Monday, February 10, 2014
Marine Migration is the Bellweather of Climate Change
For the past couple of years I've been noticing the arrival of newcomers to our local waters. Humboldt squid, the denizens of the Sea of Cortez, washing up in their hundreds on the beaches of Tofino. A green sea turtle spotted in the waters off Haida Gwai. Huge schools of sardines apparently emigrating from California. A flock of brown pelicans taking up permanent residence in the waters between Victoria harbour and Race Rocks. The giant white sunfish. And, of course, the return of the Humpback whale in large numbers around Vancouver Island.
Now the marine migration phenomenon has been documented by scientists from the Scottish Association for Marine Science (SAMS) in a paper published in the journal, Nature.
The paper, the collaborative effort of researchers from the U.S., Australia, the U.K. and Europe, finds that some prey species, such as krill, have already migrated up to 1000 km. northward. Some species, however, get trapped by coastlines and find migration routes blocked. The Mediterranean and Baltic seas are clear examples.
Species that cannot easily find their way to cooler waters run the risk of extinction.
While some species may be able to adapt fast enough to changes in their environment and while others may disperse to colonise new habitats with thermal conditions they can tolerate, there will be species that can neither adapt nor move. Those species are likely to go extinct.
A key finding of the Nature study is that routes to the shifted climates are often blocked by coastlines. Coastlines can act as barriers to the migration of marine life just as mountains ranges do for terrestrial life. Species seeking refuge from increasing temperatures in enclosed seas like the Mediterranean and the North Sea are at risk because those seas are not directly connected to the North Atlantic or Indian Oceans.
"Mapping these areas around the globe shows those places where biodiversity may be compromised by climate change, alongside all the other threats to life in an increasingly crowded and developed world," said Professor Burrows.
In the ocean, the biodiversity of equatorial regions is especially vulnerable. As sea temperatures increase, species are migrating to cooler places. These migrants are not being replaced and so biodiversity is declining.
"Knowing the areas of potential vulnerability to the effects of blocked shifts can help focus conservation efforts. In an unprecedented period of climate change, economic development and fast growing demand on an already pressured planet, we need to act fast to make sure as much of the world’s living resources survive that change," Professor Burrows urged.
This is also borne out by the migration of the Pacific grey whale. They used to travel up from the Sea of Cortez past Vancouver Island en route to their feeding grounds in the Bering Sea. The krill, however, have migrated which now forces the whales to journey further, into the Beaufort Sea in pursuit of the krill. The extra time and travel spent in pursuit of the krill was said to result in lower body mass for the grey whales.
We might know how climate change was impacting fish stocks and marine life along British Columbia's coast if only Harper hadn't thought it helpful to dismember the Department of Fisheries and Oceans in preparation for his bitumen purge to Asia.