Alabama’s aquatic diversity runs north to south

Last month’s column explored the basics of the water cycle and how it functions naturally in a freshwater environment. This month will highlight the aquatic biodiversity that is supported by healthy freshwater systems.

As Southerners, we are blessed to live in a culture infused with water. One look at an Alabama state map will reveal a network of streams at the mercy of the state’s dramatic geologic history. From the Tennessee Valley to the Mobile Delta, Alabama is drenched in more than 77,000 miles of freshwater streams, ranking this Sweet Home as the No. 1 habitat nationally for a multitude of freshwater aquatic species including fish, crayfish, mussels and snails.

More than 310 species of fish swim in Alabama’s waters. Though bass, bream and catfish garner the most public attention, those tiny fish you catch in the minnow basket can be some of the most creatively colored creatures in the water. From shimmering shiners to dashing darters, these flashy fins showcase a rainbow of hues that rival any land-loving bird or mammal.

With monikers like Painted Devil, Rusty Grave Digger, Mountain Midget, Cockscomb and Phallic, crayfish are an incredibly diverse group of crustaceans staking their claim to ditches burrows, pools and streams. More species of crayfish reside in Alabama than in any other place in North America, with 86 species known to exist and more still being described.

Hanging out on the bottom of Alabama’s freshwater world are 180 species of mussels. More than just a seemingly static bivalve, mussels feature a unique adaptation that allows them to display a mimic of fish prey species. Adult mussels depend on fish to “take the bait” and then attach their larvae to the gills of the fish where they remain until the juvenile mussels drop to the bottom of the water. In addition to filtering water for phytoplankton, these unique animals play a vital role as bio-indicators of stream health and cannot thrive in streams that are degraded. Another group of mollusks that relies heavily on healthy streams is snails. More than 160 species of snails still call Alabama home despite habitat degradation due to dams, erosion, sedimentation, channelization, pollution and invasive species.

Fish, crayfish, mussels and snails are not only vital for a functioning ecosystem, their presence or absence clues us into the state of affairs regarding water quality. While these animals depend on healthy water for habitat and food, there is one other species that relies heavily on water for a daily existence—Homo sapiens.

Check out next month’s column where we will explore the human influence and dependence on our water resources.

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