Dispatches
2013; Wiley; Volume: 11; Issue: 8 Linguagem: Inglês
10.1890/1540-9295-11.8.400
ISSN1540-9309
AutoresESA,
ResumoSome salamander populations may have an invisible microbial shield protecting them from the deadly chytridiomycosis disease that is currently devastating amphibian populations worldwide, according to new research presented at the 2013 Ecological Society of America conference in Minneapolis, MN, in August. Researchers at the University of Maryland hypothesized that salamander declines along the US east coast may be due to Batrachochytrium dendrobatidis, the fungus that causes chytridiomycosis. However, field surveys revealed that only 1% of the salamanders tested harbored B dendrobatidis, even though they are susceptible to the fungal infection in lab experiments. The researchers therefore shifted their focus to determining whether something in nature was protecting the salamanders from infection. Carly Muletz, a PhD student at the University of Maryland, presented initial results comparing the skin microbiome composition – the cutaneous bacterial communities – of two species of terrestrial salamanders (Plethodon cinereus and Plethodon cylindraceus) in the Shenandoah, Catoctin, and Mt Rogers National Parks in the Appalachian Mountains of the eastern US. Skin swabs of salamanders reveal disease-fighting bacteria. To identify antifungal bacteria, Muletz pursued two approaches. First, she swabbed the salamanders' skin and cultured bacteria to determine which individuals could inhibit B dendrobatidis. Then she amplified the 16S rDNA sequences – the conserved genetic region of prokaryotic ribosomes – from the skin swabs to identify and characterize the entire skin bacterial community, a technique referred to as metagenomics. In total, Muletz identified 131 strains of bacteria capable of inhibiting B dendrobatidis. Interestingly, she found that salamanders in Shenandoah National Park contained the most antifungal bacteria (on average, four strains each). Furthermore, 96% of Shenandoah salamanders had at least one B dendrobatidis-inhibiting bacteria, whereas less than 50% of salamanders at Catoctin and Mt Rogers harbored any. “Something is happening at Shenandoah National Park, but I'm not yet sure what”, admits Muletz. It's not clear how the diversity of microbial communities relates to disease – does disease lower microbial diversity? Or does having lower diversity predispose a salamander to disease? These are questions increasingly being asked by wildlife biologists. “Pairing culturing work with metagenomics is a spectacular way to get at how microbes are involved in disease resistance”, says Valerie McKenzie, an amphibian ecologist at the University of Colorado Boulder, who is also exploring the importance of amphibian skin microbes in fending off disease. “It could be that the environment is shaping the microbiome, which shapes the organisms' response to disease”, she suggests. Wind power is often seen as an environmentally friendly energy source as it does not involve the burning of fossil fuels; however, construction of large-scale wind farms in environmentally sensitive areas may be ecologically harmful. India, the fifth largest wind power producer in the world, has seen a growing demand that wind power projects be subject to the same regulatory rigor as thermal and hydropower stations. At present, it is not mandatory to conduct an environmental impact assessment (EIA) for wind power projects under India's Environment Protection Act; approval from the Ministry of Environment and Forests is required only if the location of a wind power project is within a forested area or wildlife sanctuary. Now, an assessment conducted by the New Delhi-based advocacy group Centre for Science and Environment (CSE) has found that even these basic restrictions are routinely violated; about 45% of the total wind power generated in India derives from turbines located in forested areas. “Erection of turbines on hilltops and in forests means building access roads, which causes linear fragmentation of habitat and scares away animals, and the [subsequent] soil erosion results in silting of streams and water bodies”, explains Chandra Bhushan of CSE. Wind farms pose a threat to migratory birds if they are located in flight corridors and may also have human health impacts due to noise pollution and shadow flicker. Calls for more stringent regulation of wind power generation have intensified in light of these findings. “The environmental footprint of wind farms can be minimized by developing and implementing strict criteria for site selection and ensuring that ecologically sensitive lands are not used for wind farms”, says Ritwick Dutta (EIA Resource Centre, New Delhi, India). Some believe that subjecting wind energy to the same level of environmental regulation as other power sources could hamper the development of green energy. Alok Jindal of The Energy and Resources Institute (New Delhi, India) warns that regulation “may lead to delays