One reads stories of pork/etc carcasses that aren't being processed right now, perhaps we could ship those onto barges and into the ocean and dump them overboard to seed new pockets of offshore life on the sea floor.
I'm not sure if our primary goal in "improving nature" is to help "nature" or simply keep nature sustainable for humans and future humans.
Note that this is a vague impression of a topic I know next to nothing about; I could easily be wrong here.