The oceans have always worked in conjunction with trees and other plants to help reduce CO2 in the air. Unfortunately, human activity has put so much CO2 into the atmosphere that the oceans can’t keep up, and as a result, they’re becoming acidic. The acidification of the oceans isn’t visible to the naked eye yet, but it is starting to cause some problems for aquatic species, which will only get worse if emissions stay at current levels, or rise.
This is not the first time in Earth’s history that the oceans have become more acidic than normal, and that time life managed to survive, but only just. Natural selection is a powerful force in nature, which allows some species to thrive even in changing environments.
A recent study has found that some aquatic organisms take greater care of their young when living in more acidic environments. Researchers discovered this by studying polychaete worms that live near volcanic vents. Outside of the vents, these kind of creatures normally swim to the surface and “broadcast” their eggs to let them drift in the water. Near the vents though, they lay larger eggs, which they brood, or keep in a kind of tube or other shelter. Within these shelters, the young worms have more time to safely develop within the more acidic environment.
They even found that crossbreeding worms from these two regions resulted in brooding eggs, so it seems like the worms developed brooding long ago, but those living away from the vents evolved other systems for laying eggs as well. What this tells scientists is that at least some species will likely develop or return to systems to shelter their young for longer as acid levels rise.
Although most aquatic life went extinct the last time the oceans became extremely acidic, some did survive, and then later went on to evolve into yet more species. It seems likely that these kind of adaptations were integral to that survival, and might be integral again in the future.