Above: Zebra walk the barren bed of Kenya’s Lake Amboseli, which dried completely during a two-year drought. The zebra population in this critical dry-season refuge has declined by more than 70 percent during the past three years, reducing prey for lions and other carnivores. Photo by Michael Burnham.
Africa's oldest and deepest lake has experienced unprecedented warming during the past century, a trend that scientists say threatens fish stocks that feed millions of people.
The surface of finger-shaped Lake Tanganyika, which stretches 420 miles along the Great Rift Valley, is 26 degrees Celsius -- its warmest temperature in 1,500 years, according to an analysis of lakebed core samples by U.S. scientists.
The lake surface experienced its biggest temperature jump -- 2 degrees Celsius -- during the past 90 years, a period corresponding with increased combustion of fossil fuels and emissions of heat-trapping gases, lead scientist Jessica Tierney explained in an interview.
"A lot of that increase has happened in the last 50 years, so we do believe man-made global warming is responsible," added Tierney, whose findings appear in the latest edition of Nature Geoscience.
Lake Tanganyika, which reaches a dark and anoxic depth of more than 4,800 feet, is highly stratified and needs winds to churn its waters and push nitrogen and other nutrients to the surface to feed phytoplankton. As the lake surface warmed and cooled during the past 1,500 years, its biological productivity fluctuated, core samples show.
"When the surface is really warm, it's much less dense than the deep water, so there is not as much mixing," said Tierney, who completed her doctorate degree at Brown University and will soon begin post-doctoral research at Columbia University. "The food web is affected from the bottom on up."
Tierney and her fellow researchers were able to reconstruct lake-surface temperature, productivity and wildfire frequency over the 1,500-year period by measuring shell remnants and charcoal in the drill cores.
"We can see in the biogenic silica record that there's been a big drop-off in the 20th century," said Andrew Cohen, the report co-author and University of Arizona geosciences professor. "The big concern is the fishery is going to be affected by that, but it's difficult to quantify how much."
Reliable estimates of the fishery's size are outdated, he said.
A 2006 report from the U.N. Environment Programme estimated that roughly 200,000 tons of fish were harvested annually from the lake, which borders the Democratic Republic of Congo, Burundi, Tanzania and Zambia. The report estimated that the lake's drainage basin is home to about 10 million people; most of the rural population fishes or farms for a living.
Scientists do not have as long of a sedimentary record for Africa's six other "Great Lakes," which dot the Rift Valley from Uganda to Malawi, but research shows that at least one of the lakes is undergoing similar changes.
A 2004 study published in the Royal Swedish Academy of Sciences' journal Ambio noted that the silica concentration in Lake Victoria was a tenth of what it was 40 years before.
"These and other related environmental changes, arising out of natural or anthropogenic causes, have significantly impacted Lake Victoria's fish populations," the report says.
Among other threats the study cites is polluted runoff from the lake's drainage basin, whose 30 million inhabitants are spread through parts of Kenya, Tanzania, Uganda, Rwanda and Burundi. The lake supports Africa's largest freshwater fishery.
"Algal biomass concentration is almost five times greater in the surface waters today than reported in the 1960s, which indicates higher rates of photosynthesis," the Ambio study says.
Untreated industrial and municipal effluent, together with agricultural runoff, are the main sources of chemicals and nutrients contributing to eutrophication, UNEP says in its report.
The same report attributed localized fish die-offs in Lake Tanganyika to surface runoff. The large volume of the lake, however, may provide a "temporary buffer" against widespread deterioration of its water, the report concludes.
-- Michael Burnham and Nathanial Gronewold
Kenya is significantly scaling up investments in agriculture, energy and water projects to hasten the nation's recovery from the global recession and a regional drought. Finance Minister Uhuru Kenyatta's 997 billion Kenyan shilling ($12.2 billion) budget for the 2010/2011 fiscal year, which begins today, includes 182 billion Ksh for energy and transportation infrastructure projects -- a more than 20 percent increase over the previous fiscal year. The record budget also includes 32 billion Ksh for agriculture and rural development and 51 billion Ksh for environment, water and sanitation projects.
AMBOSELI NATIONAL PARK, Kenya -- The attack came swiftly and silently in the night.
The lioness bounded over the thatch of acacia thorns that surrounds the Maasai village and headed for the donkey pen.
The predator was clawing at a donkey's haunches by the time men stirred in their dung-covered huts. A warrior confronted the dusty tangle of teeth and fur, and sunk a spear through the big cat's right rear leg.
| PART FOUR |
In this four-part series, E&E explores how climate change and population growth are exacerbating water quality and quantity challenges throughout Kenya and the rest of Africa, the continent that many see as least able to adapt to global warming. |
Then, as swiftly as she had appeared, the lioness scrambled over a rooftop and vanished in the darkness.
