ECOHAB 1999: Project Summaries

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Anderson, D.M. (WHOI) and J. Rensel (Rensel Associates). ECOHAB: Mitigation of fish-killing algal blooms using clay. 09/01/99- 08/31/01. National Sea Grant Office. Email:

Harmful Algal Blooms (HABs) are a serious and growing threat to coastal waters throughout the U.S. and the world. One of the more significant HAB impacts is the mass mortality of aquaculture fish, leading to substantial economic losses on fish farmers and their insurers. Fish farmers have a few techniques for reducing the impacts of HABs, but none are fully reliable or effective; and several involve serious risk for loss of the fish and facilities. The overall objective of this project will be to field test a combination of strategies - clay treatment (to remove cells from the water column) and perimeter skirting (to retain treated water and prevent recontamination). Neither of these technologies is unique individually, but they have never been applied in combination in the manner we envision. This will also be the first concerted bloom control or removal effort attempted in the U.S. for fish mariculture. Preliminary laboratory experiments indicate there are specific types of clays that effectively remove several HAB species at relatively low application rates. As part of this proposal, more work will be conducted to optimize the types of clay needed for Heterosigma removal, and to establish clay loadings and application protocols best suited for fish farms. The project will then conduct a series of pilot-scale clay treatments inside experimental fishnet pens operated by an active net-pen aquaculture facility. This facility has an NPDES permit allowing for water column and benthic impact zones and we will strive to retain all effects within that zone and not exceed Washington State water quality standards for turbidity (i.e., no greater than 5 NTU above background). Effects of the clay treatment on the fish, the plankton community, the water quality, and the benthic community will all be assessed. The information to be collected in this manner is essential if this approach to HAB mitigation is to be used on a larger scale at fish farms or other environments.

  Haab, T. C. ( ECU), J. Whitehead (ECU), D. Lipton (UM), J. Kirkley (VIMS), and G. Parsons (UDE). ECOHAB: The economic effects of Pfiesteria in the mid-Atlantic region. 09/01/99- 08/31/01. National Sea Grant Office. Email: HAABT@MAIL.ECU.EDU.

While significant amounts of research are currently being conducted to assess the biological, ecological and environmental effects of Pfiesteria piscicida and other harmful algal blooms (HABs), very little work has been conducted to look at the economic impacts or lost benefits due to Pfiesteria outbreaks or HABs. To begin to assess the economic impacts of Pfiesteria and HABs, we propose a 2-year Mid-Atlantic (North Carolina, Virginia, Maryland and Delaware) study of seafood consumption combining both revealed and contingent behavior questions. The study will consist of two surveys, analysis, and a final report. The surveys (to be administered by the East Carolina University Survey Research Laboratory) will consist of two parts. The first will be a combined phone-mail survey of the Mid-Atlantic region focusing on current seafood consumption patterns and reactions to harmful algal blooms, Pfiesteria outbreaks, and education materials. The second part of the survey will consist of in-person interview surveys in North Carolina. The survey instrument will be similar to the phone-mail survey but will allow for more visual material. This will also allow us to test for differences or similarities between survey formats. By combining revealed behavior regarding seafood consumption with contingent behavior regarding future seafood consumption plans under a variety of realistic hypothetical outbreak and policy scenarios the proposed study will measure the economic effects of a Pfiesteria outbreak on the Mid-Atlantic seafood market.

Questions to be addressed include: What are the current seafood consumption patterns in the Mid-Atlantic region? What is the effect of a HAB/Pfiesteria outbreak on seafood consumption in the Mid-Atlantic region? What are the economic welfare effects of an outbreak? What are the potential economic impacts of an outbreak (as opposed to welfare losses)? What are the regional similarities or differences in response to outbreaks (Albemarle/Pamlico Sound estuary system versus Chesapeake system)? Do respondents respond differently when shown the risk or counter-information in person rather than through the mail or over the phone? Are contingent behavior surveys capable of identifying substitution effects.

The project represents a case study of the economic impacts of Pfiesteria on the Mid-Atlantic seafood industry as well as a methodological project to understand the conveyance of risk information to consumers. As such, the project will benefit the National Sea Grant College Program goal of evaluating the cost-effectiveness of potential management actions relating to Pfiesteria and HABs.

