Flood pulses are critical to the way the Amazon, its tributaries and other tropical rivers function – and these seasonal flood pulses are a huge driver of ecological productivity and diversity.
Floodplain forests depend upon annual flood pulses to bring nutrients and sediment from river channels out into the surrounding terrestrial habitat.
Reductions to flood pulses, brought by Amazon dams both large and small, could lead to shifts in tree species diversity and composition, with implications for carbon storage and emissions.
Unreliable flood regimes, as created by dams of all sizes, significantly impact Amazon river systems and species’ life cycles, population dynamics, food sources, and habitats above and below the water line.
The Santo Antônio dam on the Madeira River, Brazil, is one of hundreds currently planned, under construction, or operational across the Amazon basin. A new study has quantified the impact that 33 dams have had on river hydrology, by examining river flow before and after dam construction. Photo by the Brazil’s Growth Acceleration Program (Programa de Aceleração do Crescimento (PAC)) on flickr, used under a CC BY-NC-SA 2.0 license
According to a recent study, ecologically important flood pulses along Amazonian rivers are being substantially altered by hydropower dams. The study also finds small dams are having a disproportionately higher impact on river hydrology relative to larger dams in the region.
The new research, led by Kelsie Timpe of the University of Florida, assessed river flow both before and after construction of dams in the Brazilian Amazon.
Researchers set out to quantify the hydrological effects of dams, and identify dam characteristics that help predict the type and scale of multiple impacts. Timpe’s co-author, David Kaplan, also of the University of Florida, explains that the two undertook the study recognizing “the widespread expansion of dams in the Amazon will have a cascade of physical, ecological, and social effects, and central to those changes are how dams modify river hydrology.” Though the Brazilian government has just unofficially announced an end to its mega-dam building policy, many dams of varying size are currently planned for Amazon tributaries.
The new research has been welcomed as both “timely and important” by Isabel Jones, of the University of Stirling, UK, whose research focuses on the ecological impacts of the Balbina mega-dam, on the Uatumã river, Brazil. Though not involved with the latest study, she says it “provides a first step towards developing more robust impact assessments and mitigation strategies for existing and proposed dam development across globally important watersheds, such as the Amazon Basin.”
The study analysed 33 specific parameters of the flow regime within five broad categories: magnitude, frequency, duration, timing, and the change rate of the river’s flow. These factors were chosen because they are inextricably linked with species ecology and adaptation within the region. Changes to any one of these categories have ramifications for species lifecycles, population dynamics, and habitat availability above and below the water line.
A map of the study area illustrating the distribution of dams across the Amazon, Tocantins/Araguaia and North Atlantic basins, and highlighting those included in a recent study which quantified the impact that dams have had on river hydrology. Figure from Timpe and Kaplan (2017), used under a CC BY-NC license
Large and small dams, big impacts
An initial research challenge involved finding gauging stations, located both upstream and downstream of Amazon dams, that could provide comparisons between conditions before and after dams were built. In total, 40 stations, associated with 33 dams, were found to have been running long enough to be suitable for analysis. The dataset encompassed 17 large dams with a generating capacity of at least 30 megawatts, and 16 small dams with a generating capacity between 1 to 30 megawatts. Station positioning made it possible to assess the cumulative impact of multiple dams on the same river.
The study revealed an overall 30 percent change in hydrology due to the dams, with wide variation between individual stations. For instance, a hydrological change of over 100 percent was noted in the case of the Balbina dam, and recorded as low as 10 percent at stations in the vicinity of the Tucurui dam on the Tocantins River.
Significantly, Timpe and Kaplan found that a dam’s greatest effect was on the frequency and duration of high and low water events – the extremes of the flood pulse – and the rate at which the water level changed. Downstream impacts were generally greater than upstream. When multiple dams were built on the same river, cumulative impacts were incremental across all categories of study, but more pronounced for flood pulse frequency, duration and rate of change.
