The sight of the waters off Hong Kong these days can take your breath away -- but the haunting fluorescent blue seas can also be lethal to marine life because it deprives the water of oxygen.
The glow is a kind of red tide that is caused by Noctiluca scintillans, an algae marine biologists call "sea sparkle." It's a rare organism that can act both as animal and plant.
The algae looks red in the daytime but shows up blue once the sun sets. Scientists say the beautiful blue algae is linked to chemical run-off from farms and sewage from businesses.
Scientists warn that the blue hue is a growing global problem that could eventually boost the amount of harmful toxins in the human food chain.
The algae is most dangerous when it dies, David Baker from the Swire Institute of Marine Science at the University of Hong Kong told CNN. "That's when we have the formation of these dead zones, where anything that's living, any fish or crab species living on the bottom, is at risk of dying from the low oxygen associated with that decomposition."
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