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Revista de Biología Tropical

On-line version ISSN 0034-7744Print version ISSN 0034-7744

Rev. biol. trop vol.69 n.4 San José Oct./Dec. 2021

http://dx.doi.org/10.15517/rbt.v69i4.42589 

Artículo

Effects of the submerged macrophyte Ceratophyllum demersum (Ceratophyllaceae) and the cladoceran Moina micrura (Cladocera: Moinidae) on microalgal interactions

Efectos de un macrófito sumergido Ceratophyllum demersum (Ceratophyllaceae) y un cladócero Moina micrura (Cladocera: Moinidae) sobre las interacciones de microalgas

Vitor-Ricardo De-Souza1 
http://orcid.org/0000-0002-7291-3605

Cihelio Alves-Amorim1  2 
http://orcid.org/0000-0002-7171-7450

Ariadne-do-Nascimento Moura1 
http://orcid.org/0000-0001-5093-2840

1. Departamento de Biologia, Universidade Federal Rural de Pernambuco, Dom Manoel de Medeiros, s/n, Dois Irmãos, 52171-030, Recife, Pernambuco, Brazil; vitorricardo.biologia@gmail.com, ariadne_moura@hotmail.com

2. Department of Biological Sciences, Middle East Technical University, Üniversiteler Mahallesi, Dumlupınar Bulvarı, 60800, Ankara, Turkey; alvescihelio@gmail.com (*Correspondence)

Abstract

Introduction:

Cyanobacterial blooms in tropical water bodies are increasingly common, because of eutrophication and rising temperatures. Consequently, many freshwater systems are affected, by reducing water quality, biodiversity, and ecosystem services. With the increased frequency of harmful algal blooms, the development of biological tools to improve water quality is an urgent issue.

Objective:

To evaluate the effects of a submerged macrophyte and a cladoceran on the microcystin-producing cyanobacteria Microcystis aeruginosa (NPLJ-4) and the chlorophyte Raphidocelis subcapitata (BMIUFRPE-02) in mixed cultures.

Methods:

Two parallel experiments were carried out for ten days to evaluate the effects of the submerged macrophyte Ceratophyllum demersum and the cladoceran Moina micrura on microalgal interactions. Microalgal strains were cultivated in the ASM1 culture medium, under controlled laboratory conditions. The first experiment presented four treatments: M (C. demersum), Z (M. micrura), MZ (C. demersum and M. micrura), and C (control). Meanwhile, the second experiment consisted of five treatments, in which the microalgae were cultivated together at different Microcystis:Raphidocelis ratios: 1:0, 3:1, 1:1, 1:3, and 0:1. Biomass and growth rates of the strains were evaluated every two days, which were statistically treated with three-way or two-way repeated-measures ANOVA.

Results:

In the first experiment, M. aeruginosa was significantly inhibited in M and MZ treatments from the second day, and Z from the fourth, while R. subcapitata showed no reduction in its biomass in any treatment. On the other hand, R. subcapitata was stimulated from the eighth and tenth days in M treatment and only on the eighth day in Z treatment. In the second experiment, M. aeruginosa was significantly inhibited when cultivated with R. subcapitata in low ratios (Microcystis:Raphidocelis ratio of 1:3) throughout the experiment, while the chlorophyte was stimulated in that treatment.

Conclusions:

The coexistence of a cyanobacterium with a green alga did not alter the main negative response of M. aeruginosa to the submerged macrophyte and zooplankton but stimulated the green alga. Accordingly, the introduction of submerged macrophytes and cladocerans already adapted to eutrophic conditions, both isolated and combined, proved to be a good method to control cyanobacterial blooms without negatively affecting other coexisting phytoplankton species.

Key words: microalgal blooms; allelopathy; biomanipulation; competition; grazing

Resumen

Introducción:

Las proliferaciones de cianobacterias en los cuerpos de agua tropicales son cada vez más comunes, debido a la eutrofización y al aumento de las temperaturas. En consecuencia, muchos sistemas de agua dulce se ven afectados por la reducción de la calidad del agua, la biodiversidad y los servicios de los ecosistemas. Con el aumento de la frecuencia de la proliferación de algas nocivas, el desarrollo de herramientas biológicas para mejorar la calidad del agua es urgente.

Objetivo:

Evaluar los efectos de una macrófita sumergida y un cladócero sobre la cianobacteria productora de microcistina llamada Microcystis aeruginosa (NPLJ-4) y la clorofita Raphidocelis subcapitata (BMIUFRPE-02) en cultivos mixtos.

Métodos:

Se realizaron dos experimentos paralelos durante diez días para evaluar los efectos de la macrófita sumergida Ceratophyllum demersum y el cladócero Moina micrura sobre las interacciones microalgales. Se cultivaron cepas de microalgas en el medio de cultivo ASM1, en condiciones controladas de laboratorio. El primer experimento presentó cuatro tratamientos: M (C. demersum), Z (M. micrura), MZ (C. demersum y M. micrura) y C (control). El segundo experimento consistió en cinco tratamientos, en el que las microalgas se cultivaron juntas en diferentes proporciones de Microcystis:Raphidocelis: 1:0, 3:1, 1:1, 1:3 y 0:1. La biomasa y las tasas de crecimiento de las cepas se evaluaron cada dos días, y se trataron estadísticamente con ANOVA de medidas repetidas de dos o tres factores.

Resultados:

En el primer experimento, M. aeruginosa se inhibió significativamente en los tratamientos M y MZ a partir del segundo día, y en Z a partir del cuarto, mientras que R. subcapitata no mostró reducción de su biomasa en ningún tratamiento. Por otro lado, R. subcapitata fue estimulada a partir del octavo y décimo día en el tratamiento M y solo en el octavo día en el tratamiento Z. En el segundo experimento, M. aeruginosa se inhibió significativamente cuando se cultivó con R. subcapitata en proporciones bajas (proporción de Microcystis:Raphidocelis de 1:3) durante todo el experimento, mientras que la clorófita se estimuló en ese tratamiento.

Conclusiones:

La coexistencia de una cianobacteria con un alga verde no alteró la principal respuesta negativa de M. aeruginosa a la macrófita sumergida y al zooplancton, sino que estimuló al alga verde. En consecuencia, la introducción de macrófitos y cladóceros sumergidos ya adaptados a las condiciones eutróficas, tanto aislados como combinados, resultó ser un buen método para controlar las proliferaciones de cianobacterias sin afectar negativamente a otras especies de fitoplancton coexistentes.

