Scientists Have Solved the Mystery of the Sargasso Sea

The Sargasso Sea is an elongated region in the middle of the North Atlantic Ocean, surrounded by ocean currents: on the west by the Gulf Stream, on the north, by the North Atlantic Current, on the east, by the Canary Current and on the south, by the North Atlantic Equatorial Current.

It is about 700 miles wide and 2,000 miles long (1,100 km x 3,200 km). It stretches from roughly 70 degrees west to 40 degrees west, and from 25 degrees north to 35 degrees north, being warmer, saltier, bluer and clearer than other areas of the North Atlantic.

The Sargasso Sea is considered by many lifeless, the desert of the ocean, with few signs of life, even if seaweed of the genus Sargassum floats en masse on its surface. Now researchers have found that swirling ocean currents bring the nutrients that fuel enigmatic blooms of microscopic life in otherwise barren regions in the middle of the ocean.

The vast blooms of phytoplankton in the middle of the Sargasso Sea represented a mystery. But scientific research revealed that oxygen and other elements were being consumed at a much rapid speed than theories and models could explain, thus there must have been a source of nutrients behind these blooms.

"Past research has shown that the open ocean is far more productive than we could explain based on what we knew about nutrients in the surface water," said lead researcher Dennis McGillicuddy, oceanographer of the Woods Hole Oceanographic Institution in Massachusetts.

"Scientists have been trying to figure out where the nutrients come from to make these oases in the oceanic desert."

His team has discovered that eddies, episodic swirling current systems, bring nutrients from the bottom of the ocean to the surface, the "euphotic" zone, where the sunlight can penetrate the ocean. The combination between light and nutrients enables photosynthesis, fueling the phytoplankton bloom, which determines zooplankton boost that attracts fish and so on.

"Eddies are the internal weather of the sea, the oceanic equivalent of storms in the atmosphere" said McGillicuddy.