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Everglades National Park in Florida is the largest subtropical wilderness in the United States. While sawgrass marshes are the most predominant habitat in the Everglades, wet prairies, sloughs, mangroves, and tree islands also make up the ecosystem. The wet prairies are treeless plains that consist of low-growing vegetation, like grasses and herbs. Sloughs are the main channel of free-flowing water, and home to animals such as turtles, alligators, snakes, and fish. Mangrove forests include various species of trees that thrive in saltwater and are able to tolerate the harsh winds of the coast. Over 220 species of fish inhabit the mangrove system. In addition, birds, such as pelican, gulls, and hawks, use mangroves as nurseries for their young. Tree islands, which are also known as tropical hardwood hammocks, make up the only dry land in the park. Barred owls, snakes, frogs, woodpeckers, marsh rabbits, and white-tailed deer are some of the animals that live in the tree islands.

Beginning in the late 1940s, human population growth in Florida created an increased need for such things as dry acreage for building houses and schools, drinking water, and water for crops and livestock. In response, Congress approved the Central and Southern Florida Project, which provided flood protection and water management for the region. Engineers built more than 1,500 miles of canals and levees that drained freshwater from the Everglades out to the sea, making the land habitable and farmable. The plan satisfied human needs and land development ensued.

But the project also created a number of problems for the Everglades ecosystem. Today, half of the original Everglades' water has been drained. Canals redirect the natural water flow patterns that once fed a healthy ecosystem. The farms and homes that sprouted up all over the region now send water that is polluted with fertilizers and other waste into the marshes. As a result of the ecosystem's drastic deterioration, over a dozen species, including the Florida panther and wood stork, are endangered.

Today, people are working on a massive restoration project to bring the ecosystem back to life. Engineers and scientists have begun to clean up the polluted waters and the federal and state governments have purchased land in an effort to prevent further harmful development.

Wildlife biologists are working to monitor improvement of the ecosystem by conducting research on the Everglades' main vegetation communities and the species that live in them. By observing particular living organisms, known as indicator species, biologists can gather data related to the state of the entire ecosystem. In some cases, merely the presence or absence of the species is a sign of the condition of the ecosystem. Indicator species in the Everglades include wading birds, alligators, and tree island plants.

One type of wading bird, the wood stork, has very specific habitat requirements related to quality and quantity of water. Thus, when the wood stork population decreases, it is a sure sign that there has been a decline in these aspects of the habitat. Tree island plants are considered key indicators because they are sensitive to changes to the habitat, such as flooding and drought.  Researchers have also used indicator species to monitor the salinity of water in the Everglades.  For example, alligators are negatively affected by high salinity levels that exist when there is not enough freshwater.  Baby alligators do not have desalinating glands so they are very sensitive to high levels of salinity.

To learn about how biologists are working to preserve another ecosystem, check out Prairie Dogs QuickTime Video.

To learn more about the Florida Everglades, check out An Everglades Visit QuickTime Video.

To learn more about wetlands ecosystems, check out The Value of Wetlands QuickTime Video.

To learn about organisms in the Congaree Swamp, check out the Reptiles of the Congaree Swamp QuickTime Video, the Primitive Insects of the Congaree Swamp QuickTime Video, and the Root Systems of Trees at the Congaree Swamp QuickTime Video.

• What characteristics make a species a good indicator species to monitor ecosystem health? Name two examples of indicator species mentioned in this video.
• Why does looking at the number of alligators help to determine the health of this area?
• What kind of data do the wildlife biologists at the Loxahatchee National Wildlife Refuge collect?
• Why might there be many job opportunities for wildlife biologists?