Why in news?
The phenomenon of Mumbai’s beaches glowing in the dark maybe a consequence of global warming and not industrial pollution, according to a year-long investigation by Indian and American scientists.
Why do the beaches glow?
Dinoflagellates are basically tiny plants that can swim. Like any plant, they require certain conditions (nutrients, light, heat) to thrive, and when the conditions are right, their population can explode, creating a massive bloom.
The process can be compared to the organisms which create light to glow sticks, which contain two chemicals that create a fluorescent glow when mixed. Similarly, dinoflagellates contain an enzyme and a protein that when disturbed, combine and release a quick flash of light.
The Noctiluca algae is free-living, nonparasitic, marine-dwelling species of dinoflagellate that exhibits bioluminescence when disturbed (popularly known as mareel).
Its bioluminescence is produced throughout the cytoplasm of this single-celled protist, by a luciferin-luciferase reaction in thousands of spherically shaped organelles, called scintillons.
The Noctiluca algae, commonly known as sea tinkle occurs in patches or ‘blooms’ in the Northern Arabian Sea (though algal blooms can be observed in Pacific Ocean too).
They glow at night due to bioluminescence, and have earned them the nickname ‘sea sparkle’.
However, these patches are a sign of decline because they compete with fish for food and choke their supply.
Noctiluca devours one of the most important planktonic organisms at the base of the fish-food chain, namely diatoms, and also excretes large amounts of ammonia, which is linked with massive fish mortalities.
Why do dinoflagellates glow? THE SCIENTIFIC EXPLANATION
Scientists do not know for sure why dinoflagellates evolved this ability to create light.
1. One theory is that the light flash could startle the organisms’ main predator: microscopic crustaceans known as zooplankton.
2. Another theory, the “burglar alarm hypothesis” is that the light attracts fish who in turn prey on the zooplankton, protecting the algae from being eaten themselves.
3. Another thing dinoflagellates do is produce toxins, which is why red tides are often taken as a sign not to go in the water. But according to Latz, the species involved in the current red tide do not produce dangerous compounds.
How does Noctiluca grow despite global warming?
Though a treat to the eyes of the tourist, dangerous red tides can produce enough toxin to poison fish and other marine life.
1. One such compound is saxitoxin, a neurotoxin that tends to affect humans when they consume contaminated shellfish.
2. Another byproduct of harmful algae blooms is domoic acid, high concentrations of which have emerged as a serious threat to California sea lions and other marine mammals.