In a new paper, researchers funded by the National Centers for Coastal Ocean Science discovered that the New England red tide species called Alexandrium releases a variety of compounds to kill its predators and lengthen bloom duration. In this case, the substance they use for defense is not the potent neurotoxin that accumulates in shellfish and sickens people who eat seafood tainted with it.

The scientists put together a variety of Alexandrium strains and predators. All of them, even one that produces no neurotoxins, were equally adept at defending themselves. The investigators found that in sufficient numbers, the red tide species makes a separate, oxygen-based molecule to kill microorganisms trying to eat them. Knowing how Alexandrium prolongs its survival will lead to better early warning forecast models.

The scientists experimented with two predators and three clones of A. tamarense with varying levels of PSP toxins. Reactive oxygen species (ROS) (highly reactive oxygen compounds with unpaired electrons that can damage cells) and/or secondary compounds produced by ROS were implicated in the toxicity, with differences between the A. tamarense clones.

This project was sponsored by NCCOS'sEcology and Oceanography of Harmful Algal Blooms (ECOHAB) Program.

Read the paper online in the scientific journal Aquatic Microbial Ecology .

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In August 2012, the University of Connecticut's UConn Today covered this topic:Algal Bloom Species with Two Deadly Toxins Could Disrupt Marine Food Web