This is a rewilding article, but it's about rewilding the Southern Ocean by adding iron to restore krill populations to in turn restore whale populations.
https://www.theatlantic.com/science/archive/2021/11/whaling-whales-food-krill-iron/620604/
Interesting read
I remember a few years back we had an PM about seeding the Southern oceans with iron as an attempt to capture carbon. We talked a lot about unintended consequences as humans trying to out think nature. I still think it is an idea worth pursuing.