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

• Published in: Harmful algae Vol. 74; pp. 67 - 77
• Main Authors: Chia, Mathias A., Jankowiak, Jennifer G., Kramer, Benjamin J., Goleski, Jennifer A., Huang, I-Shuo, Zimba, Paul V., do Carmo Bittencourt-Oliveira, Maria, Gobler, Christopher J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2018
• Subjects: algal blooms; allelochemicals; allelopathy; Anabaena; Anatoxin; Aquatic ecosystems; coculture; Cyanotoxins; Diazotrophs; enzyme activity; filtrates; Glutathione S-transferase; glutathione transferase; Interspecific competitions; Microcystin; microcystins; Microcystis; mixed culture; nitrogen; nitrogen fixation; nutrient availability; nutrient content; Phytoplankton; poisonous algae; toxicity; Diazotrophs; Cyanotoxins; Anatoxin; Microcystin; Phytoplankton; Interspecific competitions; Glutathione S-transferase; Aquatic ecosystems
• ISSN: 1568-9883; 1878-1470; 1878-1470
• DOI: 10.1016/j.hal.2018.03.002

[Display omitted] •Microcystis inhibited the growth of Anabaena strains under high nutrient levels.•Allelopathic interactions were partly dependent on ambient nutrient levels.•Microcystin content of Microcystis was reduced by low nitrogen and Anabaena.•Anabaena dominated under low N, while Microcystis dominated under high N and low P.•Allelochemicals suppressed anatoxin production and N2-fixation by Anabaena. 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.