Hubbard
Katherine A.
Hubbard
Katherine A.
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ArticlePseudo-nitzschia bloom dynamics in the Gulf of Maine: 2012-2016(Elsevier, 2019-08-19) Clark, Suzanna ; Hubbard, Katherine A. ; Anderson, Donald M. ; McGillicuddy, Dennis J. ; Ralston, David K. ; Townsend, David W.The toxic diatom genus Pseudo-nitzschia is a growing presence in the Gulf of Maine (GOM), where regionally unprecedented levels of domoic acid (DA) in 2016 led to the first Amnesic Shellfish Poisoning closures in the region. However, factors driving GOM Pseudo-nitzschia dynamics, DA concentrations, and the 2016 event are unclear. Water samples were collected at the surface and at depth in offshore transects in summer 2012, 2014, and 2015, and fall 2016, and a weekly time series of surface water samples was collected in 2013. Temperature and salinity data were obtained from NERACOOS buoys and measurements during sample collection. Samples were processed for particulate DA (pDA), dissolved nutrients (nitrate, ammonium, silicic acid, and phosphate), and cellular abundance. Species composition was estimated via Automated Ribosomal Intergenic Spacer Analysis (ARISA), a semi-quantitative DNA finger-printing tool. Pseudo-nitzschia biogeography was consistent in the years 2012, 2014, and 2015, with greater Pseudo-nitzschia cell abundance and P. plurisecta dominance in low-salinity inshore samples, and lower Pseudo-nitzschia cell abundance and P. delicatissima and P. seriata dominance in high-salinity offshore samples. During the 2016 event, pDA concentrations were an order of magnitude higher than in previous years, and inshore-offshore contrasts in biogeography were weak, with P. australis present in every sample. Patterns in temporal and spatial variability confirm that pDA increases with the abundance and the cellular DA of Pseudo-nitzschia species, but was not correlated with any one environmental factor. The greater pDA in 2016 was caused by P. australis – the observation of which is unprecedented in the region – and may have been exacerbated by low residual silicic acid. The novel presence of P. australis may be due to local growth conditions, the introduction of a population with an anomalous water mass, or both factors. A definitive cause of the 2016 bloom remains unknown, and continued DA monitoring in the GOM is warranted.
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ArticleMarine harmful algal blooms (HABs) in the united states: history, current status and future trends(Elsevier, 2021-03-03) Anderson, Donald M. ; Fensin, Elizabeth ; Gobler, Christopher J. ; Hoeglund, Alicia E. ; Hubbard, Katherine A. ; Kulis, David M. ; Landsberg, Jan H. ; Lefebvre, Kathi A. ; Provoost, Pieter ; Richlen, Mindy L. ; Smith, Juliette L. ; Solow, Andrew R. ; Trainer, Vera L.Harmful algal blooms (HABs) are diverse phenomena involving multiple. species and classes of algae that occupy a broad range of habitats from lakes to oceans and produce a multiplicity of toxins or bioactive compounds that impact many different resources. Here, a review of the status of this complex array of marine HAB problems in the U.S. is presented, providing historical information and trends as well as future perspectives. The study relies on thirty years (1990–2019) of data in HAEDAT - the IOC-ICES-PICES Harmful Algal Event database, but also includes many other reports. At a qualitative level, the U.S. national HAB problem is far more extensive than was the case decades ago, with more toxic species and toxins to monitor, as well as a larger range of impacted resources and areas affected. Quantitatively, no significant trend is seen for paralytic shellfish toxin (PST) events over the study interval, though there is clear evidence of the expansion of the problem into new regions and the emergence of a species that produces PSTs in Florida – Pyrodinium bahamense. Amnesic shellfish toxin (AST) events have significantly increased in the U.S., with an overall pattern of frequent outbreaks on the West Coast, emerging, recurring outbreaks on the East Coast, and sporadic incidents in the Gulf of Mexico. Despite the long historical record of neurotoxic shellfish toxin (NST) events, no significant trend is observed over the past 30 years. The recent emergence of diarrhetic shellfish toxins (DSTs) in the U.S. began along the Gulf Coast in 2008 and expanded to the West and East Coasts, though no significant trend through time is seen since then. Ciguatoxin (CTX) events caused by Gambierdiscus dinoflagellates have long impacted tropical and subtropical locations in the U.S., but due to a lack of monitoring programs as well as under-reporting of illnesses, data on these