Gonyaulax various (red tide)

Can be found at any location on the surface of the water. In 1999 there was a very large toxic event south of Lincoln Park. There are various species in the genus Gonyaulax that cause these “algae blooms” and not all these events are toxic. There is a chance that a toxic species of Gonyaulax is involved, so it is important to check the Health Department’s hotline before harvesting and eating shellfish during one of these red tides.

In a toxic event some people who eat contaminated shellfish die. That’s because when the shellfish eat contaminated algae they are contaminated but not killed and can give off the paralytic shellfish poisoning to people who eat them. It takes awhile to clear the poisoning from their systems. Some people are temporarily paralyzed. One paralyzed person couldn’t even blink for 5 days. Once red tide occurs in an area, it’s there to stay. After the algae bloom they form cysts that settle to the ground where they wait for the next opportunity to bloom. People who want to farm oysters, for example, need to look for a place far from any known algae blooms in the past.  Gonyaulax doesn't always turn the water red, so you can't assume that shellfish are safe to eat just because the water looks clean.