Palabras clave: proliferaciones de microalgas; alelopatía; biomanipulación; competencia; pastoreo

Introduction

The occurrence of cyanobacterial blooms in freshwater environments, in response to anthropogenic eutrophication and climate change (Moura et al., 2018; O’Neil et al., 2012), has seriously damaged aquatic biota (Paerl & Otten, 2013), leading to the death of fish, mollusks, and crustaceans (Ibelings & Chorus, 2007; Zurawell et al., 2005). For the most part, blooms affect aquatic ecosystems through the production of toxic metabolites (e.g., Microcystins, Li et al., 2021) by certain cyanobacteria species (Cirés & Ballot, 2016; Harke et al., 2016). Moreover, algal blooms can represent a serious threat to freshwater biodiversity, reducing water quality and ecosystem functioning (Amorim & Moura, 2021).

Recurrent toxic blooms of these organisms seriously compromise the quality of water and make it unsuitable for human consumption, generating economic (Carmichael & Boyer, 2016) and health problems (Chen et al., 2009; Zurawell et al., 2005) and, in more serious cases, can be fatal (Azevedo et al., 2002). Among the main bloom-forming genera, Microcystis stands out with wide geographical distribution and several microcystin-producing morphospecies (Harke et al., 2016; O’Neil et al., 2012; Wiegand & Pflugmacher, 2005). To control algal blooms, laboratory and in situ studies using aquatic plants (e.g., Amorim & Moura, 2020; Amorim et al., 2019a;) and zooplankton organisms (e.g., Amorim & Moura, 2020; Amorim et al., 2019b; Diniz et al., 2019; Severiano et al., 2018; Severiano et al., 2021) have been carried out in tropical regions, specifically in the Northeastern region of Brazil. In that region, the biomanipulation of fish to control eutrophication and phytoplankton blooms can show negative (Menezes et al., 2010), positive or no effects (e.g., Dantas et al., 2019; Okun et al., 2008).

Submerged macrophytes can produce allelochemicals that are important tools for controlling cyanobacteria (Amorim & Moura, 2020; Zhu et al., 2010). The secondary metabolites released by plants into the water column can inhibit the activity of photosystem II and rupture the cell membrane, which kills the cyanobacteria (Mohamed, 2017). Macrophyte allelopathy is a biological alternative that can minimize impacts caused by harmful cyanobacteria and improve water quality (Chen et al., 2012; Hilt & Gross, 2008; Vanderstukken et al., 2014). However, unlike cyanobacteria, green algae are resistant to the inhibitory effect of allelochemicals from submerged macrophytes (Amorim et al., 2019a; Dong et al., 2014; Zhu et al., 2010). Nevertheless, it is believed that when in coexistence with a green alga, cyanobacteria can be stimulated by macrophyte allelochemicals instead of being inhibited (Chang et al., 2012).

Another way to reduce cyanobacterial blooms is through zooplankton since the herbivory pressure exerted by these organisms negatively affects the biomass of phytoplankton species (Amorim et al., 2019b; Diniz et al., 2019; Severiano et al., 2018). However, that method does not always negatively affect cyanobacteria, because they can produce large filaments and colonies, along with the production of toxic metabolites, which reduce the grazing of zooplankton on cyanobacteria (Ger et al., 2016). Cyanotoxins can negatively affect the quality of life for zooplankton, leading to death, retarding growth, and changing the ingestion rate (Bownik, 2016; Santos et al., 2021). Moreover, cyanotoxins can affect more seriously larger zooplankton than small organisms, however, the former ones can graze more efficiently on phytoplankton (Guo & Xie, 2006). With that, some zooplankton species can select palatable phytoplankton organisms, which can, in turn, increase cyanobacterial biomass (Leitão et al., 2018; Severiano et al., 2021).

Therefore, the present study aims to (1) verify the effect of the submerged macrophyte Ceratophyllum demersum L. and the cladoceran Moina micrura Kurz, 1874 on the interaction between the cyanobacteria Microcystis aeruginosa (Kützing) Kützing and the chlorophyte Raphidocelis subcapitata (Korshikov) Nygaard, Komárek, Kristiansen & Skulberg; and (2) understand the relationships between cyanobacteria and chlorophytes under different dominance scenarios for both groups.

Materials and methods

Phytoplankton organisms and culture conditions: For this study, two non-axenic strains of microalgae were selected: the cyanobacterium M. aeruginosa, and the chlorophyte R. subcapitata. The M. aeruginosa strain (NPLJ-4) (Cyanobacteria), which has been proven to produce four variants of microcystins (Amorim et al., 2017), was provided by the Laboratory of Ecophysiology and Toxicology of Cyanobacteria (LETC) at the Federal University of Rio de Janeiro (Rio de Janeiro, Brazil). The R. subcapitata strain (BMIUFRPE-02) (Chlorophyceae) was obtained from the Microalgae Culture Collection at the Federal Rural University of Pernambuco - BMIUFRPE, Recife (Pernambuco, Brazil).

Cyanobacteria and chlorophyte were grown in 1 000 ml Erlenmeyer flasks filled with 800 ml of ASM1 culture medium (Gorham et al., 1964), in a climatic chamber with controlled conditions of temperature (25 °C ± 1.5), light intensity (40 µmol m-2 s-1), pH (7.5), and 12 h photoperiod. All cultures were homogenized three times a day to avoid agglomeration and sedimentation of cells. Microalgae were cultivated until biomass of 50 mg L-1 was obtained.

Collection and maintenance of submerged macrophyte Ceratophyllum demersum: The submerged macrophyte C. demersum was collected from the Carpina reservoir, Lagoa do Carro municipality (Pernambuco, Brazil). During the sampling, 20 cm apical branches from young plants were selected and transported to the laboratory, where they were washed with distilled water jets and a soft brush to remove epiphytic microalgae, small invertebrate animals, and adhered sediments. The macrophytes were cultivated in 8 l aquaria (20 cm²) that were filled with filtered tap water and maintained under the same conditions described for microalgae, however, the aquaria were constantly aerated with aquarium aerators. Until the experiments were carried out, the water was renewed twice a week to prevent the proliferation of insects, small mollusks, and microorganisms.

Obtaining and culture of the cladoceran: The cladoceran M. micrura was collected from the Mundaú reservoir, Garanhuns municipality (Pernambuco, Brazil). This reservoir presents intense cyanobacteria blooms formed mainly by Microcystis spp. and Raphidiopsis raciborskii (Woloszynska) Aguilera, Berrendero Gómez, Kastovsky, Echenique & Salerno (Moura et al., 2015; Amorim et al., 2020). This cladoceran was collected by filtering 100 l of water with a 68 µm mesh plankton net and identified under an optical microscope using specialized bibliography. The individuals were selected and cultivated separately in 30 ml test tubes, filled with 20 ml of reconstituted water (70 % mineral water + humic acid and 30 % water from the environment that was filtered through a 20 μm mesh net), for subsequent selection of genetically identical clones from the same mother.