in approval and implementation of wind power projects and limit the growth of wind power, as in some states most potential wind farm sites are in forested areas”. Natural gas is considered an efficient energy source because its combustion yields more energy per molecule of CO2 than do other fossil fuels, so that it has a smaller impact on the planet's greenhouse-gas burden. Yet the extraction and processing of natural gas “leaks” methane (the warming impact of which is 25 times greater than CO2) to the atmosphere, thereby reducing this climate advantage. However, a new report (Geophys Res Lett 40; doi:10.1002/grl.50811) suggests that methane emissions from natural gas industrial operations may be considerably greater than previously believed. Despite the recent surge in US natural gas production, accurate and reliable assessments of the associated methane emissions have been sorely lacking, according to study coauthor and atmospheric monitoring specialist Colm Sweeney (Boulder, CO). Over the past few years, US Environmental Protection Agency estimates have fluctuated substantially – between 0.16% and 1.42% of total annual methane production – casting doubts on the results and leading government officials to call for improved methods for determining emissions. Regarding climate effects, a 2012 study (P Natl Acad Sci USA 109: 6435–40) calculated that if methane leakage exceeded 3.2% of annual natural gas production, the immediate impact would surpass that of a coal-fired plant generating a comparable amount of electricity. To obtain information on methane leakage from oil and gas fields in Utah's Uintah Basin, Sweeney and 18 colleagues affiliated with the National Oceanic and Atmospheric Administration and the University of Colorado Boulder employed a “mass balance” technique that's used for gauging the atmospheric impacts of refineries and power plants. “The technology to do this from small planes, such as the one that we used [for this study], only became available a few years ago”, Sweeney explains. “We calculated actual emissions rates for the Basin using the measured difference between air upwind and downwind of the Basin, along with the wind speed and our knowledge of how high methane molecules emitted from the ground will travel as they move across the Basin”, he continues. Although only a single day proved ideal for airborne measurements during the February 2012 field-test period, the results were clear and surprising: the rate of methane leaking from natural gas operations averaged between 6.2% and 11.7% of overall production. “This negates any short-term (ie less than 70 years) climate benefit of natural gas from this Basin for electricity generation compared to coal and oil”, the researchers conclude, adding that the findings show that the method used can reliably determine methane leakage and highlight the need for further atmospheric monitoring to better assess these emissions. The exotic emerald ash borer (Agrilus planipennis; EAB) beetle is killing millions of trees and devastating ash (Fraxinus spp) populations in the midwestern US, but insect-eating birds such as woodpeckers are taking advantage of this new food source and their populations are responding, according to a new study (Biol Invasions 2013; doi:10.1007/s10530-013-0435-x). “The EAB invasion is a remarkable ecological event –something like a giant bomb blowing up with millions of dead trees and billions of beetles, all in an epicenter around Detroit, Michigan”, says Andrew Liebhold of the US Forest Service (Morgantown, WV), a coauthor of the study. “This [means] that there is a tremendous resource for anything that eats insects.” Liebhold and colleagues from Cornell University – with the help of a cadre of citizen scientists from Project FeederWatch (run by the Cornell Lab of Ornithology) – tested the responses of three different species of woodpecker and one species of nuthatch to the EAB outbreak, and found a surprising amount of variation in the responses of each type of bird. All four species eventually experienced population increases, although two of the species first showed declines. “Given that prior work had demonstrated that several species of woodpeckers can eat a high proportion (around 30–40%) of EAB larvae in an area, perhaps the biggest surprise was that we didn't see a more dramatic or obvious increase in several of those species”, explains coauthor Walt Koenig (Cornell University, Ithaca, NY). Liebhold and Koenig believe that although the increase in woodpecker populations is unlikely to stop the spread of EAB, it may slow it in some areas, and they note that many other species may benefit from the EAB invasion. “No doubt this invasion causes a huge pulse of dead trees, which triggers a succession of population responses by a lot of different organisms that are affected by dead and dying trees”, says Liebhold. Downy woodpecker (Picoides pubescens) populations initially declined in response to EAB, but after several years their numbers