events are not available for time series analysis. Geographic expansion of Gambierdiscus into temperate and non-endemic areas (e.g., northern Gulf of Mexico) is apparent, and fostered by ocean warming. HAB-related marine wildlife morbidity and mortality events appear to be increasing, with statistically significant increasing trends observed in marine mammal poisonings caused by ASTs along the coast of California and NSTs in Florida. Since their first occurrence in 1985 in New York, brown tides resulting from high-density blooms of Aureococcus have spread south to Delaware, Maryland, and Virginia, while those caused by Aureoumbra have spread from the Gulf Coast to the east coast of Florida. Blooms of Margalefidinium polykrikoides occurred in four locations in the U.S. from 1921–2001 but have appeared in more than 15 U.S. estuaries since then, with ocean warming implicated as a causative factor. Numerous blooms of toxic cyanobacteria have been documented in all 50 U.S. states and the transport of cyanotoxins from freshwater systems into marine coastal waters is a recently identified and potentially significant threat to public and ecosystem health. Taken together, there is a significant increasing trend in all HAB events in HAEDAT over the 30-year study interval. Part of this observed HAB expansion simply reflects a better realization of the true or historic scale of the problem, long obscured by inadequate monitoring. Other contributing factors include the dispersion of species to new areas, the discovery of new HAB poisoning syndromes or impacts, and the stimulatory effects of human activities like nutrient pollution, aquaculture expansion, and ocean warming, among others. One result of this multifaceted expansion is that many regions of the U.S. now face a daunting diversity of species and toxins, representing a significant and growing challenge to resource managers and public health officials in terms of toxins, regions, and time intervals to monitor, and necessitating new approaches to monitoring and management. Mobilization of funding and resources for research, monitoring and management of HABs requires accurate information on the scale and nature of the national problem. HAEDAT and other databases can be of great value in this regard but efforts are needed to expand and sustain the collection of data regionally and nationally.
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ArticleEmerging harmful algal blooms caused by distinct seasonal assemblages of a toxic diatom(Association for the Sciences of Limnology and Oceanography, 2022-10-07) Sterling, Alexa R. ; Kirk, Riley D. ; Bertin, Matthew J. ; Rynearson, Tatiana A. ; Borkman, David G. ; Caponi, Marissa C. ; Carney, Jessica ; Hubbard, Katherine A. ; King, Meagan A. ; Maranda, Lucie ; McDermith, Emily J. ; Santos, Nina R. ; Strock, Jacob P. ; Tully, Erin M. ; Vaverka, Samantha B. ; Wilson, Patrick D. ; Jenkins, Bethany D.Diatoms in the Pseudo‐nitzschia genus produce the neurotoxin domoic acid. Domoic acid bioaccumulates in shellfish, causing illness in humans and marine animals upon ingestion. In 2017, high domoic acid levels in shellfish meat closed shellfish harvest in Narragansett Bay, Rhode Island for the first and only time in history, although abundant Pseudo‐nitzschia have been observed for over 60 years. To investigate whether an environmental factor altered endemic Pseudo‐nitzschia physiology or new domoic acid‐producing strain(s) were introduced to Narragansett Bay, we conducted weekly sampling from 2017 to 2019 and compared closure samples. Plankton‐associated domoic acid was quantified by LC‐MS/MS and Pseudo‐nitzschia spp. were identified using a taxonomically improved high‐throughput rDNA sequencing approach. Comparison with environmental data revealed a detailed understanding of domoic acid dynamics and seasonal multi‐species assemblages. Plankton‐associated domoic acid was low throughout 2017–2019, but recurred in fall and early summer maxima. Fall domoic acid maxima contained known toxic species as well as a novel Pseudo‐nitzschia genotype. Summer domoic acid maxima included fewer species but also known toxin producers. Most 2017 closure samples contained the particularly concerning toxic species, P. australis, which also appeared infrequently during 2017–2019. Recurring Pseudo‐nitzschia assemblages were driven by seasonal temperature changes, and plankton‐associated domoic acid correlated with low dissolved inorganic nitrogen. Thus, the Narragansett Bay closures were likely caused by both resident assemblages that become toxic depending on nutrient status as well as the episodic introductions of toxic species from oceanographic and climatic shifts.
