Cycles of iron

Photo by J.  Brokowski
© Commonwealth of Australia

A whale’s circling gesture reflects a scientific observation.

Dr Steve Nicol says (AAD 2010):

Approximately 24% of the total iron in the Southern Ocean surface water is currently stored within krill body tissue … When whales consume the iron-rich krill, they excrete most of the iron back into the water, therefore fertilising the ocean and starting the whole food cycle again.