As warming seas menace fish, communities suffer Corrosive water threatens wide range of sea life
When nearly all the young oyster crop died two years in a row at shellfish farms in the US Pacific Northwest, workers at first suspected a virus. But the real culprit was a new worry: a change in the acidity of the sea water feeding the oyster tanks. As the world’s oceans absorb carbon dioxide that is building up in the atmosphere, seas have become 30 percent more acidic than they were before the industrial era, said Carol Turley, a senior scientist at Britain’s Plymouth Marine Laboratory.
The increasingly corrosive water threatens a wide range of sea life, particularly shellfish such as oysters and scallops, making it hard for them to form and maintain shells.
Warming of the world’s oceans, as they absorb rising heat associated with climate change, also is killing coral reefs and driving more fish species toward cooler seas and away from the regions where they have traditionally lived and been caught, Turley said on the sidelines of the recent U.N. climate talks in Marrakesh. Another effect of warming is a reduction in the amount of oxygen in the sea, threatening fish, said Ulf Riebesell, a German ocean researcher who works on acidification, among other problems.
“The ocean is under a major challenge. It’s not only heating up, it’s also acidifying and losing oxygen. The three stressors come simultaneously and they play out worldwide,” he said in Morocco.
That is fuelling new challenges for both rich and poor communities around the world, from small-scale fishermen who can no longer bring in a catch, to conservationists watching fish move out of hard-won reserves, and coastal and island states fearful their tourist industries will collapse with their ailing reefs.
“It’s happening too fast for organisms and ecosystems to develop strategies to cope,” said Hans Portner, a scientist with the German-based Alfred Wegener Institute and a contributor to the work of the Intergovernmental Panel on Climate Change.
“There’s a high risk of losing up to 90 percent of coral reefs in a 1.5-degree Celsius warmer world by the end of the century. This is a system that has already gone beyond its tolerance limits,” he said. — Reuters
SVALBARD, Norway: A polar bear stands on an ice floe near the Arctic archipelago of Svalbard, Norway. Scientists said yesterday that Svalbard has seen such extreme warmth this year that the average annual temperature could end up above freezing for the first time on record. — AP