For past and other agency sponsored ECOHAB projects, visit the WHOI website.
Institutions: Woods Hole Oceanographic Institution, University of Massachusetts, United States Geological Survey
Investigators: D. Anderson, D McGillicuddy, C. Pilskaln, R. Signell, B.Butman, A. Solow
The Gulf of Maine (GOM) supports productive shellfisheries frequently impacted by paralytic shellfish poisoning (PSP) - a serious threat to human health caused by the toxic dinoflagellate Alexandrium fundyense. PSP is the most widespread of the poisoning syndromes associated with harmful algal blooms (HABs). Blooms of A. fundyense in the GOM are highly seasonal, consistent with the view that life history transformations between cysts and vegetative cells are major regulatory factors. The ecology and oceanography of A. fundyense have been relatively well studied, but encystment and excystment dynamics remain poorly understood. This project is the second phase of a continuing study focusing on several aspects of that dynamic – the processes controlling the delivery, deposition, resuspension, and accumulation of resting cysts. In the parent project, researchers mapped the distribution of A. fundyense cysts in GOM bottom sediments and the benthic nepheloid layer (BNL) and obtained trap data on the sedimentation and resuspension fluxes of cysts through time.
Objectives:
Approach: Researchers will use observations from the parent project as well as new laboratory experiments and numerical model simulations to characterize cyst dynamics in surface waters, the BNL, and bottom sediments of the GOM.
Expected results: The expected results of this project will support NOAA’s planned operational forecasting system for PSP in the GOM, and fit perfectly with NOAA and ECOHAB priorities to provide “Quantitative understanding of HABs…… in relation to the surrounding environment ….. leading to development of operational ecological forecasting capabilities in areas with severe, recurrent blooms along the US coast”. Continued expansion and refinement of the coupled numerical models will greatly enhance the capability for HAB forecasting in the GOM.
Institutions: Texas A&M University, NOAA, Woods Hole Oceanographic Institution
Investigators: L.Campbell, R. Hetland, R. Stumpf; R. Olson; H. Sosik
The toxic dinoflagellate Karenia brevis is the primary harmful algal bloom (HAB) species in the Gulf of Mexico. One curious feature of K. brevis blooms is that although they occur regularly in the eastern Gulf, they occur only sporadically in the western Gulf along the Texas coast. This difference is unexpected since temperature, salinity, and nutrient conditions are similar in the two regions.
Objectives: The central hypothesis of this project is that the primary mechanism of bloom initiation in the western Gulf of Mexico is convergence and consequent downwelling at the coast, which physically concentrates Karenia cells because they swim upwards toward light. This mechanism differs from the blooms in the eastern Gulf off Florida, where blooms result from upwelling favorable winds and concentration at nearshore frontal boundaries. Specific objectives are to (1) correlate wind and bloom events using an existing hydrodynamic model to test the hypothesis that K. brevis bloom events are linked to seasonal downwelling along the Texas coast and that upwelling events may play an important role in dispersing the bloom; (2) test downwelling index predictions with field data on bloom development, including sampling targeted by the model predictions; and (3) develop a “Downwelling Index” for improved predictive capability based on local wind conditions.
Approach: A multi-investigator interdisciplinary program is proposed to develop better tools for prediction and to apply a novel imaging technology for detection and quantification of K. brevis. A numerical simulation of surface currents in the Gulf of Mexico suggested that increases in algal concentrations due to downwelling circulation may be comparable to (or, exceed) population increases due to growth alone. To investigate the relationship between K. brevis blooms and wind events, field samples will be collected by an extensive volunteer network combined with a targeted sampling program guided by model results and satellite data. Cell abundances will be analyzed in near-real time with the Imaging FlowCytobot (IFCB) and automated classification. Finally, results will enable creation of a ‘downwelling index’ based on local wind conditions that will provide a new tool to predict the likelihood of K. brevis bloom formation. This index will take into account the net accumulation of plankton near the coast due to downwelling circulation. Measured environmental conditions and observed bloom events, as well as simulated bloom events using the hydrodynamic model, will be used to develop and refine the downwelling index.
Expected results: Important outcomes of this project include new fundamental knowledge on the mechanism of bloom formation in the western Gulf and demonstration of the IFCB as a powerful technique for identification and quantification of HABs in near real time. Once validated, the downwelling Index will be made available to managers via the NOAA HAB Forecast System for prediction/ early warning of HAB events. A better understanding of how K. brevis blooms form will lead to improved prediction of harmful algal blooms throughout the Gulf.