  Hoagland, P. (WHOI), D. Jin (WHOI), and H. Kite-Powell (WHOI). ECOHAB: A framework for estimating the economic impacts of Harmful Algal Blooms (HABs) in the United States. 09/01/99- 08/31/01. National Sea Grant Office. Email:

We plan to develop a methodological framework for estimating the economic impacts of HABs on local, regional, and national scales. The proposed study is designed to achieve the following objectives: develop a framework for the economic impact analysis of HABs using an I-O modeling approach; develop detailed case studies using the framework (specific locations and types of damages); develop local, state, and national level I-O models for the case studies, generate economic impact estimates, and calculate multipliers; summarize the impact at the local, state, and national levels, and present a national overview of economic impacts HABs; extend the analysis of Anderson et al. (1998) to estimate the economic impacts of HABs during 1993-1998, resulting in a 12 year window for estimating the average annual impacts of HABs; and conduct sensitivity analyses of key factors, e.g., individual and cumulative impacts: human health, fisheries, and recreation.

This study employs an input-output (I-O) methodology to estimate, on a consistent basis, the regional and national economic impacts of HABs. The I-O methodology was developed to characterize the nature of interactions among the sectors of an economy. Application of the I-O methodology will result in estimates of the scale of economic impacts and the distribution of those impacts across economic sectors at relatively low cost relative to other valuation methods. Application of I-O analysis will help to identify geographic locations where further work should be conducted using more intensive and more costly methods of economic valuation to estimate the economic damages associated with HABs and to scale the appropriate policy responses and mitigation actions.

There is a current need to develop estimates of the economic impacts and distributional effects of marine natural hazards such as HABs. This kind of information is needed to begin to think carefully about appropriate policy responses to such hazards. To date, very little work has been done to account for the economic impacts of HABs in the United States and to report them on a consistent basis. Aggregate impacts average about $42 million per year, which is on the scale of a single HAB event with major economic impacts. When a HAB event resulting in major economic impacts is added to the annual average, impacts could approach or even exceed $100 million. The results of our study will allow public and private decision-makers to gain a better perspective on the scale of the economic impacts and employment effects associated with HABs and the distribution of impacts and employment effects across the sectors of the relevant economies. These decision-makers will be able to use the estimates to begin to assess the risks of HAB events at the local, state, and national levels and to scale appropriate policy responses to deal with those risks.

  Kana, T.M. ( HPEL), H. MacIntyre ( HPEL), J. Cornwell ( HPEL), and M.. Lomas (HPEL). ECOHAB: Benthic-pelagic coupling and LI Brown Tide. 09/01/99-8/31/02. NOAA/COP & NYS Sea Grant. Email:

The proposed research is on the controls of the initiation and maintenance of Long Island (New York) Brown Tide events. The central focus of the work is on the role of sediment and benthos as mediators of nutrient exchange with the water column. It is hypothesized that the release of dissolved organic nitrogen (DON) from the benthos plays a significant role in the selection of Aureococcus anophagefferens in Long Island bays. The release of DON relative to dissolved inorganic nitrogen (DIN) can be affected by multiple factors including the movement of groundwater, decomposition of recently sedimented organic matter, resuspension events, and light limitation. Current hypotheses regarding the control of Brown Tide by DON/DIN ratios and known controls of sediment nutrient exchange suggest that sediment processes may help explain regional differences in the occurrence of Brown Tides across the Long Island bays. A coupled benthic-pelagic model is presented as a framework for studying the role of sediments in Brown Tide behavior.

The proposed research will involve intensive sampling of several habitats in the Peconic Bay region where Brown Tide exhibits different annual behaviors. Measurements of sediment nutrient exchange, assimilation of nitrogen nutrients by the phytoplankton assemblage and the distribution of light through the water column will provide the necessary data to evaluate differences in benthic-pelagic coupling that relate to the incidence of A. anophagefferens blooms.

In addition, the proposed research will include a continuation of physiological experiments on A. anophagefferens. New technology developed in the PI¹s laboratory will allow accurate bioenergetic measurements of A. anophagefferens growth and photosynthesis under diverse organic nutrient conditions. The results of this work will be used to interpret the ability of A. anophagefferens to utilize organic matter in the field.

  Kudela, R.M. (SFSU) and W. Cochlan (SFSU). ECOHAB: Regulation of P. australis by C, N, Si interactions. 09/01/99-8/31/02. NOAA/COP. Email:

The recognition that harmful algal blooms (HABs) are becoming increasingly prevalent in coastal waters and that one such HAB genus, Pseudo-nitzschia, is a common bloom-forming diatom found in the United States, has demonstrated our limited understanding of the ecophysiology of this toxigenic diatom, and more generally of the factors which control coastal productivity. Historically, it has been assumed that the growth of coastal phytoplankton (diatoms in particular) is limited by the relative availability of nitrogen. Recently, this idea has been increasingly questioned, with recognition of the potentially important role(s) of other controlling factors, such as the availability of silicate (an obligate requirement for siliceous organisms), other trace elements, and the complex physiological responses associated with diatom bloom formation. Several models which explicitly test and attempt to quantify the role of nitrogen, silicon, light, and the complex physiological responses to these factors are now available. Although another group is currently examining the production of DA in cultured Pseudo-nitzschia, no one has attempted to integrate these various factors into a coherent ecological framework. We propose to examine the ecophysiological characteristics under which the Pseudo-nitzschia genus becomes dominant in coastal waters and initiates domoic acid (DA) production.

