New marine species are being discovered every week as scientists continue their efforts to produce the first census of marine life, writes Dick Ahlstrom
FANCY A PLATE of oysters? How about an oyster as big as a plate, a giant measuring a startling 20cm across.
Huge communities of this giant bivalve have been discovered 700m down on the fringes of the La Chapelle continental slope, off France. They represent just one of the many new findings being discussed this week in Valencia, Spain, by scientists who are producing the first Census of Marine Life.
The World Conference on Marine Biodiversity got under way last Sunday and continues through Saturday. Reporting groups are astounding their peers with news of dozens of species new to science.
The Census of Marine Life (CML) is an initiative involving the work of 2,000 scientists from 82 countries, all contributing to a census to be published in October 2010. By then scientists expect the list to include between 230,000 and 250,000 species, and the first estimates of how many more species await scientific discovery.
"The release of the first Census in 2010 will be a milestone in science," says Dr Ian Poiner, chairman of the Census's international scientific steering committee and chief executive officer of the Australian Institute of Marine Science. "After 10 years of new global research and information assembly by thousands of experts the world over, it will synthesise what humankind knows about the oceans, what we don't know and what we may never know - a scientific achievement of historic proportions," Poiner says.
The discovery of species new to science is only part of what the CML will deliver. It is also about collecting samples of known marine animals so they can have their genetic "bar code" established, a genetic fingerprint to help identify specific species.
The research also throws up surprising discoveries about animal behaviour. For example, scientists have detailed what they describe as a "white shark cafe" that forms in the Pacific each winter when the animals congregate for up to six months.
Another group working off the coast of New Zealand has discovered a "brittle star city", tens of millions of brittle sea stars living together atop a kilometre-high seamount. .
Then there are the colonies of giant oysters found 700m down in the Bay of Biscay. Their discovery shows the need for the genetic bar- coding, something that will reveal whether they are a newly discovered species or deep- water colonies that grow large because food is plentiful and they have remained untouched.
Bar-coding has also revealed the remarkable finding that many of the world's deep-sea octopus species evolved from a common progenitor that lived in the Antarctic. This work was led by Dr Louise Allcock when based at Queen's University Belfast. She has now taken up a post at NUI Galway.
The discovery arose as scientists were attempting to meet a CML goal - "to assess and explain the diversity, distribution and abundance of marine life in the oceans, past, present and future".
Working with colleagues in Belfast, at Cambridge and the British Antarctic Survey, she reported to the conference the results of their genetic work indicating that octopuses began migrating to new ocean basins more than 30 million years ago, during a period when Antarctica cooled and sea-ice spread.
This increased the salinity of local waters and a salt density variation that created a "thermohaline expressway" flowing northward. The progenitor drifted with it to colonise new ocean basins where in time it evolved to form new species. Its closest living relative, Megaleledone setebos, (seen above) still lives in Antarctic waters.
The meeting received information about a new species of amphipod, shrimp-like crustaceans just 6mm in length that live in tubes in the Mississippi Canyon, 460m down in the Gulf of Mexico. They carpet the sea-bed with up to 12,000 individuals per square metre.
The search for new species and the genetic fingerprinting of known species will continue, and there seems no prospect of the scientists running out of subjects for study. There are 16,000 known species of marine fish, but the latest research suggests that another 4,000 are yet to be discovered.
"The impressive number of landmark findings over the past two years reveals the richness of what remains to be discovered," says deep sea explorer Myriam Sibuet, vice-chair of the census.