A theory I read is that when whales dive to the deep ocean they induce currents that bring iron to the upper layers. A sibling comment points out that iron is t

A theory I read is that when whales dive to the deep ocean they induce currents that bring iron to the upper layers. A sibling comment points out that iron is the bottleneck food for algae, so even a small amount of iron can create a huge mass of algae and krill as a consequence. Just some quick Googling found this: "Other types of whales, such as sperm whales, migrate to waters much deeper than the euphotic zone and they can scavenge iron from below and then return to the surface layer to defecate."¹ ¹: https://theconversation.com/bottoms-up-how-whale-poop-helps-feed-the-ocean-27913 https://theconversation.com/bottoms-up-how-whale-poop-helps-...