June 3, 2026 — Algae is vital to a healthy marine system, and most of the hundreds of varieties in Alaska’s waters are beneficial or benign.
But the handful that are harmful are, like other algae, proliferating in warmer conditions and releasing or threatening to release toxins that can sicken people and wildlife and, in the worst cases, cause deaths.
The best-known type of algae that poses risks to people, mammals and birds in Alaska is called Alexandrium. The toxins it produces cause paralytic shellfish poisoning; they block the delivery of sodium to cells, thus interfering with or shutting down nerves essential to bodily functions.
The most potent Alexandrium toxin is saxitoxin, but there are related toxins produced by the same algae called gonyautoxins, or GTX. Some GTX varieties, including one detected in tomcod harvested in December by Nome-Beltz High School students in a yearslong science project, are nearly as toxic as saxitoxin. For simplicity’s sake, testing for paralytic toxins often lumps measurements of saxitoxin and GTX compounds together as “saxitoxin equivalent,” said Thomas Farrugia, coordinator of the Alaska Harmful Algal Bloom network.