Institutions: Woods Hole Oceanographic Institution (lead); SUNY Stony Brook (subcontractor)
Investigators: S. Dyhrman, C. Gobler
Project summary:
Harmful algal blooms (HABs) represent a significant threat to fisheries, public health, and economies around the world. Despite many years of study, fundamental questions remain regarding how nutrients drive HABs, such as the brown tides caused by Aureococcus anophagefferens. What species of dissolved inorganic nitrogen and phosphorus, or dissolved organic nitrogen and phosphorus are preferentially transported and metabolized by cells during blooms? How does nutrient transport and metabolism change as a function of ambient conditions as blooms initiate, are sustained, and decline? This project capitalizes on the recent completion of the first HAB genome sequence (A. anophagefferens) and our preliminary gene expression work with this species to develop and apply assays of gene expression to track the nutritional physiology of A. anophagefferens in its natural environment. By concurrently examining nutrient dynamics (e.g. supply, composition etc.), bloom dynamics, and gene expression we will create a clearer understanding of how nutrients influence HABs.
Objectives:
Approach:
In this targeted research study we propose the validation and application of quantitative gene expression assays to examine how nutrients influence bloom initiation, sustenance, and decline. We will link nutrient dynamics to the expression of genes involved in nutrient transport and metabolism in culture controls and through the course of a brown tide.
Expected results:
Parameterization of nutrient influences on HABs provided by the development and application of the approach described herein would 1) provide information that will enhance HAB forecasting efforts (e.g. better modeling of how eutrophication and nutrient inputs influence bloom dynamics), 2) provide decision makers with the information needed to control and mitigate blooms (e.g. assays of the effects of nutrient loading), and 3) help facilitate bloom prevention through an advanced understanding of how nutrients promote bloom formation, sustenance, and decline in different systems. Although this study uses brown tide as a model, we underscore that the approach developed and validated herein has never been conducted for any algal species and may be used as a blue-print for application to other HABs.
Institutions: University of Washington; Department of Fisheries and Oceans, Pacific Region, Institute of Ocean Sciences, Sidney, B.C., Canada; University of California, Santa Cruz.
Investigators: B. Hickey, E. Lessard, P. MacCready, N. Banas, M. Foreman, R. Thomson, D.Masson; R. Kudela
Funding Partner: National Science Foundation
Project Summary:
Objective:
The overall program objective is to improve predictability of Harmful Algal Bloom (HAB) events on Pacific Northwest (PNW) coastal beaches by advancing our understanding of HAB development/dissipation and transport and mixing processes using existing data in parallel with state of the art physical and bio-physical models that include, for the first time, both the Columbia River (CR) plume and potential HAB source regions off both Oregon and Washington.
Approach:
This project makes use of results and data from two recently completed, temporally overlapping 5-year, multi-institutional, interdisciplinary studies–ECOHAB PNW (The Ecology and Oceanography of Harmful Algal Blooms in the PNW) and RISE (River Influences on Shelf Ecosystems), to improve predictability of arrival of HABs, in particular, toxigenic Pseudo-nitzschia (PN), on PNW beaches. The overriding conclusion from both studies is that lack of understanding of the effect of the CR plume on cross-shelf and alongshelf transport and mixing is the greatest impediment to understanding how phytoplankton, in particular, HABs, arrive on coastal beaches. In this project, we will build on the wealth of complementary information and enhanced knowledge generated in these two programs to study the transport and mitigation of HABs to the Washington coast from both northern and southern sources and extend our analyses to species other than PN. Hypotheses include: 1) The CR plume is a bioreactor for growth but not for toxin production, 2) During downwelling winds, the CR plume inhibits shoreward transport of toxic blooms, 3) During upwelling winds the CR plume enhances cross-shelf transport of toxic blooms below the surface layer, and 4) The CR plume enhances northward transport of toxic blooms along the coast.
Studies will include idealized process studies addressing these hypotheses, hindcasts of selected HAB events, and development of a forecasting ability. The new Northwest Association of Networked Ocean Observing Systems (NANOOS) will be used for model verification and also model improvement via data assimilation.
Expected Benefits:
A large group of Government and Tribal bodies with interests in coastal shellfish resources will benefit from both the improved HABs understanding as well as a forecasting ability. New information on Alexandrium may allow managers to shorten annual PSP beach closures. Models in ECOHAB PNW did not include the CR plume; those in RISE did not include two known source regions for toxic PN, the Juan de Fuca eddy region (north) and Heceta bank (south). The proposed forecast/hindcast models will include both source regions and the plume as well as the other freshwater sources that impact nutrient and freshwater supply in the region. The imbedded biological model will use a new approach based on measured biological rates, providing a ten fold improvement in skill over most existing models.
