Olympic authorities were quick to deny that the green pool posed a risk to divers’ health, but that actually depends on why the water changed colour.
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?
Detail from a satellite photo of Lake Okeechobee’s algae bloom and the St. Lucie canal into which water was released. Rising water levels from heavy winter rains had water managers worried that water would breach the dike.
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.
A mass proliferation of
Noctiluca scintillans, a red tide forming dinoflagellate at Clovelly Beach, NSW. It can form dense aggregations that deplete oxygen and produce ammonia.
They give us part of the air we breathe but microscopic phytoplankton can also be toxic. They are also on the move thanks to climate change so a new Australian database hopes to monitor any changes.
Blue-green algae in the Murray River upstream of Mildura in April.
Toxic algal blooms were unheard of in Australia's major waterways before 1991. Now the Murray River has been struck by four major events in less than a decade, with more likely in the future.
Cannonball Jellyfish in the Gulf of California.
Yazmin Flores for GCMP
In a changing climate, ocean populations sometimes rise and fall in unpredictable waves. Scientists, managers and fishers must make economically and ecologically sound decisions based on long-term outlooks.
Spot the algae.
Algae isn’t just found in your garden pond or local river. Sometimes it explodes into vast “blooms” far out to sea, that can be the size of a small country. Such algal blooms can match even a rainforest…