By Jonathan Fildes, Science and technology reporter, BBC News, San Francisco
The delicate interplay between the oceans and atmosphere is changing with catastrophic consequences.
That is the conclusion of researchers investigating 'dead zones' off the coast of the US, where populations of marine life were suddenly wiped out.
These vast graveyards occur where there are disturbances to currents driven by coastal winds, they say.
Dead zones have been recorded off the coast of California and Oregon every year for the last five years.
The most intense event, which left the ocean floor littered with the carcasses of crabs, happened in 2006.
'It was unlike anything that we've measured along the Oregon coast in the past five decades,' said Dr Francis Chan of Oregon State University (OSU).
Dead zones have also been seen in the waters off Chile, Namibia and South Africa."
Read more at BBC News...
http://news.bbc.co.uk/1/hi/sci/tech/6370905.stm
Kristin Rasmussen at Cascadia Research Collective in Olympia, Washington, US, and colleagues photographed the tails of humpbacks wintering off the Caribbean coast of Costa Rica. From their individual tail patterns they identified seven of the same animals after they had returned to the Antarctic. One mother and calf made the 8300-kilometre (5160-mile) trip in 161 days.
Using satellite data, the team also recorded sea-surface temperatures for the sites where humpbacks spent the winter. “Wintering areas occur where waters with temperatures between 21°C and 28°C are found,” says Rasmussen. This supports the idea that the long migration saves the whales energy in the end.
Some researchers claim that the grey whale holds the record for longest mammalian migration – from Mexico to the Arctic, estimated at about 7600 km (4700 miles). “However, no individual grey whale has been documented travelling the full extent of their migratory range, and it's possible that no grey whales actually make the entire migration,” says Rasmussen. Only humpbacks have been documented making the full trip.
Rasmussen says that proposals to hunt humpbacks – such as Japan’s decision to catch 50 humpbacks each year as part of its “scientific” programme – makes it important to understand whale migration. “Whales don’t respect political boundaries,” she says. “Killing whales in one area could potentially impact their population half way around the world.”
Journal reference: Biology Letters (DOI: 10.1098/rsbl.2007.0067)