Meet the fish that happily live in the lake that turns birds to stone
Perhaps you have recently heard about Tanzania's Lake Natron, a body of water that has become famous on the Internet over the last couple of days because of the work of artist Nick Brandt, who took some eerie, posed photos of the calcified corpses of birds that he found along the lake's shore.
Natron, the stuff for which the lake is named, should also sound a bit familiar to you. That's because it's the mineral salt the ancient Egyptians used as part of their mummification rituals. (In fact, they used to harvest it from dry lake beds — Lake Natron isn't the only lake in Africa that's home to large quantities of naturally occurring natron.) It's both a serious drying agent and anti-bacterial, so immersion in natron can suck all the moisture out of a dead body while simultaneously preserving it against the ravages of microorganisms. As far as I can tell, that's what you're seeing in Brandt's creepy photos — birds and bats that look like Tim Burton's garden statuary, but are actually just mummified (and then propped up for artistic purposes).
Which brings us back to the video above. If Lake Natron mummifies birds, how do the fish survive?
Here's the smart-ass answer: Evolution.
Turns out, Lake Natron is an amazing example of an extreme niche environment where most life forms can't survive — but where a precious few adapt and thrive. The Lake is extremely salty and extremely warm (water temperatures can push above 100 degrees F). Because it's located in an arid region, rainfall is erratic, and so Lake Natron is also very shallow and prone to shrinkage. It's fed by hot mineral springs that bubble out of the ground. What you're left with is hot, salty, very very soft water that can, purportedly, feel viscous to the touch.
But those same conditions turn out to be pretty nice for certain species of algae. And the algae make great food for a species of tilapia that's adapted to the heat and the salinity. Both the algae, and the fish that eat them, live along the Lake's shorelines, near the hot spring inlets where mineral content (and, thus, food for the algae) is highly concentrated. The algae feed the fish ... and they also feed flamingoes.
Yes, flamingoes. The lake that looks like a death trap in photographs is actually a major flamingo breeding ground, crucial to the birds' continued survival. That's because the flamingoes use the Lake as a defense mechanism, building up muddy "nests" near the shore, surrounded by just enough of the gross-feeling, undrinkable, smelly Lake Natron water to be a turnoff to would-be predators.
All told, Lake Natron is an incredibly cool (and weird) ecosystem — and one that won't be around forever. This, and a couple of other alkaline, high-salinity lakes in the same region, is slowly disappearing. Eventually, it'll become a plain, where grasses grow out of the salty, mineral-rich soil, and a whole new ecosystem develops.