The goal of the proposed research is to examine the interactions of multiple nutrients (C, N, Si) and light using continuous and batch culturing methods in the laboratory, and to test these interactions in the field. We have the unique ability to utilize both stable and radio-isotope tracers (15N, 14C, 32Si, 32P) for these experiments, and are proposing to integrate both field and laboratory measurements. This approach to understanding DA production sets us apart from the other research groups in Monterey Bay, and provides the ability to assess the overall dynamics of this system. The following two hypotheses will be tested as part of this project. H1. Silicate limitation has modulating effects on the rate of nitrogen uptake and cell growth, normalized to carbon, nitrogen, or pigments in natural diatom assemblages. H2. Significant expression of DA by diatoms (i.e. toxic outbreaks) in the field are rare because nitrogen or light limitation typically occurs before silicate or phosphorous limitation in diatom-dominated coastal upwelling regimes. The primary product of this proposed research is the development of more detailed knowledge of the interactive role(s) of these factors in the development and regulation of HABs in particular, and coastal production in general; by doing so, we can provide the basis for future successful management and modeling efforts.

By capitalizing on the extensive background in research of multiple light and nutrient interactions in Monterey Bay, the extraordinary oceanographic and laboratory resources available at MBARI and SFSU, and the continuing commitment by MBARI and colleagues at UCSC to the development of a DA research program, there is an unprecedented opportunity to better understand the regulation of potentially toxic diatom blooms. Related but fundamentally different efforts at MBARI by Dr. Chris Scholin (development of a real-time monitoring capability using genetic probes), and at the University of California Santa Cruz by Drs. Mark Wells and Dave Garrison (influence of trace-metal availability on DA production in P. australis), provide the opportunity to develop a synergistic research program in Monterey Bay. We will also coordinate our efforts with other groups who are interested in DA dynamics by participating in the regional bi-monthly meetings held at UCSC. Clearly, if we are to understand how and why toxic blooms of Pseudo-nitzschia occur in areas such as Monterey Bay, we must first understand the fundamental controlling factors regulating new and primary production by diatoms. This proposal will address both of these questions.

  Lonsdale, D. (SUNY at Stony Brook), D.A. Caron (WHOI), and R. Cerrato (SUNY at Stony Brook). ECOHAB: Causes and prevention of Long Island Brown Tides. 09/01/99-8/31/02. NOAA/COP & NYS Sea Grant. Email:

The research project is an experimental study of brown tides caused by outbreaks of the pelagophyte Aureococcus anophagefferens in Long Island coastal waters. This project entails the manipulation of natural water samples enclosed in mesocosms on-site in the Peconic Bay estuary system (Coecles Harbor, Shelter Island). The research we propose is a direct result of, and continued effort on, our studies to understand the factors leading to outbreaks, persistence, decline and (potentially) prevention or mitigation of brown tides. During the past three years, we have established an experimental mesocosm system in which we have been able to consistently shift phytoplankton community structure to dominance by A. anophagefferens. We propose to exploit this experimental system, and our results to date, to address three related aspects of the ecology of this harmful algal bloom species. First, we propose a study to examine changes in plankton community structure that take place as A. anophagefferens increases in relative and absolute abundance within a natural plankton assemblage, and the effects that perturbations to the pelagic food web have on success or failure of the brown tide alga. We hypothesize that selective grazing by microbial consumers in the plankton provide A. anophagefferens with a competitive advantage relative to other phytoplankton, and thus bring about a shift in the assemblage to dominance by the brown tide alga. This work will entail planktonic food web manipulations and microbial population measurements, as well as experimental determinations of growth and mortality of A. anophagefferens and co-occurring phytoplankton. Second, we propose a set of experiments to examine the effect of the chemical form of growth-limiting nutrients and the rate of nutrient loading as factors affecting brown tide initiation and the magnitude of blooms. We hypothesize that nutrient loading rate, but not the form of the nutrient per se, can affect the relative abundance of A. anophagefferens in the phytoplankton assemblage, but that total nutrient loading dictates bloom magnitude. We will experimentally investigate the effect of a number of specific nutrients that have been implicated in the stimulation of brown tide outbreaks. Third, we will employ our mesocosms to investigate how filter-feeding bivalves affect planktonic food web structure, and how their activities affect the absolute and relative abundance of A. anophagefferens.

