December 15, 2007
Lobsters Caught in Global Warming Pot
New research paints a bleak picture for coral reefs and the communities that depend on them if emissions of greenhouse gases are not dramatically curbed.
But if you think what happens in the warm, clear waters of the tropics has little to do with Maine's cold and choppy seas, think again.
Lobsters, sea urchins, clams and scallops -- all critical to Maine's commercial fishing industry -- and even Atlantic salmon could fall prey to the same environmental changes killing off coral reefs in warmer climes, according to a University of Maine scientist involved in the latest research.
"We're not talking about something confined to coral reefs. We're talking about something that is global," said Robert Steneck, a University of Maine professor of oceanography, marine biology and marine policy, and a leading authority on lobster biology.
In a report published Friday in the journal Science, Steneck and a team of global researchers warn that the buildup of atmospheric carbon dioxide from fossil fuel combustion may make the oceans too acidic for coral to survive in less than 50 years.
A mass die-off of coral -- already under way in some areas -- would have enormous implications for not only marine ecosystems but also the multibillion-dollar tourism industry and rural communities that survive on the bounty of sea life around reefs.
"This crisis is on our doorstep, not decades away," Ove Hoegh-Guldberg, a professor at the University of Queensland in Australia and the report's lead author, said in a statement. "The livelihoods of 100 million people living along the coasts of tropical developing countries will be among the first major casualties of rising levels of carbon in the atmosphere."
While the Science paper focused on coral reefs, Steneck warned in an interview that the same human-driven changes that are killing off coral could wreak havoc on the economy of Maine and its North Atlantic neighbors.
Coral reefs and hard-shelled marine life, such as lobster, likely will face a double-whammy in the near future, according to the researchers.
First, an estimated 25 percent of all atmospheric carbon dioxide is absorbed by the oceans, where it reacts chemically with water to produce carbonic acid. The more CO2 in the atmosphere, the more acidic ocean water becomes.
Carbonic acid affects organisms' ability to access or maintain levels of calcium carbonate. More commonly known as limestone, calcium carbonate makes up the hard part of coral and is key to the ability of lobsters, clams and other organisms to calcify their exoskeletons.
Less available calcium carbonate means lobsters and other creatures have to spend more energy forming their shells, thereby diverting energy from foraging for food and reproduction. It also could affect shell thickness and strength, Steneck said.
"This is armor, this is not something you mess around with," said Steneck, who has studied lobsters for more than two decades. "It's also absolutely essential for their locomotion and their feeding. Calcium carbonate is not negotiable for them."
The second part of the double-punch comes from rising ocean temperatures.
Even a slight rise in temperature can further stress marine organisms, making them more susceptible to disease. And global ocean temperatures already have risen by more than 1 degree during the past century.
Steneck pointed to Rhode Island, where in 1998 a shell disease of unclear origin caused a huge die-off of lobsters.
Even a short-term die-off of Maine's lobster population likely would cripple the state's fishing fleet, which makes the vast majority of its money from the iconic crustacean, Steneck said.
"I don't want to be too alarmist, and I'm not saying lobster are going to crash tomorrow," he said. "But we know from Rhode Island that lobsters are susceptible to disease."
Richard Wahle, who studies lobsters as a senior research scientist with the Bigelow Laboratory for Ocean Sciences in West Boothbay Harbor, said he and other researchers believe lobster populations will be forced to migrate farther north as climate change increases ocean temperatures.
Wahle, who was not part of the coral reef research team, said it is unclear exactly how much climate change played a role in the disease outbreak in Rhode Island and another die-off in Long Island Sound. But it is clear that global warming will affect lobsters, he added.
Ocean acidity and its effects on lobsters and other hard-shelled organisms is an important issue that will have to be closely watched, he said.
"Bob's work really shows there are aspects of global climate change other than the rise in temperature" that must be considered, Wahle said of Steneck.
Lobsters would not be the only species affected, either.
Clams, sea urchins, scallops and other invertebrates depend on calcium carbonate for survival. So do pteropods, tiny mollusks believed to be a food source for the already imperiled Atlantic salmon.
The outlook for coral reefs is decidedly gloomy, however.
The researchers point out that atmospheric carbon dioxide levels are higher than at any point in the past 740,000 years and rising fast as fossil fuel-dependent societies pump out more and more greenhouse gases.
If levels continue to grow, coral reefs could be gone by 2050, the researchers said. They used the research paper to call on world leaders to commit to steps to dramatically reduce CO2 emissions.
While there is consensus among leading scientists about the impending danger of global warming, achieving international agreement on policy responses to climate change will not be easy.
As evidence of that, delegates at a United Nations climate conference in Bali, Indonesia, continued to argue Friday over the specifics of a draft "road map" for cutting greenhouse gas emissions. The U.S. delegation has led the fight against specific commitments to reduce emissions by 2020.
Delegates are expected to gather again today in hopes of agreeing on a document to guide future negotiations to replace the 1997 Kyoto Protocol.