I'm always surprised by what I find while looking from above. Providencia - Colombia

[WillDunwoody]

 

[MAvic_South_Oz]

Any idea what caused this ?
Perhaps some sort of algae.

That's a beach shack there ?
Beautiful front yard.

 

[WillDunwoody]

We asked the locals and they told us it was bacteria, on another forum though someone replied with this: "this happens when waves or storm runoff create a channel from the beachfront to the lower area behind the beach. Very salty seawater gets in there and ends up 'trapped' in the low area. This water becomes ultra-salty as it evaporates. One of the few things that live in that water are a form of red algae that live on the mangrove trees. They turn the water a reddish color."

 

[MAvic_South_Oz]

Ah, we get that here in places, like Western Australia's Lake Hillier . . .

It is a bacteria that forms this red algae.

 

[Thomas B]

Is this toxic to fish like the red tides that occur in Florida’s gulf coast at times?

 

[MAvic_South_Oz]

Is this toxic to fish like the red tides that occur in Florida’s gulf coast at times?

I think so, most or the red algae is what's known as HABs (harmful algal bloom), microscopic algae that produce toxins that kill fish and make shellfish dangerous to eat.