Bright Microbes; May 2012; Scientific American Magazine; by Cheryl Lyn Dybas; 1 Page(s)

Bioluminescent bays are among the rarest and most fragile of ecosystems. They form when large numbers of micro­organisms, often dinoflagellates such as Pyrodinium bahamense, congregate in a lagoon with an opening narrow enough to keep the organisms from escaping. The dinoflagellates feed on vitamin B₁₂ produced by red mangrove trees and glow bluish-­green when disturbed by motion of any kind, although scientists have yet to fully understand the phenomenon. Because “bio bays” need very specific conditions to survive, there are only a handful worldwide, and most of the known ones are in the Caribbean.

In 2010 ecologists identified a new bio bay in Puerto Rico’s Humacao Natural Re­serve and are studying it for clues to how best to preserve these ecosystems. The Humacao bio bay formed after the U.S. Army Corps of Engineers built channels to protect near­by towns from flooding. The channels allowed saltwater from the Caribbean to flow into once brackish Humacao lagoons. “Along with the tide, in came a bioluminescent dinoflagellate,” says Ricardo Colón-Rivera, an ecology graduate student at Texas A&M University.