What happens when humans meddle with nature? | Environment

1. As Indian vultures decrease, the number of rabies cases increases

In the early 1990s, vultures across India began dying out inexplicably. The long-billed, slender-billed, and eastern white-backed vultures have declined to the brink of extinction, with the numbers of India’s three most common vulture species declining by more than 97 percent between 1992 and 2007 Six other species were also in sharp decline. Scientists began testing the dead birds and found they had been exposed to diclofenac, an anti-inflammatory drug routinely given to livestock in South Asia at the time. Vultures fed on the carcasses of cows and were poisoned.

A vulture next to a sheep carcass at Zojila pass in Kashmir. Photography: Anadolu Agency/Getty Images

That was the beginning of a far-reaching chain reaction. As vulture populations crashed, cow carcasses began piling up, and the numbers of rats and feral dogs increased. Dogs have become the primary scavengers in landfills formerly used by vultures. Data suggests that from 1992 to 2003, dogs increased by 7 million. The number of dog bites has soared and rabies infections have soared, claiming the lives of tens of thousands of people each year. In 2006 diclofenac was banned and vulture populations have slowly started to recover.

2. Slaughter of sparrows in China triggers insect plague

In the late 1950s, the Chinese leader, Mao Zedong, wanted to rapidly industrialize the country through the Great Leap Forward. This resulted in the “four pest campaign”, targeting mosquitoes, rats, flies and sparrows. He ordered to kill all the sparrows in the country because he thought they fed on rice and grains and reduced the amount available to people. Citizens were told to shoot birds, tear down their nests, crack their eggs, and bang pots so they would be spooked into the sky and fall to their deaths, exhausted. Sparrows were nearly driven to extinction in China.

Sparrows on a stone pillar at Beihai park Beijing, China
Sparrows gather on a stone pillar in a Beijing park. Photography: VCG/Getty Images

What Mao’s officials didn’t realize is that sparrows rely on grains for only a small portion of their diet: most of it includes insects. After the mass killing, there was an eruption of insect pests that destroyed the country’s crops. “This ecological catastrophe, coupled with a multi-year drought and disastrous agricultural policies, led to one of the most devastating famines in history. An estimated 45 million people died,” says Professor Marc Cadotte, an ecologist at the University of Toronto.

3. Deadly frog fungus causes malaria spikes

A deadly mushroom called chytrid Batrachochytrium dendrobatidis (Bd) swept through Panama and Costa Rica from the 1980s to the mid-1990s, leading to the extinction of dozens of amphibian species, with some scientists putting the number at 90. It has been described as “the largest loss of biodiversity attributable to disease”, but most people would not have noticed the tragedy.

A man treats a frog at the amphibian conservation center, El Valle de Antón, Panama.
A frog being cared for at the El Valle de Antón amphibian conservation center in Panama. Photograph: Ron Giling/Alamy

After the deaths, there was an eight-year spike in malaria cases in Central America as mosquitoes thrived, likely because there were no frogs, salamanders and other amphibians to prey on their eggs, researchers reported recently. . At its peak there was a fivefold increase in malaria cases.

“If we allow massive ecosystem disruptions to happen, it can substantially impact human health in ways that are difficult to predict in advance and difficult to control once they are underway,” says Michael Springborn, a professor at the University of California, Davis and lead author of the article.

4. Mangrove loss worsens Asian tsunami

In 2004, an earthquake and tsunami in the Indian Ocean killed more than 230,000 people. The hardest-hit countries were Indonesia, Sri Lanka, India and Thailand, all of which experienced significant declines in mangrove cover, according to a report by the Environmental Justice Foundation. From 1980 to 2000, the area covered by mangroves in these countries decreased by 28%. In places where trees had been destroyed, the waves surged inland, killing more people and exacerbating the destruction of homes and livelihoods. “Mangrove forests have played a crucial role in saving lives and property,” the report said.

A man searches for mud crabs in the mangroves, Indonesia.
Mangroves’ large root systems absorb some of the impact of the waves. Photograph: James Morgan/WWF

Mangroves absorb the impact of waves and sea level rise with their large root systems, which dissipate energy. “Conservation and restoration of coastal mangrove areas is essential if coastal communities are to recover and be protected from similar events,” the report concludes.

5. As bees disappear, fruit trees in China are being hand-pollinated

In southwest China’s Sichuan province, widespread pesticide use coupled with habitat destruction means farmers have to haul pots of pollen to self-pollinate pear and apple trees, according to Dave Goulson, a biology professor at the University of Sussex. This means using a brush attached to a long bamboo pole to dab inside each flower. According to one study, about 30% of Chinese pear trees are artificially pollinated.

A farmer hand pollinates a pear tree, China.
A farmer hand pollinates pear blossoms in an orchard in China’s Hebei province. Photograph: Xinhua/Rex/Shutterstock

Pollinating insects are vital to human food security: three quarters of crops depend on them. They are also crucial to other wildlife, as a food source and as pollinators of wild plants. But the lack of wild pollinators is impacting food production around the world. In the United States, researchers studied seven crops grown in 13 states and found five showed that a lack of bees is affecting how much food can be grown, including apples, blueberries and cherries.

6. Pesticides kill more than bad pests

Since World War II, our main defense against crop pests has been man-made pesticides. But these chemicals also kill off beneficial insects, including parasitoid wasps, lacewings and ladybugs, which prey on common pests and provide support for farmers and gardeners.

An ant carries away food in Van Province, Turkey.
An ant carries away a feast from the fields of Van Province, Turkey. Photography: Anadolu Agency/Getty Images

Researchers in Brazil have found that ants may be more effective than pesticides at helping farmers produce food because they are better at killing pests, reducing plant damage and increasing crop yields. This is because they are “generalist” predators, hunters of parasites that damage fruits, seeds and leaves. Scientists looked at the impact of 26 ant species (mainly tree ants) on 17 crops, including citrus, mango, apple and soybean. According to the paper, published in Proceedings of the Royal Society B, they do best in diverse agricultural systems, such as agroforestry and shade cropping, because they have more places to nest.

7. The loss of coral reefs leaves coastal properties unprotected

Like mangroves, coral reefs are a natural barrier to waves and storms. Because of their hard and jagged formations they can protect coastal communities and reduce the threat of erosion. They make it more likely that waves will break offshore, reducing wave energy by an average of 97% by the time they hit land. It is estimated that nearly 200 million people in coastal areas around the world depend on the protection of coral reefs. Research shows that in the United States they provide more than $1.8 billion annually in flood protection benefits.

Coral Reef, Key West, Florida, USA
A coral reef on the Florida coast. Photography: Joseph Prezioso/Zuma Press Wire/Rex/Shutterstock

However, developments such as marinas and docks as well as pollution damage these reefs. Corals are also destroyed by rising temperatures, leading to mass bleaching. Research suggests that virtually all of the planet’s corals will suffer from severe bleaching if global temperatures rise by 1.5C.

Find more information on the age of extinction here and follow biodiversity journalists Phoebe Weston And Patrick Greenfield on Twitter for all the latest news and features

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