Deana Erdner - US grants

Harmful algal blooms (HABs) are a serious and growing problem in the US and the world. Among the multiple poisoning syndromes linked to HABs, Paralytic Shellfish Poisoning (PSP) is arguably the most widespread and significant on a global basis. Dinoflagellates within the genus Alexandrium (and in particular within the tamarensis and minutum species complexes) are responsible for many of these PSP outbreaks in the US and in Europe. Several characteristics of the temporal and spatial pattern of Alexandrium species are noteworthy. First, over the last several decades, the distribution of species within both complexes has expanded geographically as a result of natural and human-assisted dispersal mechanisms. Second, there are both toxic and non-toxic varieties of certain species within each of these complexes, and sometimes these bloom in relatively close proximity to each other. This latter observation is particularly noteworthy given recent results, which demonstrate that toxic, and non-toxic strains of A. tamarense can mate and produce resting cysts, but the cells that germinate from these cysts quickly die as they attempt to divide. A reproductive barrier thus exists for at least some strains of this species. The overall objective of this project is to investigate mating compatibilities among toxic and non-toxic members of the tamarensis and minutum species complexes of Alexandrium. This will involve a combination of laboratory and field studies in a direct collaboration between US and EU partners under the EC-NSF Cooperative Activity in Environmental Research. Specific objectives are to: 1) Establish and characterize additional toxic and non-toxic Alexandrium cultures from the northeastern U.S. and Europe; 2) Determine mating compatibility between toxic and non-toxic strains of A. tamarense and A. minutum; 3) Identify a genetic marker to distinguish between toxic and non-toxic minutum; 4) Develop methods to determine the toxic/non-toxic genotype of planktonic cells and cysts; 5) Determine mating selectivity of toxic and non-toxic A. minutum and A. tamarense strains; 6) Participate in European field surveys to map Alexandrium populations in the plankton and sediments; and 7) Employ growth rate, grazing rate and mating preference data to model the outcome of a variety of invasion scenarios and to evaluate the potential of introduced non-toxic Alexandrium species as a bloom control or mitigation strategy.

The scientific merits of the proposed study are significant, as the mating incompatibilities to be explored may explain observed distributions of toxic and non-toxic Alexandrium species throughout the world and relate directly to the potential success of an invasion of one toxin-type into the domain of the other, such as through natural currents and storms, or ballast water discharge. The broader impacts are also significant. HABs represent a serious threat to public health and efficient utilization of coastal resources. In addition to practical implications with respect to species dispersal via ballast water discharge or other human-assisted means, a novel bloom control or mitigation strategy of potential value to society will be investigated whereby a non-toxic strain of Alexandrium could be introduced to an area subject to toxic outbreaks in a manner analogous to the release of sterile males to control insect pests. Other broad impacts include strengthening the EU-US HAB network of scientists, communicating results via conference presentations, scientific publications, and articles in the popular press, and training and education of young scientists. In the latter context, students and postdoctoral investigators from both the US and the EU will work in the PI's laboratory on this project, supported by outside fellowships, EU funds, internal WHOI funds (Summer Student Fellowships, Minority Traineeships), and REU (Research Opportunities for Undergraduates) support, for which proposals will be submitted. The PI has always placed a high priority on the integration of research and education, and this project will be no exception.

