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Landfall-Learning > Environment > Rivers


Before leaving on our journey, Landfall spent two years in the Dog River. The Dog River is located on the west shore of Mobile Bay, in southwestern Alabama. The Dog River Watershed covers approximately 95 square miles. South of Mobile Bay is the Gulf of Mexico.

Map courtesy of the Dog River Watershed project conducted by Dr. Mimi Fearn's Field Work in Geography class
Department of Earth Sciences
University of South Alabama

Southeastern US
South Florida and the Everglades
Central America
South America

Southeastern US
The rivers and streams of the American Southeast are unusually rich in aquatic biodiversity. They are home to such colorfully named fish as the Pygmy Madtom (the world's smallest catfish), the Halloween Darter, and mussels like the Tennessee Heelsplitter and the Purple Wartyback. From the huge paddlefish and sturgeon to tiny daces and shiners, these rivers and streams are of global significance and home to freshwater mussels, fish and snails found nowhere else in the world.

The rich biodiversity of the area has its roots in history. While glaciers covered other parts of the temperate world during the last Ice Age, they stopped just north of what is today the southeastern United States. Plants and animals died from the prolonged freeze in other regions, but the rivers and streams of the American Southeast had a favorable climate for a long time, which allowed new species to evolve and thrive. The result today is one of the most species-rich river ecosystems in the world.

Rivers in this Southeast ecoregion begin as small streams in the Appalachian and Cumberland Mountains, flow down across the Piedmont, and meander across the Gulf coastal plains. This varied geography contains a mixture of aquatic habitats that contribute to the region's diversity of wildlife. The Tennessee/Cumberland and Mobile Basins contain the greatest levels of fish and mollusk diversity in the temperate world! About 90 percent of the mussels and almost 73 percent of the aquatic snail species in the United States are found here. The area's freshwater mollusk population is also one of the world's most threatened. The Cahaba River, which flows through central Alabama, carries within its waters at least 131 fish species, including 18 that exist only in this river. There are more fish species per mile in the Cahaba than in any other North American river. And, recently, scientists discovered that the Duck River, which flows though central Tennessee, rivals the Cahaba in its diversity of fish species and its thriving mussel populations.

More than 250 species of crayfish, nearly 300 species of mussels, and over half of all freshwater fish species in the United States are found in the waters of the Southeast. Many native species are found in just one stream or watershed here and nowhere else on the continent or the world. In addition to fish and mollusk species, the Southeast's rivers and streams' varied freshwater habitats also sustain numerous species of birds, mammals, reptiles, and amphibians. Some of the better known species include: the wood stork, North America's only stork; the river otter; the American alligator; the ringed map turtle; and the alligator snapping turtle, which can exceed 300 pounds and live more than 100 years. Also found only in the area is the rare Tennessee cave salamander and the Nashville Crayfish.

People, too, have been living near the southeastern rivers and streams for at least 12,000 years. We have relied on them for food, transportation, drinking water and spiritual solace. These places have witnessed eons of human and natural history and are testaments to the resilience of life on Earth.

People farm, use timber and build cities and towns, and in doing so affect the rivers and streams they rely on for water. As more people move into the region, the impacts on our freshwater resources increase markedly. The rivers and streams of the Southeast are the centerpiece of a way of life steeped in outdoor traditions, from fishing and swimming to boating, playing, or resting on the shady banks. However, runoff, water supply issues, suburban sprawl, unchecked road construction, unsustainable agricultural and forestry practices, dams, mining, and point source pollution threaten this rich natural legacy and the aquatic life that live beneath the region's waters.

These threats illustrate that freshwater conservation in the southeastern United States is a complex issue. Yet, protecting aquatic biodiversity from these threats also protects our own water quality. Clean freshwater is critical to life on earth and water quality is essential for all human communities.


1. Look at a map of your area and see how many rivers you can find.

2. What river is the closest to your school? To your house?

3. Organize a field trip to a nearby river, and see how many animals, birds and other creatures you can identify. While standing by the river, see how many threats to the river's water quality you can identify just by looking around you.

4. Would you eat a fish caught in that river? Why? Why not?