10 million scallops that died in the waters off Vancouver Island were the victims of a falling pH. level in the ocean. The pH. has fallen a full point, from 8.2 to 7.2 and the more acidic water means the shellfish can't properly form shells.
Acidic water blamed for West Coast scallop die-off
"Oyster die-offs in Washington state and Oregon dating back a decade have also been linked by National Oceanic and Atmospheric Administration researchers to acidification and rising carbon dioxide levels."