Did you know that over 17,000 species thrive in the deep sea where no light penetrates the ocean waves? Or that an old restaurant menu can teach us about the history of fish populations? Or that there are 38,000 different kinds of microbes in a liter of seawater? These were all discoveries made by the Census of Marine Life, a 10-year international effort that assessed the diversity (how many different kinds), distribution (where they live), and abundance (how many individuals) of marine life. The effort brought together unprecedented amounts of information on marine species into databases that provide a ‘phone book’ of sorts for the ocean.
During the decade of the Census of Marine Life, more than 6,000 potential new ocean species were discovered by the roughly 2,700 participating scientists from more than 80 countries. Census scientists searched the global ocean to learn more about species as large as the blue whale and as small as a zooplankter or microbe. They sampled from the world's coldest regions to the warm tropics, from deep-sea hydrothermal vents to coastal ecosystems. They tracked the movements of fish and dug up studies from long ago to learn what the ocean used to be like before the influence of humans. And, of course, the scientists also used this information about the past and present to consider what the future holds for the ocean.
The scope of the Census of Marine Life was unprecedented and inspired authors and artists to tell its story. In 2011 the Census Scientific Steering Committee received the prestigious COSMOS prize in recognition of its decade of international ocean research spanning multiple scientific disciplines.
Most of the ocean is very difficult for humans to reach and explore. Coastal shallow areas are relatively easy to access, but these continental shelves that extend from the shorelines only make up ten percent of the ocean. Five Census projects explored the hard-to-reach areas of the ocean: continental margins (the point where the continental shelf slopes down to meet the abyssal plain), the abyssal plain (the muddy seafloor past the continental slope), the Mid-Atlantic Ridge (part of the longest mountain range on the planet), and the once unsuspected ecosystems that thrive on chemical seeps and whale falls.
The Arctic Ocean Diversity (ArcOD) project and the Census of Marine Antarctic Life (CAML) brought international researchers together to record biodiversity in the Arctic and Antarctic: from the sea ice, water column and sea floor, ranging from the shallow shelves to deep basins of the ocean. Researchers found more than 300 species that seemed to occur in both the Arctic and Antarctic oceans despite the great distance. But things aren’t always as they seem; genetic testing shows that most are, by and large, not the same species.
Most of the life in the ocean we can't see with the naked eye: microbes. In addition to the microscopic viruses, bacteria and other microbes are the plankton, tiny plants (phytoplankton) and animals (zooplankton) that drift with the ocean currents. The International Census of Marine Microbes (ICOMM) and the Census of Marine Zooplankton (CMarZ) explored these tiny but important forms of life that are found around the planet.
Although the Census of Marine Life was a ten-year project, concluding in 2010, its legacy continues on in the many projects that resulted from Census collaborations and in the scientific data that was compiled during the decade of work from over 2,500 scientists.