 covering, like shells and corals, 
depends on that level of acidity to allow their life forms to exist.
  Our coral reefs now are in deep trouble because of temperature. We 
have had massive bleaching, which is basically the death of coral 
reefs. They have a life form that builds the reef, and those have died 
just because of the warmer water. But the changes in the acidity 
levels, the PH levels, is also a means of mortality for our reef 
system. Many scientists are very concerned that this could greatly