The overall goal of this project is to identify the key cellular processes involved in harmful algal blooms (HABs), commonly known as red tides. HABs pose a major threat to human health, ecosystem health, and fisheries resources throughout the world. One of the most important model systems for studying this process is the toxic dinoflagellate Alexandrium tamarense, a unicellular alga that produces neurotoxins that cause paralytic shellfish poisoning, and is the most widespread of all HAB poisoning syndromes. With the recent development of genomic resources for A. tamarense, it is now possible to conduct studies on the environmental regulation of gene expression in this important species, and to begin to unravel the mysteries of bloom dynamics and cellular metabolism at a level that has never before been possible. This project will identify transcriptionally regulated genes and pathways during the three general stages of a bloom: initiation, development, and termination. Specifically, the investigators will create a microarray for A. tamarense to: 1. identify the key genes involved in the initiation of A. tamarense blooms, specifically those regulated during the germination of resting cyst life stages; 2. identify the key genes involved in the development and maintenance of A. tamarense blooms, specifically those involved in the assimilation of organic and inorganic nutrients, the process of photosynthesis, the production of toxins, and cell division cycle; 3. identify the key genes involved in the termination of A. tamarense blooms, specifically those regulated in response to nutrient limitation, and during the transition from vegetative growth to the sexual cycle that results in resting stage formation;and 4. investigate the physiological state of dinoflagellate cells in situ, by comparing expression profiles of a natural bloom population with the data generated from laboratory cultures. This study is an integrated, collaborative program that relies on expertise in A. tamarense molecular evolution, genomics, physiology, ecology, and toxicity. The investigators hope to produce a valuable molecular resource for scientists working to understand the ecology and toxicity of A. tamarense and other HAB species as well as help train the next generation of scientists working on this important problem. Additionally, the results of these studies will provide insights into the unique genome of these fascinating, evolutionarily and economically important, yet understudied organisms.

Abstract: 0754750
This award provides funding for a new Research Experience for Undergraduates (REU) program at University of Texas at Austin. The program will support ten students each summer during a ten week summer research program. The program will emphasize coastal dynamics, including natural variability and human-driven change. Projects will take advantage of the wide temporal and spatial variations in environmental characteristics along the south Texas coast. REU students will be widely recruited from across the U.S, with a focus on recruiting students from the Hispanic majority population in Texas and from historically minority-serving institutions. During a 10-week summer program, students will: 1) participate in a two-day research cruise along the south Texas coast; 2) develop independent research projects; 3) attend weekly research seminars and professional development discussions; 4) curate individual web pages; and 5) present their research results at a symposium hosted at the Institute. This proposal is supported by the entire faculty of the Marine Science Institute, which has a long history of undergraduate training, through its educational programs and involvement in NSF-sponsored undergraduate research initiatives.

This award provides renewed funding for a Research Experience for Undergraduates (REU) program at the University of Texas Marine Science Institute (UTMSI), which is located in Port Aransas, TX and is part of the University of Texas at Austin. Each year, eight students will be supported during a ten week summer research program. The program will recruit nationally and from many Texas universities and colleges. The main focus of the program will be independent research projects by the students, but the program includes a two day research cruise at the start of the program, a series of seminars in marine sciences, web-based communication and career workshops. At the end of the summer, REU students present their results during a student research symposium. Students also will be encouraged to present their results at national research conferences. Support provided by NSF includes funding for student stipends, student travel to and from the site, student housing and meals and some administrative costs.

The US and other countries throughout the world are affected by harmful algal blooms (HABs) that negatively impact human health, marine ecosystems, fisheries resources, and local economies. Anthropogenic nutrient loadings have been linked to expanding HAB incidence, but the relationship is site- and organism-specific, and is still poorly understood. The main challenge in this regard is to determine the relative importance of natural versus anthropogenic nutrient sources in the development of an individual HAB species. Given the diverse nature of the planktonic assemblage in which HABs occur, and the lack of appropriate measurement techniques, this is exceedingly difficult to accomplish.

In this project, research teams at the Woods Hole Oceanographic Institution and University of Texas at Austin will take a novel approach to this challenge: They use use the nitrogen isotopic signature (del15N) of a species-specific HAB toxin to identify the nitrogen source and chemical form that promotes cell growth and toxin production. The bloom-forming dinoflagellate Alexandrium fundyense and its class of bioactive compounds, saxitoxins (STXs), are an ideal model system as STXs are nitrogen-rich and are typically only produced by a single species in mixed plankton assemblages. The guiding overall hypothesis is that the isotopic signature of a HAB-specific toxin can be used to discriminate between anthropogenic and natural sources of N and provide more details than bulk material del15N on the source, chemical form, and processing of N that lead to blooms of a particular toxic species. This hypothesis is based on the principle that human and animal waste in groundwater and sewage become 15N-enriched and inorganic fertilizers 15N-depleted, relative to natural sources of N in catchment waters. While the use of the isotopic ratio del15N of bulk biomass to identify nitrogen sources to coastal waters is a widely accepted practice, this use of a toxin as a species-specific tracer or marker is new and will provide details on the explicit source, chemical form, and processing of nitrogen that results in blooms of a particular HAB species.

