Some of you chemistry whizzes might know that the chemical name for water is H2O. The “O” stands for “oxygen,” while the “H” means “hydrogen.” This means water contains oxygen.
In fact, water from healthy rivers, lakes, and bays actually contains EXTRA oxygen. This extra oxygen is called “dissolved oxygen,” and it is necessary for fish, crabs, and other water animals to breathe underwater.
Fish pull oxygen out of the water when they breathe with their gills. But because we humans don’t have gills (check in the mirror to make sure), we can’t breathe underwater.
How much dissolved oxygen is in the water sometimes depends on water plants known as “algae.” If too many nutrients (plant food) wash into a lake, river, or bay, algae can grow wild. As the algae dies and rots, it can steal oxygen from the water, leaving little to none for fish and other water animals.
If humans had gills, we would be able to breathe underwater. For now, we’ll stick with diving tanks.
Photo: OAR/National Undersea Research Program (NURP)