Marine life spawns sooner as oceans warm

August 6, 2013
This eastern shovelnose stingaree was once unheard of in northern Tasmania. Now it is abundant. Image: Peter Last.

Warming oceans are impacting the breeding patterns and habitat of marine life, effectively 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 led by CSIRO's Climate Adaptation Flagship and University of Queensland Elvira Poloczanska and Anthony Richardson, based their findings on a review of peer-reviewed literature from around the world, identifying more than 1700 changes, including 222 in Australia.

CSIRO's Dr Poloczanska said are shifting their geographic distribution towards cooler regions and doing so much faster than their land-based counterparts.

Despite the ocean having absorbed 80 per cent of the heat added to the , the ocean's thermal capacity has led to surface waters warming three times slower than over land.

"The leading edge or 'front line' of a marine species' distribution is moving towards the poles at the average rate of 72 kilometres per decade, which is considerably faster than terrestrial species moving poleward at an average of six kilometres per decade," said Dr Poloczanska.

"This is despite warming three times slower than land temperatures."

Are changes in marine life consistent with climate change? Credit: Elvira Poloczanksa.

Dr Poloczanska said winter and spring temperatures, over both the ocean and land, are warming fastest, which might advance phenological events such as the start of and the timing of reproduction. In addition, anthropogenic carbon dioxide uptake by the oceans is altering seawater carbonate chemistry, which can impact some .

"Given these findings, we expect marine organisms to have responded to recent climate change, with magnitudes similar to or greater than those found for ," she said.

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.

"Essentially, these findings indicate that changes in life events and distribution of species indicates we are seeing widespread reorganisation of marine ecosystems, with likely significant repercussions for the services these ecosystems provide to humans.

"For example, some of the favourite catches of recreational and commercial fishers are likely to decline, while other species, not previously in the area, could provide new fishing opportunities," Dr Poloczanska said.

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

Explore further: Study finds climate change is causing modifications to marine life behavior

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2.3 / 5 (6) Aug 06, 2013
It's great news that natural warming plus a small kick from CO2 is allowing the biosphere to expand again just as it must have done in the Roman and medieval eras that the vast majority of proxy studies* continue to confirm were hotter than today. Combined with massive biosphere fertilization by CO2 this will indeed have delightfully "significant repercussions for the services these ecosystems provide to humans," including their mention of "new fishing opportunities."

It's just too bad that artificial energy rationing based on precautionary principle tunnel vision means fewer people who don't happen to profit from climate alarm will be able to afford that fish though.

* A temperature proxy study archive can be found here that includes ocean temperature reconstructions extending back many centuries:
1.8 / 5 (5) Aug 07, 2013
Great news for those that can exploit the ability to expand their range. Not so good for those who will ultimately lose their entire range (those that survive at near-freezing temperatures near round in the arctic and antarctic). Before the obvious "who cares" - one of those is the Antarctic Toothfish, otherwise a food stock called "Chilean Seabass." Without cold nutrient-rich water upwelling, many fisheries will experience collapse, as north sea fisheries are some of the (currently) most productive.

If anything, it will reduce overall ocean productivity, while allowing some fish to spawn where they might not have been able to before. There is still no guarantee that any sessile organisms will similarly be able to move, and more likely things like "zebra mussels" (non-foodstock organisms) will take over range of more sensitive foodstock animals.

Enjoy your hagfish sandwich.

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