds to support the growth and maintenance of brown tide blooms and the types of compounds that stimulate growth. In addition, it will provide insights as to how bloom-forming phytoplankton can compete with bacteria for organic substrates. Because many harmful algal species appear to bloom under organically enriched conditions, this research should be broadly applicable to harmful algal blooms in general. The combined flow cytometric and stable isotope studies will offer a new mechanism whereby bacteria and phytoplankton interactions can be teased apart.
DANCE
GEO-CAPE: Primary productivity in coastal waters in the western Gulf of Mexico
https://geo-cape.larc.nasa.gov/
“Forecasting ecological impairments from continuous monitoring systems.” The Virginia Environmental Endowment.
“ECOHAB: Karenia Nutrient Dynamics in the Eastern Gulf of Mexico.” NOAA ECOHAB. With Cindy Heil (FWRI), Debbie Bronk (VIMS), Judy O’Neil (UMCES), Kellie Dixon (Mote), Gary Hitchcock (Univ. Miami), Gary Kirkpatrick (Mote), John J. Walsh (USF), Robert Weisberg (USF).
“Collaborative Research: CO2 control of oceanic nitrogen fixation and carbon flow through diazotrophs.” The National Science Foundation.
“Collaborative Research: Resistance of peptide degradation products in seawater.” The National Science Foundation. With Cindy Lee (Stony Brook University), Zhanfei Liu (ODU) and Patrick Hatcher (ODU).
“Biodiesel production from algae.” Virginia Coastal Energy Research Consortium, Commonwealth of Virginia. With Patrick Hatcher, Andy Gordon, Harold Marshall and Gary Shafran (ODU)
“Nutrient Controls Contributing to Karenia Brevis Blooms in the Gulf of Mexico.” Red Tide Control and Mitigation Grant Program. Fish and Wildlife Research Institute. PI is Jason Lenes (USF).
“Collaborative Research: Assessing the Bioavailability of effluent organic nitrogen (EON) along a freshwater to saltwater continuum.” The National Science Foundation. With Nancy G. Love (University of Michigan), Debbie Bronk and Elizabeth Canuel (VIMS), and Patrick Hatcher (ODU).
“The Impacts of Climate Variability on Primary Productivity and Carbon Distributions in the Middle Atlantic Bight and Gulf of Maine.” The National Aeronautic and Space Administration. With Antonio Mannino (NASA Goddard), John O’Reilly (NOAA NEFSC), David Lary (UMBC JCET – GSFC), and Kimberly Hyde (NOAA NEFSC).
“Bioavailability of effluent organic nitrogen in Virginia coastal waters.” Virginia Sea Grant. With Deborah A. Bronk (VIMS).
DOTGOM??
H2S?