Lemurs Are the World’s Most Endangered Mammals, but Planting Trees Can Help Save Them
By Andrea L. Baden
The island of Madagascar off the southeastern coast of Africa hosts at least 12,000 plant species and 700 vertebrate species, 80% to 90% of which are found nowhere else on Earth.
Isolated for the last 88 million years and covering an area approximately the size of the northeastern United States, Madagascar is one of the world's hottest biodiversity hotspots. Its island-wide species diversity is striking, but its tropical forest biodiversity is truly exceptional.
Sadly, human activities are ravaging tropical forests worldwide. Habitat fragmentation, over-harvesting of wood and other forest products, over-hunting, invasive species, pollution and climate change are depleting many of these forests' native species.
Among these threats, climate change receives special attention because of its global reach. But in my research, I have found that in Madagascar it is not the dominant reason for species decline, although of course it's an important long-term factor.
As a primatologist and lemur specialist, I study how human pressures affect Madagascar's highly diverse and endemic signature species. In two recent studies, colleagues and I have found that in particular, the ruffed lemur – an important seed disperser and indicator of rainforest health – is being disproportionately impacted by human activities. Importantly, habitat loss is driving ruffed lemurs' distributions and genetic health. These findings will be key to helping save them.
The Forest Is Disappearing
Madagascar has lost nearly half (44%) of its forests within the last 60 years, largely due to slash-and-burn agriculture – known locally as "tavy" – and charcoal production. Habitat loss and fragmentation runs throughout Madagascar's history, and the rates of change are staggering.
This destruction threatens Madagascar's biodiversity and its human population. Nearly 50% of the country's remaining forest is now located within 300 feet (100 meters) of an unforested area. Deforestation, illegal hunting and collection for the pet trade are pushing many species toward the brink of extinction.
In fact, the International Union for Conservation of Nature estimates that 95% of Madagascar's lemurs are now threatened, making them the world's most endangered mammals. Pressure on Madagascar's biodiversity has significantly increased over the last decade.
Deforestation Threatens Ruffed Lemur Survival
In a newly published study, climate scientist Toni Lyn Morelli, species distribution expert Adam Smith and I worked with 19 other researchers to study how deforestation and climate change will affect two critically endangered ruffed lemur species over the next century. Using combinations of different deforestation and climate change scenarios, we estimate that suitable rainforest habitat could be reduced by as much as 93%.
If left unchecked, deforestation alone could effectively eliminate ruffed lemurs' entire eastern rainforest habitat and with it, the animals themselves. In sum, for these lemurs the effects of forest loss will outpace climate change.
But we also found that if current protected areas lose no more forest, climate change and deforestation outside of parks will reduce suitable habitat by only 62%. This means that maintaining and enhancing the integrity of protected areas will be essential for saving Madagascar's rainforest habitats.
In a study published in November 2019, my colleagues and I showed that ruffed lemurs depend on habitat cover to survive. We investigated natural and human-caused impediments that prevent the lemurs from spreading across their range, and tracked the movement of their genes as they ranged between habitats and reproduced. This movement, known as gene flow, is important for maintaining genetic variability within populations, allowing lemurs to adapt to their ever-changing environments.
Based on this analysis, we parsed out which landscape variables – including rivers, elevation, roads, habitat quality and human population density – best explained gene flow in ruffed lemurs. We found that human activity was the best predictor of ruffed lemurs' population structure and gene flow. Deforestation alongside human communities was the most significant barrier.
Taken together, these and other lines of evidence show that deforestation poses an imminent threat to conservation on Madagascar. Based on our projections, habitat loss is a more immediate threat to lemurs than climate change, at least in the immediate future.
This matters not only for lemurs, but also for other plants and animals in the areas where lemurs are found. The same is true at the global level: More than one-third (about 36.5%) of Earth's plant species are exceedingly rare and disproportionately affected by human use of land. Regions where the most rare species live are experiencing higher levels of human impact.
Crisis Can Drive Conservation
Scientists have warned that the fate of Madagascar's rich natural heritage hangs in the balance. Results from our work suggest that strengthening protected areas and reforestation efforts will help to mitigate this devastation while environmentalists work toward long-term solutions for curbing the runaway greenhouse gas emissions that drive climate change.
