First, the earth's biodiversity provides us with essential resources, including food and oxygen, ecological services such as natural pest control, and pleasure, because nature is beautiful and interesting.
Second, through various activities, we are eliminating and degrading many biologically diverse ecosystems, such as tropical forests, that are potential sites for the emergence of new species.
These new species will be needed to replace species that will be going extinct and to maintain the planet's vital biodiversity.
Third, many people share the ethical view that wild species have a right to exist as long as they can, regardless of their usefulness to us.
The current rapid loss of the species and ecosystems that make up the earth's biodiversity, hastened by human activities, as the most serious and long-lasting environmental and ethical issue that humanity faces.
A species' role, or total way of life, in an ecosystem. It includes all physical, chemical, and biological conditions that a species needs in order to live and reproduce in an ecosystem.
A species' niche includes its habitat, which is the physical place where a species lives.
Species with a broad ecological niche. They can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions.
Examples: flies, cockroaches, mice, rats, and humans, raccoon
Species with a narrow ecological niche. They may be able to live in only one type of habitat, tolerate only a narrow range of climatic and other environmental conditions, or use only one type or a few types of food.
Examples: the giant panda feeds almost exclusively on bamboo, which limits the areas where it can live.
The corals that create spectacular coral reefs in tropical waters can thrive only within a narrow range of water temperatures.
indicator species—a species that is especially sensitive to, and very responsive to, changes in long-term environmental conditions.
Such a species can provide early warnings of damage to an ecosystem.
Ex: Most trout species found in lakes and streams cannot survive if the water they live in falls above or below a certain temperature range. They also need clear, clean water with high levels of dissolved oxygen. When their populations decline, it is a strong sign of changes in temperatures, clarity, or pollution levels in their waters.
any species that, by filling its niche, has a large effect on the types and abundances of other species found in its ecosystem.
In short, it plays a key role in the functioning of its ecosystem. The loss of a keystone species can lead to population crashes and extinctions of other species that have evolved to depend on it for food or shelter or other benefits.
For example, when the American alligator nearly disappeared from its natural habitat in the southeastern United States, the ecosystem it had occupied for thousands of years began to unravel
certain species of bees, butterflies, hummingbirds and bats that play a critical role in pollinating flowering plant species.
When the American alligator nearly disappeared from its natural habitat in the southeastern United States, the ecosystem it had occupied for thousands of years began to unravel
Most of the people killing these alligators probably did not know about the important ecological roles that this keystone species plays in its wetland habitat. Alligators literally help to create their ecosystems by digging deep pits in the swamps, called "gator holes," which store freshwater during dry spells and serve as habitat for some species of fish, insects, snakes, and birds. They build large nesting mounds for themselves, but these mounds also become nesting and feeding sites for herons and egrets.
Alligators also eat a lot of gar, a predatory fish that feeds on game fish such as bass and bream. In this way, they help maintain populations of these game fish. As alligators move from their gator holes to nesting mounds, they help to keep freshwater ponds and coastal wetlands free of invasive shrubs and trees that would otherwise crowd out native species of plants and animals.
A third type of species interaction is parasitism, which occurs when one organism (the parasite) feeds on the body of, or otherwise makes use of the energy of, another organism (the host).
The parasite is typically much smaller than its host and rarely kills its host.
Ex: Tapeworms- live inside their hosts.
Blood-sucking sea lampreys- attach themselves to the outsides of their hosts.
Some parasites move from one host to another, as fleas and ticks do.
Parasitism can benefit ecosystems by helping to control the populations of host species.
In a fourth type of species interaction, called mutualism, both species benefit by providing one another with food, shelter, or some other resource.
Ex: Clownfish- usually live with sea anemones, whose tentacles sting and paralyze most fish that touch them except for the clownfish. The clownfish also feed on the leftovers of the anemones' meals. In turn, the clownfish fight off or eat some of the predators and parasites that threaten the anemones.
armies of bacteria that live in our digestive tracts and help us digest our food. They in turn get a safe habitat and a food supply from us, their hosts.
A fifth type of species interaction, called commensalism, benefits one species but has little or no effect on the other.
Ex: Plants called epiphytes attach themselves to the trunks or branches of large trees in tropical and subtropical forests.
They benefit by having a solid base from which to receive sunlight, rainwater, moisture from the humid air, and nutrients falling from the tree's upper leaves and limbs. Their growth apparently does not harm the tree.
