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Environmental Science 101: Environment and Humanity19 chapters | 145 lessons | 14 flashcard sets
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Free 5-day trialLaura has a Master's degree in Biology and is working on her PhD in Biology. She specializes in teaching Human Physiology at USC.
The planet Earth is not static; it is constantly changing. Humans are responsible for a lot of those changes. We clear forests for land to build on, till the ground to grow crops for food and animals, and decimate acres of land so we can build roads and highways. One of the things that we don't tend to think of is where the animals and plants go when we destroy their habitat. Many of these species cannot simply migrate, or move to another area. Therefore, they go extinct, or cease to exist.
Species extinction is problematic because, if you remove one organism from an ecosystem, it changes the entire ecosystem. Ecosystems are delicately balanced; one small change drastically alters everything. Let's take a look at a quick example. Coral reefs are the perfect example of a balanced ecosystem. Corals and sponges, which are both animals, build the reef and create structure for fish.
Small fish, known as grazers, feed on the corals and sponges as well as algae. Examples of grazing fish are butterfly fish, parrotfish and damselfish. Large predators, such as sharks and eels, eat the grazing fish. The large predators drive the ecosystem by keeping all the other population numbers in check. This is called a top-down ecosystem. So, what happens when there are no more sharks?
In the absence of sharks, the grazing fish populations explode because there aren't any predators to keep the population numbers at a reasonable level. The increased number of grazing fish means there is more grazing upon the reef itself, and the corals and sponges die off, which means the reef is dead. So, where are the sharks going?
Shark populations are diminished mainly due to an over-fishing practice known as 'finning.' Large fishing vessels catch hundreds of sharks and cut off their fins in order to make shark fin soup. They throw the fin-less sharks back into the water where it dies because it cannot swim without its fins. Sharks are also caught as bycatch, or catching something you weren't intending to catch in large fishing nets. These fish need to swim in order to breathe, so when caught in a net, they quickly drown.
In order to prevent animals and plants from going extinct, the Endangered Species Act , or ESA, was enacted in 1973. The act was designed to protect species from going extinct as a 'consequence of economic growth and development untempered by adequate concern and conservation.' The act's purpose is to protect species as well as 'the ecosystem on which they depend.' This means that organisms that are in danger of going extinct because of humans destroying their natural habitat for development need to be monitored, and their habitats need to be conserved.
The ESA is administered by two federal administrations, the United States Fish and Wildlife Service (FWS), as well as the National Oceanic and Atmospheric Administration (NOAA). NOAA manages the marine, or seawater, species that are protected under the ESA, and FWS monitors the freshwater fish and all other species.
There are two main categories under the ESA: threatened and endangered. A threatened species is one that faces endangerment in the near future. An endangered species is one that is in danger of becoming extinct in the near future. Under the ESA, a species is classified as 'endangered' if it meets one of the following criteria:
After a species is put on a list to be considered as threatened or endangered, there is a 90-day waiting period where investigations are made to determine if the species is indeed in danger of going extinct or becoming endangered. Many factors are taken into account, such as habitat, economic and educational importance and money that would be required to conserve the species.
If the species is found to be in need of protection from the ESA, a one-year study is performed, which is then followed by a hearing to vote on the species' placement on the Endangered Species List. If the species is granted protection under the ESA, the public is notified in the area where the species resides. Remember that if a species is granted protection under the ESA, so is its habitat. This can have large effects on farmers, miners and loggers, who all work in areas with hundreds of species. So, you can see that getting an animal listed as 'endangered' or 'threatened' is quite a process!
After an organism is put on the Endangered Species List, the FWS and NOAA are responsible for creating a Species Recovery Plan: in short, how they are going to keep the species from going extinct, and how they are planning on increasing the population number. These plans typically involve labeling a habitat as a 'protected area,' so the species can survive in their native environment and can also include breeding programs through captive individuals of endangered species in zoos. Sand dunes are a great example of a protected area. Green turtles are listed as endangered, so the sand dunes in which they lay their eggs are considered a protected area.
There are also large penalties for those who violate the Endangered Species Act. People who traffic, or capture, wound or kill an endangered or threatened species for the purpose of selling it, can receive a fine of $50,000 and up to one year in jail. There can also be up to a $25,000 fine per violation of the ESA.
Since the ESA's enactment in the 1970s, hundreds of species of plant and animal have been listed as threatened or endangered. Once on the list, the protection of the ESA can make it possible for a species to re-populate, and either be de-listed or removed from the Endangered Species List entirely.
There are also cases of down-listing, where a species is moved from being 'endangered' to being 'threatened.' Some well-known success stories of the ESA include the bald eagle, whooping crane, gray wolf, grizzly bear and gray whale. As of 2012, a total of 56 species have been removed from the Endangered Species List, and 25 have been down-listed from endangered to threatened.
There can be no argument that once an organism is listed as endangered, it takes a long time for the population to come back to a healthy level. The success rate of the ESA is only about 1% over a span of almost 40 years. Some would say that isn't worth the time and money recovery efforts have cost. However, thinking back to our coral reef example, you could argue that keeping ecosystems healthy and balanced is worth any price.
While the ESA is the main piece of legislature we have in the U.S. for protecting species, the International Union for Conservation of Nature, or IUCN, is responsible for publishing the Red List of Threatened Species, which is a global list of all species that are considered threatened or endangered. The World Conservation Strategy of the IUCN is a plan to bring governments and local communities together in an effort to eradicate animal and plant extinction.
A major premise of the World Conservation Strategy is that 'protected areas and threatened species could most effectively be safeguarded if local people considered it in their own interest to do so.' This means that if people in a local area or region took it upon themselves to conserve a habitat and species instead of being forced to do it by the government, the number of organisms on the Endangered Species List would be much lower.
Animal and plant extinctions can have detrimental effects on ecosystem balance. For example, overfishing causes a drastic decrease in shark populations, which has devastating effects on coral reefs. In 1973, the Endangered Species Act , or ESA, was enacted, which protects organisms that are endangered, or under threat of going extinct, or threatened, which means they will soon become endangered. The United States Fisheries and Wildlife Service as well as the National Oceanic and Atmospheric Administration are responsible for administering the ESA.
These federal agencies are also responsible for putting new species on the Endangered Species List and creating recovery plans for the species that are already on the list. While the ESA has had several large success stories such as the bald eagle, there are those that feel the ESA takes too much time and money for the number of species it helps. The ESA is specifically for conservation and preservation in the United States. The International Union for Conservation of Nature publishes a global list of threatened and endangered species and tries to bring the global community together for conservation efforts.
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Environmental Science 101: Environment and Humanity19 chapters | 145 lessons | 14 flashcard sets