As July ends and we welcome August we are in the time of year that we have typically seen more toxin producing phytoplankton in Kachemak Bay. There are three species of concern in Kachemak Bay that can produce toxins and lead to shellfish poisoning when shellfish accumulate these species, they are Alexandrium, Dinophysis and Pseudo-nitzschia. In Alaska the presence of these species has not yet been associated with any change in the color of the water. A few factors that can influence the color of our coastal waters are run-off, spruce pollen or other pollens, and tidal changes. To date harmful algal blooms in Kachemak Bay have not been associated with changes in water color. Toxins produced by harmful algal blooms are accumulated and flushed from shellfish tissue at different rates depending on the shellfish species. Mussels for example tend to accumulate toxins relatively rapidly and flush them over several days. This contrasts with the butter clam that can accumulate toxins and remain toxic for up to 2 years. Washing, cooking and freezing do not break down the toxins in shellfish tissue.
Additional information, including qualitative analysis of phytoplankton data, is available in the Phytoplankton Update for Jul. 24th – Jul. 30th.