"Canadians enjoying their summer at the cottage need to know that those green scums of algae washing up on their beach are not only unsightly, but can also be a threat to their health and their children's health," says lead author, Diane Orihel, a researcher with the Department of Biological Sciences at the University of Alberta. "It's time to get serious about cleaning up the nutrients polluting our lakes."
Microcystins are well-established as potent liver toxins to humans and other mammals, and are classified as possible human carcinogens. "Blue-green algae present a growing health concern for domestic, agricultural and recreational water use in Canada and world-wide", warns Dr. David Kinniburgh, the Director of the Alberta Centre for Toxicology at the University of Calgary. "The microcystin toxins they produce can cause acute liver failure in humans and may even cause cancer with long-term exposure."
This study is the first to report on microcystin prevalence at a national scale–data from 246 bodies of water across Canada were collected. The authors determined that water quality was most at risk in lakes with the highest concentrations of nutrients. Nutrient-rich lakes and reservoirs, particularly in central Alberta and southwestern Manitoba, proved to have highest toxin concentrations, though all regions in Canada contained lakes that reached microcystin levels of concern.
A very important finding–that calls for further research–was the strong association between low nitrogen-to-phosphorus ratios and high microcystin concentrations. The authors recommend whole-ecosystem experiments be performed to understand how changing nutrient inputs to lakes affects microcystins and other cyanobacterial toxins. This information is essential for governments to develop effective management strategies for improving water quality in nutrient-polluted lakes.
"Harmful algae blooms are a growing problem worldwide. The more we look, the more we find," remarked international water expert Dr. Stephen Carpenter, Director of the Center for Limnology at the University of Wisconsin-Madison, "Orihel and colleagues help define the conditions when we would expect highly toxic freshwater. These insights make it possible to focus management and research on the highest-risk situations."
"This study addresses an issue that has important health consequences, but also highlights the importance of both the underlying basic science and monitoring programs essential to determine environmental changes," says Don Jackson, Co-Editor of the Canadian Journal of Fisheries and Aquatic Sciences.
Earth's carbon sinks have doubled their uptake in past 50 years, lessening the warming impacts on Earth's climate even as CO2 emissions have quadrupled. It's unclear how long this trend can continue, say scientists involved in study led by CU-Boulder. Credit: Global Campaign for Climate Action, Alfred Palmer
Despite sharp increases in carbon dioxide emissions by humans in recent decades that are warming the planet, Earth's vegetation and oceans continue to soak up about half of them, according to a surprising new study led by the University of Colorado Boulder.
The study, led by CU-Boulder postdoctoral researcher Ashley Ballantyne, looked at global CO2 emissions reports from the past 50 years and compared them with rising levels of CO2 in Earth's atmosphere during that time, primarily because of fossil fuel burning. The results showed that while CO2 emissions had quadrupled, natural carbon "sinks" that sequester the greenhouse gas doubled their uptake in the past 50 years, lessening the warming impacts on Earth's climate.
"What we are seeing is that the Earth continues to do the heavy lifting by taking up huge amounts of carbon dioxide, even while humans have done very little to reduce carbon emissions," said Ballantyne. "How long this will continue, we don't know."
A paper on the subject will be published in the Aug. 2 issue of Nature. Co-authors on the study include CU-Boulder Professor Jim White, CU-Boulder doctoral student Caroline Alden and National Oceanic and Atmospheric Administration scientists John Miller and Pieter Tans. Miller also is a research associate at the CU-headquartered Cooperative Institute for Research in Environmental Sciences.
According to Alden, the trend of sinks gulping atmospheric carbon cannot continue indefinitely. "It's not a question of whether or not natural sinks will slow their uptake of carbon, but when," she said.
"We're already seeing climate change happen despite the fact that only half of fossil fuel emissions stay in the atmosphere while the other half is drawn down by the land biosphere and oceans," Alden said. "If natural sinks saturate as models predict, the impact of human emissions on atmospheric CO2 will double."
Ballantyne said recent studies by others have suggested carbon sinks were declining in some areas of the globe, including parts of the Southern Hemisphere and portions of the world's oceans. But the new Nature study showed global CO2 uptake by Earth's sinks essentially doubled from 1960 to 2010, although increased variations from year-to-year and decade-to-decade suggests some instability in the global carbon cycle, he said.
White, who directs CU-Boulder's Institute of Arctic and Alpine Research, likened the increased pumping of CO2 into the atmosphere to a car going full throttle. "The faster we go, the more our car starts to shake and rattle," he said. "If we drive 100 miles per hour, it is going to shake and rattle a lot more because there is a lot more instability, so it's probably time to back off the accelerator," he said. "The same is true with CO2 emissions."
The atmospheric CO2 levels were measured at 40 remote sites around the world by researchers from NOAA and the Scripps Institution of Oceanography in La Jolla, Calif., including stations at the South Pole and on the Mauna Loa Volcano in Hawaii.
Carbon dioxide is emitted into the atmosphere primarily by fossil fuel combustion and by forest fires and some natural processes, said Ballantyne. "When carbon sinks become carbon sources, it will be a very critical time for Earth," said Ballantyne. "We don't see any evidence of that yet, but it's certainly something we should be looking for."
