Ocean acidification: A bleak future for pacific biodiversity - from corals to crabs

Researchers from the Australian Institute of Marine Science (AIMS) have published a paper today in the UK-based Royal Society's peer-reviewed journal, Proceedings of the Royal Society B, which shows the detrimental effects of increasing levels of carbon dioxide (CO₂) on the diversity of invertebrates that inhabit our coral reefs. It's a snapshot of the centuries to come for our coral reefs, which house hundreds of thousands of species, including: octopi, clams and crabs.

 

"We have shown how detrimental high CO₂ can be for corals. When CO₂ from the atmosphere mixes with water, it causes ocean acidification, lowering the pH of the water and changing its carbonate chemistry. This in turn makes it harder for a range of marine animals to form their shells and skeletons," said AIMS coral reefs research scientist, Dr Katharina Fabricius.

 

Ocean acidification slowly selects boulder-like massive coral over structurally complex branching and foliose (leaf-like) corals, which are the home of many species like crabs, shrimps and sea stars. As a result, ocean acidification has a domino effect: as the habitat structure decreases, the animals that live and hide in their nook sand crannies find it far harder to survive, simply because they cannot hide from predators."

 

Fabricius' team has been investigating the consequences of long-term exposure to high CO₂ on coral reef communities around three, shallow volcanic CO₂ seeps (or vents) in eastern Papua New Guinea (PNG) in Milne Bay province over the past few years. This location is one of the few known CO₂ seep sites in tropical waters within coral reef ecosystems.

 

"The decline of the structurally-complex corals means the reef will be much less rich and complex, and there will be less habitat for the hundreds of thousands of species we associate with today's coral reefs," she added.

 

The AIMS research project has given scientists valuable insights into what tropical coral reefs could look like if human-induced atmospheric CO₂ concentrations continue to rise at the present rate. The ecological effects of ocean acidification has been largely unstudied until now.

 

The research also shows how important it is for scientists to conduct field-based research alongside laboratory work.

 

"We observed ecological outcomes that were not always predictable from laboratory experiments," said Fabricius.

 

According to AIMS Research Director, Dr Jamie Oliver: "It is important that we now intensify efforts to run controlled laboratory studies, in our new SeaSim facility at AIMS where we can manipulate a range of factors such as temperature and light as well as pH. If we can replicate the long-term responses that we find at the PNG seeps, then we can use our experimental system to explore the outcomes of future scenarios involving different rates of CO₂ increase combined with other stresses that are occurring on the Great Barrier Reef."

 

Article title: Ecological effects of ocean acidification and habitat complexity on reef-associated macro-invertebrate communities

Journal: Proceedings of the Royal Society B

 

For interviews, contact: Dr Katharina Fabricius, k.fabricius@aims.gov.au; +61 (0)7 4753 4412, +61 (0)428713845 (QLD, ten hours ahead of the UK); Georgina Kenyon (AIMS Communications), g.kenyon@aims.gov.au, +61 (0)7 4753 4265.