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PreprintDiversity and toxicity of Pseudo-nitzschia species in Monterey Bay : perspectives from targeted and adaptive sampling( 2018-08) Bowers, Holly A. ; Ryan, John P. ; Hayashi, Kendra ; Woods, April ; Marin, Roman ; Smith, G. Jason ; Hubbard, Katherine A. ; Doucette, Gregory J. ; Mikulski, Christina M. ; Gellene, Alyssa G. ; Zhang, Yanwu ; Kudela, Raphael M. ; Caron, David A. ; Birch, James M. ; Scholin, Christopher A.Monterey Bay, California experiences near-annual blooms of Pseudo-nitzschia that can affect marine animal health and the economy, including impacts to tourism and commercial/recreational fisheries. One species in particular, P. australis, has been implicated in the most toxic of events, however other species within the genus can contribute to widespread variability in community structure and associated toxicity across years. Current monitoring methods are limited in their spatial coverage as well as their ability to capture the full suite of species present, thereby hindering understanding of HAB events and limiting predictive accuracy. An integrated deployment of multiple in situ platforms, some with autonomous adaptive sampling capabilities, occurred during two divergent bloom years in the bay, and uncovered detailed aspects of population and toxicity dynamics. A bloom in 2013 was characterized by spatial differences in Pseudo39 nitzschia populations, with the low-toxin producer P. fraudulenta dominating the inshore community and toxic P. australis dominating the offshore community. An exceptionally toxic bloom in 2015 developed as a diverse Pseudo-nitzschia community abruptly transitioned into a bloom of highly toxic P. australis within the time frame of a week. Increases in cell density and proliferation coincided with strong upwelling of nutrients. High toxicity was driven by silicate limitation of the dense bloom. This temporal shift in species composition mirrored the shift observed further north in the California Current System off Oregon and Washington. The broad scope of sampling and unique platform capabilities employed during these studies revealed important patterns in bloom formation and persistence for Pseudo-nitzschia. Results underscore the benefit of expanded biological observing capabilities and targeted sampling methods to capture more comprehensive spatial and temporal scales for studying and predicting future events.
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ArticleProjected effects of climate change on Pseudo-nitzschia bloom dynamics in the Gulf of Maine(Elsevier, 2022-03-24) Clark, Suzanna ; Hubbard, Katherine A. ; Ralston, David K. ; McGillicuddy, Dennis J. ; Stock, Charles A. ; Alexander, Michael A. ; Curchitser, Enrique N.Worldwide, warming ocean temperatures have contributed to extreme harmful algal bloom events and shifts in phytoplankton species composition. In 2016 in the Gulf of Maine (GOM), an unprecedented Pseudo-nitzschia bloom led to the first domoic-acid induced shellfishery closures in the region. Potential links between climate change, warming temperatures, and the GOM Pseudo-nitzschia assemblage, however, remain unexplored. In this study, a global climate change projection previously downscaled to 7-km resolution for the Northwest Atlantic was further refined with a 1–3-km resolution simulation of the GOM to investigate the effects of climate change on HAB dynamics. A 25-year time slice of projected conditions at the end of the 21st century (2073–2097) was compared to a 25-year hindcast of contemporary ocean conditions (1994–2018) and analyzed for changes to GOM inflows, transport, and Pseudo-nitzschia australis growth potential. On average, climate change is predicted to lead to increased temperatures, decreased salinity, and increased stratification in the GOM, with the largest changes occurring in the late summer. Inflows from the Scotian Shelf are projected to increase, and alongshore transport in the Eastern Maine Coastal Current is projected to intensify. Increasing ocean temperatures will likely make P. australis growth conditions less favorable in the southern and western GOM but improve P. australis growth conditions in the eastern GOM, including a later growing season in the fall, and a longer growing season in the spring. Combined, these changes suggest that P. australis blooms in the eastern GOM could intensify in the 21st century, and that the overall Pseudo-nitzschia species assemblage might shift to warmer-adapted species such as P. plurisecta or other Pseudo-nitzschia species that may be introduced.
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ArticleHarmful algal blooms in the Alaskan Arctic: an emerging threat as the ocean warms(Oceanography Society, 2022-04-18) Anderson, Donald M. ; Fachon, Evangeline ; Hubbard, Katherine A. ; Lefebvre, Kathi A. ; Lin, Peigen ; Pickart, Robert S. ; Richlen, Mindy L. ; Sheffield, Gay ; Van Hemert, CarolineHarmful algal blooms (HABs) present an emerging threat to human and ecosystem health in the Alaskan Arctic. Two HAB toxins are of concern in the region: saxitoxins (STXs), a family of compounds produced by the dinoflagellate Alexandrium catenella, and domoic acid (DA), produced by multiple species in the diatom genus Pseudo-nitzschia. These potent neurotoxins cause paralytic and amnesic shellfish poisoning, respectively, in humans, and can accumulate in marine organisms through food web transfer, causing illness and mortality among a suite of wildlife species. With pronounced warming in the Arctic, along with enhanced transport of cells from southern waters, there is significant potential for more frequent and larger HABs of both types. STXs and DA have been detected in the tissues of a range of marine organisms in the region, many of which are important food resources for local residents. The unique nature of the Alaskan Arctic, including difficult logistical access, lack of response infrastructure, and reliance of coastal populations on the noncommercial acquisition of marine resources for nutritional, cultural, and economic well-being, poses urgent and significant challenges as this region warms and the potential for impacts from HABs expands.