Broader Impacts: This project addresses fundamental issues underlying the most widespread of all HAB poisoning syndromes, paralytic shellfish poisoning (PSP), a major form of shellfish poisoning that affects countries throughout the world. Project results can also assist in policy decisions about pollution control and other bloom mitigation strategies, and can be applied to a range of HAB species - those that produce saxitoxins, as well as those that produce other toxins that are nitrogen rich. Project results will be broadly disseminated through scientific papers, presentations at workshops, domestic and international conferences, and departmental seminars, and discussions with the media.

The University of Texas Marine Science Institute (UTMSI) http://www.utmsi.utexas.edu, established in 1941, has a long history of excellence with respect to innovation and application of stable isotope techniques in biogeochemical and ecological studies. This project will improve research infrastructure for stable isotope analyses at the UTMSI through acquisition of instrumentation as well as renovations to existing space that will house the instrumentation. A new isotope ratio mass spectrometer (IRMS) and peripheral components will be purchased to improve natural abundance stable isotope analysis capabilities. In addition, a unique Ammonium Isotope Retention Time Shift (AIRTS) high performance liquid chromatography system that is used for measurements of 15N-enriched ammonium in nitrogen process studies at the Institute will be upgraded. Improvement of stable isotope analysis capabilities at the UTMSI will advance scientific discovery by supporting more investigators, using a wider range of stable isotope techniques in their work. The new instrumentation will enable development and application of a variety of stable isotope techniques that are pushing the frontiers of biogeochemical and ecological studies, while enhancing our ability to support internal and external users that rely on existing analysis capabilities at the Institute.

With respect to education, the improvements will 1) promote greater training of graduate students and postdoctoral scientists in stable isotope analysis and application techniques, and 2) support additional opportunities for undergraduates to employ stable isotopes in research projects. A new undergraduate education program (Semester by the Sea) initiated in spring 2013 is bringing more undergraduates to the Institute. This program includes a major research component, and students in the program are encouraged to consider stable isotope applications as they develop research projects. The project also includes a commitment to public outreach. Project personnel will work with ongoing programs at the Institute to share their knowledge and interest in stable isotope applications with a broader audience. This will include development of a new food-web oriented module for the Summer Science Camp at UTMSI that highlights how stable isotopes help scientists understand dietary relationships.

The Research Experience for Undergraduates (REU) program at the University of Texas Marine Science Institute (UTMSI) is located at the UT campus in Port Aransas, Texas. The common theme of student research projects is the interplay between natural variability and anthropogenic drivers of change in coastal ecosystems. Specific REU projects to date have focused on pressing research questions that have global implications, including impacts of land use and freshwater demand on coastal nutrient dynamics, effects of oil spills and hydrocarbons on organismal functioning, harmful algal blooms, hypoxia, spatiotemporal community interactions, and population dynamics of mobile macrofauna. South Texas experiences extremes of environmental conditions, making it an excellent natural laboratory for studying coastal dynamics in a changing environment. UTMSI faculty research spans the biological, chemical and physical processes that occur in coastal habitats, and the laboratories and research fleet are well equipped for such studies. The program is designed to raise student awareness of the conduct of science and the importance of coastal change issues, thereby preparing students to make informed decisions about their subsequent career paths. Specific activities provide exposure to the breadth of marine science, increase knowledge of ethical conduct of research, and develop crucial scientific communication skills for targeting both specialist and generalist audiences. This program will support research experiences and career training for a total of forty undergraduates over five years. Co-funding for this program will be provided by the Directorate of Biological Sciences.