The donkey survived, but the lioness died of its wound. Villagers blame hunger and parched conditions for the late-March attack.
"This wasn't the first time," said Wilson Koite, chief of this encampment of more than 300 people in southern Kenya, near the Tanzania border. "There's no wildlife inside of the park, so [lions] just come into the villages."
When the rains failed for the second straight year in 2009, plants withered to their roots in this critical dry-season refuge. Marshes and the shallow bed of Lake Amboseli, usually fed by seasonal rains and runoff from snow-capped Mount Kilimanjaro, cracked in equatorial sun. With little to eat or drink, more than 70 percent of Amboseli's zebra and wildebeest died of starvation, predation or opportunistic infections.
The onset of long rains in recent weeks has begun to rehydrate Amboseli's landscape. But with their traditional prey diminished in numbers, the park's top predators are targeting livestock and risking death. At least nine Amboseli-area lions have been speared or poisoned to death during the past six months, say wildlife managers and conservationists.
"We suspect that there are many more happening," said Paula Kahumbu, executive director of WildlifeDirect, a Nairobi-based organization founded by conservationist Richard Leakey. "[Predator] attacks have been going on for years, but things are really escalating."
Killing lions and other wildlife is illegal but often goes unpunished in Kenya. If goats or cattle are slain by predators, the government or a handful of nonprofit organizations may compensate herdsmen for the loss. But cash is often not enough to cool tempers.
In late March, Maasai warriors stalked a lioness into the bush and speared her after she slaughtered cattle south of the park, Amboseli warden Joseph Nyongesa said. In ensuing weeks, conservationists confirmed the poisoning deaths of five Amboseli-area lions and three more near the Maasai Mara National Reserve, 175 miles to the northwest.
Map of Kenya courtesy of the United Nations. Click on the image for a larger version of the map. |
At the height of the drought some southern villages were suffering lion attacks several times a week, Kahumbu said. Young lions, apparently unfamiliar with how to hunt natural prey, were also stalking permanent settlements for livestock.
"The rate has declined, but lion attacks continue because their natural prey is still diminished," she added. "It will take a while for wildlife to recover."
A March 2010 aerial census recorded three lions in a 24,000-square-kilometer area encompassing Amboseli and parts of northern Tanzania. A May 2007 census recorded 10 lions.
The population is likely higher, the latest census underscored, as lions are difficult to spot from the air and are most active at night. Kenya Wildlife Service (KWS) officials and conservationists who study Amboseli estimate that the area had about 30-40 resident lions prior to the recent killings.
What's certain, wildlife managers say, is some Amboseli lions are roaming unexpectedly long distances in search of wildebeest, zebra and other wild prey. Six lions fitted with KWS satellite collars have been tracked far into northern Tanzania, said park warden Nyongesa.
"We have heard there are quite a number of lions killed on that side, but most of them are the lions of Amboseli," he said.
Wildebeest and zebra constitute the greatest biomass in Amboseli but suffered the greatest losses during the drought.
The wildebeest population fell by about 83 percent, from 18,538 in 2007 to 3,098 in 2010, according to the aerial counts. Zebra declined by around 71 percent, from 15,328 to 4,432.
The prolonged dry spell also took a heavy toll on livestock.
The area's cattle population is less than half of what it was three years ago, the counts show. Livestock are critical to the Maasai, who build their homes with dung, cover their blades with leather, and fill their bellies with meat, milk and blood.
Maasai elder Kayian Olekiraku said the drought killed all but 20 of his 200 cattle. The same night of the attack in Koite's village another lion broke the leg of one of Olekiraku's bulls before being chased off.
"When I was young, we just killed the lion," he recalled at the edge of his hardscrabble village. "Now we don't. We fear the government will take us to jail."
Wildlife service officials say they have been meeting with southern Kenya residents over the past few months to discuss better animal husbandry practices and changes to the ecosystem.
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| Maasai herdsman Ole Saitoti plants kai apple behind a chain-link fence he installed around his livestock recently with the help of the Anne K. Taylor Fund. Since the start of the year, the U.S.-based nonprofit has helped fortify 70 village bomas against predator attacks near Maasai Mara National Reserve. Photo courtesy of Anne K. Taylor. |
"We had to calm down the situation by talking to them," said KWS senior scientist Charles Musyoki. "We know they are incurring losses, but we needed to talk to them so that they don't retaliate by killing the animals."
In February, the wildlife service launched nationwide strategies for managing lions, cheetahs, hyenas and wild dogs. The plans are intended to preserve ecologically viable predator and prey populations inside of reserves, create carnivore conservation zones outside of government-protected areas and cull animals that attack livestock repeatedly.