After at least 20 individuals grew in each tube, one clonal lineage was selected and the cladocerans were transferred to 250 ml Erlenmeyer flasks filled with 200 ml of reconstituted water and constant aeration. Thirty days before the experiments, the cladocerans were cultivated in 1 000 ml Erlenmeyer flasks at 27 °C, 40 µmol m-2 s-1 light intensity, constant aeration, and 12 h photoperiod; and were fed with the chlorophyte R. subcapitata every day.

Experimental design: The experiments were carried out in an aseptic room with the same conditions described for the cultivation of the microalgae strains. Twenty-four 1 000 ml Erlenmeyer flasks were filled with 500 ml of ASM1 nutrient medium containing cyanobacteria and chlorophyte inoculum. Two parallel experiments were carried out for ten days to observe the allelopathic effects of C. demersum and the grazing pressure of the cladoceran M. micrura, both isolated and together, on the interaction between M. aeruginosa and R. subcapitata; as well as to observe possible allelopathic interactions between cyanobacteria and green algae at different dominance ratios.

The experimental design consisted of eight treatments with three replicates that were divided between the two parallel experiments (Table 1). For both experiments, all microalgal treatments were grown in coexistence or isolated with initial biomass of approximately 35 mg l-1. In the first experiment, the proportion of microalgae biomass was 1:1 in all treatments. In the second experiment, the interaction treatments consisted of different concentrations of Microcystis and Raphidocelis, while the controls consisted of the isolated cultures of the cyanobacterium and the chlorophyte. Thus, there was a gradient in the Microcystis and Raphidocelis ratios of M:R = 1:0; 3:1; 1:1; 1:3; and 0:1 (Table 1).

Table 1 Descriptions of the treatments used in the allelopathy and grazing experiment (Exp. 1) and microalgae interaction experiment (Exp. 2) with different proportions of microalgae. 

Experiment / Treatment Microcystis Percentage (%) Raphidocelis Percentage (%) Ceratophyllum demersum Moina micrura
Exp.1 / M 50 50 X -
Exp.1 / Z 50 50 - X
Exp.1 / MZ 50 50 X X
Exp.2 / 1:0 100 0 - -
Exp.2 / 3:1 75 25 - -
Exp.1 and 2 / C and 1:1 50 50 - -
Exp.2 / 1:3 25 75 - -
Exp.2 / 0:1 0 100 - -

X: presence; -: absence. The 1:1 treatment of the second experiment was also used as a control for the first since they were developed in parallel.

To determine the exact ratio between Microcystis and Raphidocelis cultures for the experiments, the biomasses of the stock cultures were analyzed. The proportions were achieved using the ASMI medium dilution method. Three days before the experiments began, young and apical branches of C. demersum were selected, washed several times with distilled water, cut to obtain an 8 gFW l-1 biomass (g of fresh weight), then grown in ASM1 medium for acclimatization. Similarly, three days before the experiment, visibly healthy (actively swimming) cladocerans of the same age were selected (120 ind l-1) and transferred to 250 ml Erlenmeyer flasks containing ASM1 medium for acclimatization.

At the beginning of the experiment, one macrophyte branch was added to each experimental unity in the M and MZ treatments. Similarly, 50 M. micrura individuals were transferred to each experimental unit in the Z and MZ treatments. During the transfer of cladocerans to microalgae cultures, about 5 ml of ASM1 medium was also transferred, thus, the same amount of medium from the cladoceran cultures was added to all treatments. Aliquots of 1 ml were collected every two days for 10 days (0, 2, 4, 6, 8, and 10) from all experimental units to determine cell density and biovolume. Microalgal density was determined by counting cells in a Fuchs-Rosenthal chamber (hemocytometer) under an optical microscope. Also, the length and width of the cells were measured to obtain the biovolume as proposed by Hillebrand et al. (1999), which was multiplied by density for conversion into biomass. In the second experiment, growth rates were determined for each species in all treatments, following the formula described by Wood et al. (2005).

Statistical analyses: A three-way repeated-measures ANOVA was used to compare the biomass of microalgae in the first experiment, based on the factors Macrophyte, Zooplankton, Time, and their interactions. Likewise, a two-way repeated-measures ANOVA was used to compare the growth rates of the cultures in the second experiment, based on the factors Ratios, Time, and their interactions. Before the analysis of variances, the data were tested for normality with the Kolmogorov-Smirnov test and homoscedasticity with Bartlett’s test. For statistical analyses, the R program was used, with a significance level of P < 0.05 (R Core Team, 2021).

Results

Experiment 1: The cyanobacterium and green alga strains responded differently to the treatments and time (Table 2). Ceratophyllum demersum significantly reduced the biomass of M. aeruginosa from the second day of the experiment in treatment M (P < 0.05) (Fig. 1A). However, R. subcapitata was not significantly affected in treatment M when compared to the control (P > 0.05) until the sixth day. After that, R. subcapitata showed significantly higher biomass in the treatment M, compared to the control (P < 0.05) (Fig. 1B).

Table 2 Results of the three-way repeated-measures ANOVA comparing the effects of Ceratophyllum demersum (macrophyte), Moina micrura (zooplankton), and time on the biomass of Microcystis aeruginosa and Raphidocelis subcapitata in the first experiment. 

Factors df F p
Microcystis aeruginosa
Macrophyte 1 6681.14 < 0.001
Zooplankton 1 1129.62 < 0.001
Time 5 120.38 < 0.001
Macrophyte:Zooplankton 1 726.46 < 0.001
Macrophyte:Time 5 206.70 < 0.001
Zooplankton:Time 5 182.68 < 0.001
Macrophyte:Zooplankton:Time 5 194.49 < 0.001
Raphidocelis subcapitata
Macrophyte 1 25.65 0.037
Zooplankton 1 23.12 0.041
Time 5 174.30 < 0.001
Macrophyte:Zooplankton 1 73.75 0.013
Macrophyte:Time 5 8.27 0.003
Zooplankton:Time 5 13.26 < 0.001
Macrophyte:Zooplankton:Time 5 20.39 < 0.001

Fig. 1 Isolated effects of Ceratophyllum demersum (M) and Moina micrura (Z), besides the combined addition of C. demersum and M. micrura (MZ), and control (C) on A. Microcystis aeruginosa and B. Raphidocelis subcapitata in mixed cultures for ten days. The different letters indicate significant differences between treatments for each day (P < 0.05). Lines and shaded areas represent the mean and 95 % confidence interval, respectively. 

