ECOHAB 2017 Project Summaries

Principal Investigators and Institutions: Ming Li, Patricia M. Glibert, University of Maryland Center for Environmental Science

The over-enrichment of Chesapeake Bay (CB) by nutrients has been well recognized and documented. Among the effects of this over-enrichment is an increasing proliferation of HABs, ranging from toxic dinoflagellates (e.g. Karlodinium veneficum), to ecosystem disruptive high-biomass dinoflagellates (e.g., Prorocentrum minimum) as well as toxic and high-biomass cyanobacterial blooms. HABs in CB are now more frequent, and of significantly higher densities, than several decades ago. Although many HABs develop when nutrients are not in Redfield proportion, traditional biomass-based plankton models assume fixed stoichiometry and operate using Monod kinetics. These models are unsuitable, and are considered as dysfunctional for descriptions of algal growth under variable nutrient conditions. This proposal aims to develop a new, spatially explicit, mechanistic HAB model for CB that integrates physics, nutrient cycling, food web interactions, physical factors and nutrient physiology to improve predictions of the long-term changes of two dominant HABs, P. minimum and K. veneficum seasonally and under various scenarios of change. A coupled hydrodynamicbiogeochemical model (ROMS-RCA) will be coupled to a new HAB model for P. minimum and K. veneficum. RCA includes 3 phytoplankton functional groups (cyanobacteria, diatoms and flagellates), separate cycling of N, P, Si and C, and is coupled to a sediment diagenesis model. The HAB model will consider nutrient preferences, life history including diel regulation, internal cellular nutrient storage and mixotrophy. The models will be applied to 1) spatially explicit seasonal forecasts, i.e. forecast summer HAB based on winter-spring nutrient loading and spring bloom development, and 2) scenario analysis to examine how HABs respond to nutrient management strategies (higher or lower loading) and climate change (warming, salinity change due to sea-level rise or changes in stream flows etc.) as projected by global and regional climate models. Model comparisons will be made in hind-cast mode with the extensive CB monitoring data. The proposed effort will also include a suite of laboratory experiments to obtain the necessary parameters to quantify cell quota, nutrient acquisition and growth for multiple nutrients and under a range of nutrient, temperature, and light conditions. Seminars and training on the model will be provided to management agencies, such as the Maryland Department of Natural Resources, the Department of the Environment, BayStat working groups, and the Harmful Algal Task Force. Based on their input, specific scenarios for various specific nutrient reduction goals will be run. The proposed analysis of nutrient loading and climate change scenarios will be useful for designing restoration strategies for CB. The end result will be more effective nutrient reductions that will have significant effects on reducing the numbers of HABs, their frequency or their duration, with positive consequences on fisheries and shellfish habitat.

Principal Investigators and Institutions: Elizabeth Tobin (Lead PI), Ginny Eckert, University of Alaska Fairbanks; Chris Whitehead, Sitka Tribe of Alaska Project Partner: Kate Sullivan, Southeast Alaska Regional Dive Fishery Association
The Southeast Alaska geoduck clam fishery, worth $4.9 million annually in past years, is an economically important wintertime fishery. However, the fishery has been plagued by unexplained toxicity from paralytic shellfish toxins (PSTs) resulting in substantial economic losses. In Alaska, PSTs are attributed to the marine dinoflagellate, Alexandrium sp., and typically threaten shellfisheries during summer months when conditions support Alexandrium growth. Yet, geoduck clams show elevated and erratic patterns toxicity in fall and winter. It is currently not understood what factors lead to fall and wintertime toxicity in geoduck clams. While it has been proposed that benthic resting cysts contribute to the toxicity of certain shellfish, this alternate mechanism for geoduck clam toxicity through direct cyst ingestion or germination following sediment disturbance has not been tested. Further, nothing is known about cyst distributions in relation to geoduck clam harvest areas in Southeast Alaska. Knowledge about distributions of cyst populations and if cyst resuspension contributes to geoduck clam toxicity would provide critical information to reduce the impacts of PSTs to geoduck clam fisheries and inform management response. Thus, the primary objectives of this proposal are to:

• examine the relationship between cyst distributions and geoduck toxicity patterns within commercial harvest areas to identify areas of greater or lower exposure risk to paralytic shellfish toxins;
• identify whether cyst ingestion is a mechanism for geoduck clam toxicity to improve understanding of toxin transfer dynamics for geoduck clams and other shellfish species;
• determine if current geoduck harvest and/or management approaches contribute to the frequent occurrence of wintertime toxicity in geoduck clams; and
• involve geoduck clam dive industry and resource managers in research to ensure projectoutcomes meet stakeholder information needs.