The study also demonstrated that the best predictors of hydrological impact were dam elevation and reservoir size. These two factors are frequently connected, as low-elevation dams often allow widespread flooding. Many of the dams currently under construction or planned in the Amazon lowlands are in this category. That large, low-elevation reservoirs such as at Balbina have major impacts was not surprising, said Kaplan, “but the picture changed significantly once dam generating capacity was taken into account.”
When study results were scaled to reflect the hydrological impact per unit of energy generated, “small dams caused particularly high levels of hydrologic alteration relative to their potential electricity production,” said Kaplan. Some were even worse, per unit of energy, than a larger dam like Balbina. “This is particularly troubling given the lower permitting and monitoring requirements for these small systems.”
An oxbow lake in the Amazon floodplain. Floodplain forests depend upon the annual flood pulse to bring nutrients and sediment from river channels into the forest. Reductions to the flood pulse could lead to shifts in tree species composition, with implications for carbon storage and emissions. Unpredictable flood regimes could disrupt cues that fish use to spawn. Photo by Rhett A. Butler / Mongabay
Ecological effects
For species living within and alongside Amazonian rivers, unpredictable changes to the annual flood pulse are bad news. The flood pulse “is critical to the way that the Amazon and other tropical rivers function and a huge driver of why they are so productive and diverse,” notes Kaplan.
“Water provides a significant part of the physical structure which fish, as well as many other aquatic biota, live in,” explains Leandro Castello, a researcher of Amazonian fish ecology and conservation at Virginia Polytechnic Institute and State University, “so even the smallest changes can have profound effects on them. For example, a small decrease in the maximum water level reached by a river annually can mean the loss of large areas of feeding and nursery habitat.”
Kaplan agrees, and further notes that these changes can disrupt “natural spawning cues and trap aquatic organisms in floodplain lakes or strand terrestrial organisms on floodplain islands,” as well as reducing invertebrate abundance. This all has a pronounced effect on the fish, birds, and other animals that feed on invertebrates and other food enhanced by flood pulses. “We found the impacts on the hydrological regime could be seen as far as 300 kilometers (186 miles) away,” Kaplan says.
Put simply, the forest itself needs the floods to continue being highly productive and diverse: the floodplain is bathed in nutrients and sediment when water levels rise. Floodplain forests, which “hold significant stocks of carbon,” are therefore vulnerable to changes in the flood pulse, says Jones. The focus of her research, the Balbina mega-dam, is the worst ecological offender in Timpe and Kaplan’s analysis.
The semiaquatic capybara – the largest rodent in the world – is a floodplain resident frequently sighted along Amazonian waterways. Photo by Rhett A. Butler / Mongabay
Jones warns that a reduction in the flood pulse could lead to a change in species composition and interactions within the floodplain forest “such that carbon storage capacity is reduced,” which could lead to an increase in carbon emissions, bad news for the global climate.
During her research at the Balbina dam, Jones witnessed the problems that arise for dam operators when reservoir levels drop during drought. “Under a changing climate, such low-flow periods may become increasingly common, and thus the dam-induced hydrological impacts revealed in the study by Timpe and Kaplan could well increase.”
Study results should spur change
In light of the hundreds of dams, both large and small, that are planned or under construction across the Amazon, this study could help point the way to minimizing the ecological damage they will cause, Kaplan says. “We hope that these results can help motivate planners and policymakers to critically assess just how sustainable dams are as an alternative to other energy sources (wind and solar), particularly given the potential for tropical reservoirs to emit substantial amounts of methane, a powerful greenhouse gas.”
Political pressure continues to exist in Brazil to push forward with small- and medium-sized dam construction, especially to meet energy needs for the mining industry and for agribusiness, so “reducing environmental impacts is critical, including by optimizing dam operations to more closely mimic the natural flow regime, in other words, lowering the hydrological alteration in our study,” Kaplan urges.
