Unlabelled: In 2015, the largest recorded harmful algal bloom (HAB) occurred in the Northeast Pacific, causing nearly 100 million dollars in damages to fisheries and killing many protected marine mammals. Dominated by the toxic diatom , this bloom produced high levels of the neurotoxin domoic acid (DA). Through molecular and transcriptional characterization of 52 near-weekly phytoplankton net-tow samples collected at a bloom hotspot in Monterey Bay, California, we identified active transcription of known DA biosynthesis ( ) genes from the three identified toxigenic species, including as the primary origin of toxicity. Elevated expression of silicon transporters ( ) during the bloom supports the previously hypothesized role of dissolved silica (Si) exhaustion in contributing to bloom physiology and toxicity. We find that co-expression of the and genes serves as a robust predictor of DA one week in advance, potentially enabling the forecasting of DA-producing HABs. We additionally present evidence that low levels of iron could have co-limited the diatom population along with low Si. Iron limitation represents a previously unrecognized driver of both toxin production and ecological success of the low iron adapted genus during the 2015 bloom, and increasing pervasiveness of iron limitation may fuel the escalating magnitude and frequency of toxic blooms globally. Our results advance understanding of bloom physiology underlying toxin production, bloom prediction, and the impact of global change on toxic blooms.
Significance: diatoms form oceanic harmful algal blooms that threaten human health through production of the neurotoxin domoic acid (DA). DA biosynthetic gene expression is hypothesized to control DA production in the environment, yet what regulates expression of these genes is yet to be discovered. In this study, we uncovered expression of DA biosynthesis genes by multiple toxigenic species during an economically impactful bloom along the North American West Coast, and identified genes that predict DA in advance of its production. We discovered that iron and silica co-limitation restrained the bloom and likely promoted toxin production. This work suggests that increasing iron limitation due to global change may play a previously unrecognized role in driving bloom frequency and toxicity.
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http://dx.doi.org/10.1101/2023.11.02.565333 | DOI Listing |
Birth Defects Res
December 2024
Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Sacramento, California, USA.
Background: Current US federal action levels for domoic acid (DA) in seafood are based on acute toxicity observed in exposed adult humans. Life course considerations have not been incorporated. The potential for developmental neurotoxicity (DNT) at permissible DA levels has previously been noted, but not methodically assessed.
View Article and Find Full Text PDFHarmful Algae
January 2025
Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya 16310 Bachok, Kelantan, Malaysia. Electronic address:
The benthic pennate diatom Nitzschia navis-varingica, known for producing domoic acid (DA) and its isomers, is widely distributed in the Western Pacific (WP) region. To investigate the genetic differentiation and gene flow patterns among the populations in the WP, the genetic diversity of 354 strains of N. navis-varingica was analysed using two nuclear-encoded rDNA loci: the large subunit rDNA (LSU rDNA) and the internal transcribed spacer 2 (ITS2).
View Article and Find Full Text PDFHarmful Algae
December 2024
Fisheries Ecology Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 110 McAllister Way, Santa Cruz, CA 95060, USA.
Unprecedented warm ocean conditions, driven by the Large Marine Heatwave (LMH) and the 2015-16 El Niño in the Northeast Pacific favored pervasive toxigenic Pseudo-nitzschia spp. blooms that caused widespread ecological impacts, but little is known about the magnitude to which marine food webs were altered. Here, we assessed the trophic transfer of domoic acid (DA; a neurotoxin) and changes in trophic position from multiple key species during the peak of the LMH and El Niño in 2015 in comparison with 2018, a reference non-anomalous warm year.
View Article and Find Full Text PDFAntioxidants (Basel)
November 2024
Center for Marine Research, Ruđer Bošković Institute, 52210 Rovinj, Croatia.
In this review, we toxicologically assessed the naturally occurring toxin domoic acid. We used the One Health approach because the impact of domoic acid is potentiated by climate change and water pollution on one side, and reflected in animal health, food security, human diet, and human health on the other. In a changing environment, algal blooms are more frequent.
View Article and Find Full Text PDFMar Drugs
November 2024
Key Laboratory of Aquatic Eutrophication and Control of Harmful Algal Blooms of Guangdong Higher Education Institute, College of Life Science and Technology, Jinan University, Guangzhou 510632, China.
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