The proposed research meets the two overall goals stated in the 2017 ECOHAB RFP. This research will address goal 1) to develop “Quantitative understanding of HABs and, where applicable, their toxins… to aid managers in coastal environments;” by quantifying the relationship between benthic cyst distributions and frequency of geoduck clam toxicity, and through direct involvement of industry (geoduck dive fishery) and management (ADF&G) partners in research activities to ensure project outcomes address stakeholder needs. This work meets goal 2) “Understanding leading to models of trophic transfer of toxins…” by establishing the ecological pathway for algal toxin transfer to commercially important geoduck clams and identifying the role of harvest and/or management approaches to amplify or mitigate shellfish toxicity. This proposal directly aligns with target areas identified as a priority for proposals in this RFP, “Determining the trophic transfer of toxins within food webs and the impacts of toxins on individual organisms and food webs”. This research will identify the mechanism for toxin transfer to geoduck clams, which are then eaten by people.

Principal Investigators and Institutions: Marilou Sison-Mangus (Lead PI), Phil Crews, Juhee Lee, University of California Santa Cruz

Domoic acid (DA) poisoning is a pervasive problem in the coastal oceans of the Northeast and Northwest United States. Discovered in 1987 from algal bloom forming diatom Pseudo-nitzschia, the trigger for its production and the chemical and molecular mechanism for its biosynthesis is still not completely understood to date. Although several physical and biological factors have been implicated for the production of DA, bacterial metabolites as potential triggers for DA synthesis has not been investigated. The overarching goal of this proposal is to gain an understanding of the biosynthetic machinery of domoic acid in Pseudo-nitzschia and the influence of marine bacteria that leads to the synthesis of domoic acid and other kainoid families, which will provide fundamental new insights about chemical, molecular and biotic factors at work during Pseudo-nitzschia bloom. The proposed goals and approaches aim to (1) map out the diverse but unknown major and minor biosynthetic DA congeners potentially synthesized via interaction between Pseudo-nitzschia and epibiotic bacteria using state of the art isolation and identification techniques, (2) shed light into the mixed terpene-amino acid hybrid biosynthetic machinery and pathways hypothesized to produce the domoic acid framework by using labeled substrates that can elucidate the chemical pathways at work during DA synthesis (3) investigate the modulation of DA production in the ocean and in the laboratory by studying the metabolome of Pseudo-nitzschia-bacteria cocultures and natural associations during bloom, (4) employ molecular genetic tools including integrated pathway analysis to define the basis for the Pseudo-nitzschia – marine bacteria interaction required to produce DA analogues in culture and natural blooms, (5) Use Bayesian statistical approach to quantify the contribution of marine bacteria to toxic Pseudo-nitzschia bloom formation against other co-varying physical and biological factors. Important outcomes include the generation of transformative information about the DA biosynthetic machinery at work that can lead to a better mitigation and management of Pseudo-nitzschia toxic bloom. Understanding the influence of bacteria on toxic Pseudo-nitzschia bloom formation can lead to the use of this biotic factor as a potential determinant of Pseudo-nitzschia bloom toxicity and can be integrated with other environmental factors in making better predictive models for forecasting Pseudo-nitzschia bloom. Our findings will be disseminated to managers of ocean monitoring systems to provide information about the potential adoption of bacteria and metabolites as additional important markers for monitoring and predicting Pseudo-nitzschia bloom toxicity.

Principal Investigators and Institutions: Juliette Smith (Lead PI), Virginia Institute of Marine Science; Lisa Campbell, Texas A&M University; Christopher Gobler, Theresa Hattenrath-Lehmann, Stony Brook University; Vera Trainer, NOAA/NMFS/NWFSC; Jonathan Deeds, US FDA, College Park

