by Whit Gibbons

October 15, 2017

The Southeast has the nation’s highest biodiversity of plants and animals.

Within this region, an astonishing array is concentrated in Alabama. The remarkable numbers of native freshwater fish, mollusk and turtle species have been documented in numerous books, many published by the University of Alabama press. Among these is "Southern Wonder: Alabama’s Surprising Biodiversity" by R. Scot Duncan, which gives a thorough account of the state’s biological and geological heritage.

“Alabama Wildlife,” a four-volume series edited by Ralph Mirarchi, provides extensive background on the richness of the vertebrate and invertebrate fauna of the state. These volumes offer checklists and descriptions of species found in the state, with color photographs of those identified as imperiled. Conservation and management recommendations are provided for land managers and everyday citizens interested in helping protect endangered populations. The 2017 publication of "Alabama Wildlife, Volume 5,” edited by Ericha Shelton-Nix, adds to this valuable series.

The original volumes in the series were published more than a decade ago. A key feature of volume 5 is an update of the taxonomic and conservation status of numerous nongame wildlife species. A variety of mammals, birds, reptiles, amphibians and fish, as well as freshwater snails and mussels, are discussed. But the major accomplishment is information on 84 different kinds of crayfish, a group not included in the earlier volumes. Crayfish are yet another taxonomic group whose diversity in the Southeast is astounding.

Within that group, the largest in size is the Tennessee bottlebrush crayfish. They are difficult to study in the wild because they live in streams beneath large rock slabs. They are very rare, or at least no one knows how to capture them in large numbers. No one knows how big they may get, but the largest one found so far is around half a foot in length.

Most crayfish species look like what everyone thinks of as a typical “crawdad.” Two long claws for pinching and a flattened tail. But several species of cave crayfish have been discovered in Alabama, many as the result of accidental captures from underground streams and pools. The Alabama cave crayfish are white and have reduced eyes. The intrigue of all subterranean creatures, including fishes and salamanders, is that no one knows exactly what their distribution is or what their general ecology is. Do some live in deep aquifers that go for miles beneath the surface? What do they eat? How do they find a mate?

A disquieting reality is that a dozen species of Alabama crayfish are categorized as being of “highest conservation concern,” meaning that they are “critically imperiled and at risk of extinction (or) extirpation.” An additional 30 species fall into the “high conservation concern” category, which means they are not far behind the others in becoming endangered or threatened on a trajectory toward extinction. Not a pleasant thought that these distinctive animals might disappear from our native fauna.

Among the threats to the continued existence of crayfish is the degradation of clean streams and rivers due to pollution from unregulated human activities. Unnatural industrial effluents, runoff of sediments from agricultural and mining activities and mishandled municipal sewage all contribute to the pollution problem. Crayfish are superb indicators of environmental health in many aquatic systems, including those beneath the ground. The fact that half the species in the state are of concern to biologists who study them should alarm anyone who wants to live around natural habitats and healthy ecosystems.

Crayfish diversity is high throughout the Southeast, and each state has species that qualify for conservation concern. Each state also has its own wealth of native biodiversity and unique wildlife assemblages. Folks living there can benefit from compilations that let them know how special their region is and what threatens that specialness. "Alabama Wildlife, Volume 5” continues a tradition of high-quality presentations that inform both scientists and general readers about the biological status of Alabama's amazing faunal biodiversity.

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