A critical review on control methods for harmful algal blooms

Abstract

The impacts of harmful algal blooms on human health, tourism, fisheries and ecosystems have increased in recent decades. Eutrophication and the feared climate change are believed to further challenge authorities and those whose activity depends on coastal resources. While in most of the affected countries, regulatory steps have been taken to protect consumers of contaminated food, there has been an unequal focus on management systems. Some countries such as EEUU and Canada have focused on monitoring and prediction programs, whereas others (e.g. Korea, China) have relied on direct control of blooms in the sea. Here, we review current control methods for HABs including their fundamentals and the last scientific advances. A thorough revision of all considered approaches so far has been included. Ecological studies of the impact of the countermeasures were also considered.

Assessing risks and mitigating impacts of harmful algal blooms on mariculture and marine fisheries

“…Physical and chemical control methods can remove HABs efficiently and are used operationally as a last resort in mariculture, but they can be costly, lack specificity to HABs, and are generally less effective in coastal situations in comparison with enclosed or semi-enclosed aquatic systems. Alternatively, biological control methods can be potentially more specific for individual HAB species, minimising impact on other non-target species, but they are more difficult to constrain in non-enclosed systems and have not progressed beyond laboratory or field trials for mariculture applications (reviewed in NOAA, 2015;Sellner & Rensel 2018;Sun et al 2018;Gallardo-Rodr ıguez et al 2019).…”

“…the use of synthetic chemicals, including hydrogen peroxide and isolated algicidal compounds, or metallic compounds such as copper sulphate. These various chemicals (metals and organic compounds) can interfere with HAB cell survival (algicidal chemicals), growth and reproduction (algistatic chemicals) through a variety of mechanisms (NOAA, 2015;Gallardo-Rodr ıguez et al 2019). Biochemicals are advantageous in terms of their higher diversity, biodegradability and, in some cases, specificity and potentially lower toxicity to the wider environment (Ahn et al 2003).…”

“…Biochemicals are advantageous in terms of their higher diversity, biodegradability and, in some cases, specificity and potentially lower toxicity to the wider environment (Ahn et al 2003). Although many effective aqueous algicidal treatments exist, few are approved for use in open marine systems, due to environmental concerns, although some have restricted use in antifouling paints and surface treatments (NOAA, 2015;Gallardo-Rodr ıguez et al 2019). Several biocidal chemicals have been tested and approved for use in mariculture, for controlling shellfish and finfish pathogens or parasites (Johnston & Santillo 2002;Read & Fernandes 2003) and some of these may be effective in killing some HAB species.…”

Production of extracts with anaesthetic activity from the culture of Heterosigma akashiwo in pilot-scale photobioreactors

“…Raphidophytes like Heterosigma akashiwo, Fibrocapsa japonica, Chattonella spp. and Pseudochattonella are known to cause mass mortalities of cultivated and wild fish [10]. In particular, H. akashiwo has had an enormous impact on the coasts of Japan [11] and in other parts of the world [12,13].…”

Understanding and Managing Harmful Algal Bloom Risks in a Changing Climate: Lessons From the European CoCliME Project

“…Economic factors related to business activities that affect vulnerability and adaptive capacity to HAB risks include the size of firms and levels of integration and/or collaboration across them (with smaller firms typically, though not always, being more vulnerable), the extent of economic diversification across geographic areas, species and markets, the potential for substitution (i.e., sourcing fish or shellfish from other locations), the flexibility of operations (e.g., the potential to move planned maintenance activities to periods of closures, delay harvesting, and the flexibility of the workforce), and the extent of economic support mechanisms such as insurance or other compensation measures in the event of prolonged closures or large-scale mortalities of farmed fish. Technological factors such as access to, and ability to implement, mitigation options, such as raising or lowering fish cages, and the use of physical control methods such as "bubble curtains" (e.g., Gallardo-Rodríguez et al, 2019) also play a role. Finally, aspects related to the social infrastructure, including the extent of local networks and cooperation for monitoring, mitigation, and emergency preparedness and response, shape stakeholders' vulnerabilities, and adaptation to HAB risks and their ability to mitigate impacts (e.g., Le Bihan et al, 2013;Guillotreau et al, 2017).…”