Institutions: University of Texas Marine Science Institute
Investigators: D. Erdner
Harmful Algal Blooms (HABs) in estuarine and coastal waters can endanger both public and ecosystem health, and their incidence and extent are increasing worldwide. The toxic dinoflagellate Alexandrium tamarense is responsible for outbreaks of paralytic shellfish poisoning, one of the most widespread HAB syndromes. While numerous laboratory and field studies have greatly increased our understanding of the biological and physical processes that lead to the initiation of blooms and their subsequent growth and transport, very little is known about the causes of bloom decline and termination. Preliminary results suggest that Alexandrium may initiate programmed cell death in response to nutrient stress, leading to the hypothesis that an active cell death pathway in Alexandrium may contribute to the decline of blooms in situ.
Objectives: The overall goal of this project is to evaluate the relationship between nutrient stress, programmed cell death (PCD), and encystment in Alexandrium by: (1) documenting the PCD process in Alexandrium, including the genetic, biochemical, and morphological changes that occur; (2) identifying the triggers of PCD in Alexandrium; (3) investigating the link between PCD and the encystment process; and (4) assessing the presence and magnitude of PCD in a natural Alexandrium bloom.
Approach: A suite of genetic and biochemical assays will be used to determine the existence of the PCD process in Alexandrium under conditions that result in nutrient stress or encystment. These include measures of caspase activity, DNA fragmentation, maintenance of membrane integrity, inversion of phosphatidylserine in the cell membrane, and metacaspase gene expression. These analyses will also be used with natural bloom populations, to assess the role of PCD in bloom decline in situ.
Expected Results: The end results of the work will be: a description of the PCD process in a toxic dinoflagellate; an understanding of the environmental triggers of PCD; elucidation of the link between PCD and encystment pathways in Alexandrium; and assessment of the role of PCD in bloom decline in situ. The results of this project will provide valuable information on the links between nutrient conditions and bloom termination, contributing directly to all three of EPA’s desired outcomes: 1) assessment of the role of PCD in bloom decline will contribute to better modeling of harmful blooms, thereby providing information that will enhance HAB forecasting efforts; 2) data on the links between nutrient conditions and bloom decline (or persistence) will help to provide decision makers with the information needed to control and mitigate blooms; and 3) knowledge of cell death processes in toxic dinoflagellate will help facilitate bloom prevention through an advanced understanding of the conditions and processes that promote their formation, maintenance, and decline.
Institutions: University of Maine
Investigators: L. Karp-Boss, D. Townsend
Toxic species of the dinoflagellate genus Alexandrium are responsible for outbreaks of Paralytic Shellfish Poisoning (PSP), a recurrent and serious problem in the Gulf of Maine (GOM). Hence, understanding bloom dynamics of Alexandrium spp. is a major research focus in the GOM and other coastal areas. Previous ECOHAB-funded studies have documented that the highest Alexandrium cell concentrations are located in offshore waters, well away from most coastal shellfish beds, and are delivered to inshore waters by physical mechanisms. An intriguing question is: What restricts Alexandrium from blooming in inshore waters? One hypothesis suggested by Townsend et al. (2005), is that Alexandrium bloom dynamics may be controlled not only by physical and chemical factors but also by biological interactions with other phytoplankton taxa – in particular, diatoms.
Objectives: This research will test the hypothesis that bloom dynamics of Alexandrium are influenced by competitive interactions with diatoms, and that the interactions are reciprocal. That is, while field observations and preliminary lab studies indicate that high densities or growth rates of diatoms impede the growth of Alexandrium in early spring and in near-shore waters, either by virtue of their rapid growth rate and exploitation of essential resources or via alleopathic interactions, Alexandrium blooms that have been established after the decline of the diatom bloom can prevent a second diatom bloom via allelopathy.
Approach: This project will conduct detailed laboratory studies that will 1) examine allelopathic interactions between the toxic dinoflagellate A. fundyense and diatoms; 2) obtain ecophysiological parameters on nutrient-dependent growth kinetics of A.fundyense and diatoms common to the GOM, and apply them to a resource-based competition model to predict outcome of competition between A. fundyense and diatoms; and, 3) conduct competition experiments between A. fundyense and diatoms over a range of nitrate and silicate concentrations and compare the experimental results to model predictions. Laboratory efforts will be supplemented with field data for the evaluation of distributions of Alexandrium with respect to distributions of other phytoplankton taxonomic groups, in particular diatoms, nutrients and hydrographic condition.
Expected results: Results from this study will provide new information on the interactions of HAB species with other members of the phytoplankton community, which could lead to new insights into potentially novel mechanisms by which HAB blooms may be controlled. On a more basic level, this study will provide physiological data on uptake kinetics of A. fundyense (which are currently lacking) that is necessary for the development and improvement of forecast models for Alexandrium blooms. The study will also provide information on inter- and intra- variations in physiological parameters between Alexandrium strains, new reference material, and will support the training of graduate and undergraduate students.
