Deep Sea | Climate Shifts

Off the back of the last post, here is an interesting article from the Washington Post on the discovery of deep sea reefs in Hawaii. Deep reefs (‘mesophotic’ coral reefs) exist at the edge of the photic zone (upto 150m depth) and are still dependent on light. These are fascinating ecosystems that to date have been poorly studied:

“We were seeing reefs that no human has ever laid eyes on before,” Randall Kosaki, the research mission’s lead scientist and diver, said Tuesday. “We literally have better maps of the moon than we do of coral reefs in the Hawaiian archipelago.”

Between the area where scuba divers and submersible vehicles have traveled is a “twilight zone” that has long been unexplored, he said. It includes large swaths of coral reefs that can grow up to 400 feet underwater.

“The coral reef habitat goes four times deeper than where we’ve been working prior to this,” Kosaki told reporters.

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Using a submersible robot to penetrate depths of up to 4000m, a joint US-Australian team have reported some extraordinary organisms off the coast of Tasmania.

“Our sampling documented the deepest known Australian fauna, including a bizarre carnivorous sea squirt, sea spiders and giant sponges, and previously unknown marine communities dominated by gooseneck barnacles and millions of round, purple-spotted sea anemones”

However, a news report by the AFP suggests that even at 4km beneath the surface, there is cause for concern:

“Modern-day deep-water coral reefs were also found, however, there is strong evidence that this reef system is dying, with most reef-forming coral deeper than 1,300 metres newly dead,” he said.

Though close analysis of samples was still required, Thresher said modelling suggested ocean acidification could be responsible.

“If our analysis identifies this phenomenon as the cause of the reef system’s demise, then the impact we are seeing now below 1,300 metres might extend to the shallower portions of the deep-reefs over the next 50 years, threatening this entire community,” he said.

The lead researcher Dr Ron Thresher from CSIRO is blogging the voyage from the Research Vessel ‘Southern Surveyor’ in incredible detail, and is well worth a read.

The submersible vehicle "Jason" pictured on board the RV Southern Surveyor, exploring the deep reefs of the Tasman Fracture Zone, southern Australia.

Climate Shifts

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Tag Archives: Deep Sea

Deep sea coral reefs discovered in Hawaii

Demise of newly discovered Australian deep water reefs, 4000m below the oceans of Tasmania