Already, nonprofits are working hard toward these goals. A partnership between Dr. Edward E. Louis Jr., founder of Madagascar Biodiversity Partnership and director of Conservation Genetics at Omaha's Henry Doorly Zoo, and the Arbor Day Foundation's Plant Madagascar project has replanted nearly 3 million trees throughout Kianjavato, one region identified by our study. Members of Centre ValBio's reforestation team – a nonprofit based just outside of Ranomafana National Park that facilitates our ruffed lemur research – are following suit.
At an international conference in Nairobi earlier this year, Madagascar's president, Andry Rajoelina, promised to reforest 40,000 hectares (99,000 acres) every year for the next five years – the equivalent of 75,000 football fields. This commitment, while encouraging, unfortunately lacks a coherent implementation plan.
Our projections highlight areas of habitat persistence, as well as areas where ruffed lemurs could experience near-complete habitat loss or genetic isolation in the not-so-distant future. Lemurs are an effective indicator of total non-primate community richness in Madagascar, which is another way of saying that protecting lemurs will protect biodiversity. Our results can help pinpoint where to start.
Andrea L. Baden is an assistant professor of anthropology at Hunter College.
Andrea L. Baden receives funding from the National Science Foundation, The Leakey Foundation, J. William Fulbright Foundation, Primate Conservation, Inc., and the Margot Marsh Biodiversity Fund. She is affiliated with Hunter College of the City University of New York, The Graduate Center of the City University of New York, and the New York Consortium in Evolutionary Primatology, and is a Scientific Advisor for the Mangevo research site to the Centre ValBio Research Station.
Reposted with permission from The Conversation.
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By Lynne Peeples
Editor's note: This story is part of a nine-month investigation of drinking water contamination across the U.S. The series is supported by funding from the Park Foundation and Water Foundation. Read the launch story, "Thirsting for Solutions," here.
In late September 2020, officials in Wrangell, Alaska, warned residents who were elderly, pregnant or had health problems to avoid drinking the city's tap water — unless they could filter it on their own.
Unintended Consequences<p>Chemists first discovered disinfection by-products in treated drinking water in the 1970s. The trihalomethanes they found, they determined, had resulted from the reaction of chlorine with natural organic matter. Since then, scientists have identified more than 700 additional disinfection by-products. "And those only represent a portion. We still don't know half of them," says Richardson, whose lab has identified hundreds of disinfection by-products. </p>
What’s Regulated and What’s Not?<p>The U.S. Environmental Protection Agency (EPA) currently regulates 11 disinfection by-products — including a handful of trihalomethanes (THM) and haloacetic acids (HAA). While these represent only a small fraction of all disinfection by-products, EPA aims to use their presence to indicate the presence of other disinfection by-products. "The general idea is if you control THMs and HAAs, you implicitly or by default control everything else as well," says Korshin.</p><p>EPA also requires drinking water facilities to use techniques to reduce the concentration of organic materials before applying disinfectants, and regulates the quantity of disinfectants that systems use. These rules ultimately can help control levels of disinfection by-products in drinking water.</p>
Click the image for an interactive version of this chart on the Environmental Working Group website.<p>Still, some scientists and advocates argue that current regulations do not go far enough to protect the public. Many question whether the government is regulating the right disinfection by-products, and if water systems are doing enough to reduce disinfection by-products. EPA is now seeking public input as it considers potential revisions to regulations, including the possibility of regulating additional by-products. The agency held a <a href="https://www.epa.gov/dwsixyearreview/potential-revisions-microbial-and-disinfection-byproducts-rules" target="_blank">two-day public meeting</a> in October 2020 and plans to hold additional public meetings throughout 2021.</p><p>When EPA set regulations on disinfection by-products between the 1970s and early 2000s, the agency, as well as the scientific community, was primarily focused on by-products of reactions between organics and chlorine — historically the most common drinking water disinfectant. But the science has become increasingly clear that these chlorinated chemicals represent a fraction of the by-product problem.