  Shields, J.D. (VIMS), W. Vogelbein (VIMS), L. Haas (VIMS), H. Kator (VIMS), and V. Blazer (USGS). ECOHAB: Pfiesteria or fungus? Etiology of lesions in menhaden. 09/01/99-08/31/02. EPA. Email:

Menhaden, Brevoortia tyrannus, develop ulcerous skin lesions that have been attributed to exposure to Pfiesteria piscicida toxins. The characteristic lesions present as deep penetrating circular ulcers with intense granulomatous inflammation. The presence of these lesions in conjunction with counts of presumptive Pfiesteria-like cells in water samples are the primary criteria for river closures in Maryland and Virginia due to local, recent Pfiesteria activity. There is, however, controversial evidence that the lesions are caused by an oomycete fungus, Aphanomyces sp., either as a primary or secondary invader. The fungus is almost always associated with the lesions, with hyphae penetrating the tissues and organs of the infected fish.

Biological and environmental stressors appear central to the etiology of ulcers on menhaden. We hypothesize that the development of the disease requires some initiating stressor(s) that erode, damage or penetrate the epidermis and expose the underlying dermis. Recent experiments with striped bass and tilapia exposed to sublethal levels of P. piscicida indicate that fish experience an initial loss of the epidermis. This may provide the portal of entry for propagules of Aphanomyces to attach and invade the dermis and internal tissues of the fish. The resulting granulomatous ulcer is subsequently colonized by secondary invaders (bacteria, saprophytic fungi, etc.), that further influence the pathogenesis of the lesion. Hence, we suggest that the syndrome is most likely a multifactorial disease that arises from the interplay between fish, fungus, and stressors such as Pfiesteria, hypoxia, pH, or pollution.

The goal of the project is to identify the interrelationships between menhaden, Pfiesteria, and Aphanomyces, and the environmental conditions that may modulate or contribute to the epizootics of ulcers on the fish. The objectives are to conduct controlled laboratory exposure studies with menhaden to (1) identify the causal agents responsible for the ulcerous lesions, and (2) identify contributory environmental and biological conditions that are required for the development and progression of the lesions.

  M. Sieracki (BLOS). ECOHAB: The effects of microbial food web dynamics on the initiation of Brown Tide blooms. 09/01/99- 08/31/02. NOAA/COP & NYS Sea Grant. Email:

Since its first, dramatic appearance in 1985, a great deal of research has been done on the brown tide-forming phytoplankton, Aureococcus anophagefferens. As a result, our understanding of its biology and the ecology of the Long Island Bays where it occurs have grown considerably. Aureococcus possesses an unusual ability to use organic nitrogen and carbon, which may allow it to thrive in the turbid, low inorganic nutrient conditions that prevail in the summer in these embayments. However, a variety of other picoalgae, including the typically dominant Synechococcus may also be capable of effectively utilizing the same environment. It is critical to determine what events are controlling the composition of the spring, pre-bloom populations in the impacted areas. To address these issues, we propose here to examine the growth and grazing of Aureococcus within the context of the microbial plankton community. Our experimental manipulations of grazing pressure and organic nutrients during the initiation phase of the bloom will show us how the organism gains a foothold in the "picoalgal niche" that opens at this time of the year.

Our sampling period will bracket the important "hinge point" period, beginning in late April and ending in late May, when a fundamental shift to small cells occurs. We will sample in an area where Aureococcus biomass is accumulating and it is becoming a dominant component of the population, to compare with our previously collected profiles of "non-bloom" populations. We believe that the picoalgal niche is typically occupied by Synechococcus, and that Synechococcus must be selectively removed or reduced to open the niche to Aureococcus. We also believe that a unique bacterial consortia co-occurs with Aureococcus, and may play a crucial role. Thus, our focus will be the picoplankton community, including phototrophic and heterotrophic components. A reduction in Synechococcus populations may be associated with a bloom of a highly size- selective protozoan grazer.

We will use a combination of in situ observations of microbial community structure and experiments on natural populations to evaluate some of the possible controlling factors. Dilution experiments will be conducted on the evolving microbial community throughout the bloom initiation period to estimate selective grazing rates on different components of the phytoplankton community. With Synechococcus populations diminished, we hypothesize that Aureococcus outcompetes other co-occurring eukaryotic picoalgae through its ability to utilize dissolved organic carbon and nitrogen. Its association and possible symbiosis with a unique bacterial consortia may also be a selective advantage.

