Algae-Bot Scouts for Toxic Blooms

April 18, 2008 -- Some make your limbs feel numb. Some give you the stomach flu. Others will even kill you.

These are the scary consequences of shellfish poisoning caused when populations of certain types of toxic algae grow rapidly, or "bloom," in a given spot in the ocean, accumulating in oysters and other shellfish that feed on them -- and then become our dinner.

Now seafood-loving Texans can thank an underwater instrument designed by researchers with the geeky goal of studying plankton ecology for detecting a surprise bloom of a diarrhea-causing algae in the Gulf of Mexico -- just days before a major oyster festival.

The researchers believe more widespread use of this sea sentinel could improve early detection of harmful algal blooms, preventing future outbreaks of shellfish poisoning.

The instrument is the Imaging Flow Cytobot, designed by Rob Olson and Heidi Sosik at Woods Hole Oceanographic Institution in Woods Hole, Mass. It sits on the ocean floor, photographing every cell in samples of water drawn in from its surroundings, around the clock for up to six months at a time.

The Cytobot also measures laser light scattering from each particle, and sends all the information back to the lab to a central a computer that identifies each cell.

"It's something we envisioned for helping us to answer very basic questions about the diversity and ecology of plankton in the ocean," Sosik said.

But the team thought it might be useful for detecting blooms of harmful species, so they collaborated with Lisa Campbell at Texas A&M University in College Station to post another instrument in the Gulf of Mexico, to look for seasonal blooms of Karenia brevis, which can cause shellfish poisoning.

They found a bloom, but it wasn't Karenia brevis.