The possible culprits are: a sudden algae bloom; a change in pool alkalinity; or a chemical reaction in the water. How do these cause a change in the colour of the water?
Toxic algae blooms like the intense one now fouling Florida’s waterways harm wildlife and people in various ways. They're also on the rise.
The oxygen is being sucked out of the ocean, and while much of it is happening far below the surface, it will still affect us above.
Low oxygen levels in the oceans can dramatically change the community of organisms that live there -- but new techniques to re-introduce oxygen have given a breath of life to a Swedish fjord.