It's not the iron that's toxic, but the oxygen depletion and other toxins expelled from the algae. https://en.wikipedia.org/wiki/Algal_bloom#Harmful_algal_bloo

It's not the iron that's toxic, but the oxygen depletion and other toxins expelled from the algae. https://en.wikipedia.org/wiki/Algal_bloom#Harmful_algal_blooms https://en.wikipedia.org/wiki/Algal_bloom#Harmful_algal_bloo...