</p><p>For example, bromide or iodide can get caught up in the reaction, too. This is common where seawater penetrates a drinking water source. By itself, bromide is innocuous, says Korshin. "But it is extremely [reactive] with organics," he says. "As bromide levels increase with normal treatment, then concentrations of brominated disinfection by-products will increase quite rapidly."</p><p><a href="https://pubmed.ncbi.nlm.nih.gov/15487777/" target="_blank">Emerging</a> <a href="https://pubs.acs.org/doi/10.1021/acs.est.7b05440" target="_blank" rel="noopener noreferrer">data</a> indicate that brominated and iodinated by-products are potentially more harmful than the regulated by-products.</p><p>Almost half of the U.S. population lives within 50 miles of either the Atlantic or Pacific coasts, where saltwater intrusion can be a problem for drinking water supplies. "In the U.S., the rule of thumb is the closer to the sea, the more bromide you have," says Korshin, noting there are also places where bromide naturally leaches out from the soil. Still, some coastal areas tend to be spared. For example, the city of Seattle's water comes from the mountains, never making contact with seawater and tending to pick up minimal organic matter.</p><p>Hazardous disinfection by-products can also be an issue with desalination for drinking water. "As <a href="https://ensia.com/features/can-saltwater-quench-our-growing-thirst/" target="_blank" rel="noopener noreferrer">desalination</a> practices become more economical, then the issue of controlling bromide becomes quite important," adds Korshin.</p>
Other Hot Spots<p>Coastal areas represent just one type of hot spot for disinfection by-products. Agricultural regions tend to send organic matter — such as fertilizer and animal waste — into waterways. Areas with warmer climates generally have higher levels of natural organic matter. And nearly any urban area can be prone to stormwater runoff or combined sewer overflows, which can contain rainwater as well as untreated human waste, industrial wastewater, hazardous materials and organic debris. These events are especially common along the East Coast, notes Sydney Evans, a science analyst with the nonprofit Environmental Working Group (EWG, a collaborator on <a href="https://ensia.com/ensia-collections/troubled-waters/" target="_blank">this reporting project</a>).</p><p>The only drinking water sources that might be altogether free of disinfection by-products, suggests Richardson, are private wells that are not treated with disinfectants. She used to drink water from her own well. "It was always cold, coming from great depth through clay and granite," she says. "It was fabulous."</p><p>Today, Richardson gets her water from a city system that uses chloramine.</p>
Toxic Treadmill<p>Most community water systems in the U.S. use chlorine for disinfection in their treatment plant. Because disinfectants are needed to prevent bacteria growth as the water travels to the homes at the ends of the distribution lines, sometimes a second round of disinfection is also added in the pipes.</p><p>Here, systems usually opt for either chlorine or chloramine. "Chloramination is more long-lasting and does not form as many disinfection by-products through the system," says Steve Via, director of federal relations at the American Water Works Association. "Some studies show that chloramination may be more protective against organisms that inhabit biofilms such as Legionella."</p>
Alternative Approaches<p>When he moved to the U.S. from Germany, Prasse says he immediately noticed the bad taste of the water. "You can taste the chlorine here. That's not the case in Germany," he says.</p><p>In his home country, water systems use chlorine — if at all — at lower concentrations and at the very end of treatment. In the Netherlands, <a href="https://dwes.copernicus.org/articles/2/1/2009/dwes-2-1-2009.pdf" target="_blank">chlorine isn't used at all</a> as the risks are considered to outweigh the benefits, says Prasse. He notes the challenge in making a convincing connection between exposure to low concentrations of disinfection by-products and health effects, such as cancer, that can occur decades later. In contrast, exposure to a pathogen can make someone sick very quickly.</p><p>But many countries in Europe have not waited for proof and have taken a precautionary approach to reduce potential risk. The emphasis there is on alternative approaches for primary disinfection such as ozone or <a href="https://www.pbs.org/wgbh/nova/article/eco-friendly-way-disinfect-water-using-light/" target="_blank" rel="noopener noreferrer">ultraviolet light</a>. Reverse osmosis is among the "high-end" options, used to remove organic and inorganics from the water. While expensive, says Prasse, the method of forcing water through a semipermeable membrane is growing in popularity for systems that want to reuse wastewater for drinking water purposes.