This is a form of "compatibility" that og Quark already did for other mods.
Basically, if Oceanic-Expanse is installed, it also add crab mobs. To prevent duplicates, if the player forget to disable Quark's crabs, the feature should be auto-deactivated when Quark detects the presence of Oceanic-Expanse on the pack.

Also, Oceanic-Expanse also adds something similar to Squids ink you feature, so it should be also auto-deactivated on Quark's side.