I believe this subject merits a section of its own for the following reasons
A good summary of the dangers is given in this NOAA lecture.
Shells 33 percent thinner 20/06/16
Artificial Coral to restore endangered reefs 07/10/14
Ocean Algae can evolve faster than thought to combat rising temperatures and acidity 11/09/14
Ocean Algae Reef Fish Lose Brain Power as Oceans Acidify 23/05/14
Ocean Acidification Concerns 15/11/13
Ocean Change Fastest for 300 million years 02/03/12
Ocean Acidification could be unprecedented 01/03/12
Arctic Corrodes Shellfish by 2018 02/10/09
Climate Change Clues from Algae 03/02/13
Comprehensive Ocean Acidity Measurements 25/01/12
Ocean Dead Zones Likely to Expand 01/11/09
Ocean Acidity May Have Caused Great Extinction 06/09/11
Sea Urchins Tolerate Acid Oceans - but calcify less 26/10/10
On Plankton Warming and Whiplash 05/05/11
Declining Plankton 10/08/10
Shell Weight Evidence of Danger 10/03/09
Southern Ocean Tipping Point by 2030 09/02/09
Climate, Carbon Cycling, and Deep Ocean Ecosystems - changes measured 16/11/09
Ocean Acidity 10 times faster than models predict 03/12/08
Warmest Ocean on Record 17/07/09
Update - Ocean Acidification 21/05/08
Relationship between Ozone and Oceans 12/12/08
Nitrogen Danger - the science 06/09
Current Targets Endanger Ocean Life 09/07/08
Greater Acidification Danger 25 years to disaster 30/11/08
Oceans Becoming Corrosive 23/05/08
Jellyfish - Problem or Food? 09/10/08
Adding Lime to Seawater 22/07/08
Diazotrophs to the Rescue 22/07/08
Ocean Collapse Possible 27/12/07
Ocean Acidity Concerns 21/02/08
Resilience of Coral Reefs 15/08/03
North Sea Recovery 09/06/07