The secrets of Milky Sea Effect

(Illumination of glowing wave, Krabi, Thailand.)
Milky Sea effect is referred to an unusual marine phenomenon in the ocean in which a large amount of sea water appears to glow brightly at night.This effect is caused by some bioluminescent bacteria or dinoflagellates, causing the sea to uniformly display an eerie blue glow at night. This effect is so bright that it can also been seen from space.

This phenomenon is observed form many centuries and is notably mentioned in 1870 novel ‘20,000 Leagues Under the Sea’, by Jules Verne.

In 1995, a British merchant vessel in the Arabian Sea took water samples during milky seas. The captain and his crew were surrounded by glowing water that “appeared to cover the entire sea area, from horizon to horizon.” And knowing that it took them full six hours to cross from one edge of the glowing water to the other, it was quite the eerie scene. Their conclusions were that the effect was caused by the bacteria Vibrio harveyi.

Vibrio harveyi. In 2005, Steven Miller of the Naval Research Laboratory in Monterey, California, was able to match 1995 satellite images with a first-hand account of a merchant ship. U.S. Defense Meteorological Satellite Program showed the milky area to be approximately 15,400 sq.km.

{A composite rendering showing a satellite perspective of the first bioluminescent milky sea recorded from space ( by Miller in 2005, 2006).}
While a similar phenomenon occurs alot near the beaches also known as Mareel.
The effect is more obvious at the shore, where the waves stir up the luminescent bacteria from the water, but also near the ships and nautical equipment. Mareel are often observed at Vaadhoo Island, Maldives and in the north-west of the Indian Ocean and close to Indonesia.
This spectacular event is more prevalent from late summer to the end of the year.

Mareel at Vaadhoo Island, Maldives The most common bacteria that create the effect of milky sea is the Noctiluca scintillans. It is a part of the group of the marine dinoflagellates, which is an important part of the plankton.
Stress, caused by the movement of the sea and waves, leads the plankton to emit light, or bioluminescence as a defence mechanism in a similar way to some fireflies.

Noctiluca scintillans But still no modern research proves that bioluminescent bacteria are capable of illuminating the ocean from horizon to horizon and for days at a time.
Milky Sea Effect is one of the rarest event that occurs naturally without full explanations by scientists.

Originally published at mybookofmysteries.blogspot.com.