A protest against the construction of the Belo Monte dam on the Xingu River, Brazil, in 2012, by indigenous people, small farmers and local residents. Located at a low elevation, this mega-dam is likely to have a particularly high impact on the Xingu’s hydrology, according to Timpe and Kaplan’s study. Photo by International Rivers on Flickr, used under a CC BY-NC-SA 2.0 license
But, Castello warns, the analysis by Timpe and Kaplan likely exposes just “the tip of the iceberg” regarding dam impacts on hydrology. Kaplan sees an urgent need to consider other kinds of impacts, particularly when considering the optimum size and siting of dams to minimize harm. “Location really matters for dam impacts, not only on hydrology, but also, for example, to migratory fish passage and impacts on human communities.”
“Our analysis does not assess how dams and reservoirs affect biotic connectivity,” Kaplan points out, nor did it address the disruption to the vital flow of sediment from Andean headwaters to the Amazon basin and estuary.
“Without a more critical look at the impacts of dams, and ways to better mitigate their impacts, the outlook for the Amazon and its tributaries is not great,” Kaplan says, adding that “citizens of countries with dam building booms should also be involved in asking difficult questions,” such as “how much biodiversity loss, fisheries productivity decline, and human rights violations are we willing to trade for these projects?”
Author By Morgan Erickson-Davis On 11 January 2018
Researchers were surprised to discover white-naped mangabeys (Cercocebus lunulatus) while reviewing camera trap footage captured in Ghana’s Atewa mountain range.
The white-naped mangabey has declined by more than 50 percent in less than three decades and is listed as Critically Endangered by the IUCN. Habitat loss and hunting are its major threats. The camera trap footage is the first record of the species in eastern Ghana.
threatened by bauxite mining. Deposits of bauxite, from which aluminum is produced, underlie Atewa’s forests. The Ghanaian government is reportedly gearing up to develop mining operations and associated infrastructure for bauxite extraction, refinement and export.
Conservation organizations and other stakeholders are urging the government to cease its plans for mining and more effectively protect Atewa by turning the region into a national park.
While surveying the rainforests of eastern Ghana’s Atewa mountain range, scientists stumbled upon a surprise as they were checking footage from their camera traps: monkeys with long tails and distinctive, dark, sideburn-like markings on their faces.
The monkeys, to the scientists’ amazement, were white-naped mangabeys (Cercocebus lunulatus), a species of ground-dwelling primate listed as Critically Endangered by the IUCN. White-naped mangabeys are known to exist in a handful of forests in the western part of the country, as well as eastern Code d’Ivoire and southern Burkina Faso. But never before had scientists recorded them in eastern Ghana.
The discovery was made by researchers with A Rocha International, a network of environmental organizations, during a two-year monitoring survey of Atewa’s forests to determine what species live there and how they are distributed. The photos of the mangabeys were captured in May 2017, but the researchers didn’t realize it until they collected and analyzed the images in December.
Camera trap footage shows a white-naped mangabey (Cercocebus lunulatus) in a forest in the Atewa mountains. Photo courtesy of A RochaWhite-naped mangabeys are mostly ground-dwelling, but will also climb up into trees. Photo courtesy of A Rocha
The discovery is being heralded by conservationists as fodder for hope for a species hovering on the precipice of extinction. According to the IUCN, white-naped mangabeys have declined by at least 50 percent in less than 30 years, with habitat loss and bushmeat hunting their biggest threats.
“White-naped Mangabeys are so rare that I think these may be the first photographs of them in the wild in Ghana,” Andrea Dempsey at West African Primate Conservation Action (WAPCA) said in a statement. “Finding them in Atewa Forest gives hope to our efforts to save them. “
But with this hope is tainted by fear. The forests of the Atewa mountains are earmarked for the mining of bauxite, the ore from which aluminum is produced. Bauxite is found primarily in the top few meters of rock, and conservationists are worried mining will destroy large swaths of the mangabeys’ forest habitat in their search for ore. According to Jeremy Lindsell, director of science and conservation at A Rocha, the bauxite deposits underlie the area’s most intact tracts of forest – which is where the monkeys were recorded.
Officials from the IUCN also contend bauxite mining will irreparably harm Atewa’s forests and wildlife.
“Extracting bauxite from Atewa Forest is incompatible with biodiversity conservation and the ecosystem services that the forest provides. It will spell the end of the unique and irreplaceable species that the forest contains,” said Jan Kamstra of the IUCN Netherlands.
