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Scientists think a third of sea species unknown
WILDLIFE Scientists estimate a third of ocean species still unidentified
Updated 11:21 pm, Thursday, November 15, 2012
The world's oceans are teeming with as many as a million different species - from microscopic plankton to monster whales - and possibly a third of them are still unknown to science, according to the first full-scale register of the seas' diversity.
The census of all the ocean's plants and animals by hundreds of ocean scientists from around the world is just an estimate, but even still the species-by-species count is crucial for understanding the biodiversity of all the oceans and for protecting their future in a swiftly changing environment, said Stephen Palumbi, director of Stanford's Hopkins Marine Station in Pacific Grove.
"It's the best job ever of tallying everything we know - and what we don't know - about life in the oceans today," Palumbi said. "It's the first time anyone's done this kind of dirty work that's so important with the world's oceans facing a biodiversity crisis."
Scientists say the crisis has many causes, including overfishing as human populations increase, widespread damage to coastal environments, and increasing acidification of ocean waters as carbon dioxide levels rise in the atmosphere, to name three of the most significant threats.
Collection of research
The inventory, which is continuing, is called the World Register of Marine Species. It is being amassed by a unique collaboration among marine scientists - 270 experts from 146 institutions in 32 countries - from many disciplines whose specialized research is being gathered into a single database.
Their findings were reported Thursday in the journal Current Biology.
"For the first time, we can provide a very detailed overview of species richness, partitioned among all the marine groups," said Ward Appeltans, a biologist at UNESCO's International Oceanographic Commission office in Ostend, Belgium, who led the effort. "It is the state of the art of what we know - and perhaps do not know - about life in the ocean."
One contributor is Rich Mooi, curator of invertebrate zoology at the California Academy of Sciences, who studies the life and death of organisms like sea urchins, sea stars and sea cucumbers, known as echinoderms.
Mooi, who collects echinoderms from the Philippines to Antarctica, estimated they number from 7,000 to 8,000 separate living species, with 13,000 to 15,000 long gone and in the fossil record.
"You can't understand the evolution of all today's organisms without comparing them as they are now with how they were long, long ago," Mooi said.
Among the million or so ocean species living today, a third are completely unknown, the scientists estimated. Understanding just how and where the varied species thrive or may be threatened should help efforts to protect their ocean environments, they say.
"All those species have figured out how to live in the world that's been changing for millions of years," Palumbi said. "So if you want to know how they've lived through climate changes in the past, they could have lessons for us."
To illustrate the problems of identifying individual species in a census like this, Palumbi, a marine biologist, recalled his own difficulties as a specialist in the life of corals. He studied the forms of what scientists had long thought were two coral species living in habitats spread across the Pacific from Samoa to Zanzibar.
The samples of each coral species looked alike, but when he and his colleague Jason Ladner analyzed the genes of those corals, they found that the two were actually six distinct species. The discovery was an example of what scientists call "cryptic diversity," Palumbi said.
A bigger puzzle for the census takers was estimating the number of marine species that are still unknown to science. So they examined hundreds of collections in museums around the world, and from the number of species that remain unidentified there, they calculated that about one-third of the ocean's species are yet to be discovered.
The complete results of the continuing inventory are now listed in an open-access database called the World Register of Marine Species at www.marinespecies.org.