With the addition of cladocerans, there was a significant reduction in the biomass of M. aeruginosa (P < 0.05) from the fourth day (Fig. 1A). Regarding the green alga, M. micrura stimulated the growth of R. subcapitata on the eighth day, with significant differences when compared to the control (P < 0.05) and showing no significant grazing by cladocerans (Fig. 1B).

The coexistence of aquatic macrophytes with the cladoceran in the MZ treatment significantly reduced the biomass of M. aeruginosa from the second day of the experiment compared to the control (P < 0.05) but did not show significant differences to the M treatment (P > 0.05) (Fig. 1A). For green alga, the combined treatment of the plant and microcrustacean (MZ) did not alter the biomass of R. subcapitata (P > 0.05) (Fig. 1B). Raphidocelis subcapitata also did not show any significant differences between the treatments M, Z, and MZ (P > 0.05). During the experiment, R. subcapitata tended to form small to large colonies in all treatments with the macrophyte and the cladoceran (data not shown).

Experiment 2: The mixed cultures, with different ratios of M. aeruginosa and R. subcapitata, showed distinct responses to the treatments and time (Table 3). In the controls, M. aeruginosa (M:R 1:0) maintained a constant growth (Fig. 2A), while R. subcapitata (M:R 0:1) decreased its growth during the experiment (Fig. 2B). For the treatment with 75 % Microcystis and 25 % Raphidocelis (M:R 3:1), both cyanobacterium and green alga did not differ from the controls throughout the experiment (P > 0.05) (Fig. 2A, Fig. 2B). The opposite effect was observed for the treatment with 25 % Microcystis and 75 % Raphidocelis (M:R 1:3), when the green alga strain significantly inhibited the growth of Microcystis from the second day of the experiment (P < 0.05) (Fig. 2A). Also, Raphidocelis presented higher growth rates in treatment M:R 1:3 than in M:R 1:1 on the fourth and eighth days. In equal proportions of microalgal biomass, i.e. 50 % of both strains (M:R 1:1), neither strain differed significantly from the controls (P > 0.05) (Fig. 2).

Fig. 2 Growth rate of A. Microcystis aeruginosa and B. Raphidocelis subcapitata in treatments with different M:R (Microcystis:Raphidocelis) ratios: 1:0, 3:1, 1:1, 1:3, and 0:1 during ten days of the experiment. The different letters indicate significant differences between treatments for each day (P < 0.05). Bars and error bars represent the mean and standard deviation, respectively. 

Table 3 Results of the two-way repeated-measures ANOVA comparing the effects of different ratios between Microcystis and Raphidocelis and time on the growth rate of Microcystis aeruginosa and Raphidocelis subcapitata in the second experiment. 

Factors df F p
Microcystis aeruginosa - Growth rate
Ratios 3 1049.02 < 0.001
Time 4 16.27 < 0.001
Ratios:Time 12 22.26 < 0.001
Raphidocelis subcapitata - Growth rate
Ratios 3 5.74 0.034
Time 4 152.95 < 0.001
Ratios:Time 12 2.75 0.017

Regarding the ratio between the biomass of M. aeruginosa and R. subcapitata in the treatments with the dominance of M. aeruginosa (M:R 3:1) or in equal proportions (M:R 1:1), there was an increase in the relative participation of cyanobacteria compared to green algae from the fourth day until the end of the experiment. On the other hand, under the dominance of R. subcapitata (M:R 1:3), M. aeruginosa showed a reduction in relative participation from the second day (Fig. 3).

Fig. 3 The ratio between the biomass of M. aeruginosa and R. subcapitata in treatments with 75 % Microcystis and 25 % Raphidocelis (3:1), 50 % Microcystis and 50 % Raphidocelis (1:1), and 25 % Microcystis and 75 % Raphidocelis (1:3) during 10 days of the experiment. Lines and shaded areas represent the mean and 95 % confidence interval, respectively. 

Discussion

Competition for nutrients (Zhang et al., 2013), light (Marinho et al., 2013), and allelopathy (Bittencourt-Oliveira et al., 2015; Harel et al., 2013) are variables that strongly regulate the development of phytoplankton species. The availability of nitrogen and phosphorus contributes to the growth and helps to maintain the metabolism of microalgae, increasing the biomass of species that better absorb inorganic compounds (Carey et al., 2012; Markou et al., 2014). Nevertheless, in our study, we excluded the effect of nutrient competition by using ASM1 culture medium in optimum quantities for the development of both strains.

The presence of morphological structures that facilitate fluctuation, as well as the presence of accessory pigments that protect cells from excessive light, are adaptive advantages that cyanobacteria species present (Carey et al., 2012). Microcystis aeruginosa is a strong competitor for light, as verified by Marinho et al. (2013). However, we discarded this type of competition through the uniform and random light supply between treatments, as well as by manually agitating the experimental units three times a day to reduce cell sedimentation. Finally, by excluding other possible forms of competition, we suggest that allelopathy was the main mechanism of action among photosynthesizing organisms, especially the macrophyte Ceratophyllum demersum.

In treatments with C. demersum, cyanobacterial biomass was reduced too much after the second day of coexistence. Previously, Amorim et al. (2019a) reported that the biomass of M. aeruginosa was inhibited by the presence of C. demersum in unialgal cultures. Therefore, the macrophyte effect could be attributed to allelopathy herein, as also verified by Nakai et al. (1999), Dong et al. (2014), and Amorim et al. (2019a). Furthermore, in a field experiment, Amorim and Moura (2020) showed a significant reduction in cyanobacterial blooms composed mainly of Microcystis spp. (reduction of 85 % in the total biomass and 99 % in the biomass of filamentous morphotypes) by C. demersum in a tropical reservoir in Northeast Brazil.

