Earthwatch Hong Kong's Jonathan Ho reported the return of the sea sparkle phenomenon near Shenzhen, China:
A blueish glow, covering almost three square miles, lit up a coastal area near Shenzhen from March 30th to April 3rd.
The neon display is caused by Noctiluca scintillans, a species of marine plankton. Their bioluminescent characteristic is attributed to chemical reactions that occur in their organelles throughout their cytoplasm. Their presence and their glow are commonly known as “sea sparkle”.
Blooms such as the one observed in Shenzhen result when there are abundant nutrients in the water, especially nitrogen and phosphorus. Although they create a spectacular display, these blooms consume huge amounts of oxygen when they die and decompose – potentially harming other marine life.
We should keep our freshwater bodies clean, as freshwater all eventually flow into the sea.
There was a similar event in Hong Kong in 2015 here are some articles with pictures: