The dark side of the biological pump: the impact of iron availability on heterotrophic bacterial carbon consumption in the mesopelagic

Below the surface, in the ocean’s “twilight zone” – the water from roughly 150 to 600 meters deep – sinking organic matter from surface waters is consumed by bacteria. The more organic carbon is consumed in the twilight zone, the less sinks to the deep ocean and to sediments. Thus, the activity of bacteria in the twilight zone is an important…