Biodiversity at Risk
Biologists estimate that there are between 10 and 100 million species living on Earth. At current rates of extinction, over half of these species will be gone by the end of this century. Across the globe, animal species that are threatened with extinction include
- 12 percent of all birds
- 21 percent of all mammals
- 28 percent of all reptiles
- 30 percent of all amphibians
- 70 percent of all plants
Extinction is a natural process and is always occurring. Using evidence from the fossil record, the
background extinction rate is calculated to be between 10 and 100 species per year. However, the
current rate of extinction greatly exceeds that number; we lose a species every 20 minutes! Hundreds of thousands of species will disappear before we are even aware of their existence.
The Value of Biodiversity
Ecosystems provide human communities with a number of services free of charge, including air and water purification, flood and drought control, pollination of crops and other vegetation, dispersal of seeds, and nutrient cycling. These services have an economic value. If humans had to pay for ecosystem services based on their market value, biologists estimate that the cost would be approximately $33 trillion annually.
In addition, 40 percent of all medicines are derived from plants, animals, and microbes. For example, biologists are developing a painkiller based on an extract from the skin of an Ecuadorian frog. The painkiller is 200 times stronger than morphine, but is not addictive. Every time a plant, animal, or microbe becomes extinct, biologists lose whatever knowledge they might have been able to gain by studying it.
Does Biodiversity Really Matter?
Some people might suggest that biodiversity belongs in a zoo and the rest of the world belongs to humans to develop. Arguments in favor of development include the following:
- The rise and fall of species is part of nature. No species lives forever. New species replace old ones.
- Economic development provides jobs to people who are living in poverty.
- Land set aside as wilderness could be better used as farmland to provide more food for a rapidly
increasing human population.
Conservation biologists view the pro-development arguments as shortsighted. Their view is that the Earth must be maintained for future generations, not simply harvested to provide for the needs of its
current population. In fact, they argue that biodiversity plays an important part in ecosystem stability.
In general, the more species that live in an ecosystem, the more efficient and stable that ecosystem will be. For example, a rain forest can produce much more oxygen than an orchard full of apple trees. Also, many plants, including 75 percent of the world’s staple crop plants, need animal pollinators such as birds and insects to help them reproduce.
As you have learned, biodiversity is very valuable. Yet questions remain about how best to protect biodiversity. Two of these unanswered questions include
- How can we slow down the current extinction rate?
- Some of the areas with the highest amount of biodiversity are located in developing countries. How can biodiversity be preserved without harming the country’s economic growth?
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Microorganisms can be used to clean up wastes that are spilled. Some bacteria can eat substances that would be fatal to humans and most other animals. Using microorganisms to clean up a polluted environment is called bioremediation.
- Toxic waste, such as crude oil, is spilled on soil or in water.
- The waste kills most bacteria, but a few survive and adapt.
- Surviving bacteria feed on the toxins that were spilled and break them down. They may change the toxin to another form that is not dangerous, break the compound into smaller parts, or completely degrade it into inorganic molecules such as carbon dioxide and water.
- Oxygen and nutrients are added so that more bacteria will survive to help break down the toxins.
- When the spill has been completely broken down, bacteria die because they have run out of food.
Sometimes the needed microbes do not naturally occur in the contaminated site. When this is the case, the clean-up crew adds the specialized microbes to the site to break down the toxins.
Conservation Biologist in Action
In 1990, Angel Montoya was a student intern working at Laguna Atascosa National Wildlife Refuge in Texas. He became interested in the Aplomado falcon, a bird of prey that disappeared from the southwestern United States during the first half of the 20th century. Montoya decided to go looking for the raptors, and he found a population of Aplomados in Chihuahua, Mexico. His work helped to make it possible for the falcons to be reintroduced to an area near El Paso, Texas.
Restoration of the Aplomado falcon became Montoya’s life work. He has monitored and researched the falcon since 1992. He helps release falcons that have been raised in captivity back into the wild, and monitors falcons that have already been released. It isn’t easy to keep tabs on a falcon, however. “Their first year they are pretty vulnerable because they haven’t had parents,” Montoya says. “Just like juveniles, they’re always getting into trouble. But I think they will do just fine.”