Exploring the mystery of the oceans

Australia and Japan are both island nations with vast maritime reserves and responsibilities. Together we’re developing the science needed to understand, use, enjoy and protect our unique marine ecosystems. And we’re collaborating to solve some of the mysteries of the ocean systems that drive the world’s climate.

Attack of the giant starfish

The waters off Japan’s tropical Okinawa Islands are home to hundreds of species of coral. The reefs attract a rich diversity of life: fish, turtles, whale sharks, and… the crown-of-thorns starfish.

Five thousand kilometres to the south is the Great Barrier Reef—the world’s largest reef system and one of the richest and most diverse natural ecosystems on Earth. The Australian Government is committed to protecting the Reef and has developed a plan to 2050 to ensure the sustainability of the Reef. But the Reef has lost half its coral cover in the past 30 years and periodic plagues of crown-of-thorns are responsible for more than forty per cent of the coral loss.

Crown-of-thorns starfish are natural predators on coral reefs around the Pacific. But currently there are estimated to be about five million of these starfish on the Great Barrier Reef. So the challenge is to determine what causes the periodic plagues, and what we can do about them.

Researchers from the Okinawa Institute of Science and Technology are working with their colleagues at the Australian Institute of Marine Science in Townsville to better understand the starfish. They’re working at every level from the underlying genetics of the starfish, the ecology and behaviour of its larval stages, which is likely to be the key that triggers periodic plagues, through to understanding its predators and developing active control options.

Exploring the ocean depths

In the deep oceans north and south of Australia is unseen life—animals never seen by human eyes. In 2010 an autonomous visual plankton recorder was lowered into the freezing waters of the Southern Ocean. It travelled 1 km down taking photos of the living plankton of the deep ocean. The survey machine was developed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). In 2012 it ventured into the warmer waters of the Coral Sea snapping photos of plankton 600 metres deep.

JAMSTEC also manages Japan’s contribution to the International Ocean Discovery Program—with over twenty nations working together to explore Earth’s last frontiers. Australia and New Zealand are members of the IODP via the Australian and New Zealand International Ocean Discovery Program Consortium, giving them access to the cruises of the Chikyu, a remarkable ship owned by JAMSTEC that can drill deeper than any other marine science drilling vessel to date.

With their partners at JAMSTEC, Australian scientists are now working to set a new agenda for cooperation in marine research for the future.

Elephant seals discover bottom water

Japanese and Australian researchers deployed elephant seals to solve a Southern Ocean mystery in 2013.

Elephant seals helped solve an ocean mystery, credit: Chris Oosthuizen.
Elephant seals helped solve an ocean mystery, credit: Chris Oosthuizen.

Southern elephant seals fitted with satellite tags foraged on the continental shelf down to 1,800 metres and revealed a layer of dense cold water—so called Antarctic bottom water—flowing out into the deep ocean.

“These seals are fantastic oceanographers,” says Tim Moltmann, Director of Australia’s Integrated Marine Observing System. “They dive and explore under the Antarctic ice sheets reaching places that we just can’t get to.”

The discovery filled an important gap in our understanding of how the Southern Ocean affects global climate.

The project was led by researchers from Hokkaido University with collaborators from the University of Tasmania and other Japanese, Australian and European organisations.