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Warming oceans are impacting the distribution and breeding patterns and habitat of marine life, re-arranging the broader marine landscape as species adjust to a changing climate, according to a three-year international study published today in Nature Climate Change.

The international team - including co-author Winthrop Professor Carlos Duarte from The University of Western Australia's Oceans Institute and School of Plant Biology - based their findings on a synthesis of peer-reviewed literature from around the world, identifying more than 1,700 changes, including 222 records from Australia's marine life.

The team was led by CSIRO's Climate Adaptation Flagship and University of Queensland marine ecologists Elvira Poloczanska and Anthony Richardson.

The study found that marine species are shifting their geographic distribution poleward and doing so much faster than their land-based counterparts.  Despite the ocean having absorbed 80 per cent of the heat added to the global climate system, the ocean's thermal capacity has led to surface waters warming three times slower than air temperatures over land.

"The leading edge or ‘front line' of a marine species distribution is moving towards the poles at the average rate of 72 km per decade, which is considerably faster than terrestrial species moving poleward at an average of 6 km per decade," said Dr Poloczanska.  "This is despite sea surface temperatures warming three times slower than land temperatures."

"The rapid poleward shift of marine life tracks the poleward migration of isotherms across the ocean, and represents an effort of marine life to keep within the thermal regimes they are adapted to, avoiding warmer waters and those experiencing heat waves impacting on marine life," said Professor Duarte.

The research team also considered changes in species' life cycle, such as breeding times, to find these are also changing as seas warm.

Associate Professor Richardson explained that the timing of breeding and migration are, on average, occurring much earlier in the sea with marine species advancing by 4.4 days each decade which is also much faster than land based species which are breeding around 2.3 - 2.8 days earlier each decade.

Although the study reported global impacts, there is strong evidence of change in the Australian marine environment.

Dr Poloczanska said that in Australia's south-east tropical and subtropical species of fish, molluscs and plankton are shifting much further south through the Tasman Sea.  In the Indian Ocean, there is a southward distribution of sea birds as well as loss of cool-water seaweeds from regions north of Perth.

"We are seeing widespread reorganisation of marine ecosystems, with likely significant repercussions for the services these ecosystems provide to humans," Dr Poloczanska said.

"The analysis presented provides a basis to predict shifts in the distribution of marine life and can help design dynamic marine reserve systems, able to track the species they are designed to conserve, and help the fishing industry anticipate shifts in target species that could, otherwise, cause economic collapse," Professor Duarte said.

The international team included 19 researchers from Australia, USA, Canada, UK, Europe and South Africa.

Media references

Winthrop Professor Carlos Duarte (UWA Oceans Institute, School of Plant Biology)  (+61 8)  6488 8123
Simone Hewett (UWA Public Affairs)  (+61 8)  6488 7977  /  (+61 4) 13 444 154