Ocean acidification appears to be harming oysters in Australia already.

Agricultural runoff has an effect locally, and we could reduce it by changing agricultural practices, However, CO2 in the air also contributes, and it will continue making worse acidification as long as we increase the CO2 in the air.

In a few more decades, there may not be any oysters, clams, mussels, snails, or coral, or the species whose larvae or juveniles depend on coral reefs.