Institutions: NOAA Northwest Fisheries Science Center, University of Washington
Investigators: K. Lefebvre, M. Myers, F. Farin, T. Bammler, R. Beyer
The potential impacts of chronic algal toxin exposure have long been a concern. One HAB toxin, domoic acid (DA), is a potent neurotoxin that interacts with the vertebrate central nervous system (CNS). Although the clinical signs of acute DA toxicity have been well defined, virtually nothing is known about the impacts of chronic, low-level toxin exposure, primarily due to the difficulties associated with long-term exposure studies. It is known that vertebrates such as fish, seabirds, marine mammals, and humans are repeatedly exposed to DA at levels below those that cause outward signs of toxicity, yet it remains unknown how these chronic sub-acute exposures may impact these organisms. This project plans to quantify gene expression patterns in whole brain and characterize histopathological aberrations in major organs as endpoints to examine the effects of chronic exposure in zebrafish. The overall goal of this project is to develop a general model for the characterization of gene expression effects in the vertebrate CNS and morphological damage in major organs associated with long-term, low-level toxin exposure.
Objectives:The objectives of this project are to 1) quantify gene expression changes in the vertebrate CNS and characterize differentially expressed genes based on function to identify potential pathways of chronic disease associated with long-term, low-level algal toxin exposure, 2) quantify circulating blood toxin levels associated with changes in gene expression, and 3) perform histologic examinations of all major organ systems to characterize pathological impacts of chronic toxicity.
Approach: The toxicogenetic approach will be to use microchip gene array technology to quantify differential gene expression in whole brain during a one-year DA exposure study using a vertebrate model system (zebrafish, Danio rerio). Through pilot studies, the investigators have quantified appropriate sub-acute doses, developed effective repetitive dosing procedures, and developed a statistically rigorous experimental design. RNA isolation methods, microchip array procedures, qRT-PCR confirmation procedures, and bioinformatics processes for grouping and identifying gene clusters of interest have also been perfected. In addition to gene expression analyses, this research will employ standard histology procedures to visualize potential pathological aberrations caused by chronic DA exposure.
Expected results:This research is expected to yield several results that will directly aid assessments of HAB impacts on marine biota. First, this research will provide the only available data on the impacts of chronic, low-level algal toxin exposure using a realistic long-term exposure time scale. It is also likely that new pathways of DA toxicity will be identified since a single dose exposure pilot study has already revealed gene expression patterns unique to sub-acute exposure. The gene lists generated will be widely disseminated and publicly available for researchers to use as a starting point for species-specific studies on chronic HAB toxin exposure effects. Finally, the study will quantify circulating blood toxin levels that are associated with the observed gene expression effects. These blood toxin levels can be used for characterizing the potential risk to other vertebrates exposed to DA in the field.
Institutions: University of Maine, National Research Council Canada
Investigators: L. Connell, V.M. Bricelj, P. Rawson
Abstract:
Paralytic shellfish toxins (PSTs) are potent neurotoxins produced by dinoflagellates, Alexandrium spp. on the eastern seaboard of North America, and are accumulated by filter feeding shellfish. Human consumption of toxic shellfish (paralytic shellfish poisoning (PSP)) can result in serious illness or death. Shellfish that consume PSTs may also be affected, leading to an inability to burrow and a high mortality rate. The softshell clam, Mya arenaria , is a commercially important bivalve with wide latitudinal distribution in North America. Populations of clams with a history of repeated exposure to toxic Alexandrium spp. have developed a natural resistance to the PSTs produced by these algae. Our previous work has identified a mutation in some M. arenaria conferring resistance to PSTs. The clams bearing this mutation display a resistance to toxic levels of Alexandrium spp and accumulate up to 100-Fold toxin as compared to wild-type clams. These toxins may act as potent natural selection agents, leading to a spread of toxin resistance to PSTs in M. arenaria populations and accompanying higher toxin accumulation. Higher accumulation of PSTs in clams can increase the risk of PSP in humans. Furthermore, global expansion of PSP to previously unaffected coastal areas might result in long-term changes to shellfish communities and ecosystems.
Objectives:
This project will focus on establishing the range and extent of the mutation currently found in wild populations as well as determining the selective pressure blooms of Alexandrium spp. places on these populations, thereby, altering the amount of toxin entering the food web. Correlations will be explored between areas with historical PSP exposure and those with the probability of new blooms. In addition to these population studies we will explore the physiological mechanism for toxin-induced mortality though anoxia of the mantle cavity in young clams (spat).
