Messing with Mother Nature: 5 Cautionary Tales

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The balance of nature took about four billion years to settle into the pattern the earth now holds. When humans change one thing, large or small, it begins a chain reaction that we often can't foresee. We don't know everything there is to know about Mother Nature yet.

Killer Bees

In 1956, Brazilian geneticist Warwick Kerr imported a robust but aggressive African strain of honeybee named Apis mellifera adansonii to breed with the European species that were used for honey production. Before the planned mating the next year, 26 swarms of the African bees escaped from the apiary in Sao Paulo. They bred with wild bees and their descendants became known as Africanized bees, or "killer bees". They have a tendency to attack any animal that wanders into their territory, sting their enemies in large groups, and remain agitated for up to 24 hours after the slightest provocation. They spread over South America into North America, and were found in the United States in 1990. Colonies have been reported in all the southernmost states from California to Florida. Fourteen people have been killed by the Africanized bees, but the biggest impact is the genetic invasion of the commercial beekeeping industry, which has always bred bees to be as docile as possible.

Fireweed

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The primitive weed Lyngbya majuscula is called fireweed by ocean fishermen in Moreton Bay, Australia who suffer blisters and rashes from contact or just by breathing around the weed.

As the weed blanketed miles of the bay over the last decade, it stained fishing nets a dark purple and left them coated with a powdery residue. When fishermen tried to shake it off the webbing, their throats constricted and they gasped for air.

After one man bit a fishing line in two, his mouth and tongue swelled so badly that he couldn't eat solid food for a week. Others made an even more painful mistake, neglecting to wash the residue from their hands before relieving themselves over the sides of their boats.

Divers describe the weed as "brown fuzz". In summer, Lyngbya majuscula covers a 30 square mile area of Moreton Bay and produces about 100 kinds of toxin.

William Dennison, then director of the University of Queensland botany lab, couldn't believe it at first.

"We checked this 20 times. It was mind-boggling. It was like 'The Blob,'" Dennison said, recalling the 1950s horror movie about an alien life form that consumed everything in its path.

Lyngbya majuscula thrives on oxygen-depleted water, leading scientists to believe that industrial and sewage runoff has allowed the plant to proliferate, especially as other plant and animal species die out. It grows as fast a 100 square meters a minute! Once established, Lyngbya creates its own nitrogen fertilizer from decaying parts of the plant. Many fishermen in Moreton Bay avoid working in the four months every year that Lyngbya clogs their waters.

Kudzu

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Kudzu (Pueraria lobata) covers over seven million acres of the American Deep South. At the 1876 Exposition in Philadelphia, Pennsylvania, the Japanese government made an impression by building a beautiful garden featuring their native plants, including kudzu. Americans wanted the charming vines for their own gardens. In the 1920s, the Glen Arden Nursery in Chipley, Florida promoted the plant as animal food. The US government promoted the plant for erosion control in the 30s and 40s, and paid Civilian Conservation Corps workers and farmers to plant it all over. The vine grows up to a foot a day, with reports of two or three feet a day. Kudzu covered buildings, crops, and forests. Native plants died from lack of light. Herbicides were ineffective. The government promotion of kudzu stopped in 1953, and it was declared a weed in 1972. Kudzu has quite a few uses for food, medicine, and household products, but is considered a nuisance. Image by ClintJCL.

The Manmade Aquarium Plant

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Officials at the Wilhelmina Zoo in Stuttgart selected a strain of seaweed to use as an aquarium plant. Their choice was the hardy and attractive Caulerpa taxifolia. They selectively bred an even more robust strain they named Caulerpa taxifolia (Vahl) C. Agandh, which they shared with other aquariums. A sample escaped into the wild, possibly by a drain at Monaco's Oceanographic Museum. In 1984, a patch of the seaweed was found in the Mediterranean Sea. In 2000, it was detected in waters off the US and Australia. It spread into thousands of acres of sea by 2001. Caulerpa was spread by boats and fishing nets, and by aquarium owners cleaning their tanks. It was bred to taste bad, so native animals won't eat it. As little as one square centimeter of Caulerpa can regenerate and start a new colony. The state of California battled the weed by covering and poisoning patches, a very expensive but rather successful method. European countries with more to battle remove it mechanically, which may control but will not eradicate Caulerpa. The man made strain Caulerpa taxifolia (Vahl) C. Agandh is now an illegal species in many countries. The World Conservation Union named it one of the 100 World's Worst Invasive Alien Species.

Operation Cat Drop

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A case in Borneo illustrates the delicate balance of nature and the unintended consequences of human intervention. An early 50s outbreak of malaria led the World Health Organization (WHO) to bring in massive amounts of DDT to kill mosquitoes. They killed the mosquitoes, but also virtually wiped out a particular species of parasitic wasp. The wasp fed on thatch-eating caterpillars. With the wasps gone, the caterpillars ate the villager's roofs! An even worse consequence was that geckos ate the poisoned insects and were in turn eaten by native cats. The native cats died from DDT poisoning, and therefore the rat population flourished. This lead to an outbreak of typhus and plague among humans. To assuage the damage, WHO arranged for a supply drop that included a couple dozen healthy cats! This supply drop (which included other supplies) was dubbed Operation Cat Drop. The cats were able to reduce the rodent population to controllable levels, and DDT was eventually outlawed.

As we continue to "improve" the environment and serve a growing human population, there will be more such stories to come.

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December 4, 2008 - 5:09am
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