Studies highlight that M. aeruginosa is sensitive to chemical compounds released by several macrophyte species (Nakai et al., 1999; Zhu et al., 2010). In this case, Ceratophyllum demersum, a free-living submerged macrophyte, can produce secondary metabolites (Hilt & Gross, 2008) which inhibit competitors’ photosystem II, compromising the photosynthetic activities of the target cell (Körner & Nicklisch, 2002). Sulfur or lipophilic labile sulfur compounds are the major allelopathic substances released by C. demersum (Wium-Andersen et al., 1983). Also, some volatile compounds from C. demersum, including fatty compounds, terpenoids, phenolic compounds, and phthalates, can show a strong inhibitory effect on M. aeruginosa (Xian et al., 2006). Further compounds present in C. demersum tissues, such as hexanoic acid, phthalic acid, octanedioic acid, butenoic acid, azelaic acid, palmitic acid, alpha-linolenic acid, and pentanedioic acid, can also inhibit the growth and induce colony formation in green algae species (Dong et al., 2019). Therefore, allelopathy can act as one of the main adaptative strategies of submerged macrophytes, especially C. demersum, in their competition with phytoplankton (Gross et al., 2003), as well as to maintain the clear state of shallow lakes (Hilt & Gross, 2008). So, this macrophyte can support the eutrophic and cyanobacterial blooms conditions, as it has potent antioxidant and biotransformation mechanisms to alleviate the effects of cyanotoxins on its physiology, besides removing cyanotoxins from the water (Pflugmacher, 2004).

In our study, M. aeruginosa was significantly inhibited in coexistence with an allelochemical-producing macrophyte and green algae, differing from the results observed by Chang et al. (2012), who recorded the stimulus of M. aeruginosa in coexistence with a submerged macrophyte and the chlorophyte Desmodesmus armatus (R. Chodat) E. Hegewald. Furthermore, R. subcapitata was not inhibited in coexistence with C. demersum (M and MZ treatments), corroborating the results of Amorim et al. (2019a), who found that biomass from R. subcapitata was not significantly affected by C. demersum throughout the experiment. This response could be attributed to the low sensitivity of chlorophytes to the inhibitory metabolites released by macrophytes in comparison to cyanobacteria, as verified by Zhu et al. (2010). Moreover, Körner and Nicklisch (2002) suggest that phytoplankton species can physiologically adapt to allelochemicals. One important evolutionary adaptation of green algae to coexist with allelopathically active macrophytes is colony formation (Dong et al., 2018), as also observed in our study for R. subcapitata.

In tests with the addition of cladocerans, we observed that the cyanobacterial biomass was significantly reduced from the fourth day and the green alga was stimulated on the eighth day, differing statistically from the control. This result differs from previous findings in the literature, where zooplankton are assumed to select the palatable food source in co-cultures, and thus stimulate cyanobacterial growth (Leitão et al., 2018; Severiano et al., 2021). However, in experimental studies, Guo and Xie (2006) found that populations of M. micrura pre-exposed to toxic strains M. aeruginosa may become more resistant to cyanobacteria metabolites compared to other large cladocerans, enabling the predation of cyanobacteria. Herein, the cladoceran M. micrura proved to be resistant to toxins from the Microcystis strain, which may have favored its predation on cyanobacteria, considering that the cladoceran was isolated from a reservoir with a history of Microcystis blooms (Moura et al., 2015; Amorim et al., 2020). Similarly, Santos et al. (2021) showed that cladocerans isolated from lakes with cyanobacterial blooms are less affected by cyanotoxins through the diet or the absorption of dissolved toxins.

Although being considered a palatable food source for zooplankton, R. subcapitata was stimulated in treatment Z, instead of being grazed. This can be attributed to the colony formation in the presence of predators or competitors. Both the presence of macrophytes and zooplankton grazers can induce colony formation in green algae species, with a strong effect in the presence of zooplankton cues, which can act as an important anti-grazer defense (Zhu et al., 2021). The stimulus of Raphidocelis in cladoceran treatments can also be attributed to a reduction in Microcystis biomass. Furthermore, zooplankton contributes to nutrient cycling in the water column, favoring the growth of phytoplankton species (Attayde & Hansson, 1999), which may justify the significant stimulus of R. subcapitata in Z treatment.

As for the interaction between microalgae, different results between Microcystis and Raphidocelis were observed. Raphidocelis subcapitata inhibited M. aeruginosa in the treatment with low concentrations of cyanobacteria (M:R ratio 1:3). Li and Li (2012), in co-cultivation experiments with M. aeruginosa and Anabaena, found that the species with higher proportions at the beginning of cultivation (1:9 and 9:1) remained dominant throughout the experiment. In our study, although M. aeruginosa did not inhibit R. subcapitata growth when dominant (M:R 3:1), the ratio between Microcystis and Raphidocelis increased throughout the experiment, showing that M. aeruginosa remained dominant, corroborating with Li and Li (2012). Another factor that may be strictly related to the inhibition of M. aeruginosa is allelopathy. Some chlorophyte species can release chemical compounds that inhibit cyanobacteria, as verified by Harel et al. (2013), who demonstrated that Scenedesmus sp. inhibited the growth of Microcystis sp. by producing secondary metabolites that disrupted the cell membranes of cyanobacteria.

Bittencourt-Oliveira et al. (2015) showed that the density of M. aeruginosa decreased in mixed cultures with 1:1 ratios of cyanobacteria and chlorophytes Monoraphidium convolutum (Corda) Komárková-Legnerová and Scenedesmus acuminatus (Lagerheim) Chodat, with more significant effects when coexisting with the latter species. However, in our experiment, the growth rates of M. aeruginosa and R. subcapitata did not differ statistically from controls in the treatment with proportions of M:R 1:1. Li and Li (2012) found that M. aeruginosa and Anabaena, in 1:1 ratios, maintained similar growth for 15 days, reinforcing that the dominance of a given strain is related to the values of inoculated biomass on the first day. This result also reinforces the main effects of the submerged macrophyte and the cladoceran in the first experiment, proving that the microalgae species do not affect each other under the same proportion of biomass.

The submerged macrophyte C. demersum considerably inhibited M. aeruginosa in coexistence with the green alga, controlling the cyanobacteria biomass, differing from previous research (e.g., Chang et al., 2012). However, this macrophyte stimulated R. subcapitata growth since the chlorophytes present physiological mechanisms that protect them against the allelopathic effects of C. demersum. The cladoceran M. micrura also reduced the biomass of M. aeruginosa and favored the growth of R. subcapitata, but in a less remarkable way than the macrophyte C. demersum, also differing from previous findings where zooplankton can graze on palatable food and stimulate cyanobacterial growth (Leitão et al., 2018). As we used a cladoceran isolated from a hypereutrophic reservoir, already adapted to cyanobacterial blooms, it could efficiently graze on cyanobacteria. In small ratios, M. aeruginosa was severely inhibited by R. subcapitata in comparison to the competitor. However, in equal and dominant proportions, no cyanobacteria inhibition was observed. Unlike M. aeruginosa, R. subcapitata was not inhibited in low proportions but maintained constant growth when compared to the control. On the other hand, in cultures with lower proportions of M. aeruginosa, chlorophyte was stimulated.

