Bioluminescence appears in the Sarasota Bay

The week before midterms hundreds of thousands of tiny organisms graced New College with their luminous presence.

The bioluminescence in the Sarasota Bay is caused by a high concentration of dinoflagellates, tiny organisms that give off a bright flash when stimulated. According to Professor of Biology Sandra Gilchrist, dinoflagellates usually flourish in the fall and ctenophores flourish in the spring. Ctenophores are animals, as opposed to dinoflagellates, which are plants.

The bioluminescence is a chemical reaction that dinoflagellates and ctenophores both have, as well as many other organisms. Scientists speculate that it could serve many purposes, including scaring off predators or attracting mates.

The dinoflagellates, as well as the ctenophores, live in the bay year round, but their highest concentration appears from June to early October. Florida is not the only state that has bioluminescent organisms; gulf and coastal states have them as well, including Alabama, New Jersey and California.

“What happens during the fall is the nutrient conditions and the temperature conditions are such that it increases the density [of the dinoflagellates] so instead of having something that’s so dim you can’t see it you have several thousands of these that will begin to luminesce when they’re stimulated,” Gilchrist said. She added that the shallow water is also a factor because the water warms up “kind of like a soup bowl” and helps the organisms increase in number. The quality and amount of light is also an important element because dinoflagellates are photosynthetic.

Interestingly, the organisms of red tide are dinoflagellates as well, but a different genus than the bioluminescent ones. The conditions under which the density of the bioluminescent dinoflagellates increase also contribute to the concentration of organisms that cause the bloom of red tide. “It’s the same kind of phenomenon but they don’t really interact with each other,” Gilchrist said.

“It looked magical,” second-year marine biology Area of Concentration (AOC) Camila Vallejo said about the bioluminescence at the bay. “My favorite part was when the fish would move and you would be able to see them.”

Vallejo was most amazed by the fact that no matter how many times she kicked the water or threw things in the water the dinoflagellates never stopped lighting up because there were so many of them.

However, both Gilchrist and Vallejo recommend against swimming in the bay during bioluminescence, partly because if there is high red tide it can cause skin and eye irritation and also because swimming at night can mean one might be swimming with the sharks.

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