I've read that if you spray Iron onto the Ocean you get 'algae blooms' -I guess we could 'harvest' these... (Couldn't this also be used to dramatically increase offshore fish populations too?)

Nick.

Doesn't work. There will be a secondary surge in population of grazing zooplankton and predatory zooplankton. All comes to naught. Unless perhaps you do a prediction of which zooplankton species will surge in population, and do a pre-emptive spraying of viruses and phages to wipe out the grazing zooplanktons.