"It is important to understand that CO2 sinks are not really sinks in the sense that the extra carbon is still present in Earth's vegetation, soils and the ocean," said NOAA's Tans. "It hasn't disappeared. What we really are seeing is a global carbon system that has been pushed out of equilibrium by the human burning of fossil fuels."
Despite the enormous uptake of carbon by the planet, CO2 in the atmosphere has climbed from about 280 parts per million just prior to the Industrial Revolution to about 394 parts per million today, and the rate of increase is speeding up. The global average of atmospheric CO2 is expected to reach 400 ppm by 2016, according to scientists.
The team used several global CO2 emissions reports for the Nature study, including one by the U.S. Department of Energy's Carbon Dioxide Information Analysis Center. They concluded that about 350 billion tons of carbon -- the equivalent of roughly 1 trillion tons of CO2 -- had been emitted as a result of fossil fuel burning and land use changes from 1959 to 2010, with just over half moving into sinks on land or in the oceans.
According to the study, the scientists observed decreased CO2 uptake by Earth's land and oceans in the 1990s, followed by increased CO2 sequestering by the planet from 2000 to 2010. "Seeing such variation from decade to decade tells us that we need to observe Earth's carbon cycle for significantly longer periods in order to help us understand what is occurring," said Ballantyne.
Scientists also are concerned about the increasing uptake of CO2 by the world's oceans, which is making them more acidic. Dissolved CO2 changes seawater chemistry by forming carbonic acid that is known to damage coral, the fundamental structure of coral reef ecosystems that harbor 25 percent of the world's fish species.
The study was funded by the National Research Council, the National Science Foundation and NOAA.
A total of 33.6 billion tons of CO2 were emitted globally in 2010, climbing to 34.8 billion tons in 2011, according to the International Energy Agency. Federal budget cuts to U.S. carbon cycle research are making it more difficult to measure and understand both natural and human influences on the carbon cycle, according to the research team.
"The good news is that today, nature is helping us out," said White also a professor in CU's geological sciences department. "The bad news is that none of us think nature is going to keep helping us out indefinitely. When the time comes that these carbon sinks are no longer taking up carbon, there is going to be a big price to pay."
A mysterious condition called Inclusion Body Disease (IBD) strikes captive boa constrictors and pythons, causing bizarre behavioral changes and eventually death. Scientists investigating an outbreak of IBD among snakes at the Steinhart Aquarium in San Francisco report they may well have found a virus that is responsible for this common but deadly disease, a discovery that could eventually lead to prevention and treatment options. The study appears in the August 14 issue of mBio®, the online open-access journal of the American Society for Microbiology. The authors report that the virus represents a whole new class of arenaviruses scientists have never seen before.
Among captive boas, IBD is the most commonly diagnosed disease that is thought to be caused by a virus. Snakes that have contracted IBD may initially regurgitate food, but they eventually show dramatic neurological problems, says Michael Buchmeier, a professor of infectious diseases at the University of California, Irvine. Neurological signs include "stargazing," in which the snake stares upwards for long periods of time.
"Some of the symptoms are pretty bizarre - this stargazing behavior, looking like they're drunk, they tie themselves in a knot and they can't get out of it," says Buchmeier. The condition, which is named for the inclusions, or pockets of foreign material, found inside the cells of affected animals, is ultimately fatal. IBD is devastating for large aquariums, as it can infect a large number of snakes before it is identified and quarantine measures can be put in place. Since there is currently no treatment for the disease, infected snakes must be euthanized to prevent them from infecting other animals.
When the disease recently struck a number of boas and pythons at the Steinhart Aquarium at the California Academy of Sciences, the aquarium requested help from scientists at the University of California San Francisco who specialize in discovering novel viruses.
The researchers extracted DNA from tissue samples taken from boas and pythons diagnosed with IBD, and used rapid, high-throughput techniques to learn the sequence of those strands of DNA. In amongst all the snake DNA sequences there were sequences of DNA that clearly belonged to viruses - viruses that are members of the arenavirus family. The authors were later able to grow and isolate one of those viruses using snake tissues cultured in the laboratory.
While it is an important development from a practical standpoint, since identifying the causative agent for a disease is the first step in developing treatments, vaccines, diagnostics, and prevention policies it is also an incredible discovery for virology: the virus belongs to a group of viruses no one knew existed.
"This is one of the most exciting things that has happened to us in virology in a very long time. The fact that we have apparently identified a whole new lineage of arenaviruses that may predate the New and Old world is very exciting," says Buchmeier.
According to Buchmeier, this new isolate doesn't fall neatly into either of the two known categories of arenaviruses, Old World arenaviruses and New World arenaviruses. The fact that the virus was found in snakes adds another surprise twist, since up until now arenaviruses had only ever been found in mammals.
Metagenomic techniques that examine large samples of DNA for small bits of information, like the approach used in the study, are extremely powerful for identifying new viruses, Buchmeier says.
"Twenty years ago we would have called this a fishing expedition. It is fishing, but the techniques are so good and so sensitive that they allow us to determine which new types are there," says Buchmeier.
mBio® is an open access online journal published by the American Society for Microbiology to make microbiology research broadly accessible. The focus of the journal is on rapid publication of cutting-edge research spanning the entire spectrum of microbiology and related fields. The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.