Atewa is part of the Upper Guinean Forest, a once-vast area of rainforest that stretches from Guinea and Sierra Leone east to Ghana and Togo. Today, the Upper Guinean Forest exists largely as shrinking fragments and is considered one of the planet’s most threatened forest systems.
The Atewa range sits near the eastern extent of the Upper Guinean Forest ecoregion and contains an estimated 18 threatened species. Several, such as the critically endangered Togo slippery frog (Conraua derooi), are found nowhere else in the world.
Satellite data show heavy tree cover loss in the Upper Guinean Forest between 2001 and 2016. The forests of the Atewa range, protected as a Forest Reserve, are still relatively intact compared to the surrounding landscape. Data source: Hansen/UMD/Google/USGS/NASA, accessed through Global Forest Watch
Ghana has around 960 million metric tons of bauxite deposits that, if refined, would be worth an estimated $460 billion, according to Gideon Boako, an economic adviser for Ghanaian Vice President Mahamudu Bawumia, as reported by Bloomberg. In addition to mining bauxite, Boako said infrastructure such as refineries and railways will need to be built in order to process and transport mined ore.
In 2017, Ghana reportedly signed a $10 billion memorandum of understanding (MOU) with China towards the development of its bauxite industry. According to Daryl Bosu, deputy national director at A Rocha, technicians from China have visited Atewa in preparation for mining. Bosu said bauxite mining is likely the Atewa white-naped mangabey’s biggest threat, “which without doubt will completely wipe off the forest, leaving no suitable habitat for any species much more the mangabey.”
Mongabay sent requests for comment to Chinese and Ghanaian governments, but had received no response by presstime.
Industrial mining isn’t the only threat to Atewa. Small-scale mining in streams and rivers, poaching and timber harvesting – all illegal – are also big problems, Bosu said. He blames this on what he says is a lack of enforcement and protection.
“The reason why these continue is because enforcement and compliance by the state institutions is just poor,” Bosu told Mongabay. “It is as though the perpetrators of such illegal activities act more smart than the institutions mandated to secure our forests against such unsustainable vices.”
A Rocha staff member Ransford Agyei fixes a camera trap in the forest. Photo by Jeremy Lindsell
Much of the Ateway range is officially designated a Forest Reserve, but stakeholders like A Rocha, IUCN and others are worried this is not enough to protect it from mining and other threats. They are rallying for the area to be upgraded to national park status, a move supported by many local communities and leaders.
“The discovery of White-naped Mangabey in Atewa Forest is of enormous importance for the future of the species, and makes it a matter of some urgency that the forest is properly protected both from hunting and from habitat change,” Russ Mittermeier, chair of the IUCN Primate Specialist Group, wrote in a December letter to Ghana’s president, Nana Akufo-Addo. “When [wildlife conservation is] considered together with the recent demonstration of the forest’s enormous importance to the water supply of millions of people in Accra, the argument for protecting the forest becomes very compelling.
“I urge that Ghana’s commitments to the Convention on Biological Diversity and to the Sustainable Development Goals take precedence in this case and that Atewa Forest is removed from mining plans once and for all and made into a National Park.”
The detection of white-naped mangabeys may also mean more species may be awaiting discovery in Atewa’s forests, said A Rocha Ghana director Seth Appiah-Kubi. He urges Ghana’s government to more effectively protect Atewa and its inhabitants by turning it into a national park and permanently stopping plans to mine bauxite.
“It would be appalling to see a decision taken that would push so many species that much closer to extinction.”
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Indonesian legislators have prioritized deliberations of a bill regulating the country’s palm oil industry, hoping to have it passed this year.
The bill in its current form conflicts with the government’s own recently adopted measures to protect peatlands, a point that legislators have acknowledged must be addressed.
While its proponents say the bill is needed to protect the industry, citing a Western conspiracy against Indonesian palm oil, environmental activists say it will do little to address the ills attributed to the industry.