Approach:
The methods used for this project have already been well developed. Those methods include a nerve trunk assay for the determination of potential toxin binding in individual clams, established cDNA and DNA sequencing protocols to conduct a phylogeographic survey of the prevalence of Na+ channel mutations. Selectively bred M. arenaria will be exposed to Alexandrium spp. containing various amounts of toxin and with a range of cell concentrations both in the laboratory and in filed situations to determine the effects on both individual clams and the genetic structure of the population as a whole. Oxygen microprobes will be used to determine the level of anoxia in both resistant and sensitive clams that have been exposed to PST in order to determine if anoxia is a primary mechanism of mortality.
Expect Results:
The increase of clams carrying a toxin resistant mutation can significantly effect the toxin transfer in other areas of the food web. Genotype information can be used to predict potential toxin load of an individual clam after a highly toxic Alexandrium spp. bloom and clam seed can be set accordingly to limit the overall impact of toxic blooms. Information about the population structure and its ability to sequester toxin will be useful for shellfish resource managers.
Institution: University of South Florida, http://www.marine.usf.edu/microbiology/genosensor.shtml
Investigators: J.H. Paul, D.P. Fries, M. Smith.
Abstract:
Harmful algal blooms can be major catastrophes in terms of economic losses, aquatic organism mortalities, and deleterious impacts on human health. To predict onset of harmful algal blooms, monitor their severity, and to accurately determine their termination, rapid, reliable, and accurate methods are needed to detect HAB species. A major goal is to incorporate rapid and accurate detection methods into ocean observing systems. We have used the ribulose-1,5-biphosphate carboxylase/oxygenase large subunit gene ( rbcL ) as a molecular tag to detect K. brevis in a prior ECOHAB-funded project . We developed an assay that uses the novel Nucleic Acid Sequence-Based Amplification (NASBA) and molecular beacon technology. NASBA amplification, which is isothermal, is more amenable to field assays and autonomous platforms than PCR, which requires thermal cycling. With prior funding from ONR and NSF, we have incorporated our NASBA-based detection technology into the Autonomous Microbial Genosensor (AMG), the first sensor buoy to perform nucleic acid amplification to detect harmful algae. Based upon our experience with this system we would now like to improve the AMG with several engineering upgrades and embark on a series of field deployments to fully test this system. Our objectives are to:
For Objective 1, we will install a second fluorescence channel in the AMG to enable detection of an internal control for quantitation and determination of performance. Alternatively, the second channel can enable detection of a second target species or a different gene (ie. a K. brevis PKS gene). Objective 2 aims to decrease the overall size and weight of the AMG to facilitate easy deployment. Construction of a second AMG (Objective 3) will enable simultaneous deployment and data collection from two sites, which is the main goal of Objective 4. We will manually sample during operation modes of the AMG during field deployments to ensure proper performance, and simultaneous samples will be microscopically counted for K. brevis . The outcome of this research will be an autonomous RNA amplification platform capable of detecting and providing quantitative information on K. brevis populations in near real time. The system will be targeted toward Karenia brevis but with simple modification should be able to target any HAB species. This proposal coincides with the NOAA agency interests described in the RFP: "Development of new methods for measuring HAB cells and toxins, especially those that can be used in observing systems or provide enhanced monitoring capability are especially encouraged".
Institution: Western Washington University
Investigators: S. L. Strom and S. Menden-Deuer
Abstract:
We propose an experimental investigation into the regulation of Heterosigma akashiwo blooms by protistan predators. H. akashiwo causes fish kills yearly in coastal waters of the Pacific. Food web interactions involving H. akashiwo . a raphidophyte that may have multiple modes of toxicity, are poorly understood. Our study focuses on the interactions between H. akashiwo layer-forming behavior, nutrient use, and susceptibility to predation mortality. Predation and behavioral experiments will utilize heterotrophic protists, the major consumers of phytoplankton in the world's oceans, and will address both toxicity and predator deterrence as phenomena with different implications for bloom formation and maintenance. This is a novel approach that integrates traditionally separate 'bottom up' and 'top down' aspects of HAB ecology. Results will significantly contribute to our understanding of H. akashiwo in coastal food webs, as well as to our knowledge of competitive strategies (layer formation, use of organic nutrient sources, deleterious effects on predators) that are employed by a number of HAB taxa.
Objectives:
Approach:
We will conduct laboratory experiments with H. akashiwo and heterotrophic protist isolates from the coastal northeast Pacific. Regional waters and natural blooms of H. akashiwo will be sampled to obtain new isolates of the raphidophyte and of protist predators that both do and do not co-occur with the natural blooms. Work on layer formation and associated H. akashiwo and protist predator behavior will be conducted in novel spatially structured laboratory environments, using video and motion analysis techniques to quantify individual- and population-level behavioral effects.