Species of Dinophysis, known to produce toxins that cause diarrhetic shellfish poisoning (DSP), have threatened the safety of shellfish consumers in Asia and Europe for decades. Recently, harmful algal blooms (HAB) caused by Dinophysis spp. have emerged as a human health threat in the US. Since first detected on the coast of Texas in 2008, D. ovum has been detected in six of the last eight years and has resulted in the closures of shellfish harvesting to prevent DSP. Since 2011, closures due to DSP from D. acuminata and D. fortii have also been enforced annually at multiple sites throughout Puget Sound, WA, and toxin levels in shellfish exceeding FDA regulatory limits have been reported in New York, Maine, and Massachusetts due to blooms of D. cf. acuminata and most recently D. norvegica (ME). Chesapeake Bay and the larger DELMARVA region (Delaware, Maryland, and Virginia) harbor toxin-producing species of Dinophysis. The region, however, provides contrast as a relatively new area of concern, with evidence of an approaching tipping point. Rationale: Given the rapid increase in frequency of Dinophysis blooms on nearly every US coast, with clear regional variability in timing and species, it is essential that the drivers of Dinophysis success in coastal ecosystems be identified using a coordinated, nationwide effort. Such a cross-regional comparative study will identify not only potential drivers, but create a baseline for understanding how future climate and eutrophication scenarios will influence intensity, frequency, and toxicity of blooms. Objective: The goal of this project is to identify and quantify factors controlling Dinophysis blooms and DSP across the US as a means of developing optimized regional early warning systems and management plans. It is hypothesized that a combination of temperature, stratification, prey, and nutrient input combine to determine the success of Dinophysis in US coastal ecosystems. A carefully coordinated and collaborative study including high-resolution phytoplankton time series, field collections, and multi-factorial laboratory experiments using isolates of Dinophysis species from important shellfish harvesting sites in the US (Gulf of Mexico, Puget Sound, Long Island Sound and Chesapeake Bay), will be undertaken to address the following objectives: 1) Identify the environmental factors that control Dinophysisblooms and toxicity within and across regions; 2) Use isolates to characterize genetic variability and potential toxicity, under a variety of conditions; 3) Develop and optimize an early warning system for Dinophysis blooms and DTXs in US coastal regions; and 4) Partner with state and industry groups to closely match management needs, disseminate results, and aid regional management programs. Outcomes: Implementation of optimized DSP early warning systems will be a critical first step towards ensuring public safety while also minimizing negative economic impacts on local communities. The proposed work will also identify the environmental regulators of DSP toxin production and Dinophysis species success, providing the context with which to better understand, predict, and detect potential threats now and under future climate and nutrient management scenarios. As evidenced by the increasing frequency and duration of DSP-related harvesting closures, and unfortunately human illness events, there is a critical and urgent need to develop improved early warning systems for Dinophysis and DSP in Washington State, New York, Texas, and DELMARVA, serving as a template to guide ecoforecasting efforts in the rest of the U.S.

Principal Investigators and Institutions: Michael Parsons, Florida Gulf Coast University; Alison Robertson, Marine University of South Alabama & Dauphin Island Sea Lab; Donald Anderson, Mindy Richlen, Woods Hole Oceanographic Institution; Tyler Smith, University of the Virgin Islands

Ciguatera fish poisoning (CFP) is the most prevalent phycotoxin-borne illness worldwide. This debilitating human poisoning syndrome is caused by consumption of tropical marine organisms contaminated with ciguatoxins (CTXs) and related precursors produced by benthic dinoflagellates in the genus Gambierdiscus. Ecological understanding and resultant management solutions lag far behind for CFP versus other HAB syndromes, due to insufficient information regarding the identification of the truly toxigenic Gambierdiscus species/strains (e.g., the “super bug”), and elucidation of the ciguatoxin precursors produced by these species. In addition, the introduction and biotransformation of these precursors into the marine food web is poorly understood. These knowledge gaps severely limit the ability of resource managers to monitor for and protect the public against ciguatera fish poisoning. To date, forecasting/predictive capabilities are limited to non-existent, and responses are reactionary and ex post facto when CFP outbreaks occur. This project builds on several important breakthroughs in ciguatera research in the Caribbean including the identification of Gambierdiscus“super bugs” in the region, the development of molecular probes to characterize community structure in field samples, the development of toxin detection methods and reference materials for CTX assessment and quantification, and the development of a numerical toxicity model. The overarching goal identified by investigators in this targeted proposal is to characterize ciguatoxin production and flux into Caribbean reef food webs for prediction and prevention of CFP. Specific objectives are to determine: 1) the spatio-temporal population dynamics of newly characterized ciguatoxin-producing Gambierdiscus “super bug” species; 2) how Gambierdiscus cellular toxicity translates into toxin body burden in reef herbivores; and 3) the environmental conditions and habitats that produce the highest abundances of Gambierdiscus “super bugs”. The outputs of these objectives will be incorporated into the next-generation toxicity risk model to forecast and predict toxigenic Gambierdiscus populations and toxin entry into the food web (Objective 4) to aid in management strategies to minimize human illness. Leveraged in this proposal is an extensive collection of archived algae and fish samples, which will allow exploration of “super bug” population dynamics. The analysis of archived samples will be supplemented by quarterly field sampling to validate findings of cell and toxin thresholds. This approach will provide six full years of data to characterize spatio-temporal community dynamics that would otherwise be impossible or impractical to collect.