These results reinforce the applicability of submerged macrophytes and cladocerans, both isolated and combined, to control cyanobacterial blooms. The coexistence with other microalgal species does not reduce the allelopathic effect of the submerged macrophytes or grazing efficiency of the cladoceran on cyanobacteria but can increase the inhibitory effect when the proportion of cyanobacteria is low. However, it is important to use organisms already adapted to the cyanobacterial blooms and eutrophic conditions. Besides that, the reduction of external sources of nutrients and fish biomanipulation should be considered to allow the development of macrophytes and zooplankton.

Ethical statement: the authors declare that they all agree with this publication and made significant contributions; that there is no conflict of interest of any kind; and that we followed all pertinent ethical and legal procedures and requirements. All financial sources are fully and clearly stated in the acknowledgements section. A signed document has been filed in the journal archives.

Acknowledgments

This work was supported by the Brazilian National Council of Technological and Scientific Development (CNPq) Brazil (grant ID 305829/2019-0), and Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (FACEPE), Brazil (grant ID BIC-1020-2.03/18).

References

Amorim, C. A., Dantas, Ê. W., & Moura, A. N. (2020). Modeling cyanobacterial blooms in tropical reservoirs: The role of physicochemical variables and trophic interactions. Science of The Total Environment, 744, 140659. https://doi.org/10.1016/j.scitotenv.2020.140659 [ Links ]

Amorim, C. A., & Moura, A. N. (2020). Effects of the manipulation of submerged macrophytes, large zooplankton, and nutrients on a cyanobacterial bloom: A mesocosm study in a tropical shallow reservoir. Environmental Pollution, 265, 114997. https://doi.org/10.1016/j.envpol.2020.114997 [ Links ]

Amorim, C. A., & Moura, A. N. (2021). Ecological impacts of freshwater algal blooms on water quality, plankton biodiversity, structure, and ecosystem functioning. Science of The Total Environment, 758, 143605. https://doi.org/10.1016/j.scitotenv.2020.143605 [ Links ]

Amorim, C. A., Moura-Falcão, R. H., Valença, C. R., Souza, V. R., & Moura, A. N. (2019a). Allelopathic effects of the aquatic macrophyte Ceratophyllum demersum L. on phytoplankton species: contrasting effects between cyanobacteria and chlorophytes. Acta Limnologica Brasiliensia, 31, e21. https://doi.org/10.1590/s2179-975x1419 [ Links ]

Amorim, C. A., Ulisses, C., & Moura, A. N. (2017). Biometric and physiological responses of Egeria densa Planch. cultivated with toxic and non-toxic strains of Microcystis. Aquatic Toxicology, 191, 201-208. https://doi.org/10.1016/j.aquatox.2017.08.012 [ Links ]

Amorim, C. A., Valença, C. R., Moura-Falcão, R. H., & Moura, A. N. (2019b). Seasonal variations of morpho-functional phytoplankton groups influence the top-down control of a cladoceran in a tropical hypereutrophic lake. Aquatic Ecology, 53(3), 453-464. https://doi.org/10.1007/s10452-019-09701-8 [ Links ]

Attayde, J. L., & Hansson, L. A. (1999). Effects of nutrient recycling by zooplankton and fish on phytoplankton communities. Oecologia, 121(1), 47-54. https://doi.org/10.1007/s004420050906 [ Links ]

Azevedo, S. M. F. O., Carmichael, W. W., Jochimsen, E. M., Rinehart, K. L., Lau, S., Shaw, G. R., & Eaglesham, G. K. (2002). Human intoxication by microcystins during renal dialysis treatment in Caruaru-Brazil. Toxicology, 181, 441-446. https://doi.org/10.1016/S0300-483X(02)00491-2 [ Links ]

Bittencourt-Oliveira, M. C., Chia, M. A., Oliveira, H. S. B., Araújo, M. K. C., Molica, R. J. R., & Dias, C. T. S. (2015). Allelopathic interactions between microcystin-producing and non-microcystin-producing cyanobacteria and green microalgae: implications for microcystins production. Journal of Applied Phycology, 27(1), 275-284. https://doi.org/10.1007/s10811-014-0326-2 [ Links ]

Bownik, A. (2016). Harmful algae: Effects of cyanobacterial cyclic peptides on aquatic invertebrates-a short review. Toxicon, 124, 26-35. https://doi.org/10.1016/j.toxicon.2016.10.017 [ Links ]

Carey, C. C., Ibelings, B. W., Hoffmann, E. P., Hamilton, D. P., & Brookes, J. D. (2012). Eco-physiological adaptations that favour freshwater cyanobacteria in a changing climate. Water Research, 46(5), 1394-1407. https://doi.org/10.1016/j.watres.2011.12.016 [ Links ]

Carmichael, W. W., & Boyer, G. L. (2016). Health impacts from cyanobacteria harmful algae blooms: Implications for the North American Great Lakes. Harmful Algae, 54, 194-212. https://doi.org/10.1016/j.hal.2016.02.002 [ Links ]

Chang, X., Eigemann, F., & Hilt, S. (2012). Do macrophytes support harmful cyanobacteria? Interactions with a green alga reverse the inhibiting effects of macrophyte allelochemicals on Microcystis aeruginosa. Harmful Algae, 19, 76-84. https://doi.org/10.1016/j.hal.2012.06.002 [ Links ]

Chen, J., Xie, P., Li, L., & Xu, J. (2009). First identification of the hepatotoxic microcystins in the serum of a chronically exposed human population together with indication of hepatocellular damage. Toxicological Sciences, 108(1), 81-89. https://doi.org/10.1093/toxsci/kfp009 [ Links ]

Chen, J., Zhang, H., Han, Z., Ye, J., & Liu, Z. (2012). The influence of aquatic macrophytes on Microcystis aeruginosa growth. Ecological Engineering, 42, 130-133. https://doi.org/10.1016/j.ecoleng.2012.02.021 [ Links ]

Cirés, S., & Ballot, A. (2016). A review of the phylogeny, ecology and toxin production of bloom-forming Aphanizomenon spp. and related species within the Nostocales (cyanobacteria). Harmful Algae, 54, 21-43. https://doi.org/10.1016/j.hal.2015.09.007 [ Links ]

