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  New Scientist 31 Jul 07
Methane found to fuel rare glass sponge reefs
Catherine Brahic

Yahoo News 31 Jul 07
Rare Reef-building Sponge Found in Pacific
Andrea Thompson LiveScience Staff Writer

Reef-building glass sponges, thought until recently to be long extinct, have been found off the coast of Washington state, scientists announced yesterday.

Solitary glass sponges, so named because they are made of silica (the same material as beach sand and that is used to make glass), can be found living in many parts of the world's oceans, but they are different species than those that build themselves into reefs.

The three reef-building species were thought to be extinct for 100 million years until they were found a few years ago in protected Canadian waters. The same three species were recently discovered 30 miles west of Grays Harbor off Washington state, showing that they can also thrive in the open ocean.

The Washington reefs are each hundreds of feet in length and width, and rise between 6 and 15 feet (about 2 to 4.5 meters) above the sea floor. They host a thriving community of creatures including zooplankton, sardines, crabs, prawns and rockfish in an otherwise sparsely populated stretch of seafloor, said Paul Johnson, of the University of Washington, chief scientist of the expedition that found the reefs.

"It's like looking at an overcrowded aquarium in an expensive Japanese restaurant," he said.

Glass sponges range in color from a creamy white to bright yellow and grow in shapes similar to cups and funnels, unlike other sponges.

Because the newly discovered reefs are in open water and exposed to winter storms, it is likely that other reef-building glass sponges exist in other parts of the ocean, Johnson said.

New Scientist 31 Jul 07
Methane found to fuel rare glass sponge reefs
Catherine Brahic

Reef-building glass sponges were once thought to have been extinct for 100 million years. But a new live cluster of the organisms has been discovered off the west coast of the US – only the second known to exist.

Furthermore, unlike the other known glass sponge reefs in Canada, the US reefs appear to be fuelled by methane.

Paul Johnson, of the University of Washington, US, led the expedition that discovered the reefs on 10 June off the coast of Washington state.

He says they are oases of marine life, several hundred feet across, and surrounded by uninhabited expanses of seafloor. The reefs are teaming with sardines, crabs, prawns, rockfish and zooplankton, says Johnson:

"It's like looking at an overcrowded aquarium in an expensive Japanese restaurant."

'Unknown ecosystem'

The team were stunned to find large amounts of methane gas seeping out of the nearby seafloor, and even more surprised to find that the reefs appear to be fuelled by the gas.

Specialised bacteria consume the methane, and the sponges suck in the bacteria.

The Canadian glass reefs, though, are not fuelled by methane, and Johnson believes his team has discovered something new.

"Everybody is feeding off the methane," he says. "It's a whole ecosystem that people didn't know about."

Individual glass sponges, such as the Venus' flower basket, are found in various oceans, but are a different species to the ones that form colonies to build reefs.

Shelter in the deep

Until the discovery of the Canadian example, reef-building species were thought to have been driven to extinction 100 million years ago by competition from newly arrived diatoms.

Like glass sponges, these single-celled algae also use silica dissolved in seawater to build their shells.

However, the newly discovered US reefs are nearly 200 metres below the surface – too deep for diatoms, which need natural light to survive.

The discovery of glass sponge reefs in the sheltered waters of the Canadian Georgia and Hecata straits in 1991 led scientists to believe that reef-building glass sponges could only survive in benign ecological niches to survive.

But the US reefs are in open water, exposed to rough winter storms, suggesting other glass sponge reefs may exist elsewhere.

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