Published online 7 November 2008 | Nature | doi:10.1038/news.2008.1216

News

Marine census discovers more than 200 new species

Octopus origins, shark migrations and giant bacteria to be unveiled

Researchers holding giant sea starsResearchers from New Zealand holding giant sea stars that can grow up to 60cm across.National Institute of Water and Atmospheric Research, New Zealand, 2007

Scientists have discovered more than 200 new marine species, including giant sea stars, during work on the first global marine-life census. They have also documented novel fish behaviours, such as the deep-sea diving habits of the great white shark, and have revealed new ocean habitats.

Work began in 2000, and will not be complete until 2010. But the findings so far from the 2,000-strong international marine-scientist team will be released at the World Conference on Marine Biodiversity in Valencia, Spain on 11-15 November.

The census aims to map the distribution, diversity and abundance of marine species, including a complete list of up to 250,000 named species. It also aims to provide a fresh estimate of the number of species yet to be discovered, for which current estimates vary widely from 500,000 to several million. It will provide global traffic patterns of common marine species, and document DNA barcodes to identify many species.

Ian Poiner, chairman of the census' scientific steering committee, says, "The release of the first census in 2010 will be a milestone in science. After 10 years of new global research and information assembly by thousands of experts, it will synthesize what humankind knows about the oceans, what we don't know and what we may never know."

The descent of octopuses

Research findings from the census to be revealed at the conference also include evidence of the evolutionary origins of a large proportion of the world's deep-sea octopus species. The study, to be published in the journal Cladistics, suggests that the octopuses evolved from a common ancestor, of which the closest relative, Megaleledone setebos, still exists in the Southern Ocean today.

Juvenile octopusA young Megaleledone setebos, the closest living relative of the common ancestor of all deep-sea octopuses.M. Rauschert

The researchers discovered that octopuses ride the Antarctic thermohaline expressway – a northbound flow of water with high salt and oxygen content. They suggest that the animals started to migrate to new ocean basins more than 30 million years ago when Antarctica cooled and a large ice sheet grew, creating the expressway. Once isolated in their new habitats, different octopus species evolved. For example, some lost their defensive ink sacs, which give no advantage in the dark depths of the ocean.

Great white sharks can migrate long distances to live out the winter in the Pacific for up to six months. Using satellite tagging, marine scientists discovered that during their stay in the Pacific, both male and female sharks make frequent dives to depths of 300 metres. The researchers hypothesize that the dives may be important for feeding or reproduction.

Behemoth bugs

Other new species discovered include a type of giant bacteria living in the eastern South Pacific that can grow several centimeters long. The researchers say the bacteria could be "living fossils" that developed in the earliest ocean when oxygen was either absent or much diminished, living on hydrogen sulphide. They suggest that communities of these bacteria could be used to help clean up pollution or waste.

White sharkCensus researchers have used DNA barcoding to track sharksPunchstock

The data collected will also be used to inform conservation policies. For example, researchers used DNA barcoding to track sharks and their products, including dried fins, having found a genetic marker in the organisms' mitochondrial DNA to identify it as belonging to a particular species. The technology will help to estimate how many sharks are being fished and to enforce prohibitions on the sale of their products.

Mollusc expert Patricia Miloslavich, a senior scientist on the census, says, "We are beginning to pull together a picture and clarify the complicated and interconnected global drivers of marine biodiversity patterns and changes, and we are starting to see the conservation-related implications and benefits from small coves of the near shore to the vast abyss." 

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