</p><p>Remucal notes that some treatment technologies may be good at removing a particular type of contaminant while being ineffective at removing another. "We need to think about the whole soup when we think about treatment," she says. What's more, Remucal explains, the mixture of contaminants may impact the body differently than any one chemical on its own. </p><p>Richardson's preferred treatment method is filtering the water with granulated activated carbon, followed by a low dose of chlorine.</p><p>Granulated activated carbon is essentially the same stuff that's in a household filter. (EWG recommends that consumers use a <a href="https://www.ewg.org/tapwater/reviewed-disinfection-byproducts.php#:~:text=EWG%20recommends%20using%20a%20home,as%20trihalomethanes%20and%20haloacetic%20acids." target="_blank" rel="noopener noreferrer">countertop carbon filter</a> to reduce levels of disinfection by-products.) While such a filter "would remove disinfection by-products after they're formed, in the plant they remove precursors before they form by-products," explains Richardson. She coauthored a <a href="https://pubs.acs.org/doi/10.1021/acs.est.9b00023" target="_blank" rel="noopener noreferrer">2019 paper</a> that concluded the treatment method is effective in reducing a wide range of regulated and unregulated disinfection by-products.</p><br>
Greater Cincinnati Water Works installed a granulated activated carbon system in 1992, and is still one of relatively few full-scale plants that uses the technology. Courtesy of Greater Cincinnati Water Works.<p>Despite the technology and its benefits being known for decades, relatively few full-scale plants use granulated active carbon. They often cite its high cost, Richardson says. "They say that, but the city of Cincinnati [Ohio] has not gone bankrupt using it," she says. "So, I'm not buying that argument anymore."</p><p>Greater Cincinnati Water Works installed a granulated activated carbon system in 1992. On a video call in December, Jeff Swertfeger, the superintendent of Greater Cincinnati Water Works, poured grains of what looks like black sand out of a glass tube and into his hand. It was actually crushed coal that has been baked in a furnace. Under a microscope, each grain looks like a sponge, said Swertfeger. When water passes over the carbon grains, he explained, open tunnels and pores provide extensive surface area to absorb contaminants.</p><p>While the granulated activated carbon initially was installed to address chemical spills and other industrial contamination concerns in the Ohio River, Cincinnati's main drinking water source, Swertfeger notes that the substance has turned out to "remove a lot of other stuff, too," including <a href="https://ensia.com/features/drinking-water-contamination-pfas-health/" target="_blank" rel="noopener noreferrer">PFAS</a> and disinfection by-product precursors.</p><p>"We use about one-third the amount of chlorine as we did before. It smells and tastes a lot better," he says. "The use of granulated activated carbon has resulted in lower disinfection by-products across the board."</p><p>Richardson is optimistic about being able to reduce risks from disinfection by-products in the future. "If we're smart, we can still kill those pathogens and lower our chemical disinfection by-product exposure at the same time," she says.</p><p><em>Reposted with permission from </em><em><a href="https://ensia.com/features/drinking-water-disinfection-byproducts-pathogens/" target="_blank">Ensia</a>. </em><a href="https://www.ecowatch.com/r/entryeditor/2649953730#/" target="_self"></a></p>
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Earth had its second-warmest year on record in 2020, just 0.02 degrees Celsius (0.04°F) behind the record set in 2016, and 0.98 degrees Celsius (1.76°F) above the 20th-century average, NOAA reported January 14.
Figure 1. Departure of temperature from average for 2020, the second-warmest year the globe has seen since record-keeping began in 1880, according to NOAA. Record-high annual temperatures over land and ocean surfaces were measured across parts of Europe, Asia, southern North America, South America, and across parts of the Atlantic, Indian, and Pacific oceans. No land or ocean areas were record cold for the year. NOAA National Centers for Environmental Information
Figure 2. Total ocean heat content (OHC) in the top 2000 meters from 1958-2020. Cheng et al., Upper Ocean Temperatures Hit Record High in 2020, Advances in Atmospheric Sciences
Figure 3. Departure of sea surface temperature from average in the benchmark Niño 3.4 region of the eastern tropical Pacific (5°N-5°S, 170°W-120°W). Sea surface temperature were approximately one degree Celsius below average over the past month, characteristic of moderate La Niña conditions. Tropical Tidbits
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