Researchers have made one of the strangest-sounding discoveries in a while: Long-dead African fish are helping feed the Amazon. How, you ask? Well, millions of tons of dust blow west from the Sahara Desert across the Atlantic Ocean each year. The dust, which acts as a natural fertilizer where it lands in the Amazon, often comes from Chad's Bodélé Depression, one of the windiest places on Earth, the BBC reports. For the first time, however, researchers have tested the dust to find it contains powdered fish bones and scales, as well as the remains of other organisms that lived in a massive lake that covered much of north-central Africa before it dried up over the last 10,000 years, Phys.org reports.
As the organisms died, they sank into sediments, leaving behind apatite or phosphorus minerals which have since been revealed by the gusting winds. Though phosphorus minerals—essential for photosynthesis—also come from weathered rocks, the bone phosphorus flying across the Atlantic to the Amazon is "more soluble" and "more readily available to plants," a researcher explains. That's good news—until the stuff runs out. Eventually the dust from the Bodélé Depression will erode away and the Amazon will have to make do with rock phosphorus, which is "much harder to solubilize," an expert says. Researchers hope to next determine when the supply could run out. (In a discovery at a polar-opposite climate, scientists have figured out why Antarctic fish don't freeze to death.)