The Blue World: The glowing sea
By CGTN's Gao Yuxin

When the night falls, the sea sparkles neon blue, like fireflies swimming in the sea. The glowing sea refers to the bioluminescent sea. 

One can witness this natural phenomenon when there is lots of bioluminescence in the water, usually from an algae bloom of plankton. When algae carrying luciferin is subjected to stress like waves on a beach and the agitation of calm water, its luciferin mixes with the luciferase, which produces a chemical reaction that causes the glow.

Dinoflagellates are widely believed to be responsible for the formation of bioluminescent sea, according to Chinese Society for Oceanography.

For humans, the view of a bioluminescent sea formed by algae is of great ornamental value, however, it can also be a threat to marine life and marine environment.

Certain nutrients, such as phosphorus, potassium and ferrum, increase the number of dinoflagellates and bacteria, cyanobacteria and single-celled algae that feed on dinoflagellates, allowing the bioluminescent microbes to shine brightly, but this is actually one of the harbingers of eutrophication of seawater. 

The eutrophication can lead to red tides, which can rapidly consume oxygen in the water, causing the asphyxiation and death of other marine organisms, seriously threatening the quality of sea water and the artificial aquaculture industry.

At the same time, dinoflagellates synthesize a variety of toxins during their growth like brevetoxin, which can accumulate in shellfish and other marine products, increasing the safety risk of marine food.

In China, the Yellow Sea and Bohai Sea are the best places to watch the glowing sea from late April to early May.

About The Blue World series:

The ocean covers more than 70 percent of the Earth. In this blue world, there are all kinds of marine life with surprising abilities we don't know about. In this series, CGTN guides you through the journey of exploring the amazing animals in the ocean. 

For more:

The Blue World: The mystery of the sex of green turtles

The Blue World: Brainless jellyfish

The Blue World: Half asleep, half awake dolphins

The Blue World: Never make a pufferfish angry

The Blue World: From round fish to flatfish

The Blue World: When a whale sinks into the sea

The Blue World: Sea otter's treasure chest

The Blue World: Mother octopuses' mission

The Blue World: When the beauty of coral fades

The Blue World: Whale beachings

The Blue World: A shark's sixth sense

(All images via VCG)

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