The genus Karenia includes 12 species of bloom-forming mixotrophic dinoflagellates that can be found in oceanic and coastal waters worldwide. When they bloom, many Karenia species produce toxins that negatively affect marine ecosystems. These negative effects cascade into local coastal communities by requiring resources to remove dead sea life, harming human health, and decreasing business revenue. Significant advancements have been made in Karenia research focused on bloom monitoring and forecasting, species identification and differentiation, culturing and ecophysiology, microbial interactions and toxin production, impacts on human health and local economies, and climate change-induced range expansion and enhanced detection. Despite these advances, major gaps in knowledge hamper our ability to predict bloom dynamics, such as incomplete genome sequencing and how or why toxins are synthesized. To gain new perspectives and synthesize recent progress, we broadly encourage the submission of abstracts focusing on all aspects of Karenia research. Which Karenia species are affecting our neighborhoods? How do physical oceanographic processes influence bloom formation? What are we learning about this genus in the laboratory and how can this knowledge be applied to understand better and predict Karenia blooms? How do our marine communities respond to blooms and what techniques are we using to build resiliency? Ultimately, we aim to foster a discussion around global Karenia research in order to enhance our understanding of this important genus while identifying commonalities and unique features across species and environments. With this aim in mind, we strongly encourage abstract submissions on topics covering (but not limited) to physical and chemical oceanographic processes influencing Karenia , modeling and monitoring of blooms, ecophysiology and toxin production, molecular and genetic studies, and newly-developed technologies that facilitate research progress of Karenia .
Lead Organizer: Anne Booker, Bigelow Laboratory for Ocean Sciences (abooker@bigelow.org)
Co-organizers:
Tristyn Bercel, Mote Marine Laboratory & Aquarium (tbercel@mote.org)
Carly Moreno, New York University Abu Dhabi (cmm9990@nyu.edu)
Cong Fei, New York University Abu Dhabi (cf2290@nyu.edu)
Cynthia Heil, Mote Marine Laboratory & Aquarium (cheil@mote.org)
Presentations
03:00 PM
WHAT DRIVES RED TIDES - CLIMATE FORCINGS AND THEIR RELATIONSHIPS TO <em>KARENIA BREVIS</em> BLOOMS IN SOUTHWEST FLORIDA (6972)
Primary Presenter: Tristyn Bercel, Mote Marine Laboratory (tbercel@mote.org)
<em>Karenia brevis</em>, a toxic dinoflagellate, forms harmful agal blooms (HABs) along the West Florida Shelf (WFS) nearly annually, making it one of the most predictable HABs globally. These blooms create significant ecological and economic impacts for affected areas, which make understanding the underlying mechanisms that drive bloom initiation and severity important for modeling efforts. We examined various global and regional climatic stressors for specific regime shifts or trends which might play a role in forcing in long-term trends in <em>K. brevis</em> bloom severity along the southwest Florida coast. Regime shifts in the North Atlantic Oscillation (NAO) to a positive phase between 1989 and 1995 and then to a negative phase between 1995 and 2008 were identified in the <em>K. brevis</em> bloom severity index, a measure derived from historical cell count data from 1953 to 2019. Changing patterns in the accumulated cyclone energy index were also reflected in the bloom severity index. We hypothesize that the warmer temperatures and higher precipitation seen in the southeastern United States during the positive NAO phases played a role in changes to observed bloom severity.