In March, KWS and the nonprofits Born Free Foundation and Kenya Wildlife Trust began building demonstration "predator proof" barriers adjacent to Amboseli. The barriers, called bomas, include concentric circles of acacia branches and chain-link fencing, Born Free Foundation CEO Will Travers explained.
"You're using the wall of thorns as a kind of airbag," Travers added. "It slows down the predator, and then there's a fence."
The bomas are modeled after ones Kenyan conservationist Anne Taylor built northwest of the Maasai Mara reserve, an area that has seen significant wildlife poaching and habitat loss over the past decade. Taylor, who owns a house there and runs the nonprofit Anne K. Taylor Fund, has helped bolster 70 bomas with metal fencing since the start of the year.
The Maasai Mara barriers, which include 8-foot-high fences fortified with plants and branches, are 100 percent successful at stopping attacks, she said. Boma owners must provide the labor.
"Compensation is never enough," she added. "They need to stop the predation."
Maasai chief Koite said his people cannot afford to buy metal fencing for their village near Amboseli. Speaking the morning after the lion attack, he vowed to bolster his boma's four gates with bigger branches.
"We can't contribute our own money to fence," Koite added, "so we use just the bush."
Kenyan wildlife managers' most ambitious attempt to reduce human-carnivore conflicts -- bringing prey to predators -- appears to have failed.
One crisp February morning, a helicopter swung low over the Soysambu Conservancy near the Great Rift Valley city of Nakuru. Startled zebra ran from the thumping blades, past stick-wielding rangers and into a tarpaulin pen.
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| In February, the Kenya Wildlife Service began relocating zebra from central Kenya to parched Amboseli National Park, near the country's southern border with Tanzania. The exercise, pictured above, was designed to provide prey for the park's carnivores. Photo courtesy of Kenya Wildlife Service. |
KWS rounded up 137 zebra that day and the next and drove the animals 200 miles southeast to Amboseli. The agency planned to move 4,000 zebra and 3,000 wildebeest to Amboseli by the end of the year but halted the translocation effort after moving 700 zebra, according to conservationists familiar with the effort.
The brief operation was over budget, politically motivated and poorly executed, charged WildlifeDirect director Kahumbu, who monitored an initial roundup.
Wildlife service rangers failed to capture entire zebra family groups and condition the animals before releasing them into Amboseli, she said. As zebra typically live in highly sociable harems and herds, she explained, many of the disoriented animals fled the park and died of exhaustion or predation within days.
"They were just panic-stricken and ran off in all directions," Kahumbu added.
KWS officials in Nairobi failed to respond to requests for comment about the translocation project's status and the lion poisoning incidents.
Factor into all of this a warming world and a cold calculation.
Three-quarters of Kenya's annual visitors are tourists, and most head straight from Nairobi to the national parks and reserves in hopes of seeing the Big Five -- a lion, leopard, elephant, buffalo and rhinoceros. Losing lions to spears, poison or starvation threatens Kenya's tourism industry -- revenues peaked at $835 million, coming from more than 1 million air and sea arrivals in 2007, before the regional drought and global economic slowdown.
"Tourism is an important contributor to the economy here, and tourism in Kenya is dependent upon wildlife and protected areas," explained Taye Teferi, the World Wildlife Fund's conservation director for East Africa.
The wildlife service estimates that Kenya has about 1,970 lions, down from about 2,750 in 2002. Kahumbu warned that Kenya's wild lions could go extinct within a decade if the cats continue to lose habitat and prey.
Kenya has lost more than 60 percent of its large wildlife since 1977, despite a ban on game hunting, according to government data. Poaching for bush meat and ivory remain lucrative ventures, in poor, rural areas, conservationists say.
Global warming -- and the specter of deeper and more frequent droughts -- is yet another challenge, scientists from the wildlife service and other organizations contend.
The United Nations' Intergovernmental Panel on Climate Change (IPCC) projects that the portion of arid and semiarid areas in Africa is likely to increase 5 to 8 percent by 2080. Between 25 and 40 percent of mammal species in sub-Saharan Africa's national parks will become endangered, according to one study analyzed by the panel.
To cope with the latest drought -- what some are calling the worst in living memory -- the wildlife service spent $250,000 to build dams and dig boreholes in the Maasai Mara reserve and Tsavo West National Park, 50 miles east of Amboseli.
Kenya Wildlife Service should be investing $5 million annually in such water-storage projects nationwide, agency scientist Patrick Omondi estimated. "That would put us at a level," he said, "where we could at least minimize the impacts of climate change."
The Maasai Mara reserve, north of Tanzania's Serengeti, is a critical stopping point in the world's largest overland migration. Omondi and other scientists are watching closely how well the reserve's plants and animals recover from the drought.
Every June to October, millions of wildebeest, zebra and other herbivores slog between the Serengeti and the reserve and cross the muddy Mara River. The circular migration is a major tourist draw and is considered one of 10 natural wonders of the world.
