This is a relatively new issue associated with fossil fuel consumption that some of you may not be aware of: ocean acidification.
Basically, anthropogenic release of CO2 is absorbed by the world's oceans. This eventually lowers the pH of ocean waters with potentially disastrous consequences for species that must form and maintain calcium carbonate skeletons or shells. Corals, shell fish, sea urchins and star fish will not grow as fast or survive as long.
Read about it:
A lot of info here from NOAA and the Pacific Marine Environmental Laboratory
Note the connection with sonar and marine mammals and the impact on algea and some types of plankton. This could get really ugly really fast.
NOAA and the National Science Foundation are looking for answers:
"The first comprehensive national study of how carbon dioxide emissions absorbed into
the oceans may be altering fisheries, marine mammals, coral reefs, and other natural
resources has been commissioned by NOAA and the National Science Foundation".
NOAA press release here (pdf file)