Eight hours on a zodiac inflatable boat on the Juan de Fuca Strait off the coast of B.C., and Dr. Peter Ross has yet to spot a killer whale. At this time of year, the animals are hardly elusive. They return to the waters between Vancouver Island and Washington state every summer to hunt big, fat chinook salmon, which make up 60 per cent of their diet. In July, Victoria’s whale tour operators—which send out a new boat every hour—claim a 93 per cent success rate. Spotting a pod is “pretty much a guarantee,” says Ross, a crew-cut, fortysomething marine mammal toxicologist with the Department of Fisheries and Oceans. But B.C.’s 85 southern resident killer whales have not been seen in three days, and it’s putting some people on edge.
Last year, seven southern residents disappeared, the biggest recorded one-year loss in a decade. (They’re called residents because they come back here every summer for the chinook.) In some cases, scientists had noted a condition known as “peanut head,” a dip in the blubber below the blowhole, indicating probable starvation. The die-off coincided with a low year for chinook returns on B.C.’s south coast, and Ross believes the southern residents are going hungry again this summer. Led by the matriarchs, the oldest females, who retain a corporate memory of area fishing grounds, he figures the whales have left their summer stomping grounds to hunt chinook elsewhere—wasting needed energy in the chase.
The killer whale is a powerful messenger. In the Pacific Northwest, where it has near-mythical status, it swims at the top of the marine food web, acting as a key indicator of the health of the ocean below. In southern B.C., its message has been grim lately, and there are signs it will get worse. Scientists have long been concerned about the combined threat of pollution, global warming and overfishing, but now they say the oceans are facing a terrifying new threat that will affect the entire marine food chain: the water is slowly but surely becoming more acidic.
More than 80 per cent of the heat generated by climate change and a third of all carbon dioxide released into the atmosphere winds up in the ocean. That carbon dioxide—a whopping 118 billion tons—is not innocuous, as scientists once thought. When it dissolves in briny seawater, it produces an acidic molecule known as carbonic acid (the same substance used in soft drinks). Seawater pH is now between eight and 8.3 in most areas, 30 per cent lower than in pre-industrial times. If trends continue, the ocean’s pH will fall by 0.3 by the year 2100—a 130 per cent increase in acidity. Dubbed “the other CO2 problem,” researchers are just beginning to grapple with what it will mean for marine communities.
In 1998, before the issue had hit even the scientific radar, oceanographer Joanie Kleypas was at a Boston conference with top U.S. biologists. With access to early experimental data, she was doing “back-of-envelope” carbon calculations relating to ocean pH when, “all of a sudden,” she realized the math was spelling a potential marine disaster. She was so shocked by the magnitude of the problem that she ran from the boardroom and threw up in a nearby bathroom. The geological record is “terrifying,” she says from her Boulder, Colo., office at the National Center for Atmospheric Research. The last time the ocean’s pH changed anywhere nearly as rapidly was 55 million years ago in an event oceanographers call the “Palaeocene-Eocene thermal maximum,” or PETM, and there was a mass extinction of calcareous organisms. Now “we seem on track to do in about 300 years what PETM did over 3,000 years,” says Debby Ianson, a climate modeller with the Department of Fisheries and Oceans.
While sea grasses and jellyfish will thrive in a more acidic environment, marine organisms with calcium carbonate shells likely will not. Indeed, shells and mollusks start to dissolve within 48 hours in seawater as acidic as the oceans are projected to be by the end of the century. So does coral—which is already suffering the impacts of global warming, local pollution, overfishing and habitat destruction. Battered by so many stressors, coral reefs, which are home to 25 per cent of all marine life, will almost certainly disappear, robbing fish of the crevasses and critical refuge from the awaiting “wall of mouths,” says Simon Fraser University biologist Nick Dulvy. Some 20 per cent of all coral reefs have already been destroyed, including a full 80 per cent of all Caribbean reefs, while another 50 per cent teeter on the brink.
Coral, with its calcium carbonate skeleton, may seem an obvious victim, but there have been some surprises. Squid—which have no shell—have trouble swimming when pH is artificially lowered in the lab. Clownfish, immortalized in the film Finding Nemo, become disoriented and have difficulty finding their anemone, according to a five-month-old study in the journal of the U.S. National Academy of Science. Other data suggests certain marine species may show sensitivity to acidification at the larval stage.
It’s early days yet, but the acidification process is happening 10 times faster than previously believed, according to the latest science. And a controversial study, sampling chemical water properties from B.C.’s Queen Charlotte Islands down to Baja California, showed that the pH in some places had already deteriorated to levels not anticipated until the end of the century, says Ianson, the coastal study’s lone Canadian. Another study, published three months ago in Nature, suggests that southern ocean planktonic organisms called foraminifera are already showing thinner shells.
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