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ArticleInvestigating Pseudo-nitzschia australis introduction to the Gulf of Maine with observations and models(Elsevier, 2021-07-08) Clark, Suzanna ; Hubbard, Katherine A. ; McGillicuddy, Dennis J. ; Ralston, David K. ; Shankar, SugandhaIn 2016, an unprecedented Pseudo-nitzschia australis bloom in the Gulf of Maine led to the first shellfishery closures due to domoic acid in the region's history. In this paper, potential introduction routes of P. australis are explored through observations, a hydrodynamic model, and a Lagrangian particle tracking model. Based on particle tracking experiments, the most likely source of P. australis to the Gulf of Maine was the Scotian Shelf. However, in 2016, connectivity between the Scotian Shelf and the bloom region was not significantly different from the other years between 2012 and 2019, nor were temperature conditions more favorable for P. australis growth. Observations indicated changes on the Scotian Shelf in 2016 preceded the introduction of P. australis: increased bottom salinity and decreased surface salinity. The increased bottom salinity on the shelf may be linked to anomalously saline water observed near the coast of Maine in 2016 via transport through Northeast Channel. The changes in upstream water mass properties may be related to the introduction of P. australis, and could be the result of either increased influence of the Labrador Current or increased outflow from the Gulf of St. Lawrence. The ultimate source of P. australis remains unknown, although the species has previously been observed in the eastern North Atlantic, and connectivity across the ocean is possible via a subpolar route. Continued and increased monitoring is warranted to track interannual Pseudo-nitzschia persistence in the Gulf of Maine, and sampling on the Scotian Shelf should be conducted to map upstream P. australis populations.
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ArticleCenters for Oceans and Human Health : a unified approach to the challenge of harmful algal blooms(BioMed Central, 2008-11-07) Erdner, Deana L. ; Dyble, Julianne ; Parsons, Michael L. ; Stevens, Richard C. ; Hubbard, Katherine A. ; Wrabel, Michele L. ; Moore, Stephanie K. ; Lefebvre, Kathi A. ; Anderson, Donald M. ; Bienfang, Paul ; Bidigare, Robert R. ; Parker, Micaela S. ; Moeller, Peter D. R. ; Brand, Larry E. ; Trainer, Vera L.Harmful algal blooms (HABs) are one focus of the national research initiatives on Oceans and Human Health (OHH) at NIEHS, NOAA and NSF. All of the OHH Centers, from the east coast to Hawaii, include one or more research projects devoted to studying HAB problems and their relationship to human health. The research shares common goals for understanding, monitoring and predicting HAB events to protect and improve human health: understanding the basic biology of the organisms; identifying how chemistry, hydrography and genetic diversity influence blooms; developing analytical methods and sensors for cells and toxins; understanding health effects of toxin exposure; and developing conceptual, empirical and numerical models of bloom dynamics. In the past several years, there has been significant progress toward all of the common goals. Several studies have elucidated the effects of environmental conditions and genetic heterogeneity on bloom dynamics. New methods have been developed or implemented for the detection of HAB cells and toxins, including genetic assays for Pseudo-nitzschia and Microcystis, and a biosensor for domoic acid. There have been advances in predictive models of blooms, most notably for the toxic dinoflagellates Alexandrium and Karenia. Other work is focused on the future, studying the ways in which climate change may affect HAB incidence, and assessing the threat from emerging HABs and toxins, such as the cyanobacterial neurotoxin β-N-methylamino-L-alanine. Along the way, many challenges have been encountered that are common to the OHH Centers and also echo those of the wider HAB community. Long-term field data and basic biological information are needed to develop accurate models. Sensor development is hindered by the lack of simple and rapid assays for algal cells and especially toxins. It is also critical to adequately understand the human health effects of HAB toxins. Currently, we understand best the effects of acute toxicity, but almost nothing is known about the effects of chronic, subacute toxin exposure. The OHH initiatives have brought scientists together to work collectively on HAB issues, within and across regions. The successes that have been achieved highlight the value of collaboration and cooperation across disciplines, if we are to continue to advance our understanding of HABs and their relationship to human health.