PI: Alison Robertson (University of Southern Alabama)
co-PIs: Donald Anderson (Woods Hole Oceanographic Institution)
Deana Erdner (University of Texas - Austin)
Michael Parsons (Florida Gulf Coast University)
Tyler Smith (University of the Virgin Islands)

Nontechnical Abstract:
Coral reef ecosystems are among the most biodiverse habitats on earth, providing societal benefits and fishery resources critical to coastal communities. A significant threat to utilizing these resources is ciguatera fish poisoning (CFP), the most prevalent non-bacterial seafood illness. CFP is caused by the consumption of reef fish that have accumulated ciguatoxins (CTXs). These potent neurotoxins are produced by microscopic algae (dinoflagellates) that live on the surfaces of aquatic plants (e.g., macroalgae, seagrasses) and enter reef food webs through the diet of herbivorous fish and invertebrates. As these toxins move through the marine food web they are structurally modified via metabolism and increase in potency. Human exposure to CTX results in rapid onset of illness and duration of 6-8 weeks. Symptoms include gastrointestinal distress, neurological dysfunction, and cardiovascular abnormalities. There are currently no effective treatments or diagnostic tests available for CFP, and no field tests feasible for pre-market surveillance of fish destined for human consumption. Despite its severity and prevalence, CFP remains an underappreciated and under-reported problem. Most CFP affects low socioeconomic groups in remote island communities who rely on local seafood for subsistence. However, fish poisonings from recreational fishing and the international seafood trade are increasing in continental areas increasing exposure in temperate regions. A major goal of this PIRE project will be to better understand the environmental conditions affecting the production of CTXs by the source organisms and to determine the fate of the toxins through the food web across geographical regions. International partners are from Hong Kong, Cuba, Norway, Canada, Scotland (UK) and Australia.

Technical Abstract:
While the mechanisms and environmental drivers of toxigenic phenotypes of Gambierdiscus spp. remain unknown, many other toxigenic algae live in the same community and are capable of producing toxic metabolites that can enter the food web. The identity and toxicity of these toxins are largely unknown, but their elucidation is critical to the development of monitoring approaches for public health protection of CFP. Management strategies for CFP lag far behind other seafood safety issues due to four major deficiencies: 1) the inability to easily identify and monitor for the toxigenic Gambierdiscus species and strains responsible for CFP; 2) a lack of knowledge on the toxicity and structure secondary metabolites produced by these benthic micro-algae; 3) a limited understanding of the food web dynamics and biotransformations of these metabolites; and, 4) the inability to predict when and where CFP outbreaks are most likely to occur. Based on these interlinked needs, we have developed a central hypothesis for our PIRE program: toxigenic benthic dinoflagellates produce a stable suite of secondary metabolites (meta-metabolome) allowing them to prosper in an otherwise unstable environment driven by shifts in the epiphytic flora, available substrates, and environmental conditions. Moreover, the stability and advantages gained in this meta-metabolome are universal across toxigenic genera and applicable to many (sub)tropical reef environments. This hypothesis will be tested by examining the dynamics and persistence of toxigenic Gambierdiscus in reefs around the globe to better understand the production and fate of their toxic metabolites. Hypothesis testing will comprise three research objectives: 1) Evaluate epiphyte and Gambierdiscus community diversity and macrophyte host selectivity across spatio-temporal scales and environmental gradients in coral reef ecosystems; 2) Characterize the meta-metabolome of these communities, structurally elucidate key metabolites, and develop methods to evaluate their toxicity and functional role; 3) Utilize chemical biomarkers (toxins, lipids, stable isotopes) in bio-indicator species (primary producers and consumers) and model their fate in reef food webs. To achieve these research goals we will engage in a research program with US and International partners that integrates expertise, addresses the global nature of CFP by working across hyper-endemic regions, and develops unique and lasting educational experiences for undergraduate and graduate students from the US and abroad.