Succession and toxicity of Microcystis and Anabaena ( Dolichospermum ) blooms are controlled by nutrient-dependent allelopathic interactions

Abstract

Microcystis and Anabaena (Dolichospermum) are among the most toxic cyanobacterial genera and often succeed each other during harmful algal blooms. The role allelopathy plays in the succession of these genera is not fully understood. The allelopathic interactions of six strains of Microcystis and Anabaena under different nutrient conditions in co-culture and in culture-filtrate experiments were investigated. Microcystis strains significantly reduced the growth of Anabaena strains in mixed cultures with direct cell-to-cell contact and high nutrient levels. Cell-free filtrate from Microcystis cultures proved equally potent in suppressing the growth of nutrient replete Anabaena cultures while also significantly reducing anatoxin-a production. Allelopathic interactions between Microcystis and Anabaena were, however, partly dependent on ambient nutrient levels. Anabaena dominated under low N conditions and Microcystis dominated under nutrient replete and low P during which allelochemicals caused the complete suppression of nitrogen fixation by Anabaena and stimulated glutathione S-transferase activity. The microcystin content of Microcystis was lowered with decreasing N and the presence of Anabaena decreased it further under low P and high nutrient conditions. Collectively, these results indicate that strong allelopathic interactions between Microcystis and Anabaena are closely intertwined with the availability of nutrients and that allelopathy may contribute to the succession, nitrogen availability, and toxicity of cyanobacterial blooms.

Deciphering the effects of nitrogen, phosphorus, and temperature on cyanobacterial bloom intensification, diversity, and toxicity in western Lake Erie

“…Together, these finding suggest the green and brown algae may benefit from nutrient additions but are outcompeted by cyanobacteria (Dokulil and Teubner ; Wilhelm et al ; Paerl and Paul ), particularly in combination with warmer temperatures (Rigosi et al ). Beyond nutrient competition (Elliott et al ), these patterns may also be associated with allelopathic inhibition by cyanobacteria (Sukenik et al ; LeBlanc et al ; Chia et al ), which can become more intense under nutrient‐limited conditions (Chia et al ) such as those described here.…”

The Impact of Lake Water Quality on the Performance of Mature Artificial Recharge Ponds

“…The majority of the extracellular are removed in the infiltration pond, likely by microbial degradation [55]. While biodegradation on cyanotoxins was dependent on the pH and temperature [56], it might require other barrier to complement microbial activities especially when it comes to the autumn, when it is likely that cyanobacteria start to decay and release toxins in water [46]. We did not find this in our study site during the study time.…”

“…Microcystis and Anabaena (Dolichospermum) are listed as the most toxic cyanobacterial genera and often succeed each other during harmful algal blooms [46]. Woronichinia naegeliana appears frequently in freshwater and one study showed that blooms of W. naegeliana was toxic towards invertebrate zooplankton [47].…”

Bioenergy production using Trichormus variabilis – a review

“…Furthermore, T. variabilis growth is impaired by some allelochemicals such as harmane (1‐methyl‐ β ‐carboline) and fischerellin B causing cell lysis and photosynthesis inhibition respectively. Microcystins have an intense allelopathic inhibition effect on T. variabilis growth and on the differentiation of heterocysts and akinetes . The presence of such pollutants in wastewater streams affects nutrient removal efficiency by disrupting metabolic processes and consequently, disrupts bioenergy production pathways.…”