Hong Kong: Red Tide Alert

YUK

Looks like pollution, but it's a natural phenomenon!

Hong Kong is on 'Red Tide Alert'. Happens c.30 times a year apparently, but we've not seen it before. On the seawater in the Bay in front of our apartment, there's a massive foamy dirty-looking slick. No one on the beach at all (but weather's bad). The foam is, in fact, an algae bloom -- non-toxic. Looks horrid.

From the official HK red tide website (there is one!!):

What is red tide?

Red tides are natural phenomena in which the rapid multiplication of microscopic, unicellular algae discolour the water by the pigments contained in the algal cells. Depending on the pigments, the massive growth of algal cells may turn the water into pink, red, brown, reddish-brown, deep green or other colours. Most species of algae do not cause threats to the environment and human, rather, they serve as the energy producers at the base of the food web.

The term "red tide" has been used widely to describe the phenomena in which the water is discoloured by high algal biomass. However, most red tides are harmless. On the other hand, a few algal species may cause adverse impacts such as fish kill, seafood contamination or harmful effect on humans even at low cell densities and the blooms are so-called harmful algal blooms (HABs).

Although red tides occur quite frequently in Hong Kong, the blooms associated with harmful effects are not common and seldom caused large scale impact.

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