began to increase substantially. Liebhold also points out the important role that non-scientists played in collecting the data used in this research. “This study was possible because of citizen science. The epicenter of the EAB invasion is in an urban/suburban habitat, so the Project FeederWatch data were perfect for detecting the impact of the invasion.” Tired of buildings that are too cold in the summer and too warm in winter? Take offices that blast cold air when it's blistering outside: over-air conditioning means refrigerating the whole building to the lowest temperature anyone wants, and then re-heating the areas where people prefer it to be warmer. But relief may finally be in sight, and the fix would also save energy and cut carbon (C) emissions. “People are not comfortable and we're wasting a lot of energy”, points out David Lehrer, Communications Director at the University of California Berkeley's Center for the Built Environment (CBE). “We need to find a balance.” Now, CBE researchers think they have found a solution. Instead of setting the building temperature globally, they want to create a system that allows people to regulate their microclimates individually. This is easy to do. “When you're cold, you need to warm your extremities, and when you're hot, you need air moving around your face and head”, Lehrer explains. CBE's personal climate system includes fans, foot warmers, and chairs that, like seats in fancy cars, heat up or cool down on demand. “There's an immediate response”, Lehrer continues. “A lot of people want these chairs.” Switching from whole building to personalized climate control could lower energy use by a third, saving US$60 million and cutting 270 000 tons of C emissions per year in California alone. On the strength of on-campus pilot studies, the CBE team will optimize their system in the real world with a US$1.6 million grant from the California Energy Commission (Sacramento, CA). “We'll expand our field studies to working office buildings in a range of climates”, Lehrer continues. Participants will rate their comfort while sensors monitor building energy use. Too hot? Your workstation could shift your thermal profile toward cool greens and blues. Another energy-wasting contributor to discomfort is the high flow rate of forced-air systems. The industry standard is to exchange 30% of a building's air each hour, but a CBE study showed that dropping this to 10% increased people's comfort while cutting energy use by 5–20%, depending on the building. “We want to get the flow rate down”, Lehrer concludes. “Doing it in California could set the standard for other states.” Two Canadian environmental NGOs, Équiterre and the David Suzuki Foundation, are suing the Canadian Government for refusing to review the approval of three herbicide/pesticide compounds already banned in the European Union (EU) and for stalling on replying to requests for reviews of 26 other such chemicals. Represented by Ecojustice, an organization that provides free legal services to charities and citizens defending environmental causes, the claimants allege that by not reviewing these compounds, the Canadian Minister of Health and the Pest Management Regulatory Agency (PMRA) have not fulfilled their obligation to protect citizens' health and the environment. The three compounds at the heart of the dispute are chlorthal-dimethyl, trifluralin, and trichlorfon. Chlorthal-dimethyl, which in Canada is still used to control weed growth, was banned in the EU in 2009; the compound is a possible human carcinogen known to contaminate groundwater. Trifluralin appears in a range of herbicides used extensively in Canada, but was banned in the EU in 2007, following concerns about its persistence in soil, bioaccumulation, and toxicity to fish. Trichlorfon, which has a pesticidal action, is used in Canada to protect pine plantations and cattle; it fell from grace in the EU in 2007, over concerns about neurological effects in humans. “Recent scientific evidence has led to these substances being banned in other countries, and as such the Federal Government has an obligation to re-evaluate [them]”, says Mara Kerry, Science and Policy Director at the David Suzuki Foundation (Vancouver, Canada). “Our interpretation of the law is that it is not discretionary. The Government has a responsibility to protect the health of Canadians and the environment.” A spokesperson for Health Canada and the PMRA said: “Officials and legal counsel are currently reviewing the contents of the applications and will respond to the applications within the time frame set by the court.” The other 26 compounds for which the applicants have requested a special review of approval include atrazine, a potential endocrine disrupter often detected in drinking water. Although widely used in the US and Canada, atrazine is also banned in the EU. “It's [been] nearly a year since the request for review was submitted”, points out Elaine MacDonald, a Senior Scientist with Ecojustice (Toronto, Canada). “And still no answer.” Health Canada and the PMRA limited their reply to “Health Canada's primary objective in regulating pesticides is to protect Canadians' health and their environment.” A court date has not yet been set for hearings to begin. Businesses that plunder the environment may have a harder time obtaining cheap loans. More than 40 of the world's leading banks are launching a project to incorporate the value of natural capital into their investment risk assessments. The project springs from last year's Rio+20, the UN Conference on Sustainable Development, during which the participating banks signed the Natural Capital Declaration (NCD), a document stating that natural resource exploitation destroys ecosystem services, thereby threatening financial health. The NCD defines natural capital as the Earth's stocks of soil, air, water, and living things, and the ecosystem services they provide. “Despite being fundamental to our well-being, their daily use remains almost undetected within our economic system”, the NCD asserts. Ignorance of the environmental damage caused by businesses poses an increasing threat to bank portfolios, says Lauren Smart, executive director of Trucost (London, UK), a natural capital consulting firm. For instance, if a company pollutes the water it depends on to make its products, profits will decline and the company may be unable to pay back loans from the bank. A Trucost report estimates that annual global environmental damages will increase from US$6.6 trillion to US$28.6 trillion by 2050. The NCD signatories plan to shine a light on these neglected risks and have recently set up working groups to develop tools that investors can use to integrate natural capital into loans, investments, and insurance policies, according to Liesel Van Ast, NCD project manager (Oxford, UK). The working groups will also develop methods for companies to account for and report on natural capital in quarterly or annual financial statements. The signatories aim to complete this work by 2020. Ultimately, the NCD tools will reveal to what degree a company's environmental impact creates a risk for investment or insurance. “This could mean that banks might engage with their clients to help them adopt best practices that don't erode natural capital”, Smart suggests. Alternatively, financial institutions might boost the cost of loans or insurance to firms that degrade the environment. “If banks start paying attention to the impacts of our economy on the environment, that's a very positive development”, says Peter Victor, an economist at York University (Toronto, Canada). But such an approach doesn't guarantee that environmental impacts will be reduced below thresholds deemed protective of ecosystem quality, such as lowering atmospheric CO2 concentrations to below 350 ppm, he cautions. One of the biggest challenges for those trying to manage or protect rivers has always been identifying pollution problems as they occur –people will sometimes observe illegal dumping, for example, but may not have a way to report it quickly and accurately. Now, a team working in the Shenandoah River and Potomac River watersheds in the eastern US has developed an app to address the problem, enabling anyone with a smartphone to report an incident immediately and – if they prefer –anonymously. Known as the Water Reporter, the free app auto-tags a user's location and asks for some basic information about the incident; users can also include a photo, if desired. A report is then sent to a local clean-water advocate known as a waterkeeper –which can be either a group or simply an individual – and a live map is generated online. Potomac Riverkeeper Board Member Stanley Oaks uses the app to report pollution in Sleepy Creek. “Usually, if someone has to go through a number of fields on a web-site form, they aren't too motivated to fill it out”, explains John Dawes (Washington, DC), Administrator of the Chesapeake Commons and one of the app's developers. “We wanted to make it as easy as possible to report data.” Brent Walls (Bunker Hill, WV), of the Potomac Riverkeeper organization, says his group has already received 18 reports from the app since it was released in late summer. One even resulted in an official investigation at a leaky industrial impoundment site in his state. “We have big plans”, he says about proposed future improvements for the software. “But really, anyone can do this as long as they have a GIS server and they're connected to ESRI [GIS software and geodatabase management supplier].” Tracy Brown (Ossining, NY), a water-quality advocate with the Hudson Riverkeeper in New York, believes that the new app could be useful and may be something her own group could replicate. “I think it could really help small NGOs to manage the work flow and quality of the data that comes from these kinds of reports”, she says. “The public wants to engage on the issue of water quality and this makes it easy for them to do so.” China experienced an