Climate change is starting to have profound effects on marine ecosystems, according to a session at this year's AAAS meeting. Species are being driven into higher latitudes and deeper waters, which is bad news for countries like Chile and China.
By Jonathan M. Gitlin | Last updated March 17, 2009 8:30 AM CT
From: Ars Technica
Climate change is already causing disruption to marine ecosystems, according to a series of talks given at this years' American Association for the Advancement of Science meeting. Oceans are both warming and acidifying, and the effects are different from those traditionally faced by the conservation community, which is having to learn how to use new tools and adapt itself to this brave new world.
Prof. Dee Boersma of the University of Washington kicked things off with data from her group's work with the penguins of Punta Tombo, Argentina. Prof. Boersma sees the penguins as sentinels that are already telling us about severe changes underway. The egg-laying season has been shifting later and later, at the rate of about 3 days every decade. When this is coupled with the greater contrast between El Niño and La Niña years, the cost of living for penguins in Punta Tombo is going up. GPS data from tagged birds reveals that they have to travel up to 40 km farther in 2008 than 2002—a long way for a small bird.
One of the results has been a northward migration, with penguins starting new colonies further up the Atlantic coast. This lined up quite well with the following talks, both of which presented modeling data on how climate change will most likely affect marine ecosystems.
Dr. William Cheung of the University of East Anglia discussed research that used climate model predictions and data of species abundance to project the changes in distribution of over 1,000 commercially important fish and invertebrate species. Cheung's work points to a migration towards higher latitudes and deeper water as species seek out more hospitable habitats.
Practically, this means local extinctions in traditional fishing areas (already being witnessed in the Bering Sea), and species invasion into others. Countries are going to lose fish stocks to their neighbors, something we're already seeing with jumbo squid and salmon. Cheung predicts that Norway, Greenland, and Alaska are going to be the biggest winners, with China, the mainland US, Indonesia, and Chile losing the most.
The final talk of the session was by Prof. Patrick Halpin, from Duke, on the predicted effects of climate change on marine protected areas (MPA). Prof. Halpin's take-home message was that the effects will not be uniform; not every MPA is as tolerant as the next, and they won't all receive the same "dose."
According to Halpin, modeling the effects of climate change on MPAs is not nearly as simple as for land masses or the open oceans. MPAs tend to be near shore, which complicates the models (based on how much of a grid is land or water), but the data show a linear trend towards warming, and the mean increase is greater than that seen for the open oceans.
The damage being done to reef ecosystems is pretty well known, with warm water reefs being at greater risk; projections show that by the end of the current century, around 90 percent will be subject to heating greater than 2°C. Another risk highlighted by Prof. Halpin is that the connections among reefs might break down, wreaking havoc on connected but geographically dispersed ecosystems.
Prof. Halpin also spoke about upwelling systems, such as those off the coast of California that bring nutrient-rich water up from the depths. The models are more suspect here, but they predict an end to upwelling by 2100, which would have massive repercussions should it happen.
Halpin ended by suggesting that it's time to move away from MPAs and towards ocean zoning, a practice that is more effective both for minimizing the damage to sensitive ecosystems and also for allowing productive human use of the seas, be that fishing or industrial.
Overall, the session painted a pretty bleak picture for the oceans over the next hundred years, but as we found out in a different session that we'll cover shortly, it's not doom and gloom everywhere.