An international research team, including Dr. Robert Diaz of the Virginia Institute of Marine Science, has found hundreds of new marine species in the vast, dark deep-sea surrounding Antarctica—the bottom of the bottom of the world.
Carnivorous sponges, free-swimming worms, crustaceans, and molluscs living in the Weddell Sea provide new insights into the evolution of ocean life.
Reporting this week in the journal Nature, the scientists describe how creatures in the deeper parts of the Southern Ocean—the source for much of the deep water in the world ocean—are likely related to animals living in both the adjacent shallower waters and in other parts of the deep ocean.
A key question for scientists is whether shallow-water species colonized the deep ocean or vice versa. The research findings suggest that recurring advances of Antarctic ice may have forced shallow-water organisms into the surrounding depths, leading to an intermingling of species that originated in shallow and deep-water habitats.
Lead author Professor Angelika Brandt from the Zoological Institute and Zoological Museum, University Hamburg, says “The Antarctic deep sea is potentially the cradle of life of global marine species. Our research results challenge suggestions that deep-sea diversity in the Southern Ocean is poor. We now have a better understanding of the evolution of marine species and how they can adapt to changes in climate and environments.”
Diaz says the team's most significant finding is the unexpected vitality and diversity of the seafloor community in a setting that would seem to hold little promise for life—with water temperatures at 28-30°F, total darkness, and bone-crushing pressure. The expedition sampled at depths from 3,000 to more than 20,000 feet.
“We discovered hundreds and hundreds of new species,” says Diaz. He was particularly struck by the diversity of isopods, small crustaceans related to pill bugs. “Sampling at just 25 stations doubled the number of known deep-sea isopod species.”
Diaz's role in the international expedition was to characterize and photograph the habitats of the area's bottom-dwelling creatures. His photograph of a sea urchin, taken in the Scotia Sea at a depth of 6,414 feet, graces Nature's cover.
Dr Katrin Linse, a marine biologist from the British Antarctic Survey, adds, “What was once thought to be a featureless abyss is in fact a dynamic, variable, and biologically rich environment. Finding this extraordinary treasure trove of marine life is our first step to understanding the complex relationships between the deep ocean and the distribution of marine life.”
The Nature study reports the findings of the ANDEEP project (ANtarctic benthic DEEP-sea biodiversity), a series of three expeditions to the Southern Ocean between 2002 and 2005 aboard the German research ship Polarstern. An international team from 14 research organizations investigated the seafloor to build a picture of this little known region of the ocean. They found more than 700 new species.
In addition to Dr. Diaz, VIMS graduate student Lawrence Carpenter also took part in the research.