WWW.WA S .ORG • WORLD AQUACULTURE • JUNE 2022 25 Additional mitigation strategies include using various techniques to try and sink the algae, thereby limiting the availability of sunlight for photosynthesis that kills algal cells before they can form blooms. The MPC buoy (Fig. 4) from LG Sonic is an example of a technology that uses ultrasonic frequencies to mitigate HAB development. The use of high frequency sound waves reduces the buoyancy of phytoplankton cells, causing them to sink to deeper waters, thereby preventing surface blooms. Additionally, a study by Kirke (2001) indicated that operation of low-powered surface pumps can transport algal cells to deeper waters, reducing the impacts of surface blooms. Lastly, clay application may be used to prevent algae from aggregating in surface waters by attaching to and sinking algae cells (Yu et al. 2017). Summary As the push to move aquaculture facilities farther offshore continues, so too does the need for technological advancements to properly monitor HAB risk at these sites. Remote sensing technologies have the potential to allow for the convenient, reliable, real-time monitoring of HABs that serve as an invaluable tool for offshore aquaculture facilities. HABs can be harmful to humans and aquatic life and cause major economic losses to aquaculture globally. The impacts of HABs are diverse, as are the causes and underlying mechanisms controlling blooms. As many HAB events are spatially and temporally variable, often differing in magnitude and location from year to year, useful HAB risk assessment requires greater temporal resolution than only seasonal. An understanding of the underlying ecology and drivers of bloom events, along with the observational platforms and predictive approaches to identify and forecast developing blooms, is therefore necessary for useful expert interpretation (Davidson et al. 2021). Recent advancements in the creation of EWS using remotely sensed data, in tandem with a variety of computational methods, have made it possible for operators to implement appropriate management strategies before HABs can inflict damage. However, further research is needed on species-specific detection methods for algae, overall regional trends in HAB development and the continued creation and improvement of predictive models and forecasting methods to extend warning times. References Anderson, D.M., P. Andersen, V.M. Bricers, J.J. Cullen and J.E. Rensel. 2001. Monitoring and management strategies for HABs in coastal waters. Singapore and Intergovernmental Oceanographic Commission Technical Series No. 59, Paris, France. 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Mitigation of harmful algal blooms using modified clays: Theory, mechanisms, and applications. Harmful Algae 69:48-64. As the push to move aquaculture facilities farther offshore continues, so too does the need for technological advancements to properly monitor HAB risk at these sites. Remote sensing technologies have the potential to allow for the convenient, reliable, real-time monitoring of HABs that serve as an invaluable tool for offshore aquaculture facilities. HABs can be harmful to humans and aquatic life and cause major economic losses to aquaculture globally.
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