Though relatively few in number compared with the uppermost ocean layer, scientists were amazed by the variety of tiny animals found at depths of 1 to 5 km (0.6 to 3 miles). Among thousands captured, 500 species have been catalogued, 220 of them DNA sequenced at sea revealing a number of new species.
The 20-day cruise, completed April 30, is part of an ambitious global inventory of zooplankton by 2010 (dubbed the Census of Marine Zooplankton, CMarZ), a Census of Marine Life initiative that sheds life on some important global ecosystem processes, including the ocean's function as Earth's largest carbon sink and the impact ocean acidification may have on life in the seas.
While helping moderate climate, zooplankton species also provide a fundamental link in the food chain between ocean plant life and predators from fish to whales.
Scientists are puzzling out the types, abundances, ranges and roles within nature of these thousands of tiny animal species. Sequencing the DNA at sea, they telescoped into just three weeks what would normally represent years of laboratory work, an experience that may revolutionize the way biological research at sea is conducted.
The expedition took extraordinary samples in the ocean's deepest waters down to about the sea bottom at 5,000 meters. Biological oceanographers to now have focused almost exclusively on the oceans' uppermost kilometer, which includes only one quarter of their volume. CMarZ is designed to illuminate these important little life forms in the remaining three quarters, below 1,000 m, the point at which the deep sea (bathypelagic zone) is generally agreed to begin.