Some species have characteristics that raise their chances of becoming extinct.
Ex: the giant panda bear eats mostly bamboo, which severely limits its habitat area.
The endangered blue whale and endangered sea turtles travel the oceans within fixed corridors, or migration routes, making them vulnerable to potentially harmful human activities such as industrialized fishing.
Species such as the Florida panther and the grizzly bear are vulnerable because they need large territories to find enough food.
Other species, including popular ocean fish such as the orange roughy, are prone to extinction because of their low reproductive rates, which makes it difficult for the species to recover once their populations decline.
The Siberian tiger, as well as other tiger species, are endangered because of shrinking habitat areas and the high market prices for their skins and bones. There are only about 3,200 tigers left in the wild, and extinction experts project that before the end of this century, they will probably be extinct.
HIPPCO which stands for
1. Habitat destruction, degradation, and fragmentation
2. Invasive species
3. Population growth and rising rates of resource use per person
5. Climate change
The biggest cause of species endangerment is habitat loss.
Ex: by clear-cutting a single forest, we eliminate the habitats for hundreds to thousands of species.
In this category, we also include habitat degradation-
which occurs when natural habitat is damaged such that wildlife can no longer use it.
Ex:, when the pollution in a stream reaches a certain level, the stream can no longer support fish populations.
This category also includes habitat fragmentation- which occurs when a large, intact area of habitat is partially destroyed and divided into smaller, isolated patches, typically by roads, crop fields, logging, and urban development.
Ex: Species such as wolves, which need large areas of forest for mating, rearing young, and feeding, cannot survive in fragmented forests.
Many species, including the Indian tiger, the black rhino, and the African and Asian elephants, have been threatened by a combination of habitat loss, degradation, and fragmentation.
Adding to this threat is the illegal hunting (poaching) of these species for their valuable skins and body parts.
About 70% of the earth's known bird species are declining in numbers, and roughly 12% are threatened with extinction, mostly because of the loss, degradation, and fragmentation of their habitats.
About 75% of the word's threatened bird species live in forests. Many of these forests, especially in the tropical areas in Asia and Latin America, are rapidly being cleared or fragmented by roads and development.
In North America, populations of many forest songbirds, including tanagers, orioles, and thrushes, which spend their winters in these tropical areas, have also declined sharply.
Among the world's aquatic, or water-based bird species, about 40% are in danger, many because of the draining and degradation of their wetland habitats.
Other threats to these birds' habitats are oil spills, runoff of pesticides and fertilizers from farm fields, and other pollutants such as sediments and factory emissions.
Another threat to a number of migrating bird species are electrical power lines, cell phone and radio towers, wind turbines, and tall buildings. Every year, hundreds of millions of migrating birds are killed when they collide with such structures wherever they have been erected within bird migration routes.
The extinction of bird species can have a devastating ripple effect on the ecosystems of which they are a part.
Birds help to control populations of rodents and insects that would otherwise devour many plants.
They also help to sustain plant populations through pollination and dispersal of seeds.
Without these free ecosystem services, many plants would become extinct, especially in tropical areas, and this would be followed by the loss of the specialized animal species that feed on those plants.
In the 1930s, the kudzu ("CUD-zoo") vine was imported from Japan and planted in the southeastern United States to help control soil erosion. That goal was achieved, but the vine grew so rapidly and was so hard to kill that it took over almost everything in its path, including gardens, trees, and abandoned cars and houses. It has overwhelmed many areas of the southeastern United States and is expected to spread northward as the climate gets warmer. So far, no one has found a good way to control the spread of kudzu.
In recent years African and Burmese pythons and several boa constrictor species, acquired by people as pets, have ended up in Everglades National Park in Florida. Some of these snakes' owners found it hard to feed and manage them, and dumped them into the park's wetlands where the snakes have reproduced rapidly.
These snakes can be as big around as a telephone pole, grow to 20 feet in length, and weigh more than 200 pounds. Because of their huge appetites, they eat whatever they can catch, including raccoons, birds, pet dogs and cats, full-grown deer, and occasionally an American alligator—the only species besides humans that are capable of killing these predators. These snake populations are slowly spreading to other areas and, by 2100, could be found in many wetlands in the southern half of the United States.
