Harmful algal blooms under changing climate and constantly increasing anthropogenic actions: the review of management implications

Abstract

The present review reports all management approaches (physical, chemical, and biological) traditionally adopted in mitigating the global impact of harmful cyanobacterial blooms (cyanoHABs). It recognizes that each mitigation strategy shows characteristic associated limitations and notes that no remedial step has provided a sustainable solution to HABs on a global scale. It emphasizes that the putative anthropogenic N&P inputs reduction through improved wastewater treatment and regulation of point and non-point sources-agricultural fertilizers only offer a short term solution. These approaches are rather preventive than curative hence, do not address concerns relating to the recovery of already-eutrophic and hypereutrophic systems. It raises new concerns on the implications of non-agricultural pollutants such as hydrocarbon fractions in bloom accretions often neglected while addressing HAB triggers. It also accesses the global impacts of HABs as it pertains to socio-economic implications in the geographically diverse world. It, therefore, proposes that Integrated Management Intervention involving the merging of two or more mitigation steps be administered across the aquatic continua as a prudent management solution to complement the current N&P dual management paradigm. It stresses that the contemporaneous adoption of management options with both preventive and curative measures is a key to sustainable HAB management. This review provides sufficient advances and current scenarios for approaching cyanoHABs. Further, it advocates that future research perspectives tackle the mitigation design beyond the short-term nutrient regulations and the parochial attention to the point and non-point N&P input sources.

Keywords: Anthropogenic; Climate change; Eutrophication; Harmful algal bloom; Management.

Fig. 1

Examples of water bodies covered by different algal blooms: a left to right: Green water caused by Microcystis aeruginosa and black water caused by Peridiniopsis sp. in Xiangxi tributary, Yangtze River, China (photo credit: Yange et al. 2018a, b). b Left to right: Upper Klamath Lake, USA and Taihu Lake, China (Photo credit: Paerl 2017)

Fig. 2

a The TN and TP molar ratio indicating the forms of nutrient limitation dynamics shift (Zhou et al. 2009). b Temperature optima for maximum growth of major harmful algal bloom (HABs) formers (Paerl et al. 2016)

Fig. 3

Conceptual illustrations of bloom mechanism and the several physicochemical and biological interactions exacerbating HABs proliferation and expansions on a geographically diverse scale

Fig. 4

A typical Integrated Management (IMI) design to mitigating HAB across the geographically diverse regions