03:15 PM
TRANSFORMATION OF DISSOLVED ORGANIC MATTER FROM URBAN STORMWATER RUNOFF AND RAINFALL BY THE HARMFUL ALGA KARENIA BREVIS (7249)
Primary Presenter: Amanda Muni-Morgan, University of Florida (a.munimorgan@ufl.edu)
The southwest coast of Florida experiences near-annual blooms of the toxic dinoflagellate Karenia brevis, resulting in extensive wildlife mortalities and risks to human health. The ecological role of anthropogenic contributions of dissolved organic matter (DOM) from sources such as urban stormwater runoff (USR) and atmospheric deposition (AD) in supporting coastal K. brevis bloom populations is unknown. We examined the bioavailability of DOM in USR from two urban-residential sites (USR-1,USR-2), as well as AD (wet) collected from Pinellas County, Florida to non-axenic laboratory cultures of K. brevis in a 6-day bioassay experiment. Labile DOM compound classes and K. brevis degradation products were identified using Excitation Emission Matrices (EEMs) generated by fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) comparing changes in the fluorescence properties of DOM at the beginning and end of the incubation. Results showed the K. brevis-dominated microbial community transformed compounds which correspond to humic-like components in the USR treatment spectra. The highest overall biomass was measured in the USR-2 treatment at 594,921 cells L –1 which was more than double the maximum cell density of controls. These results confirm that inputs of stormwater runoff and AD from urbanized landscapes contain a pool of bioavailable DOM compounds that can contribute to the growth of K. brevis and have important implications for coastal blooms and DOM mitigation strategies.
03:30 PM
Natural bacterial isolates control Karenia brevis growth in culture and during bloom events in the Gulf of Mexico (6632)
Primary Presenter: Cong Fei, New York University Abu Dhabi (cf2290@nyu.edu)
Harmful algal blooms (HABs) have detrimental impacts on marine ecosystems and coastal zones. Despite the importance of interactions between microalgae and bacteria to marine ecosystems, the role of these interactions during HAB events is not yet fully understood. In this study, we isolated and characterized thirty bacterial strains from the 2021 Karenia brevis bloom in the Gulf of Mexico, and examined their effects on K. brevis growth. Results showed that the bacterium Mameliella alba CE5 significantly promoted K. brevis culture growth relative to controls, while Croceibacter atlanticus CE21 lysed K. brevis and inhibited its growth, which was coupled to strong cell aggregation. Genome sequencing of M. alba revealed genes responsible for aerobic anoxygenic photosynthesis, gene transfer agents, dimethylsulfoniopropionate metabolism, cofactors and vitamins (B12), and secondary metabolites (e.g., terpenes). In contrast, C. atlanticus possessed genes for biosynthesis of polyketide algicides. Incubation experiments with blooming and terminating K. brevis water samples from a 2023 bloom showed that M. alba inhibited K. brevis cell decline and reduced stress during the termination phase of the bloom, while C. atlanticus promoted the demise of K. brevis cells relative to controls in the K. brevis-rich water samples. These findings shed light on the complex role that bacteria play in K. brevis blooms and suggest that different bacterial strategies modulate K. brevis growth during a bloom. Ongoing work is underway to identify the molecular mechanisms controlling these interactions, which may inform future management strategies for mitigating the impact of HABs.
03:45 PM
LYTIC VIRAL INFECTION OF THE HARMFUL ALGAL SPECIES KARENIA BREVIS, A POTENTIAL FACTOR OF BLOOM TERMINATION (6886)
Primary Presenter: Anne Booker, Bigelow Laboratory for Ocean Science (abooker@bigelow.org)
The dinoflagellate Karenia brevis is responsible for red tide harmful algal blooms that negatively impact Gulf of Mexico coastal communities. These blooms have a long history in the Gulf of Mexico, but recent blooms persisting for 8-16 months have focused attention on understanding causes of termination. Previous research has shown marine viruses are capable of infecting and clearing phytoplankton blooms. Despite this, no K. brevis viruses have been isolated before and their potential influence on algal blooms are mostly unknown. To explore this microbial interaction, K. brevis cultures were incubated with 2021 K. brevis bloom waters that were size fractionated by passing it through either a 1-µm filter to remove protists, a 0.22-µm filter to remove protists and large bacteria, or a 0.02 µm filter to remove all biological particles. Uninoculated K. brevis culture acted as a control. Two-week incubations resulted in K. brevis lysis only when incubated with the 1-µm or 0.22-µm size fractionated bloom seawater. Flow cytometry identified two different viral sized populations only present in the lysed K. brevis incubations. Consistent with flow cytometry, metagenomic sequencing identified the presence of novel giant eukaryotic nucleocytoplasmic large dsDNA virus genomes only in the lysed cultures. Cumulatively these data indicate at least two undescribed large viruses may infect and lyse K. brevis. Natural marine viruses can thus influence K. brevis and may play a role in bloom termination.
