This research will identify and model the biological and physical mechanisms regulating two key processes in the blooms of Alexandrium dinoflagellates responsible for paralytic shellfish poisoning (PSP): bloom initiation and termination. A key feature of the project is that it will be conducted in the Nauset Marsh System (NMS), a shallow estuary that has recurrent A. fundyense blooms in its three terminal kettie ponds, with blooms being unequivocally tied to cyst seedbeds in those embayments. The NMS represents a natural "mesocosm" where these processes can be studied in a manner not possible in open coastal waters. The NMS also represents a major habitat for toxic Alexandrium species in the US and worldwide.
Aim 1 comprises field and lab experiments on bloom initiation. Excystment experiments will determine whether internal or external factors regulate germination seasonality, and other studies will measure the effects of temperature, salinity, and light on germination and growth. The timing and rate of escape of germinated cells will be measured using plankton emergence traps, and high-resolution sampling will be conducted throughout bloom initiation.
Aim 2 activities are focused on bloom termination. A unique submersible flow cytometer with imaging capabilities (the imaging flow cytobot, IFCB) will detect life cycle transitions in situ. Routine and adaptive field sampling (triggered by IFCB data) will document factors associated with life cycle transitions, and sediment traps will assess the timing and rate of cyst deposition. Complimentary efforts will utilize a bentop multi-daser IFCB to confirm the presence of sexual forms in field samples, an assessment of the linkage between A. fundyense encystment and parasite infection, and the development of biomarker assays for detection of gametes and planozygotes that will be applied in sampling for these stages in situ.
In Aim 3, an innovative Lagrangian approach will model Alexandrium population dynamics within the NMS, including life cycle transitions. The model will be formulated and calibrated against blooms in the NMS, but is broadly transferable to HAB models in estuarine or coastal settings, including Project 2 in this program.
PSP is the most widespread HAB poisoning syndrome. This project thus has significant relevance to resource managers, public health professionals, consumers of seafood, and local economies dependent on the shellfish industry. This project addresses the COHH goal of supporting research that can reduce public health risks, and it addresses the priority area of enhancing prediction of HAB events.
|Fernandes, Luciano F; Hubbard, Katherine A; Richlen, Mindy L et al. (2014) Diversity and toxicity of the diatom Pseudo-nitzschia Peragallo in the Gulf of Maine, Northwestern Atlantic Ocean. Deep Sea Res Part 2 Top Stud Oceanogr 103:139-162|
|Butman, Bradford; Aretxabaleta, Alfredo L; Dickhudt, Patrick J et al. (2014) Investigating the importance of sediment resuspension in Alexandrium fundyense cyst population dynamics in the Gulf of Maine. Deep Sea Res Part 2 Top Stud Oceanogr 103:79-95|
|Pilskaln, C H; Hayashi, K; Keafer, B A et al. (2014) Benthic nepheloid layers in the Gulf of Maine and Alexandrium cyst inventories. Deep Sea Res Part 2 Top Stud Oceanogr 103:55-65|
|Brosnahan, Michael L; Farzan, Shahla; Keafer, Bruce A et al. (2014) Complexities of bloom dynamics in the toxic dinoflagellate Alexandrium fundyense revealed through DNA measurements by imaging flow cytometry coupled with species-specific rRNA probes. Deep Sea Res Part 2 Top Stud Oceanogr 103:185-198|
|Koch, F; Kang, Y; Villareal, T A et al. (2014) A novel immunofluorescence flow cytometry technique detects the expansion of brown tides caused by Aureoumbra lagunensis to the Caribbean Sea. Appl Environ Microbiol 80:4947-57|
|Anderson, Donald M; Keafer, Bruce A; Kleindinst, Judith L et al. (2014) Alexandrium fundyense cysts in the Gulf of Maine: long-term time series of abundance and distribution, and linkages to past and future blooms. Deep Sea Res Part 2 Top Stud Oceanogr 103:6-26|
|Anderson, Donald M; Couture, Darcie A; Kleindinst, Judith L et al. (2014) Understanding interannual, decadal level variability in paralytic shellfish poisoning toxicity in the Gulf of Maine: the HAB Index. Deep Sea Res Part 2 Top Stud Oceanogr 103:264-276|
|Kleindinst, Judith L; Anderson, Donald M; McGillicuddy Jr, Dennis J et al. (2014) Categorizing the severity of paralytic shellfish poisoning outbreaks in the Gulf of Maine for forecasting and management. Deep Sea Res Part 2 Top Stud Oceanogr 103:277-287|
|Deeds, Jonathan R; Petitpas, Christian M; Shue, Vangie et al. (2014) PSP toxin levels and plankton community composition and abundance in size-fractionated vertical profiles during spring/summer blooms of the toxic dinoflagellate Alexandrium fundyense in the Gulf of Maine and on Georges Bank, 2007, 2008, and 2010: 1. Toxin Deep Sea Res Part 2 Top Stud Oceanogr 103:329-349|
|McGillicuddy Jr, D J; Brosnahan, M L; Couture, D A et al. (2014) A red tide of Alexandrium fundyense in the Gulf of Maine. Deep Sea Res Part 2 Top Stud Oceanogr 103:174-184|
Showing the most recent 10 out of 15 publications