One way to remedy local ocean acidification is to increase seagrass growth. Seagrass requires ocean depth to grow - this can be accomplished hand in hand with offshore buffers that also address rising sea levels, weather protection, and storm surge.
This paper talks about conserving mangroves and coral reefs A 100-meter-wide coastal strip of mangroves can reduce wave heights by as much as two-thirds, previous research has shown. Coral reefs meanwhile buffer wave energy by up to 97% in some contexts, significantly reducing erosion and cutting flood-damage costs in half annually. (Source)
Seawalls are coming up a lot in my research, but they seem expensive and ugly!!! (Source)