There is research being done on iron seeding/fertilization of barren ocean waters [0]. In such places, iron is the limiting factor for algae growth. [0] https:

There is research being done on iron seeding/fertilization of barren ocean waters [0]. In such places, iron is the limiting factor for algae growth. [0] https://en.wikipedia.org/wiki/Iron_fertilization https://en.wikipedia.org/wiki/Iron_fertilization