How is plankton affected by physical and chemical eutrophication control techniques? A systematic review

Como o plâncton é afetado pelas técnicas físicas e químicas de controle da eutrofização? Uma revisão sistemática

Abstract  Eutrophication control techniques primarily target the reduction of cyanobacterial biomass. However, it is crucial to consider the effects of these techniques on non-target planktonic organisms, as their dynamics and community structure are still not well understood.

Aim  The objective of this study was to perform a systematic review of the literature to observe the effects of chemical and physical eutrophication control techniques on planktonic organisms in eutrophic environments. It also aimed to evaluate bibliometric production and determine knowledge gaps.

Methods  The review was carried out based on the PRISMA methodology. The articles were searched in the databases of Scopus and Web of Science. The articles were screened so that only those within our objective remained. The systematic review was carried out with a final sample of 136 articles.

Results  The most frequently mentioned techniques were “Floc & Sink”, “Floc & Lock”, and algaecide application, (chemicals methods); aeration, dredging, and ultrasound (physical methods). There was an increase in the number of publications from 1974 until July 2020, especially on cyanobacteria. The identified gaps were studies on the zooplankton population and plankton community succession, and long-term experiments. All the chemical techniques remove cyanobacteria biomass or biovolume. Aeration, dredging, and ultrasound, which had conflicting results without conclusive findings. The few studies about the plankton community show positive effects on phytoplankton diversity after the “Floc & Sink” technique and an increase in richness after “Floc & Lock” and aeration. All the techniques negatively affect zooplankton, reducing biomass, survival, or abundance.

Conclusions  There are many studies on the effect of eutrophication control techniques on cyanobacteria, and they provide good removal of their biomass. However, there is a large gap regarding other phytoplankton taxonomic groups and zooplankton, making it difficult to draw definitive conclusions about the overall impacts of these techniques.

Keywords:
biomass; cyanobacteria; phytoplankton; zooplankton

Graphical abstract