Algae do battle with bioweaponry

Beneath the frozen surface of Sweden’s lakes, algae wage wars over nutrients. One combatant apparently prevails by releasing chemicals toxic to its adversaries, according to a new study.

Researchers already have found evidence in ocean settings that dinoflagellates–a class of single-celled, photosynthesizing algae–produce toxins that they use for fending off predators. In the December 2001 Limnology and Oceanography, Karin Rengefors of Lund University and Catherine Legrand of the University of Kalmar, both in Sweden, report that the freshwater dinoflagellate Peridinium aciculiferum also produces at least one toxin. In contrast to its marine counterparts, P. aciculiferum uses the agent offensively.

The researchers explored the toxin’s function by exposing several organisms to it. Crustaceans that prey on the species were unaffected, but the toxin ruptured and killed Rhodomonas lacustris, another freshwater dinoflagellate common in Sweden.

P. aciculiferum may unleash its biological poison to vie for scarce resources such as phosphorus, says Rengefors.

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