Dantas, D. D. F., Rubim, P. L., Oliveira, F. A., Costa, M. R. A., Moura, C. G. B., Teixeira, L. H., & Attayde, J. L. (2019). Effects of benthivorous and planktivorous fish on phosphorus cycling, phytoplankton biomass and water transparency of a tropical shallow lake. Hydrobiologia, 829, 31e41. https://doi.org/10.1007/s10750-018-3613-0 [ Links ]

Diniz, A. S., Severiano, J. S., Melo Júnior, M., Dantas, Ê. W., & Moura, A. N. (2019). Phytoplankton-zooplankton relationships based on phytoplankton functional groups in two tropical reservoirs. Marine and Freshwater Research, 70(5), 721. https://doi.org/10.1071/MF18049 [ Links ]

Dong, J., Chang, M., Li, C., Dai, D., & Gao, Y. (2019). Allelopathic effects and potential active substances of Ceratophyllum demersum L. on Chlorella vulgaris Beij. Aquatic Ecology, 53(4), 651-663. https://doi.org/10.1007/s10452-019-09715-2 [ Links ]

Dong, J., Gao, Y., Chang, M., Ma, H., Han, K., Tao, X., & Li, Y. (2018). Colony formation by the green alga Chlorella vulgaris in response to the competitor Ceratophyllum demersum. Hydrobiologia, 805(1), 177-187. https://doi.org/10.1007/S10750-017-3294-0/FIGURES/6 [ Links ]

Dong, J., Yang, K., Li, S., Li, G., & Song, L. (2014). Submerged vegetation removal promotes shift of dominant phytoplankton functional groups in a eutrophic lake. Journal of Environmental Sciences, 26(8), 1699-1707. https://doi.org/10.1016/j.jes.2014.06.010 [ Links ]

Ger, K. A., Urrutia-Cordero, P., Frost, P. C., Hansson, L. A., Sarnelle, O., Wilson, A. E., & Lürling, M. (2016). The interaction between cyanobacteria and zooplankton in a more eutrophic world. Harmful Algae, 54, 128-144. https://doi.org/10.1016/j.hal.2015.12.005 [ Links ]

Gorham, P. R., McLachlan, J., Hammer, U. T., & Kim, W. K. (1964). Isolation and culture of toxic strains of Anabaena flos-aquae (Lyngb.) de Bréb. SIL Proceedings, 1922-2010, 15(2), 796-804. https://doi.org/10.1080/03680770.1962.11895606 [ Links ]

Gross, E. M., Erhard, D., & Iványi, E. (2003). Allelopathic activity of Ceratophyllum demersum L. and Najas marina ssp. intermedia (Wolfgang) Casper. Hydrobiologia, 506, 583-589. [ Links ]

Guo, N., & Xie, P. (2006). Development of tolerance against toxic Microcystis aeruginosa in three cladocerans and the ecological implications. Environmental Pollution, 143(3), 513-518. https://doi.org/10.1016/j.envpol.2005.11.044 [ Links ]

Harel, M., Weiss, G., Lieman-Hurwitz, J., Gun, J., Lev, O., Lebendiker, M., Temper, V., Block, C., Sukenik, A., Zohary, T., Braun, S., Carmeli, S., & Kaplan, A. (2013). Interactions between Scenedesmus and Microcystis may be used to clarify the role of secondary metabolites. Environmental Microbiology Reports, 5(1), 97-104. https://doi.org/10.1111/j.1758-2229.2012.00366.x [ Links ]

Harke, M. J., Steffen, M. M., Gobler, C. J., Otten, T. G., Wilhelm, S. W., Wood, S. A., & Paerl, H. W. (2016). A review of the global ecology, genomics, and biogeography of the toxic cyanobacterium, Microcystis spp. Harmful Algae, 54, 4-20. https://doi.org/10.1016/j.hal.2015.12.007 [ Links ]

Hillebrand, H., Dürselen, C. D., Kirschtel, D., Pollingher, U., & Zohary, T. (1999). Biovolume calculation for pelagic and benthic microalgae. Journal of Phycology, 35(2), 403-424. https://doi.org/10.1046/j.1529-8817.1999.3520403.x [ Links ]

Hilt, S., & Gross, E. M. (2008). Can allelopathically active submerged macrophytes stabilise clear-water states in shallow lakes? Basic and Applied Ecology, 9(4), 422-432. https://doi.org/10.1016/j.baae.2007.04.003 [ Links ]

Ibelings, B. W., & Chorus, I. (2007). Accumulation of cyanobacterial toxins in freshwater “seafood” and its consequences for public health: A review. Environmental Pollution, 150(1), 177-192. https://doi.org/10.1016/j.envpol.2007.04.012 [ Links ]

Körner, S., & Nicklisch, A. (2002). Allelopathic growth inhibition of selected phytoplankton species by submerged macrophytes. Journal of Phycology, 38(5), 862-871. https://doi.org/10.1046/j.1529-8817.2002.t01-1-02001.x [ Links ]

Leitão, E., Ger, K. A., & Panosso, R. (2018). Selective grazing by a tropical copepod (Notodiaptomus iheringi) facilitates Microcystis dominance. Frontiers in Microbiology, 9, 301. https://doi.org/10.3389/FMICB.2018.00301/BIBTEX [ Links ]

Li, Y., & Li, D. (2012). Competition between toxic Microcystis aeruginosa and nontoxic Microcystis wesenbergii with Anabaena PCC7120. Journal of Applied Phycology, 24(1), 69-78. https://doi.org/10.1007/s10811-010-9648-x [ Links ]

Li, B., Liu, Y., Zhang, H., Liu, Y., Liu, Y., & Xie, P. (2021). Research progress in the functionalization of microcystin-LR based on interdisciplinary technologies. Coordination Chemistry Reviews, 443, 214041. https://doi.org/10.1016/j.ccr.2021.214041 [ Links ]

Marinho, M. M., Souza, M. B. G., & Lürling, M. (2013). Light and Phosphate Competition Between Cylindrospermopsis raciborskii and Microcystis aeruginosa is Strain Dependent. Microbial Ecology, 66(3), 479-488. https://doi.org/10.1007/s00248-013-0232-1 [ Links ]

Markou, G., Vandamme, D., & Muylaert, K. (2014). Microalgal and cyanobacterial cultivation: The supply of nutrients. Water Research, 65, 186-202. https://doi.org/10.1016/j.watres.2014.07.025 [ Links ]

Menezes, R. F., Attayde, J. L., & Rivera Vasconcelos, F. (2010). Effects of omnivorous filter-feeding fish and nutrient enrichment on the plankton community and water transparency of a tropical reservoir. Freshwater Biology, 55, 767-779. https://doi.org/10.1111/j.1365-2427.2009.02319.x [ Links ]