Expected Results:
Institution: Texas A&M University
Investigators: L. Campbell, J.R., Gold
Abstract:
Toxic dinoflagellates of the genus Karenia are a serious economic and public health concern worldwide. The major HAB species in the Gulf of Mexico is Karenia brevis, a dinoflagellate that produces a suite of potent neurotoxins (brevetoxins) that can cause fish kills, shellfish toxicity, and respiratory distress in humans. Cell counts alone are not a good predictor of potential toxicity of HABs because the quantity of toxin can vary with species composition, stage of growth, and/or environmental conditions. There also is evidence that variation in cellular toxin content and toxin profiles exist among clones of K. brevis. Factors influencing production of brevenal, the naturally occurring antagonist for brevetoxins, among clones of K. brevis also are unknown. A more detailed understanding of both genetic diversity and intraspecific toxin composition within and among blooms is needed so that the dynamics and potential potency of toxic dinoflagellate populations can be linked to environmental heterogeneity and change.
Objectives:
Approach:
Conduct field sampling in conjunction with the ongoing monitoring program for Karenia at the Fish and Wildlife Research Institute (FWRI) in St. Petersburg, Florida. A suite of nuclear-encoded microsatellite markers developed from a K. brevis genomic library will be employed as tools to characterize genetic composition of bloom populations. For each clonal isolate established during the course of a bloom event, allele and genotype distributions at 10 microsatellites will form the basis for tests of spatial and temporal (genetic) homogeneity. Bench-scale studies will be performed to evaluate differences in toxin profiles among clones when grown under identical conditions. Experiments with selected clones acclimated to a range of salinities and nutrients in semi-continuous growth and with cultures subjected to rapid changes in growth conditions will be conducted to evaluate effects of environmental conditions on toxin profiles and quantity of brevetoxins and brevenal produced. Data analysis primarily will include tests of spatial and temporal homogeneity (including molecular analysis of variance or amova ) of allele (haplotype) and genotype distributions (frequencies). Estimates of haplotype diversity and intrapopulational nucleotide diversity also will be generated. Neighbor-joining topologies of genetic-distance matrices will be used as a means to assess genetic and evolutionary relationships among spatial/temporal samples and to link diversity and structure of isolates of K. brevis with the intraspecific variation in toxin production.
Expected Results:
This study will provide critical and much needed information on the variation in toxin composition and production among K brevis clones and over the course of a Karenia bloom. The database of dinoflagellate microsatellite alleles for the Gulf will be expanded and the extent of diversity in toxin profiles together with genetic profiles will allow development of realistic predictive models. Linking allelic profiles and toxicity will allow prediction of the response of HAB populations to changes in environmental factors. Ultimately, this will result in the capability to predict how environmental factors influence toxicity or potency of a Karenia bloom.
Institution: University of Connecticut
Investigator: Hans G. Dam
Abstract:
Harmful algal blooms (HAB) pose a serious threat to public health, aquaculture and fisheries. However, the ecological and evolutionary consequences of HAB to grazers, the ramifying effects on food web structure and function, and on the transfer of toxins are not well understood. Toxic dinoflagellates of the genus Alexandrium bloom along eastern Canada and New England. In previous work, we have demonstrated local adaptation (resistance) to toxic Alexandrium in one species of copepod, Acartia hudsonica. This new information is the first documented case of resistance in marine pelagic grazers, and has helped explain disparate and sometimes contradictory results from other previously published studies. Resistance has two important consequences in food-web dynamics: 1) Potential bloom control, and 2) Potentially higher toxin transfer to upper trophic levels. Here, we propose to expand our studies to examine how resistance affects grazer toxin dynamics.
Objectives:
To determine whether there are differences in toxin accumulation, retention, depuration, and biotransformation between resistant and nonresistant phenotypes of Acartia hudsonica to toxic Alexandrium. We will test the null hypothesis that there is no difference in the ability of resistant and nonresistant phenotype to deal with toxins.
Approach:
We will continue our comparative studies and expose individuals of resistant and nonresistant phenotypes to diets containing toxic Alexandrium for sufficiently-long periods of time to achieve steady state in toxin accumulation. In both kinds of phenotypes, we will measure time-dependent toxin ingestion rates, accumulation, retention, and depuration and toxin profile in the grazers relative to the food source.
Expected results:
We expect to see differences in all or some of the processes mentioned above involved in toxin dynamics between resistant and nonresistant phenotypes. This new information is directly relevant to two of the ECOHAB study areas: trophic transfer of toxins, and impacts on higher trophic levels. An immediate outcome of this project will be to answer the question of whether resistant grazer phenotypes enhance toxin transfer up the food web. Such information will be useful in constructing more accurate models of food web dynamics, and in predicting the impact of HAB for higher trophic levels.