Principal Investigators and Institutions: Kimberly Reece, Juliette Smith, Wolfgang Vogelbein, Ryan Carnegie, William Reay, Hamish Small, Virginia Institute of Marine Science

Introduction to the Problem: Alexandrium monilatum is a common HAB species that historically has bloomed along the US southern Atlantic and Gulf coasts, but very dense blooms now occur almost annually in lower Chesapeake Bay, VA. In 2007, we identified A. monilatum as the dominant species of a late summer bloom persisting for several weeks. Although A. monilatum cells have been shown to cause toxicity in a variety of organisms, the pathway and mechanisms of toxicity including the uptake, tissue distribution, metabolism, depuration and the potential for food-web transfer of the toxin goniodomin A (GDA) all remain poorly understood. Rationale: The recent intensification and expansion of A. monilatum activity in the Chesapeake Bay region is cause for concern due to its potentially important ecological and economic impacts. With the shellfish aquaculture industry rapidly expanding and now worth over $48 million to Virginia alone, it is critical that we understand the risk posed to the health of oyster stocks, as well as to humans through consumption of shellfish exposed to A. monilatum. This team of scientists is poised to rapidly assess impacts of this species and its toxins on multiple trophic levels including determination of effects on aquaculture stocks and possible human health risks. We have purified toxin in hand and twelve A. monilatum isolates from Chesapeake Bay are in culture. Preliminary studies have demonstrated toxicity of A. monilatum and its toxin GDA to marine vertebrates and invertebrates. Scientific Objectives: The overarching goals of this project are to characterize 1) the impacts of A. monilatum and it goniodomin (GD) toxins, and 2) the association between bloom dynamics and toxigenicity as they relate to the accumulation and transfer of toxin through trophic levels. The specific objectives are to 1) Investigate the toxicity of A. monilatum and GDA in vertebrate and invertebrate organisms both in the laboratory and field; 2) Determine the toxicokinetics of GDs in a vertebrate and invertebrate model and the relevance to resource management; 3) Determine the food-web transfer of GDs to higher trophic levels; and 4) Disseminate key information to end-users to communicate results, receive feedback and improve research directives. Summary of Work to be Completed: The impacts of A. monilatum, and specifically GDA, on shellfish and finfish will be determined through laboratory dose response bioassays on sheepshead minnows and field assays on juvenile oysters. Reliable methods will be developed for quantifying toxin in crab and vertebrate tissues. Quantification of toxin in environmental waters and animal tissues from laboratory feeding studies and oyster samples collected during blooms will be coupled with molecular and microscopic methods to follow transport of A. monilatum and toxin through animal tissues providing insight into mechanisms of toxicity and metabolism of toxin, as well as elucidating pathways of trophic transfer. Two workshops will be held to communicate results to end-users including regional regulators, aquaculture industry members, NGOs and citizen groups involved in oyster restoration activities, and other scientists involved in HAB research in the Chesapeake Bay region.

Principal Investigators and Institutions: Justin Chaffin, The Ohio State University; Ed Verhamme, John Bratton, LimnoTech; Timothy Davis, Bowling Green State University; Marty Auer, Pengfei Xue, Michigan Technological University; Thomas Bridgeman, University of Toledo; Judy Westrick, Wayne State University

Contamination of drinking water by freshwater cyanobacterial toxins may be the greatest threat to human health associated with harmful algal blooms (HABs). This was demonstrated dramatically by the HAB-induced drinking water ban in Toledo, Ohio in 2014 due to elevated microcystin concentrations, which affected almost 500,000 people who depend on Lake Erie as their water supply. Lake Erie has been plagued by cyanobacterial blooms since the late 1990s and it seems that the major driver of the blooms is the spring phosphorus load from the Maumee River. In recent years, a seasonal bloom forecast has been issued in early July based on the spring phosphorus load from the Maumee River. Although HAB size and location can be reasonably well forecasted, fundamental questions remain about the controls and predictability of toxin production in blooms. One complexity in field studies has been the coexistence of toxic and non-toxic strains of the same species of cyanobacteria. The factors influencing the dynamics of toxic and non-toxic strains within blooms are only beginning to be understood, but they may be at the point where reasonable predictions of changes in toxicity could be possible. While phosphorus has a clear role in HAB dynamics, nitrogen may also be important in the occurrence and biomass of cyanobacteria and the toxicity within the blooms. Other factors, such as light intensity and temperature, may also interact with nitrogen to impact HAB toxin production. The study proposed here will consist of three primary components (1) examination of historical data to look for correlations between changes in environmental variables and changes in HAB toxin concentrations, (2) incorporation of results of Component 1 analyses into numerical models of ecological and physical processes to develop hindcasting, nowcasting, and forecasting capabilities, and (3) field and laboratory experiments to better constrain knowledge gaps identified in Components 1 and 2, including the influence of nitrogen, light, temperature, and other factors on the production and decay of HAB toxin. The products of the research study will be a suite of presentations, publications, and tools to inform stakeholder and scientific audiences of the advances made in understanding HAB toxicity and specific technical guidance to NOAACOOPS and drinking water utilities on incorporating new information and improved forecasting capabilities into their operational systems.