Oceanography Professor Tatiana Rynearson explores the real-life mystery of the shellfish-poisoning blooms.

How does a bloom get started?

An algae bloom is the result of a perfect set of conditions. Algae are like plants; they photosynthesize, so they need light and they need nutrients, like nitrogen and phosphorous. They also need to have a situation where predators aren’t there to eat all the algae.

Isn’t the timing of the last algea bloom, in the middle of winter, unusual?

You don’t generally think of blooms happening in winter—there are no flowers out yet and no leaves on the trees. But in Narragansett Bay we have a winter/spring bloom because there’s a lot of light, we have a lot of nutrients in the Bay, and some of the grazers that are so important are not around. The classic spring bloom happens many places around the world, and it’s really important for fisheries and to support the food web—it kick-starts biological activity for the year.

What do we know about this particular organism?

It’s called Pseudo-nitzschia, and it’s a genus of diatoms that has formed harmful algal blooms on the West Coast for quite some time. A lot of research has been done to try to figure what’s going on out there. Pseudo-nitzschia is comprised of a number of species, some of which produce the toxin while others don’t—and the species that produce the toxin don’t always produce the same amount, or any toxin at all. There are things going on we don’t understand.

How does it become toxic and what does it do to us?

Pseudo-nitzschia produces a toxin called domoic acid; filter feeders like clams and mussels bring it into their bodies, then get harvested and eaten by people. Domoic acid causes an illness called amnesic shellfish poisoning—you might vomit or get a headache, and you could also get a coma, develop short-term memory loss and even die. It’s potent.

Has it always been here?

We don’t actually know which species it is or where it came from. We know it’s been here for a long time. Maybe there’s a new species that we can’t identify yet—there are about 48 species in this genus, and even under a microscope, they’re hard to tell apart—or maybe the existing inhabitants of Narragansett Bay have turned toxic.