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Perceived global increase in algal blooms is attributable to intensified monitoring and emerging bloom impacts


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Hallegraeff, GM ORCID: 0000-0001-8464-7343, Anderson, DM, Belin, C, Dechraoui Bottein, M-Y, Bresnan, E, Chinain, M, Enevoldsen, H, Iwataki, M, Karlson, B, McKenzie, CH, Sunesen, I, Pitcher, GC, Provoost, P, Richardson, A, Schweibold, L, Tester, PA, Trainer, VL, Yniguez, AT and Zingone, A 2021 , 'Perceived global increase in algal blooms is attributable to intensified monitoring and emerging bloom impacts' , Communications Earth & Environment, vol. 2 , pp. 1-10 , doi: 10.1038/s43247-021-00178-8.

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Global trends in the occurrence, toxicity and risk posed by harmful algal blooms to natural systems, human health and coastal economies are poorly constrained, but are widely thought to be increasing due to climate change and nutrient pollution. Here, we conduct a statistical analysis on a global dataset extracted from the Harmful Algae Event Database and Ocean Biodiversity Information System for the period 1985–2018 to investigate temporal trends in the frequency and distribution of marine harmful algal blooms. We find no uniform global trend in the number of harmful algal events and their distribution over time, once data were adjusted for regional variations in monitoring effort. Varying and contrasting regional trends were driven by differences in bloom species, type and emergent impacts. Our findings suggest that intensified monitoring efforts associated with increased aquaculture production are responsible for the perceived increase in harmful algae events and that there is no empirical support for broad statements regarding increasing global trends. Instead, trends need to be considered regionally and at the species level.

Item Type: Article
Authors/Creators:Hallegraeff, GM and Anderson, DM and Belin, C and Dechraoui Bottein, M-Y and Bresnan, E and Chinain, M and Enevoldsen, H and Iwataki, M and Karlson, B and McKenzie, CH and Sunesen, I and Pitcher, GC and Provoost, P and Richardson, A and Schweibold, L and Tester, PA and Trainer, VL and Yniguez, AT and Zingone, A
Keywords: global harmful algal bloom status
Journal or Publication Title: Communications Earth & Environment
Publisher: Nature Publishing Group
ISSN: 2662-4435
DOI / ID Number: 10.1038/s43247-021-00178-8
Copyright Information:

© The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons Attribution 4.0 International (CC BY 4.0) licence, ( and indicate if changes were made

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