Increasing levels of ocean acidity1 could spell doom2 for British Columbia's already beleaguered3(围困的) northern abalone(鲍鱼) , according to the first study to provide direct experimental evidence that changing sea water chemistry is negatively affecting an endangered species. The northern abalone--prized as a gourmet4(美食家) delicacy--has a range that extents along the North American west coast from Baja California to Alaska. Even though British Columbia's northern abalone commercial fisheries where closed in 1990 to protect dwindling5 populations, the species has continued to struggle, largely due to poaching.
To better understand the impact climate change — and specifically, increasing ocean acidity — has on this endangered species, UBC researchers exposed northern abalone larvae6 to water containing increased levels of CO2. Increases from 400 to 1,800 parts per million killed 40 per cent of larvae, decreased the size of larvae that did survive, and increased the rate of shell abnormalities.
"This is quite bad news, not only in terms of the endangered populations of abalone in the wild, but also the impact it might have on the prospects7 for aquaculture(水产业) and coastal8 economics," says Christopher Harley, Associate Professor with the Department of Zoology9 and one of the authors of the study.
"And because the species is already thought to be limited by reproductive output and recruitment, these effects are likely to scale up to the population level, creating greater limits on population growth."
Average CO2 levels in the open ocean hover10 at 380 parts per million, a number which is excepted to increase slowly over the next century.
What concerns the researchers are the much higher spikes11 in dissolved CO2 that are already being observed along the BC coast, particularly in late spring and early summer when northern abalone populations are spawning12.
The findings were published in the latest issue of the Journal of Experimental Marine13 Biology and Ecology.
"While we're looking at a single species that is culturally important as a source of food and artistic14 inspiration for many coastal Pacific Northwest First Nations, this information may have implications for other abalone species in other parts of the world," says Ryan Crim, lead author on the paper who conducted the research while a graduate student with the UBC Department of Zoology.
Other species of abalone are farmed around the world, principally in China, Taiwan, Japan and Korea. The black, white and pink abalone are also endangered on the west coast--red abalone are still an economically viable15(可行的) food species.
The study was funded by the Natural Sciences and Engineering Research Council of Canada and conducted in collaboration16 with the Bamfield-Huu-ay-aht Community Abalone Project, a small abalone hatchery in Bamfield which has subsequently gone out of business. The dual17 mission of the hatchery was to produce cultured abalone for high end restaurants, and to restore endangered abalone by culturing and releasing larvae and juveniles18 to the wild.
Harley and Crim will continue to work with the aquaculture industry to study the effects of acidification on oysters19(牡蛎) and other shellfish.