Institutions: Woods Hole Oceanographic Insititution, Bigelow Laboratory for Ocean Sciences, Department of Fisheries and Oceans, NOAA/Northeast Fisheries Science Center, National Research Council Canada, Food and Drug Administration, University of Massachusetss, Univeristy of Maine, Stellwagen Bank National Marine Sanctuary
Investigators: D.M. Anderson, D.J. McGillicuddy, Jr., R. He, B.A. Keafer, C.H.Pilskaln, J. Martin, J. Manning, V.M. Bricelj, J. Deeds, S. Etheridge, S. Hall, J.T. Turner, N.R. Pettigrew, A. Thomas, D.W. Townsend,
Abstract:
The Gulf of Maine (GoM) and its adjacent southern New England shelf is a vast region with extensive shellfish resources, large portions of which are frequently contaminated with paralytic shellfish poisoning (PSP) toxins produced by the dinoflagellate Alexandrium fundyense . The year 2005 was an historical one for A. fundyense and PSP dynamics in this area, with a bloom that was more severe than any seen in the last thiry years. There are significant challenges to the management of toxic shellfish in this region - in particular the need to document the major transport pathways for A. fundyense , and to develop an understanding of the relationship between blooms and environmental forcings, as well as linkages to toxicity patterns in nearshore and offshore shellfish. An additional challenge is to expand modeling and forecasting capabilities to include the entire region, and to transition these tools to operational, management use.
Objective:
Here we propose GOMTOX - a regional observation and modeling program focused on the GoM and its adjacent New England shelf waters. The overall objective is to establish a comprehensive regional-scale understanding of Alexandrium fundyense dynamics, transport pathways, and associated shellfish toxicity and to use this information and relevant technologies to assist managers, regulators, and industry to fully exploit nearshore and offshore shellfish resources threatened by PSP, with appropriate safeguards for human health.
Approach:
GOMTOX will utilize a combination of large-scale survey cruises, autonomous gliders, moored instruments and traps, drifters, satellite imagery and numerical models to: 1) investigate A. fundyense bloom dynamics and the pathways that link this organism to toxicity in both nearshore and offshore shellfish in the Gulf of Maine and southern New England shelf waters; 2) investigate the vertical structure of A. fundyense blooms in the study region, emphasizing the distribution of cells, zooplankton fecal pellets, other vectors for toxin, and their linkage to toxicity in offshore shellfish; 3) assess interannual to interdecadal variability in A. fundyense abundance and PSP toxicity; 4) incorporate field observations into a suite of numerical models for hindcasting and forecasting applications; and 5) synthesize results and disseminate the information and technology, transitioning scientific and management tools to the regulatory community for operational use.
Expected results:
At its completion, this program and its predecessors will have produced a comprehensive understanding of the dynamics and forcing mechanisms underlying A. fundyense blooms and the associated toxicity of nearshore and offshore shellfish across a vast and highly complex region. Important hydrographic pathways and branch points will have been identified, and key features and processes characterized. Conceptual models will have been formulated to explain blooms and toxicity throughout the region, and sophisticated numerical models developed and tested that simulate physical, chemical, and biological processes at a highly detailed level over the region. GOMTOX will thus make significant progress towards an operational bloom forecasting system appropriate for nearshore and offshore shellfish resources. Furthermore, the information and technology developed by this initiative will contribute greatly to policy decisions concerning the re-opening, development, and management of offshore shellfish industries with potential sustained harvesting value of $50-100 million per year.
Institutions: Fish & Wildlife Research Institution,Virginia Institute of Marine Science, Mote Marine Laboratory, University of Miami - RSMAS, Old Dominion University Research Foundation, University of Maryland, University of South Florida
Investigators: C. A. Heil, D. Bronk, L.K. Dixon, G. Hitchcock, G. Kirkpatrick, M. Mulholland, J. O'Neil, J.J. Walsh, R. Weisberg
Abstract:
Objectives:
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.
Approach:
This proposal 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.
Expected Results and Significance:
Effectual 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.
Institutions: University of Washington, NOAA Northwest Fisheries Science Center, National Research Council Canada
Investigators: T. Scheuer, W.A.Catterall, V. Trainer, V.M. Bricelj
Abstract:
This multidisciplinary research collaboration will characterize the complex mechanism underlying bivalve susceptibility to paralytic shellfish toxins (PSTs) and species-specific toxin accumulation. In mammals, PSTs affect nerve function via specific block of the voltage-sensitive Na + channel. Bivalves, however, clearly have adaptations that permit them to tolerate toxins in their algal food. Specifically, "insensitive" bivalve species are known to harbor, without apparent harm, high concentrations of PSTs, while more "sensitive" species attain relatively low toxin levels and can suffer sublethal or even lethal effects from harmful algal blooms (HABs) when toxin concentrations are high. This susceptibility to ingested toxins and thus, ability to accumulate toxins, varies markedly both within and among bivalve species. The past research of this collaborative group has characterized up to a 50-fold difference in toxin affinity among populations of softshell clams, Mya arenaria , and has shown that a single, conservative mutation in the Na + channel confers resistance to PSTs. A key goal of this proposal is to extend this research to more completely characterize the molecular and biochemical basis for the much larger interspecific variation in toxin uptake and sensitivity in bivalves.
