Investigating the ocean depths can be difficult, dangerous and sometimes frustrating. On a voyage to the Cayman Trough in the Caribbean this month Dr. German and colleagues from the United States, United Kingdom and Japan were poised to explore the deepest hot springs on Earth, only to be thwarted by the arrival of tropical storm Ida.
Woods Hole Oceanographic Institution engineers recover the hybrid underwater robot Nereus in deteriorating weather conditions. (Photo by Chris German WHOI)
Still, working at depths of greater than 4,000 meters (2.5 miles), the scientists found evidence for chemically enriched plumes in the water column signaling the presence of seafloor hot vents hundreds of meters deeper still.
Funded by NASA's Astrobiology program, the team used WHOI's new hybrid robotic vehicle, Nereus, first as a free-swimming autonomous underwater vehicle and then as a tethered, battery powered remotely operated vehicle to track the plume to its source and begin to investigate the seafloor. Bad weather forced the team to break off only hundreds of meters from their target, but they intend to resume their search in 2010.
By the time the 10-year Census of Marine Life concludes in October 2010, five deep-sea projects will have fielded a total of 210 expeditions, including the first ever voyage to explore the Mid-Atlantic Ridge south of the Equator. The scientific collaboration between Russia, Brazil, South Africa and Uruguay took place in October-November this year.
Five of the Census' 14 field projects plumb the ocean depths beyond light. Each is dedicated to the study of life in progressively deeper realms - from the continental margins to the spine-like ridge running down the mid-Atlantic, the submerged mountains rising from the seafloor, the muddy floor of ocean plains, and the vents, seeps and chemically-driven ecosystems found on the margins of mid-ocean ridges and in the deepest ocean trenches.
Each voyage is enormously expensive and challenged by extreme ocean conditions and requirements that have kept the remotest reaches of the sea impenetrable until the Census began in 2000.
While the collective findings are still being analyzed as part of the final Census report to be released in London on October 4, 2010, scientists say patterns of the abundance, distribution and diversity of deep-sea life around the world are already apparent.
Edward Vanden Berghe, who manages the Ocean Biogeographic Information System, the Census' inventory of marine life observations, has compiled records of 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.
Finned octopod, Grimpoteuthis sp. nicknamed Dumbo (Photo courtesy Census of Marine Life)
One of these creatures of the depths has been nicknamed Dumbo after the cartoon flying elephant.
On a voyage to the Mid-Atlantic Ridge this year, researchers led by Mike Vecchione of the Smithsonian Institution collected a very large specimen of a rare, primitive animal known as cirrate or finned octopod, that flaps a pair of large ear-like fins to swim.
The Dumbo netted by Census explorers was nearly two meters (six feet) long and, at six kg (13 pounds), the largest of only a few individuals ever obtained.
At 2,750 meters in the Northern Gulf of Mexico a transparent sea cucumber, Enypniastes, is found. (Photo courtesy Larry Madin, WHOI)
Altogether, nine species of the gelatinous Dumbos were collected on the Mid-Atlantic Ridge, including one that may be new to science. Scientists say they were surprised to find such a plentiful and diverse assemblage of these animals, which rank among the largest in the deep sea.
On the abyssal floor, the deep mud contains biodiversity that escapes detection by video and photography since most of the animals are only a few millimeters in size and hide among the sediment particles.
Sometimes, the vast majority of creatures collected in mud from the abyssal plains are new to science, says Dr. David Billett of UK's National Oceanography Centre, who works on the Census of Diversity of Abyssal Marine Life, CeDAMar, project.
Of some 680 specimens of copepods collected on a recent CeDAMar cruise to the southeastern Atlantic, for example, only seven could be identified; 99 percent were new to science. And among hundreds of species of macrofauna - animals about the size of an earthworm - collected in different areas, 50 to 85 percent were unrecognized.
"The abyssal fauna is so rich in species diversity and so poorly described that collecting a known species is an anomaly," says Dr. Billett. "Describing for the first time all the different species in any coffee cup-sized sample of deep-sea sediment is a daunting challenge."
Far rarer than new species in the mud is the capture of a new species of sea cucumber, and rarer still a new genus. However, Dr. Billett and colleagues from the National Oceanography Centre and the Shirshov Institute, Moscow, accomplished this feat this year around the Crozet Islands, a sub-antarctic archipelago of small islands in the southern Indian Ocean.
At 1,000 meters and below abundant colorful coral is found. (Photo courtesy NIWA, New Zealand Ministry of Fisheries & Foundation for Research Science and Technology, and Land Information New Zealand)
One of the new sea cucumbers was yellowish-green, a rare find as virtually all others found in the global seas are whitish grey or purple.
However, what startled researchers most was finding that the most abundant sea cucumber around the Crozet Islands - thousands of specimens at abyssal depths - was a species never seen anywhere else before, now named Peniagone crozeti.
"The distribution of species in the deep sea is full of mysteries," says Dr. Billett. "In addition to the boundaries caused by underwater topography, ridges and seamounts, there are unseen, and as yet unexplained, walls and barriers that determine supplies of food and define the provinces of species in the deep sea."
"There is both a great lack of information about the 'abyss' and substantial misinformation," says Dr. Robert Carney of Louisiana State University, co-leader with Myriam Sibuet of France of the Census project COMARGE, studying life along the world's continental margins.
"Many species live there. However, the abyss has long been viewed as a desert. Worse, it was viewed as a wasteland where few to no environmental impacts could be of any concern. 'Mine it, drill it, dispose into it, or fish it - what could possibly be impacted? And, if there is an impact, the abyss is vast and best yet, hidden from sight,'" Dr. Carney said.
He said, "Census of Marine Life deep realm scientists see and are concerned."
The reporting Census of Marine Life 2010: A Decade of Discovery, to be released in London in October 2010, will address three questions: What lived in the ocean? What lives in the ocean? What will live in the ocean?
Information about a new book about the Census "World Ocean Census: A Global Survey of Marine Life" by authors Darlene Trew Crist, Gail Scowcroft and James M. Harding Jr. is available at: www.coml.org/results-publications/worldoceancensus
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