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Census Slowly Reveals Ocean's Hidden Denizens

Single-celled eukaryotic microbe



L. AMARAL ZETTLER
Oceans cover more than two thirds of the earth's surface and cataloging the variety of life that they contain is a monumental task. To that end, researchers in more than 70 countries are working together on the Census of Marine Life (CoML), a decade long, $1-billion project. Key project scientists will meet next week in Europe to review the census's progress. "We have barely skimmed the surface," says J. Frederick Grassle of Rutgers University, chair of the Census's International Scientific Steering Committee. "Humans have explored less than 5 percent of the world's oceans, and even where we have explored, life may have been too small to see. Thus, opportunities abound to discover species and increase our knowledge of abundance and distribution."

The CoML is compiling a massive database of both past discoveries and new finds that now has more than five million records. In the past year alone, investigators added information about 13,000 species not previously included in the database. Researchers also discovered 106 new species of fish, bringing the total of marine fish species to 15,482. Census scientists expect that there may be in excess of 4,000 fish species that are as yet undiscovered and hope to gather data about them in the project's remaining six years. Still, the bulk of ocean life is comprised of microbes (see image), which account for more than 90 percent of the marine biomass.

The researchers also teamed up with some well-known species, such as tuna, sharks and sea turtles, to learn more about uncharted regions of the ocean. By labeling more than 1,500 animal observers with electronic tags, they were able to create a map of marine highways, revealing much information about critical habitats and migratory paths. But even as scientists gather more information about sea life, the census also points out how much more there is to learn. Analysis of the current data shows that near-surface records make up 95 percent of all observations of ocean life now available. What is more, less than 0.1 percent of study results come from the bottom half of the water column. CoML participants hope to shift the balance in the coming years. Notes Grassle, ¿We're finding these doughnut-shaped pockets of life, 10 kilometers in diameter, thousands of meters below us.¿

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