04:00 PM
CHARACTERIZING THE PHOTOPHYSIOLOGY OF KARENIA BREVIS FOLLOWING EXPOSURE TO BLOOM MITIGATION COMPOUNDS (4721)
Primary Presenter: Miah Manning, Rutgers University (miahmanning1040@gmail.com)
Karenia brevis is a harmful algal bloom (HAB)-forming dinoflagellate that causes Florida red tides, resulting in fish kills, neurotoxic shellfish poisoning, and respiratory irritation. The negative impacts of K. brevis blooms create demand for effective mitigation strategies, including clay flocculation and chemical control using the naturally derived flavonoids luteolin and curcumin. Cell death is the aim of most mitigation strategies, however, by targeting physiological processes such as photosynthesis, it is possible to disrupt bloom development while conserving resources and minimizing impacts on the environment. Experiments were conducted on four strains of K. brevis (New Pass, Wilson Low Toxin, Wilson, and Manasota) to examine the photophysiological responses during exposure to modified clay (0.1 g/L), curcumin (3 mg/L), and luteolin (3 mg/L). Using Pulse-Amplitude-Modulation (PAM) fluorometry, the quantum yield of Photosystem II (PSII), relative maximum electron transport rate, and absorption cross-section of PSII were measured as the photophysiological parameters. The curcumin was the most effective compound at reducing photophysiological parameters and cell counts in all tested strains. Clay was the second most effective compound at reducing yield and relative electron transport rate. Luteolin exhibited the least effect on cell photophysiology. Inter-strain differences were observed. Notably, the Wilson strain was most impacted by luteolin, and Wilson treated with curcumin showed recovery by 24 hours while other strains did not.
04:15 PM
PATTERNS OF EFFICACY OF POTENTIAL MITIGATION COMPOUNDS ON BOTH CELLS AND TOXINS OF THE DINOFLAGELLATE KARENIA BREVIS: WHY JUST ELIMINATING CELLS ISN’T ENOUGH. (5874)
Primary Presenter: Cynthia Heil, Mote Marine Laboratory (cheil@mote.org)
Blooms of the toxic dinoflagellate <em>Karenia brevis</em> have devastating human, environmental and economic impacts in the Gulf of Mexico. We examined the efficacy of 15 potential mitigation compounds identified from the literature to simultaneously mitigate both cells and dissolved brevetoxins of <em>K. brevis</em> in laboratory experiments. While the majority of compounds had a negative effect upon cell concentrations, most reductions in cell abundance after 24 or 48 hours resulted in either no change in dissolved brevetoxin concentration (e.g. barley straw extract, linoleic acid), an increase in total dissolved brevetoxins (e.g. <em>Gracilaria curtissae</em>), or a conversion between brevetoxin forms, specifically from PbTx-2 to PbTx-3 (e.g. chitosan). Of the compounds tested, the high dose of the macroalgal species <em>Gracilaria lemaneiformis</em> was the most effective in mitigating both cells and brevetoxins, eliminating 100% of cells and 61 % of total brevetoxins after 48 hours. Effective mitigation of <em>Karenia brevis</em> blooms requires elimination of both cells and dissolved brevetoxins and concurrent monitoring of mitigation efforts.
SS088 Advances in Understanding, Prediction, and Monitoring of Toxic Karenia (Dinoflagellate) Blooms Around the Globe
Description
Time: 3:00 PM
Date: 5/6/2023
Room: Sala Portixol 1