An understanding of these processes at the early stages of a bloom is critical to the ultimate goal of increasing abilities to predict and mitigate blooms of this harmful organism.

  Silver, M..W. (UCSC), G. Doucette (NOAA), and R. Tjeerdema (UCD). ECOHAB: Domoic acid in a coastal food web. 09/01/99-8/31/02. NOAA/COP. Email:

In US coastal waters, domoic acid (DA), a toxin produced by several common species of the diatom Pseudo-nitzschia, has caused marine bird and mammal deaths and contaminated seafood products, resulting in human health problems, fishery closures and economic losses. Relatively little is known about DA transfer through food webs, and toxin detection is poor using the present sentinel species. Our proposal is concerned with examining this transfer process in a coastal site frequently subject to blooms of the toxigenic diatoms. This study will take place in Monterey Bay, a Pacific coastal site with seasonally abundant populations of DA-producing Pseudo-nitzschia, to determine the chronology of toxin passage into key food web intermediaries, both benthic and pelagic. We hypothesize that DA in the nearshore benthos reaches consumers via plankton and various detrital pathways, as reflected in the toxicity of the sand crab Emerita analoga. In the offshore region, we hypothesize that DA reaches key intermediaries, including planktivorous fish (anchovies and sardines), squid and krill, which route toxins to a wide variety of higher vertebrates and cause mortalities such as those observed in Monterey Bay in 1991 and 1998. We will test the hypothesis that benthic Emerita and pelagic anchovies serve as better sentinel species for inshore and offshore DA levels, respectively, than does the currently-used intertidal mussel, Mytilus californianus. The field study uses weekly or biweekly sampling in the nearshore region for DA-producing diatoms, sentinel benthic species (E. analoga and M. californianus), and benthic sediments, with intensified collections when toxigenic species are abundant. In the offshore region, we compare the pattern of DA in krill and commercially landed anchovies, sardines, and market squid, intensifying our offshore sampling during HAB events, with the pattern of DA in plankton populations offshore being measured by collaborators. We test the hypothesis that DA concentrations decline with increasing trophic level, which has important fishery consequences. NOAA/NOSS Marine Biotoxins Program will provide measurements of DA in some of the key organisms studied (sand crabs and krill), whereas the UCSC team will measure toxins in the others (fish, squid, mussels, sediments).

These results will provide a better understanding of the pattern of toxin transmission through marine food webs, both benthic and pelagic. The research also will lead to recommendations for more effective biomonitoring for governmental agencies concerned with seafood safety and for environmental agencies concerned with protecting vulnerable marine vertebrates, including endangered species of seabirds and mammals that forage on the potentially DA-contaminated species studied here.

  Wells, M. (UCSC) and R. Wessling (UCSC ). ECOHAB: A new chemosenser for domoic acid based on molecular imprinting. 09/01/99-8/31/01. NOAA/COP. Email:

We propose to develop a novel, highly sensitive analytical method for determining DA in tissue, plankton, and seawater. Our approach builds upon recent advances in the areas of molecular imprinting of resins and in the ability to fluorescently probe chemical environments. Briefly, we will develop a chemosensor for DA by cross-linking a polymer matrix around the analyte (DA), creating micro-cavities, or imprints for DA within the resin structure. The "template" DA is then washed from the resin leaving the imprints vacant. The imprints will contain binding sites specifically situated for DA. The resulting sterochemistry of the imprint will impart very high specificity for DA over other low molecular weight substrates, overcoming one of the two major analytical hurdles.

Detection of DA within the imprints, the second major analytical hurdle, we be accomplished by incorporating fluorescently-active molecules that are influenced by the presence of DA. We will experiment with two different approaches; fluorescent binding sites for DA which fluoresce upon association with DA, or molecules embedded within the walls of imprints which fluoresce upon the expulsion of aqueous media from the cavity by DA.

The combination of imprinting and fluorescence detection has been demonstrated in other fields to give very high selectivity and sensitivity. Based on equivalent sensitivity, it should be possible to detect the presence of DA in seawater containing as few as 1 cell ml-1. This optically-probed chemosensor will be ideally suited for simple, robust detection units that can be used on vessels, skiffs, or the beach. Ultimately, it should be possible to deploy molecular-imprinted chemosensors on mooring-based, satellite-reporting platforms in regions susceptible to toxigenic diatom blooms to provide an effective early warning coastal network system.

Last updated: July 11, 2016