unusually hot summer this year. Heatwaves blasted 19 provinces, an area of 3.18 million km2, nearly one-third of the country. Forty-three cities recorded daily temperatures in excess of 40°C (~104°F), leading the China Meteorological Administration – the nation's national weather service – to issue a heat emergency response order on July 30. In addition, drought conditions reduced drinking water supplies to over 2 million people and impacted agricultural production on 1.32 million ha in the southern part of the country. “The specific definition of heatwave varies between countries. In China, a heatwave is defined as 3 consecutive days when temperatures reach or exceed 35°C (~95°F)”, explains Tiantian Li, an Associate Professor in the Department of Environmental Health Risk Assessment at the Chinese Center for Disease Control and Prevention (Beijing, China). Chinese construction workers stayed on the job despite record temperatures this summer. Heat-related deaths were reported in many cities, with victims including outdoor workers and the elderly. While the total number of heat-related deaths is not yet known, news reports from cities throughout China provide some hints of the toll of this summer's heatwaves. Hospitals in Ningbo City treated 273 patients for heatstroke in June, three times as many as the previous year; as of July 30, at least 10 people had died from heatstroke in Shanghai; and eight laborers died between July 30–August 1 in Jinan City, when temperatures of 36°C (~97°F) were recorded. While the heat emergency response order suggested suspending outdoor work during certain times of the day, this was not mandatory. “Heatwaves are one type of extreme weather event related to global warming. According to the Intergovernmental Panel on Climate Change, we can expect more heatwaves in the future, in terms of frequency, duration, and intensity, as a result of human-emitted greenhouse gases”, says Li. The excessive heat has given ecological landscape design some leverage in terms of trade-offs with economic growth. In 2006, Wuhan, a so-called “stove city”, developed a plan to create six wind corridors that would bring cool air into the city from the Yangtze River, but eventually the project was abandoned because of cost. This year, after 22 consecutive days of temperatures in excess of 35°C, Wuhan officials restarted work on the project. Disturbed ecosystems full of invasive organisms are rapidly becoming the norm, and some scientists predict that this will drive catastrophic loss of species and ecosystem functions. However, a new study (Trop Conserv Sci 2013; 6: 325–37) shows that so-called “novel” tropical forests on the island of Puerto Rico provide abundant ecosystem services and foster regeneration of native species. Such no-analog communities (which contain previously unrecognized combinations of plants and animals) commonly occur in response to anthropogenic factors. “Novel ecosystems of native and introduced species now comprise about 35% of global lands”, says Ariel Lugo, author of the study and director of the US Department of Agriculture's International Institute of Tropical Forestry (Rio Piedras, Puerto Rico). Although resource managers tend to view these ecosystems as degraded and lacking conservation value, Lugo used novel tropical forests on Puerto Rico as a case study to look at how they functioned. After the rural human population largely abandoned farming for jobs in urban areas, Puerto Rico's forest cover rebounded from 5% in the mid-20th century to 60% today. But 75% of the forests are novel, with introduced species dominating the canopy. Nevertheless, Lugo and other researchers report that productivity, nutrient fluxes, and the number of tree species per hectare are all higher in the novel forests than in the native forests they replaced. “We found that extinction rates were well below those expected from species–area analysis”, he says. In fact, all else being equal, Puerto Rico would currently be without forests if not for the introduced species. The abandoned land was so degraded that only invasive plants were able to colonize it initially. Now, native species are becoming established within the understory, Lugo explains. “Our results hint that a conservation strategy that considers all lands and all species is needed to effectively deal with global change.” The classical approach to restoration would be to try to eradicate introduced species and return these systems to a historical state, explains Richard Hobbs, a plant biologist at the University of Western Australia (Crawley). “However, this is often expensive, doesn't always work, and perhaps takes resources away from other conservation activities that could produce more effective results.” “Given that novel ecosystems are the new normal, this study shows how we might go forward and achieve conservation objectives”, says Tim Seastedt, a terrestrial ecologist at the University of Colorado Boulder.
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