Beyond sunlight: Explorers census 17,650 ocean species between edge of darkness and black abyss

By | November 23, 2009

This unfamiliar Dumbo species collected by Census of Marine Life scientists on a 2009 MAR-ECO voyage to the Mid-Atlantic Ridge may prove new to science.

Census of Marine Life scientists have inventoried an astonishing abundance, diversity and distribution of deep sea species that have never known sunlight – creatures that somehow manage a living in a frigid black world down to 5,000 meters (~3 miles) below the ocean waves.

Revealed via deep-towed cameras, sonar and other vanguard technologies, animals known to thrive in an eternal watery darkness now number 17,650, a diverse collection of species ranging from crabs to shrimp to worms. Most have adapted to diets based on meager droppings from the sunlit layer above, others to diets of bacteria that break down oil, sulfur and methane, the sunken bones of dead whales and other implausible foods.

Five of the Census’ 14 field projects plumb the ocean beyond light, each dedicated to the study of life in progressively deeper realms – from the continental margins (COMARGE: Continental Margins Ecosystems) to the spine-like ridge running down the mid-Atlantic (MAR-ECO: Mid-Atlantic Ridge Ecosystem Project), the submerged mountains rising from the seafloor (CenSeam: Global Census of Marine Life on Seamounts), the muddy floor of ocean plains (CeDAMar: Census of Diversity of Abyssal Marine Life), and the vents, seeps, whale falls and chemically-driven ecosystems found on the margins of mid-ocean ridges and in the deepest ocean trenches (ChEss: Biogeography of Deep-Water Chemosynthetic Systems).

Edward Vanden Berghe, who manages OBIS (Ocean Biogeographic Information System), the Census’ inventory of marine life observations, notes that, unsurprisingly, the number of records in the database falls off dramatically at deeper depths (see animation at – a function of the dearth of sampling done in the deep sea.

However, Dr. Vanden Berghe reports that OBIS today records 5,722 species for which all recorded observations are deeper than 1,000 meters (~.62 miles) and 17,650 species for which all recorded observations are deeper than 200 meters, the depth where darkness stops photosynthesis.

Scientists working on the deep-sea Census number 344 and span 34 nations.

By the time the 10-year Census concludes in October, 2010, the five deep-sea projects will have collectively fielded more than 210 expeditions, including the first ever MAR-ECO voyage in October-November this year, to explore the Mid-Atlantic Ridge south of the Equator, a scientific collaboration between Russia, Brazil, South Africa and Uruguay.

Each voyage is hugely expensive and challenged by often extreme ocean conditions and requirements that have kept the remotest reaches of Neptune’s realm impenetrable until recently.

via Beyond sunlight: Explorers census 17,650 ocean species between edge of darkness and black abyss.

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