Affects aquatic species living in lakes, rivers, and oceans. About 45% of the world's people live on or close to the oceans' coasts, and this percentage is increasing. With this growing coastal population come more boats, road and housing construction, oil leaks and spills, garbage dumping, and other activities that add wastes and harmful chemicals to coastal waters. These activities threaten populations of some fish and other aquatic species, and can upset aquatic food webs.
Every year, pesticides kill more than 67 million birds and millions of fish. The U.S. Fish and Wildlife Service estimates that about one-fifth of the endangered and threatened species in the United States are at risk from pesticide poisoning.
Also, oil pollution in the Gulf of Mexico adds to the threats that have endangered all species of sea turtles living in the gulf.
Since 2006, certain pesticides have been shown to play a role in the widespread loss of many honeybee colonies in the United States and in parts of Europe because of a mysterious problem called colony collapse disorder. Other factors, such as an invasive parasitic mite from Asia, are possibly involved in this disorder. Researchers are trying to learn why this is happening and what can be done to reduce this loss of honeybees, which pollinate almost a third of all U.S. food crops.
A sixth major cause for rising extinction rates is over-exploitation—the O in HIPPCO.
With the rapid growth of the human population, hunters and fishers trying to help feed growing populations have depleted populations of many wild species.
However, some protected species are still illegally killed or captured for sale—a practice called poaching. Poachers sell the live animals and the hides, horns, and other body parts that are highly prized, to collectors in the largely illegal wildlife trade. Few of the poachers are caught or punished, and many of the live wild animals transported between countries die in transit.
This threatened white rhinoceros in South Africa was killed by a poacher for its horn. The horn can be worth many thousands of dollars because it is used to make dagger handles and is ground into powders that are used to make medicines.
Tigers, for example, are highly valued for their furs, and for body parts that are used for medicinal purposes in China and other parts of Asia.
A coat made from the fur of the highly endangered Bengal or Indian tiger can sell for $100,000.
2. Wildlife biologists estimate that for every wild animal captured and sold in the pet trade, an estimated 50 others are killed or die in transit.
Tropical birds are popular in this market, and at least 80% of these birds are imported legally or illegally from tropical forests, according to the IUCN. As a result of the pet trade, more than 60 bird species—most of them parrots—are classified as endangered or threatened
The pet trade also affects coral reef ecosystems, especially in Indonesia and the Philippines. Divers go to the reefs and catch tropical fish by squirting poisonous cyanide into the water to stun the fish. This means that many fish die for each fish that is caught and sold. The cyanide solution also kills the coral animals that build and maintain the reefs. Other wild species that are being exploited and depleted because of the pet trade include amphibians and reptiles.
3. Several plant species, too, are in danger of being depleted, largely because of the buying and selling of these plants for use in decorating houses, offices, and lawns. Several species of orchids and cacti are endangered for this reason.
integrated pest management (IPM) in which each food crop and its pests are viewed as parts of an ecological system.
With IPM, when pest populations reach an economically harmful level, farmers use various methods to control the pests.
One is cultivation controls, such as altering planting times and changing the crops planted in a particular area in order to avoid the pests.
Another is biological controls, including the use of natural predator insects, parasites, and disease organisms to kill the pests.
Beyond those measures, farmers use conventional pesticides only as a last resort, and then very carefully and in small amounts.
***** These and other programs show that by using IPM, farmers can cut pesticide use dramatically, without reducing crop yields. Thus, IPM is an important pollution prevention approach that helps farmers to keep producing while reducing their harmful effects on biodiversity. Scientists call for using it more widely, especially in areas where the habitats of threatened and endangered species can be degraded by the use of pesticides on nearby farms.
With the growth of ecotourism, people living near the habitats of endangered species such as sea turtles, tigers, and tropical birds are learning that these animals are worth more alive than dead
For example, conservation biologist Michael Soulé estimated that one male lion living to age 7 can bring in about $515,000 in tourist dollars to Kenya, while the money that a hunter can get for a lion's hide is about $1,000.
Technology can provide solutions to some overexploitation problems.
For example, one type of overexploitation is the overfishing of the oceans by industrialized fishing fleets. It not only threatens many fish species, but also results in the accidental capture of endangered sea turtles.
Some turtles get trapped in the large nets towed by fishing boats or caught on one of the thousands of hooks that are dragged along behind some boats.
However, several countries now require fishers to use turtle excluder devices, which allow turtles caught by the nets to escape before they drown.
There are also special hooks that can catch fish, but are less likely to hook turtles. Use of these devices has reduced the number of sea turtle drownings.