Mohamed, Z. A. (2017). Macrophytes-cyanobacteria allelopathic interactions and their implications for water resources management - A review. Limnologica, 63, 122-132. https://doi.org/10.1016/j.limno.2017.02.006 [ Links ]

Moura, A. N., Aragão-Tavares, N. K., & Amorim, C. A. (2018). Cyanobacterial blooms in freshwater bodies from a semiarid region, Northeast Brazil: A review. Journal of Limnology, 77(2), 179-188. https://doi.org/10.4081/jlimnol.2017.1646 [ Links ]

Moura, A. N., Bittencourt-Oliveira, M. C., Chia, M. A., & Severiano, J. S. (2015). Co-occurrence of Cylindrospermopsis raciborskii (Woloszynska) Seenaya & Subba Raju and Microcystis panniformis Komárek et al. in Mundaú reservoir, a semiarid Brazilian ecosystem. Acta Limnologica Brasiliensia, 27(3), 322-329. https://doi.org/10.1590/S2179-975X3814 [ Links ]

Nakai, S., Inoue, Y., Hosomi, M., & Murakami, A. (1999). Growth inhibition of blue-green algae by allelopathic effects of macrophytes. Water Science and Technology, 39(8), 47-53. https://doi.org/10.1016/S0273-1223(99)00185-7 [ Links ]

O’Neil, J. M., Davis, T. W., Burford, M. A., & Gobler, C. J. (2012). The rise of harmful cyanobacteria blooms: The potential roles of eutrophication and climate change. Harmful Algae, 14, 313-334. https://doi.org/10.1016/j.hal.2011.10.027 [ Links ]

Okun, N., Brasil, J., Attayde, J. L., & Costa, I. A. (2008). Omnivory does not prevent trophic cascades in pelagic food webs. Freshwater Biology, 53, 129-138. https://doi.org/10.1111/j.1365-2427.2007.01872.x [ Links ]

Paerl, H. W., & Otten, T. G. (2013). Harmful Cyanobacterial Blooms: Causes, Consequences, and Controls. Microbial Ecology, 65(4), 995-1010. https://doi.org/10.1007/s00248-012-0159-y [ Links ]

Pflugmacher, S. (2004). Promotion of oxidative stress in the aquatic macrophyte Ceratophyllum demersum during biotransformation of the cyanobacterial toxin microcystin-LR. Aquatic Toxicology, 70(3), 169-178. https://doi.org/10.1016/j.aquatox.2004.06.010 [ Links ]

R Core Development Team. (2021). R: A language and environment for statistical computing (Software). https://www.R-project.orgLinks ]

Santos, A. S. A., Vilar, M. C. P., Amorim, C. A., Molica, R. J. R., & Moura, A. N. (2021). Exposure to toxic Microcystis via intact cell ingestion and cell crude extract differently affects small-bodied cladocerans. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-021-17402-9 [ Links ]

Severiano, J. S., Almeida-Melo, V. L. S., Bittencourt-Oliveira, M. C., Chia, M. A., & Moura, A. N. (2018). Effects of increased zooplankton biomass on phytoplankton and cyanotoxins: A tropical mesocosm study. Harmful Algae, 71, 10-18. https://doi.org/10.1016/j.hal.2017.11.003 [ Links ]

Severiano, J. S., Amaral, C. B., Diniz, A. S., & Moura, A. N. (2021). Species-specific response of phytoplankton to zooplankton grazing in tropical eutrophic reservoirs. Acta Limnologica Brasiliensia, 33, 17. https://doi.org/10.1590/s2179-975x10719 [ Links ]

Vanderstukken, M., Declerck, S. A. J., Decaestecker, E., & Muylaert, K. (2014). Long-term allelopathic control of phytoplankton by the submerged macrophyte Elodea nuttallii. Freshwater Biology, 59(5), 930-941. https://doi.org/10.1111/fwb.12316 [ Links ]

Wiegand, C., & Pflugmacher, S. (2005). Ecotoxicological effects of selected cyanobacterial secondary metabolites a short review. Toxicology and Applied Pharmacology, 203(3), 201-218. https://doi.org/10.1016/j.taap.2004.11.002 [ Links ]

Wium-Andersen, S., Anthoni, U., & Houen, G. (1983). Elemental sulphur, a possible allelopathic compound from Ceratophyllum demersum. Phytochemistry, 22(11), 2613. [ Links ]

Wood, A. M., Everroad, R. C., & Wingard, L. M. (2005). Measuring Growth Rates in Microalgal Cultures. Algal Culturing Techniques, 18, 269-285. https://doi.org/10.1016/B978-012088426-1/50019-6 [ Links ]

Xian, Q., Chen, H., Zou, H., & Yin, D. (2006). Allelopathic activity of volatile substance from submerged macrophytes on Microcystin aeruginosa. Acta Ecologica Sinica, 26(11), 3549-3554. https://doi.org/10.1016/S1872-2032(06)60054-1 [ Links ]

Zhang, P., Zhai, C., Wang, X., Liu, C., Jiang, J., & Xue, Y. (2013). Growth competition between Microcystis aeruginosa and Quadrigula chodatii under controlled conditions. Journal of Applied Phycology, 25(2), 555-565. https://doi.org/10.1007/s10811-012-9890-5 [ Links ]

Zhu, J., Liu, B., Wang, J., Gao, Y., & Wu, Z. (2010). Study on the mechanism of allelopathic influence on cyanobacteria and chlorophytes by submerged macrophyte (Myriophyllum spicatum) and its secretion. Aquatic Toxicology, 98(2), 196-203. https://doi.org/10.1016/j.aquatox.2010.02.011 [ Links ]

Zhu, X., Wang, Z., Zhou, Q., Sun, Y., Zhang, L., Wang, J., Yang, Z., & Huang, Y. (2021). Species-specific effects of macrophytes on the anti-grazer morphological defense in Scenedesmus obliquus. Ecological Indicators, 120, 106942. https://doi.org/10.1016/J.ECOLIND.2020.106942 [ Links ]

Zurawell, R. W., Chen, H., Burke, J. M., & Prepas, E. E. (2005). Hepatotoxic Cyanobacteria: A Review of the Biological Importance of Microcystins in Freshwater Environments. Journal of Toxicology and Environmental Health, Part B, 8(1), 1-37. https://doi.org/10.1080/10937400590889412 [ Links ]

Received: June 29, 2020; Revised: November 10, 2021; Accepted: November 25, 2021

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