Welcome to St Croix's Bio-Bay

St Croix's Bioluminescent Bay at Salt River

What is a Bio-Bay? In this case the word "Bio" is short for the word  bioluminescent and the "Bay" is just a body of water. The term bioluminescent or bioluminescence simply means "living light". A bioluminescent bay is a natural occurrence caused by a high concentration of bioluminescent micro-organisms called Dinoflagellates.

There are many forms of bioluminescence, on land "Fire Flies" are one form of bioluminescence that most people are familiar with. At St. Croix's Bio Bays you'll see microscopic dinoflagellates known by their scientific name "Pyrodinium bahamense" which glows whenever the water is disturbed. There are also other bioluminescent organisms that you can see at the Bio-Bays including Ctenophora (comb jellies) and glow worms.

Bio-Bays are extremely rare with only seven year-round lagoons known to exist in the Caribbean and two of them are located on the island of St Croix. The most widely known and visited is located at Salt River Bay National Historical Park and Ecological Preserve. A second Bio-Bay can be found at Altona Lagoon.

A combination of factors creates the necessary conditions for bioluminescent bays to form with the most important factor being the presence of red mangrove trees that surround the bay. A series of  studies at the Bio-Bay located at Salt River are being conducted by faculty and students from the University of South Carolina, the University of North Carolina-Wilmington and the University of the Virgin Islands. Their research is focused on analyzing quality and nutrient composition of the water, the distribution of a micro-organism, the dinoflagellate Pyrodinium bahamense, and the abundance of “cysts,” dormant dinoflagellates embedded in the sea floor. Dr. Michael Latz of the Scripps Institute of Oceanography at the University of California San Diego, an expert on bioluminescent organisms says, “Any place that has a bioluminescent bay should cherish it like a natural wonder, like a treasure”.

The two Bio-Bays on St Croix have very different characteristics. The one at Altona Lagoon is large in size but is very shallow allowing one to see the various marine life swimming and agitating the water, lighting it up. The Bio-Bay at Salt River is smaller in size but is deeper than Altona Lagoon. Because of its depth this bay is also home to a second form of bioluminescence called Ctenophora or comb-jellies, which are not found at Altona Lagoon.


For information on how the see the bioluminescence contact SeaThruKayaksVI.com

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