Growth of Microcystis strains isolated from environments with the presence and absence of submerged macrophytes in coexistence with Ceratophyllum demersum

Rafael Henrique De Moura-Falcão,Cihelio Alves Amorim,Ariadne Do Nascimento Moura

doi:10.4025/actascibiolsci.v43i1.57734

Rafael Henrique De Moura-Falcão, Cihelio Alves Amorim + Show 1 more

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https://doi.org/10.4025/actascibiolsci.v43i1.57734

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Abstract

Cyanobacterial blooms can cause severe ecological and health problems in drinking water reservoirs. To alleviate this problem, allelopathically active submerged macrophytes can be used to reduce cyanobacterial growth. Accordingly, this study aimed to evaluate the sensitivity of strains of the Microcystis aeruginosa complex isolated from reservoirs with the presence and absence of submerged macrophytes to the allelochemicals of Ceratophyllum demersum. A coexistence experiment was carried out between the submerged macrophyte C. demersum and four Microcystis strains, with two treatments for each strain, one in coexistence with the submerged macrophyte (7 g L-1) and control (in the absence of the macrophyte). Two strains of M. aeruginosa (BMIUFRPE-06 and BMIUFRPE-07) and two of M. panniformis (BMIUFRPE-08 and BMIUFRPE-09) were used, which were isolated from Cajueiro (with submerged macrophytes) and Tapacurá (without submerged macrophytes) reservoirs, respectively. The biomass of Microcystis strains from the reservoir without macrophytes (BMIUFRPE-08 and BMIUFRPE-09) was significantly inhibited in 96% (T-test: p < 0.01) and 74% (T-test: p< 0.05), when compared to the control, respectively, with lower values of growth rates (ANOVA: p < 0.05). The strains isolated from the reservoir with macrophytes (BMIUFRPE-06 and BMIUFRPE-07) showed a growth delay (biomass reductions of 44 and 58%, respectively) in the coexistence treatment but without significant difference from the control on the sixth day of the experiment (biomass - T-test: p > 0.05; growth rate - ANOVA: p > 0.05). These results suggest that strains isolated from environments with submerged macrophytes are less sensitive to allelochemicals of these plants, as these strains may be adapted to the coexistence with submerged macrophytes.

Highlights

IntroductionThe increase in temperature and eutrophication of water bodies has led to an increase in cyanobacterial blooms (Paerl & Otten, 2013; Burford et al, 2020), mainly those composed of the Microcystis genus, with records in 108 countries (all continents, except Antarctica) (Harke et al, 2016)
The aquatic macrophyte C. demersum affected the growth of Microcystis strains differently and depending on the origin and history of the strains
Strains isolated from the reservoir with submerged macrophytes (BMIUFRPE-06 and BMIUFRPE-07) showed a decrease in growth, beginning on the fourth day in the coexistence treatment compared to control

Summary

Introduction

The increase in temperature and eutrophication of water bodies has led to an increase in cyanobacterial blooms (Paerl & Otten, 2013; Burford et al, 2020), mainly those composed of the Microcystis genus, with records in 108 countries (all continents, except Antarctica) (Harke et al, 2016). These blooms negatively affect public supply reservoirs through the release of cyanotoxins, which compromise water quality, and reduce recreational and fishing activities (Davis & Koop, 2006). There are more than 240 variants of microcystins, with different levels of toxicity (Svirčev et al, 2017), which can cause damage to aquatic macrophytes (Amorim, Ulisses, & Moura, 2017), zooplankton (Liang, Ouyang, Chen, Su, & Yang, 2017), fish (Boaru, Dragos, & Schirmer, 2006), and even humans (Carmichael et al, 2001)

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