The overarching goal of these studies is to understand the factors contributing to shellfish toxicity in the presence of HABs and to reduce their impact by providing tools to predict toxin retention by shellfish.
Specific objectives of this research will be to: 1. characterize the saxitoxin binding region of each of the four functional Na + channel domains in several shellfish species selected as representative of extremes of nerve sensitivity/resistance to PSTs, 2. Determine the biochemical basis for PSP insensitivity and toxin sequestration in selected bivalve species characterized by prolonged toxin retention of PSTs, 3. determine the molecular basis for the relative PSP-insensitivity of molluscs compared to vertebrates, 4. develop molecular markers for selection of non-accumulating (nontoxic) bivalve stocks. Interspecific differences in shellfish susceptibility to toxins will be explored using molecular, biochemical and physiological approaches in clams ( Siliqua patula and/or Ensis directus , Spisula solidissima, and Saxidomus giganteus ) and mussels ( Mytlilus edulis ) from historically toxic and non-toxic areas on the Pacific (including Alaska) and Atlantic coasts of N. America. Identification of inter- and intraspecific genetic and biochemical differences will contribute to our fundamental understanding of toxin resistance mechanisms and perhaps open future avenues for detoxification strategies or selective breeding. Regional characterization of bivalve responses to toxic algae will help to predict the impacts of paralytic shellfish poisoning (PSP) over a wide geographical range. Understanding of the relationship of specific toxin vectors to the intensity and frequency of HABs in a given area, will contribute to improved management of commercially important shellfisheries.
Institution: The University of Tennessee
Investigators: T.B. Henry, G.S. Sayler, S.W. Wilhelm, R. J. Strange
Abstract:
Objectives/hypothesis:
During the last 10 years, Microcystis spp. blooms have occurred in Western Lake Erie, and elevated levels of microcystins have become a concern for both human and ecosystem health. Our objective is to investigate the predominant microcystin found in this system (microcystin-LR) in model fish species and to relate laboratory results to chronic low-level toxin exposure and bioaccumulation found in higher trophic level fish in W. Lake Erie. We hypothesize that (1) specific genes that respond to microcystin-LR exposure in larval and adult zebrafish can be identified and selected as biomarkers; (2) effects of chronic, low concentration exposure of microcystin-LR can be detected by changes in biomarker gene expression, tissue histology, and reproduction in zebrafish; (3) bioaccumulation of microcystin in channel catfish is affected by route of exposure and effects can be detected in biomarker gene expression and histopathology; and (4) bioaccumulation and effects of chronic low, concentration exposure to microcystins can be detected in higher trophic level fish collected from W. Lake Erie by tissue analysis and the evaluation of biomarkers resolved from lab and mesocosm experiments.
Approach:
Commercially available microarrays will be used to interpret differences in global gene expression for nearly 15,000 genetic transcripts in zebrafish exposed to microcystin-LR. A subset of differentially expressed biomarker genes (~20-40) will be selected for larval and adult fish and adapted to a quantitative real-time PCR format for monitoring specific exposure variables. Subsequently, zebrafish will be exposed to chronic low concentrations of microcystin-LR throughout development (age 2-150 days), and survival, biomarker gene expression, histopathological lesions, and reproductive success will be evaluated. Selected biomarker genes will be adapted for use in channel catfish to evaluate effects of bioaccumulation of microcystin in channel catfish after aqueous and dietary exposure. Fish from higher trophic levels (including channel catfish) will be collected from W. Lake Erie to assess bioaccumulation of microcystin and effects on biomarkers resolved in lab experiments.
Expected results:
Genes selected from microarray experiments will improve our understanding of the mechanisms of microcystin toxicity and enable more specific probing into the factors that influence bioaccumulation and toxicity in fish via in vitro, mesocosm, and in situ approaches. Our focus on chronic, low-concentration exposures to will begin to address an important knowledge gap regarding the long-term effects of algal toxins on ecological health. We expect to determine toxin concentrations that cause negative effects in fish during chronic exposure and to demonstrate toxicogenetic and histopathological approaches that can be employed in ecological forecasting of system health.
