Yehonatan Bar-Yosef, a PhD student in Prof. Aaron Kaplan’s group at the Hebrew University’s Alexander Silberman Institute of Life Sciences, suggests a novel mechanism in a paper published online on Thursday in Current Biology.

A toxic cyanobacterial blue-green alga known as Aphanizomenon ovalisporum was first detected in Lake Kinneret in 1994, and its presence has been noted each summer since. However, how the toxic algae bloomed has remained a mystery.

Bar-Yosef has discovered that Aphanizomenon is known to produce the toxin cylindrospermopsin (CYN). Secretion of the CYN, Bar-Yosef found, induces phosphate-limitation responses in other microorganisms in the ecosystem, even in the presence of ample phosphate in the water. Phosphate is an essential nutrient for growth in many organisms.

By blocking other organisms from absorbing phosphate, Aphanizomenon reserves more of the mineral for itself.

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