Wast areas of deep sea floors (abyssal plains) are ecologically desert and they cover wast areas. Very little nutrition and life. Only small oasis like whale carcass is full of life. Of course there may be unintended consequences.

Its unclear to me where these mining operations take place. It seems that these ventures are trying to mine at the depth of 1600 m. Continental shelf has more life than continental slope or abyssal plains.