"What triggers the migration is when the rainfall starts," WWF's Teferi explained. "When the clouds start gathering, wildlife know which way to go. ... By the time they get to the Mara River, it is in full flood, and the vegetation is quite green."
When the rains failed last year, the river was critically low and the migration was smaller than it had been in the past, Teferi and others recalled. KWS scientist Omondi guessed that the wildlife were "confused."
To the north, Lake Nakuru receded far from its shore, shrinking critical habitat for pink flamingos, pelicans and hippos. Elsewhere in northern Kenya, watering holes evaporated and hundreds of elephants died of hunger, thirst and exhaustion.
Runoff from more than 19,000-foot-high Kilimanjaro makes Amboseli a critical dry-season refuge, but wildlife service scientist Omondi said he worries whether the park can sustain that role.
"Before, we could predict when we had the long and short rains, but that has changed completely," he added. "Now, we never know when the drought comes."
Water is even changing the pastoralist Maasai, who roam between Tanzania and Kenya.
Amboseli chieftain Koite and his people have lived at the park's southern edge for a decade. A hand-pumped well provides water, and a nearby school teaches children English.
Rather than move the entire village with the herds, just a handful of young warriors roam with the cattle.
"Without water, there is no life," he said. "The well -- that is why we stay here."
NAIROBI, Kenya -- It's the rainy season, but the sun is still baking the Mathare Valley slum.
A half-million people live in this warren of shacks clustered amid 10 square kilometers of the Mathare River.
When the rains fall, drops spill like marbles on corrugated metal roofs. Narrow alleys swell with murky runoff that flows past open doors and raises the risk of cholera and dysentery.
When the rains fail, as they did for most of last year, a liter of clean water can cost more than petroleum. People who cannot buy water from traveling vendors haul it from the river or steal it from the municipal main.
About half of Nairobi's 3.2 million residents live in such areas that lack municipal water and sewer services. Beatrice Cheptoo is among Mathare's fortunate.
The 26-year-old mother of two pays 100 Kenyan shillings ($1.30) a month to use a privately built water spigot, shower and toilet. Standing near the freshly mopped "Ikotoilet," Cheptoo points up the slope to a field where goats pick through garbage rotting into rust-colored soil.
"Before, we were used to going and practicing open defecation up there," Cheptoo said, broaching a subject that is taboo for many Kenyans.
NAIROBI, Kenya -- The restaurant manager shrugs as his customers eat in darkness and his kitchen limps along on half power.
"What they told us in the newspaper last week was that one section of the city would have a blackout for maintenance purposes, but right now the whole city is down," said Nicholas Kyalo, whose restaurant, Garit, serves fast food in the capital's downtown core.
At lunchtime most of the city's electricity is down for the second time in a week. Garit's cooks stand idly as they wait their turn on the only working fryer, and other staffers scramble to start emergency generators before food spoils in the refrigerator.
Blackouts are a regular occurrence in this city and throughout Africa, and the problem is getting worse. Shop owners can be seen dragging out diesel generators and firing them up in the streets. Restaurants have gotten so used to blackouts that they design their menus around them.
"When there is a blackout and you have something go bad, that's a risk and a loss to you," Kyalo said.
Nairobi goes dark not for its lack of coal or natural gas, but for a lack of water. Hydroelectric dams generate more than 60 percent of Kenya's power, much of it coming from a string of dams along the Tana River. During the 2009 dry spell, rationing was the rule and some sections of the city had power for just two days a week. A deepening drought cycle now threatens to spread Kenya's energy crisis beyond its borders to other parts of Africa, especially Tanzania and Ethiopia.
NAKURU, Kenya -- The wooded ridge rising to the west of this bustling provincial capital is the home of one of Kenya's greatest natural resources and one of Africa's biggest environmental crises.
The Mau Forest Complex encompasses almost 1 million acres of wilderness, interspersed with small farms and sprawling tea plantations. The watershed feeds 12 rivers and hydroelectric dams downstream and replenishes some of Africa's most famous lakes and wildlife preserves, including the Serengeti in Tanzania.
Kenya can ill afford to lose the Mau, but that is what's happening. A legacy of corruption, cronyism and inept management threatens to derail a fresh government effort to replant the forests and protect the water table.
In the nearly 50 years since Kenya won its independence from Great Britain, huge swaths of the Mau have been cleared to expand the tea plantations and make way for new ones on land handed over to a chosen elite. Add to this roughly 600,000 settlers staking their own claims to the Mau, most illegally.
They continue to tear down forests for cropland today. Activists warn of illegal logging activities on government lands, carried out under cover of darkness as officials willfully look the other way. It is the same in other forested parts of the country, notably the Aberdare Range and around Mount Kenya.
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