Скачать или смотреть New Trigger for Immense North Atlantic Spring Plankton Bloom

Every spring, countless microscopic plants, or phytoplankton, bloom in the North Atlantic. What turns on this huge bloom? Is it the Sun's warmth?

In research results published online July 5, 2012, in the journal Science, scientists reported evidence of another trigger—not sunlight, but whirlpools, or eddies, that swirl across the surface layer of the North Atlantic Ocean. These eddies sustain phytoplankton in the ocean's shallower waters where they can get plenty of sunlight to fuel growth, thereby keeping them from being pushed downward by the vagaries of rough processes at the ocean surface.

How important is the bloom to the North Atlantic Ocean and beyond--to the global carbon cycle?

Springtime blooms of microscopic plants in the ocean absorb enormous quantities of carbon dioxide, much like our forests, emitting oxygen via photosynthesis. Their growth contributes to the oceanic uptake of carbon dioxide, amounting globally to about one-third of the carbon dioxide we put into the air each year through the burning of fossil fuels. An important question is how this "biological pump" for carbon might change in the future as our climate evolves, particularly in the North Atlantic, which is responsible for more than 20 percent of the ocean's uptake of CO2.

In winter, cooling and strong winds generate mixing that pushes phytoplankton into deeper waters, robbing them of sunlight, but drawing up nutrients from depth. As winter turns to spring, days become longer. Phytoplankton are exposed to more sunlight, fueling their growth.

The newly discovered mechanism helps explain the timing of the spring and summer bloom, known to mariners and fishermen for centuries and clearly visible in satellite images. It also offers a new look at why the bloom has a patchy appearance: it is shaped by the eddies that, in essence, modulate its formation.

The research was funded by the National Science Foundation (NSF). More information is available at: http://www.whoi.edu/page.do?pid=7545&....