This isn't a new thing and there are heaps of evidence. Google "ocean acidification" for lots more studies and reports.

Here's 1: http://www.whoi.edu/oceanus/feature/ocean-acidification--a-r...

"In tanks filled with seawater, they raised 18 species of marine organisms that build calcium carbonate shells or skeletons. The scientists exposed the tanks to air containing CO2 at today’s level (400 parts per million, or ppm), at levels that climate models forecast for 100 years from now (600 ppm) and 200 years from now (900 ppm), and at a level (2,850 ppm) that should cause the types of calcium carbonate in shells (aragonite and high-magnesium calcite) to dissolve in seawater.

The test tanks’ miniature atmospheres produced elevated CO2 in the tiny captive oceans, generating higher acidity. The researchers measured the rate of shell growth for the diverse species ranging from crabs to algae, from both temperate and tropical waters. They included organisms such as corals and coralline algae, which form foundations for critical habitats, and organisms that support seafood industries (clams, oysters, scallops, conchs, urchins, crabs, lobsters, and prawns)."