Fishes `need to swim faster to escape extinction`

Fish and other sea creatures will have to travel large distances to survive climate change, marine scientists have warned.

Updated: Nov 04, 2011, 14:29 PM IST

Melbourne: Fish and other sea creatures will have to travel large distances to survive climate change, marine scientists have warned.

An international team has claimed in its study that sea life, particularly in the Indian Ocean, the Western and Eastern Pacific and the subarctic oceans will face growing pressures to adapt or relocate to escape extinction.

"Our research shows that species which cannot adapt to the increasingly warm waters they will encounter under climate change will have to swim farther and faster to find a new home," said team member Prof John Pandolfi of ARC Centre of Excellence for Coral Reef Studies in Australia.

Using 50 years` data of global temperature changes since the 1960s, the scientists analysed the shifting climates and seasonal patterns on land and in the oceans to understand how this will affect life in both over the coming century.

"We examined the velocity of climate change (the geographic shifts of temperature bands over time) and the shift in seasonal temperatures for both land and sea. We found both measures were higher for the ocean at certain latitudes than on land, despite the fact that the oceans tend to warm more slowly than air over the land," he said.

The finding has serious implications for marine biodiversity hotspots, such as the famous Coral Triangle and reefs that flourish in equatorial seas, and for life in polar seas, which will come under rising pressure from other species moving in, the team says.

"Unlike land-dwelling animals, which can just move up a mountain to find a cooler place to live, a sea creature may have to migrate several hundred kilometres to find a new home
where the water temperature, seasonal conditions and food supply all suit it," Prof Pandolfi said.

Under current global warming, land animals and plants are migrating polewards at a rate of about six kilometres a decade -- but sea creatures may have to move several times faster to keep in touch with the water temperature and conditions that best suit them, say the scientists.

Team member Prof Anthony Richardson of Queensland University said: "There is also a complex mosaic of responses globally, related to local warming and cooling. For example, our analysis suggests that life in many areas in the Southern Ocean could move northward."

Prof Pandolfi added: "Also, as seas around the equator warm more quickly and sea life migrates away -- north or south -- in search of cooler water it isn`t clear what, if anything,
will replace it. No communities of organisms from even warmer regions currently exist to replace those moving out."