Tuesday, 30 May 2017
The glowing night waters off the Omani coast

bright by   night

The glowing night waters off the Omani coast inspire all who witness the phenomenon of bioluminescence
By Cheryl Robertson

Bioluminescence occurs when light energy is produced by plant and animals organisms as a result of a chemical reaction

“It’s like a scene from the Life of Pi,” says Graham Church, still reeling as he recounts the events from the previous night.
“Trails of jellyfish right next to the dhow were glowing, moving through the water in shades of blue and green, while shimmering fish leapt about in the water further afield. Lights pulsated repeatedly from one end of the tide to the other. I’ve never seen anything like it.”
He wonders if the movie’s director Ang Lee had been here too, gaining inspiration from the Musandam Peninsula.

He had set sail from Dibba port on a balmy evening with a party of 20 on a traditional double-decker dhow belonging to Sheesa Dhow Cruises.
Some 40 nautical miles and five hours later they reached the serene Sheesha Bay, backed by spectacular mountains that blend into weathered fjords and sandy bays.
About 900 species of fish thrive in these waters, which is why the diving here is so good. Neil Murphy, General Manager, Sheesa Beach Travel and Tourism, and his crew see flashing lights in the water regularly on their dhow journeys, particularly towards the latter part of the evening.
“I have seen it all the way from Dibba port to the northern reaches,” he says, adding that it’s most notable from November to May.
“It is most commonly seen in the wake of the boats as well as when people are swimming. Fish also glow when they are moving — a result of them agitating the water.”

The phenomenon is called bioluminescence, which also occurs in many other parts of the world. The phenomenon occurs where light energy is produced by plants and animals as a result of a chemical reaction. These organisms produce chemicals, which react with oxygen to create light. The light produced is usually blue-green.

The science behind it

There are many different types of organisms that produce bioluminescence, from microscopic cells to fireflies and fish such as the anglerfish. The chemical reaction can occur either inside or outside the cell.
“Many species of marine phytoplankton, zooplankton and fish are capable of producing bioluminescent flashes, which have the duration of milliseconds,” says Sergey Piontkovski, Associate Professor, College of Agricultural and Marine Sciences, Sultan Qaboos University, Oman.
“However, when the concentration of these organisms reaches high values, the flashes join up and form a glowing sea.”The bioluminescence in Omani waters is associated with a phytoplankton species known as noctiluca scintillans, which also appears in the Arabian Gulf, the Red Sea, the coastal waters of the Atlantic Ocean and many other regions.

“Noctiluca scintillans forms the socalled red tides (in this case green tides, due to the green pigments inside cells) along the Omani coast,” he says, adding that the most intensive algal blooms happen during the winter, from January through to March. “The concentration reaches millions of cells per litre. The species is not toxic, but the decay of the noctiluca scintillans bloom and subsequent oxidation of decaying organic matter could cause dissolved oxygen depletion, which could result in fish-kill incidents.”

Phosphorescence is the old [nineteenth century] term used to describe bioluminescence, and I think it originated when they thought that phosphorous was the active constituent of luminescence,” says Steven Haddock, Scientist, Monterey Bay Aquarium Research Institute, California.
However, in phosphorescence, the energy from an external source of light is absorbed and the time until the energy is released is fairly long, resulting in glowing after the light source has been removed.

The pulsating lights seen by Church occur, according to marine scientists, when the phytoplankton within the brownish-red tide are jostled. Each organism gives off a flash of blue light created by this chemical reaction within the cell, and when millions of these are churned such as when the waves break on the shore there can be a neon-blue/green light show.

It’s an experience Church is more than happy to repeat. “We must go again,” he says.

 

General contact:   Prof. Sergey Piontkovski spiontkovski@gmail.com
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