Grazing of the copepod Cyclops vicinus on toxic Microcystis aeruginosa: potential for controlling cyanobacterial blooms and transfer of toxins

Abstract

Grazing of zooplankton on phytoplankton may contribute to a reduction of harmful cyanobacteria in eutrophic waters. However, the feeding capacity and interaction between zooplankton and toxic cyanobacteria vary among grazer species. In this study, laboratory feeding experiments were designed to measure the grazing rate of the copepod Cyclops vicinus on Microcystis aeruginosa and the potential microcystin (MC) accumulation in the grazer. Copepods were fed a mixed diet of the edible green alga Ankistrodesmus falcatus and toxic M. aeruginosa for 10 days. The results showed that C. vicinus efficiently ingested toxic Microcystis cells with high grazing rates, varying during the feeding period (68.9–606.3 Microcystis cells animal-1 d-1) along with Microcystis cell density. Microcystis cells exhibited a remarkable induction in MC production under grazing conditions with concentrations 1.67–12.5 times higher than those in control cultures. Furthermore, C. vicinus was found to accumulate MCs in its body with concentrations increasing during the experiment (0.05–3.21 μg MC animal-1). Further in situ studies are needed to investigate the ability of Cyclops and other copepods to assimilate and detoxify MCs at environmentally relevant concentrations before deciding on the biocontrol of Microcystis blooms by copepods.

Simultaneous biodegradation of harmful Cylindrospermopsis raciborskii and cylindrospermopsin toxin in batch culture by single Bacillus strain

“…Cyanobacterial blooms contain associated microorganisms including viruses, bacteria and fungi (Mohamed et al 2018). Some of these microorganisms exhibit strong antagonistic effects on these blooms (Li et al 2011;Van Wichelen et al 2016), and thereby they could be exploited in bio-controlling and bioremediation of harmful cyanobacteria in water bodies.…”

In Vitro Toxicological Screening of Stable and Senescing Cultures of Aphanizomenon, Planktothrix, and Raphidiopsis

“…The harmfulness of cyanobacterial blooms is modified by their stage, state, and the contribution of the toxic subpopulation. At the initial stage of development, blooms usually demonstrate low harmfulness mainly because of their low biomass and, in some circumstances, due to their partial control by grazers [15,[26][27][28] compared to dense, stable, or senescing blooms. The population dynamics and toxicity of a bloom are generally influenced by environmental factors, including mainly meteorological (as temperature and light conditions), chemical (as nutrients concentrations), and biological parameters (competition, bacterial activity, grazing).…”

Potencial das radiações ionizantes para reduzir a toxicidade da cianobactéria Microcystis aeruginosa

“…Neste caso, quando os organismos-modelo são expostos à culturas de cianobactérias ou extratos brutos obtidos de florações tóxicas. LIRA et al, (2017) observaram que suspensão de células liofilizadas das cianobactérias Microcystis aeruginosa e Cylindrospermopsis raciborskii com concentrações das toxinas MC e STX entre 1 μg•L −1 para MC e 3 μg•L −1 , respectivamente, não resultaram em mortalidade significativa para Ceriodaphnia dubia MOHAMED et al, (2018). avaliaram por 10 dias o efeito da ingestão da cianobactéria M. aeruginosa no copépode Cyclops vicinus.…”