What do H+ ions do to CO3 in CaCO3?

[chemchem]

Homework Statement

what do the H+ ions do to the CO3 in the CaCO3?
this is a report on ocean acidity and i need help to explain what H+ ions do to the CO3 in CaCO3

Homework Equations

The Attempt at a Solution

please help!

 

[Borek]

Write reaction equations for all steps of carbonic acid dissociation.

 

[chemchem]

thanks!