Marine snow is not just pretty, it forms an integral part of ocean biogeochemistry, most notably the biological pump. The wonderful world of plankton is the main driver of this pump in the open ocean. Phytoplankton convert inorganic into organic carbon in the sunlit surface ocean. When they die, they, their zooplankton predators, and various other consumers eventually sink, carrying the organic carbon locked in their cells with them.

Organic carbon inputs from marine vegetated habitats – kelp forests, seagrass meadows, mangrove forests and salt marshes – and from land predominantly drive the biological pump near the coast. This organic matter supports most animals in the deep sea with food, the only exception being those that form a symbiosis with the chemoautotrophs of hydrothermal vents and cold seeps. Large events of organic matter input to the deep sea are referred to as falls. These include whale falls, which support a succession from deep sea sharks to bone-eating worms, and wood falls. Falls have long shaped the evolution of deep sea life. Better understanding the biological pump in the context of the global carbon cycle will prove invaluable in the face of anthropogenic climate change.

Next Section »