JAKARTA — Lawmakers in Indonesia are adamant about passing new legislation on the palm oil industry this year, amid concerns from activists and even the executive branch of government.
Environmental groups warn that the bill, in its current form, favors large corporations at the expense of smallholders and rural and indigenous communities. A key criticism is that it advocates the clearing of peatlands for plantations — a position at odds with the administration of President Joko “Jokowi” Widodo, which has rolled out measures to protect peat areas.
Those measures, introduced following massive land fires in 2015 that blanketed much of the region in a choking haze for months, oblige companies with land concessions that overlap onto peatlands to conserve and restore those areas. The large-scale draining of carbon-rich peat swamps by oil palm and pulpwood planters renders the land highly combustible, and the annual burning has made Indonesia one of the world’s biggest emitters of greenhouse gases.
Legislators backing the bill appear to acknowledge the issue, but insist that economic growth must be prioritized.
“These are regions that have to be protected,” Hamdani, a legislator with the Nasdem Party, who serves on the parliamentary commission discussing the bill, said of peat areas. He added the proposed article implying that palm oil companies were entitled on plant on peatlands “has to be changed.”
Nevertheless, Hamdani, whose constituency covers Central Kalimantan, a province that is home to vast expanses of oil palm plantations, said the legislation would promote economic growth. He said he hoped it could be passed before September 2019, when a new crop of lawmakers takes office.
“This bill serves the public interest,” said Hamdhani, who like many Indonesians, goes by just one name.
Senior administration officials, though, see things differently. Darmin Nasution, the coordinating minister for the economy, has questioned the need for the new legislation.
“Based on a comprehensive study that we’ve done, and after consultation with stakeholders, the government concluded that the bill is not needed yet,” he told a parliamentary hearing in July last year.
The palm oil bill has been included in parliament’s docket of priority legislation for 2018, after getting the same treatment last year. (The fact that it failed to pass in 2017 despite being a “priority” is not unusual; parliament typically achieves only a fraction of the legislative target that it sets itself every year.)
That it’s been prioritized once again in light of the administration’s misgivings has left its critics “surprised and confused,” said Maryo Saputra, campaign head at Sawit Watch, an NGO that monitors the palm oil industry.
One of the bill’s main backers, Firman Soebagyo of the Golkar Party, says it will help protect Indonesia’s palm oil industry from foreign intervention — the argument being that Western stakeholders are behind a smear campaign aimed at boosting their own soybean and rapeseed oil industries. It’s the same theme espoused by the Indonesian Palm Oil Association, known as GAPKI, which often speaks of a conspiracy by foreign vegetable oil interests to undermine Indonesia’s palm oil industry.
United at the other end of the debate are Indonesia’s environmental NGOs, who caution that the bill will benefit the large firms that dominate the industry. They also say it will do little to address the real problems in the industry, including the grabbing of indigenous lands, or the widespread failure on the part of companies to provide local communities with smallholdings as required by law.
Andi Muttaqien, deputy director of the Institute for Policy Research and Advocacy, or ELSAM, says critical voices are being excluded from the public hearings on the bill, during which outside groups are supposed to be invited by legislators to have their say.
“Each year, the bill is always included on the legislative priority list,” Andi said. “But whenever there’s a public hearing, the meeting doesn’t involve many stakeholders.”
Public consultations are being carried out in some regions. But Andi said this in itself was problematic, because it would lend more weight to the views of businesses and local government officials — who have historically sided with the interests of palm oil companies — over those of ordinary citizens. It also undermines the work being done to “harmonize” the bill — a part of the legislative process to ensure the bill doesn’t overlap or conflict with existing laws, regulations or regional bylaws.
“Even though the bill is in the harmonization period, the legislative body keeps conducting public consultations in some regions,” Andi said, adding it was important for the harmonization to be completed before regional consultations began.
“We’re worried that when the bill enters the next stage, which is open hearings, it will have already gained lots of support from the regional level,” he said.
Banner image: An oil palm plantation adjacent to tropical forest in Borneo. Photo by Rhett A. Butler.
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