The "Glow"    back

     The bioluminescent glow is produced by a physico-chemical reaction that begins when the single celled dinoflagelate organism is disturbed.  The defense mechanism starts a chemical chain reaction that results in a blue green glow that lasts as long as the organism is disturbed.  It is not like a "glow in the dark" toy that has to be held up to a light and charged up.  This is a reaction that occurs because a very specific set of nutrients are available in the water to sustain these little "water fireflies".
     There is actually more than one bioluminescent bay on the Island of Vieques,  the brightest is the "Mosquito Bay" - it is this bay the dinoflagelate population numbers refer to.

     Several things had to come together all in one spot for bioluminescence in Puerto Mosquito and elsewhere to have evolved:

1) Mangroves (or their ancestors) had to surround the bay and provide a habitat for specific bacterium which produces vitamin B12 in large quantities as a metabolic by-product.

2) The mouth of the bay had to be narrow to keep its waters from being washed out to sea, diluting the dinoflagelate population.

3) The location had to be remote and thus without pollution.

4) The temperature had to stay warm, and constant, within a very narrow range.

5) The water had to remain calm enough so that most of the saltier water could sink to the bottom and eventually be carried away back into the ocean by mild undercurrents, since the organisms can not thrive in the saltier ocean water.

6) The population of natural predators for the organism had to remain low.

Not specific enough? Here is a more scientific explanation of bioluminescence for those of you so inclined:

     The reaction producing bioluminescence is the direct conversion of chemical energy into light energy. In the case of the bioluminescent bay organisms (dinoflagelates), the luminosity is thought possibly to be a defense mechanism.

     The reaction begins with the creation of a large packet or quantum of light energy (photon, or energy quantum), from a highly specialized physico-chemical process.  The process is a recombination of radicals (oxide, hyroperoxide) involving a specific molecule that undergoes a chemical charge when affixed by an enzyme (substrate - D-luciferin), ATP or adenosine triphosphate, the energy storing molecule of all living organisms, and oxygen.  The reaction is controlled by the enzyme, luciferase, an enzyme or biological catalyst that accelerates and controls the rate of chemical reactions in cells.  The chemical energy excites a specific molecule resulting in the photon, which produces the light.  The light emitted is independent of any light absorbed by the organism (as would be the case with a "glow in the dark" object which requires charging by direct contact with light). This whole reaction takes less than 1/1000th of a second but the light will last as long as the organism is in a state of excitability, provided the organism can absorb enough nutrients from the water to sustain it.

     Photons are discrete energy “quanta” or “packets”, and their energy is constant.  The number released (as well as the intensity with which that release is perceived by our senses) may vary.  Different types of substrates (luciferins) in organisms produce different colors.  Organisms such as the dinoflagelates emit light ranging from blue to yellow green (~490nm is the frequency of the light wave).

For those of you with a degree or two in chemistry - here's the mind numbingly concise explanation:

FMNH2 + RCHO + O2 ----> FMN + RCOOH + H2O + light (490nm)

Most sincere thanks to Barbara Baker Ph.D.. and Jeffrey Baker Ph.D.. without whose valuable help in the correction, clarification, revision and proofing, this explanation would have been impossible.

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