Food 'conveyor belt' in southern ocean
Almost all marine life on the planet turns on a single ocean circulation pattern in the Southern Hemisphere which pumps nutrient-rich water from the deep and spreads it across the seas, scientists report today.
It suggests ocean life may be more sensitive to climate change than previously believed. While oceanographers have identified many ocean circulation patterns, three quarters of all biological activity in the oceans relies on this single pattern in the Southern Ocean, reports Prof Jorge Sarmiento, of Princeton University, who led the study published today in Nature.
The discovery helps oceanographers to learn what keeps the oceans fertile. Most ocean biological activity is concentrated near the surface where sunlight is abundant to support marine food chains.
These organisms and their by-products slowly sink from the surface, decomposing along the way and carrying nutrients to the deep ocean. Until now, it has not been clear how the surface becomes replenished with the nutrients that seemed lost to the deep ocean.
Now researchers have found that a huge "conveyor belt" carries nutrient-rich seawater southward in the deep ocean, brings it to the surface in the Antarctic Ocean and ships it north. The water sinks again in the Northern Hemisphere where it starts again.