The mystery of the neon blue glow of the sea can be revealed in September in Galicia. Those who have ever admired fireflies on summer nights, it is easier to imagine a starry radiance at arm’s length. This is not a fantasy, but a biological phenomenon called “ardentía”, or a luminous sea (el mar ardora).
Despite a lot of scientific research, the bioluminescence process has not been completely studied. This phenomenon allows some organisms to emit a cold glow with a series of chemical reactions. The glow of water is explained by the interaction of millions of microorganisms with water, when they are sharply mixed due to the movement of water.
The richness of the flora and fauna of the Galician coasts allows the accumulation of myriads of microorganisms, among which there is an abundance of Noctiluca Scintillans, the name of which etymologically goes back to “shining in the night.” Now it is known as the “sea spark” (chispa de mar). This microscopic plant, sometimes remaining on the beach, can be clearly seen with the naked eye, it leaves orange spots in the water.
Studies of Galician scientists have shown that this luminescent alga shines due to the content of luciferin in it, which reacts to oxygen and causes a blue flicker. Especially spectacular reaction occurs at night with vibration or water mixing (for example, by waves from a passing boat).
The sea of Ardor, so named for the first time in Jules Verne’s novel “Twenty Thousand Leagues Under the Sea,” was for centuries a legend among sailors crossing the Indian Ocean.
Now everyone knows that this spectacle – ardentía, or the luminous sea, is not a myth or a legend. The phenomenon is studied not so long ago, but there is already a pretty convincing hypothesis why a microscopic plant fluoresces: this is due to the mechanisms of protection from those who would gladly regale plankton. This theory, called “anxiety against intruders”, suggests that these microscopic algae are food for other representatives of zooplankton, which, after swallowing prey, themselves begin to glow, attracting predators.
Scientists first registered the phenomenon in 1915. It is distributed mainly in the Indian Ocean and zones near Indonesia. It can also be observed off the coast of Somalia, in southern Portugal, in the Phosphorescent Bay of Puerto Rico and off the coast of Galicia.
Photos and video images of the glowing sea are still relatively small, and it’s better to admire such beauty personally. Ideal places to observe the miracle of nature: the paradise islands of Cies or Illa de Ons. But even in more famous places last summer you could see a luminous sea: for example, in Muxía or Carnota on the Coast of Death or on more southern beaches, like Queiruga, Porto do Son, A Lanzada, O Grove or Vigo.
The best time to observe glowing plankton is September, when the water is warmer and more restless. If the day on the surface of the water there are small orange oily stains, then before sunrise there is a chance to see and even swim in the starry sea!