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ArticleSpatiotemporal transitions in Pseudo-nitzschia species assemblages and domoic acid along the Alaska coast(Public Library of Science, 2023-03-22) Hubbard, Katherine A. ; Villac, Maria Célia ; Chadwick, Christina ; DeSmidt, Alexandra A. ; Flewelling, Leanne ; Granholm, April ; Joseph, Molly ; Wood, Taylor ; Fachon, Evangeline ; Brosnahan, Michael L. ; Richlen, Mindy ; Pathare, Mrunmayee ; Stockwell, Dean ; Lin, Peigen ; Bouchard, Josée N. ; Pickart, Robert ; Anderson, Donald M.The toxic diatom genus Pseudo-nitzschia is distributed from equatorial to polar regions and is comprised of >57 species, some capable of producing the neurotoxin domoic acid (DA). In the Pacific Arctic Region spanning the Bering, Chukchi, and Beaufort seas, DA is recognized as an emerging human and ecosystem health threat, yet little is known about the composition and distribution of Pseudo-nitzschia species in these waters. This investigation characterized Pseudo-nitzschia assemblages in samples collected in 2018 during summer (August) and fall (October-November) surveys as part of the Distributed Biological Observatory and Arctic Observing Network, encompassing a broad geographic range (57.8° to 73.0°N, -138.9° to -169.9°W) and spanning temperature (-1.79 to 11.7°C) and salinity (22.9 to 32.9) gradients associated with distinct water masses. Species were identified using a genus-specific Automated Ribosomal Intergenic Spacer Analysis (ARISA). Seventeen amplicons were observed; seven corresponded to temperate, sub-polar, or polar Pseudo-nitzschia species based on parallel sequencing efforts (P. arctica, P. delicatissima, P. granii, P. obtusa, P. pungens, and two genotypes of P. seriata), and one represented Fragilariopsis oceanica. During summer, particulate DA (pDA; 4.0 to 130.0 ng L-1) was observed in the Bering Strait and Chukchi Sea where P. obtusa was prevalent. In fall, pDA (3.3 to 111.8 ng L-1) occurred along the Beaufort Sea shelf coincident with one P. seriata genotype, and south of the Bering Strait in association with the other P. seriata genotype. Taxa were correlated with latitude, longitude, temperature, salinity, pDA, and/or chlorophyll a, and each had a distinct distribution pattern. The observation of DA in association with different species, seasons, geographic regions, and water masses underscores the significant risk of Amnesic Shellfish Poisoning (ASP) and DA-poisoning in Alaska waters.
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ArticleTracking a large-scale and highly toxic Arctic algal bloom: Rapid detection and risk communication(Association for the Sciences of Limnology and Oceanography (ASLO), 2024-07-10) Fachon, Evangeline ; Pickart, Robert S. ; Sheffield, Gay ; Pate, Emma ; Pathare, Mrunmayee ; Brosnahan, Michael L. ; Muhlbach, Eric ; Horn, Kali ; Spada, Nathaniel N. ; Rajagopalan, Anushka ; Lin, Peigen ; McRaven, Leah T. ; Lago, Loreley S. ; Huang, Jie ; Bahr, Frank B. ; Stockwell, Dean A. ; Hubbard, Katherine A. ; Farrugia, Thomas J. ; Lefebvre, Kathi A. ; Anderson, Donald M.In recent years, blooms of the neurotoxic dinoflagellate Alexandrium catenella have been documented in Pacific Arctic waters, and the paralytic shellfish toxins (PSTs) that this species produces have been detected throughout the food web. These observations have raised significant concerns about the role that harmful algal blooms (HABs) will play in a rapidly changing Arctic. During a research cruise in summer 2022, a massive bloom of A. catenella was detected in real time as it was advected through the Bering Strait region. The bloom was exceptional in both spatial scale and density, extending > 600 km latitudinally, reaching concentrations > 174,000 cells L−1, and producing high-potency PST congeners. Throughout the event, coastal stakeholders in the region were engaged and a multi-faceted community response was mobilized. This unprecedented bloom highlighted the urgent need for response capabilities to ensure safe utilization of critical marine resources in a region that has little experience with HABs.