What do “red tides” have to do with PSP?
Red tides occur when temperatures, nutrients, light and calm water conditions spur rapid reproduction of ocean plankton. This increase in the number of plankton may add a reddish cast to the water. In Alaska, red tides may be caused by the dinoflagellates Protogonyaulax cantenella which causes PSP; however many nontoxic algae can also discolor the water during a bloom stage. For this reason, there is no way an individual can determine whether shellfish from a beach are toxic or not. You cannot use a red tide, or lack of one, to determine a safe time for clamming. You cannot rely on the color of the water to indicate the presence of PSP organisms, since different types of shellfish store the PSP toxin at various rates. Remember, a beach may be unsafe even if there is no discoloration of the water. How can I best avoid PSP? • Harvest only from certified beaches. • Observe all television, radio, and other media announcements concerning paralytic shellfish poisoning alerts. • Avoid all do-
