Deep-sea reef discovered off Tasmania

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A collaborative expedition by Australian and US scientists has discovered a new deep-sea reef in the ocean southwest of Tasmania.

Although much bizarre marine life was uncovered, the findings were tempered by evidence that much of the coral reef is dying, possibly as a result of human influences.

Led by chief scientists Jess Adkins from the California Institute of Technology and Ron Thresher from CSIRO s Climate Adaptation and Wealth from Oceans Flagships, the four-week voyage of the RV Thomas G. Thompson explored the Tasman Fracture Zone, a near vertical slice in the earth s crust that drops from approximately 2000 metres to over 4000 metres.

With the aid of the deep-sea submersible Jason, the scientists found bizarre carnivorous sea squirts, sea spiders and giant sponges, and previously unknown marine communities dominated by gooseneck barnacles and millions of round, purple-spotted sea anemones at depths of more than 2000 metres.

Vast fields of fossil corals more than 10,000 years old were also found. Information on ancient climate changes from these fossils will contribute to models of regional and global climate change.

However, the scientists also found strong evidence to indicate that the present-day reef system is dying. According to Dr. Thresher, we need to closely analyse the samples and measurements we collected before we can determine what s caused this, as it could be the result of several factors, such as ocean warming, disease or increasing ocean acidity.

Mathematical models predict that we could be seeing impacts of ocean acidification in this region. If our analysis identifies this phenomenon as the cause of the reef system s demise, then the impact we are seeing now below 1300 metres might extend to the shallower portions of the deep-reefs over the next 50 years, threatening this entire community.

Pictures by Advanced Imaging and Visualization Laboratory WHOI.