The Cahaba: A Global Biodiversity Hotspot

The Cahaba River is one of the most biologically diverse rivers in North America.

More than 130 fish species, dozens of freshwater mussels and snails, rare plants, and countless other species depend on this river’s healthy, flowing water. Some of these species exist nowhere else on Earth.

This extraordinary biodiversity is the reason we work every day to protect the Cahaba.

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A Living Network of Species

The Cahaba River is more than just moving water—it is a complex, interconnected ecosystem where plants and animals depend on one another to survive. From microscopic organisms to large fish and mammals, each species plays a role in keeping the river healthy.

Fish

Historically, the Cahaba River has supported more than 130 species of fish, making it one of the richest freshwater fish habitats in the United States. At least 18 of these species are endemic, meaning they are found nowhere else in the world.

Mollusks

Freshwater mussels and snails are among the river’s most important—and most threatened—inhabitants.

The Cahaba has historically supported 48 species of freshwater mussels and 32 species of freshwater snails, including 10 species found nowhere else on Earth. These animals play a critical role in filtering water and maintaining river health.

Crustaceans

The Cahaba River watershed supports at least 17 species of crayfish. These small critters play a big role in the river’s food web.

Amphibians

Frogs and salamanders thrive in the wetlands, tributaries, and forests surrounding the Cahaba. Because amphibians are highly sensitive to pollution and habitat change, they are often considered early indicators of water quality and ecosystem health.

Reptiles

The Cahaba River provides habitat for at least 17 species of turtles. A variety of native snakes also live along the river, playing an important role in maintaining balance in the ecosystem.

Plants

The river’s most famous plant is the Cahaba lily, an iconic spider lily that blooms across the river’s rocky shoals each spring. But the Cahaba’s banks and shoals support many rare and imperiled plant species, forming the foundation of the river’s unique ecosystem.

Birds

The Cahaba River and its surrounding forests provide important habitat for a wide variety of bird species. Wading birds, songbirds, and birds of prey rely on the river’s wetlands, shoals, and riparian forests for food, nesting, and migration stopovers.

Mammals

Beavers, muskrats, and even river otters live throughout the Cahaba watershed, while the surrounding forests support species such as bats, bobcats, deer, and other native mammals that rely on the river for water, food, and habitat.

Measuring Biodiversity

Biodiversity in the Cahaba River is complex and constantly changing. While the river has historically supported more than 130 fish species, threats like pollution, drought, and stormwater runoff have likely reduced these numbers.

To understand these changes, scientists look not only at species counts but also at population sizes, ranges, and genetic diversity—a critical measure of how resilient a species is to future threats.

Cahaba River Coalition collects samples for ongoing environmental DNA (eDNA) studies, helping us track what species are present and support ongoing conservation efforts.

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Threats to Biodiversity

This incredible biodiversity makes the Cahaba River globally significant—but it is also fragile. Pollution, habitat loss, and changing environmental conditions threaten the species that depend on this river.

Protecting the Cahaba means protecting one of the most remarkable freshwater ecosystems in the world.