Chytrid in the Southeastern United States


An Eastern Newt (Notophthalmus viridescens), one of several species found to be infected with the chytrid fungus in the southeastern U.S..

The Southeastern United States is perhaps best known for its fried chicken and humid weather, but it also serves as a center of diversity for salamanders, freshwater fish and freshwater mollusks. Unfortunately, the streams and rivers that are home to these creatures are becoming threatened by pollution and environmental contamination. As anyone who has ever had the pleasure of paddling a river in Southern Virginia can tell you, you can find a ridiculous amount of trash on the riverbanks and in the water. I can not remember a time that I have been on the river and not seen a rubber tire or had to look out for broken glass on the shore and in shallow water. Unsightly as this debris may be, it is not the worst thing that aquatic organisms have to deal with. Mercury and other contaminants often accumulate in freshwater fish tissues so that they become unsafe for human consumption. Pesticides such as Atrazine and the hormones from birth control pills wreak havoc with amphibian and fish reproduction, turning males to females and causing infertility.

As if all of this wasn’t bad enough, the amphibian chytrid fungus has also been recorded for the Southeastern U.S. The good news is that not many species seem to be badly affected by it. The species recorded as having had the fungus present on them are: Northern Cricket Frogs (Acris crepitans), toad tadpoles (Anaxyrus sp.), the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis), the Northern Dusky Salamander (Desmognathus fuscus), Seal Salamanders (Desmognathus monticola), Black-bellied Salamander (Desmognathus quadramaculatus), Southern Two-lined Salamanders (Eurycea cirrigera), Gray Treefrogs (Hyla versicolor/chrysoscelis), Eastern Newts (Notophthalmus viridescens), the Yonahlossee Salamander (Plethodon yonahlossee), Spring Peepers (Pseudacris crucifer), the Cajun Chorus Frog (Pseudacris fouquettei), North American Bullfrogs (Lithobates catesbeianus), Green Frogs (Lithobates clamitans), Dusky Gopher Frog (Rana sevosa), Southern Leopard Frog (Lithobates sphenocephalus) and the Wood Frog (Lithobates sylvaticus). This represents only 17 out of 66 species swabbed for chytrid in various studies, and of these species only about seven had any appreciable amount of chytrid infection. One of those seven species is the American Bullfrog (Lithobates catesbeianus), which is believed to be a carrier of Bd that does not experience much mortality from chytridiomycosis. Appalachian salamanders have also been shown to have low prevalence of chytrid and to be less affected by the disease than other species. However, an infected species that is of concern is the Northern Cricket Frog (Acris crepitans), which has been experiencing population declines throughout its range. The infected individuals were found in Arkansas and Louisiana, but not many cricket frogs have been swabbed in other states so more surveys for chytrid prevalence would be needed to determine if it is present in other states. Studies are ongoing for the presence of chytrid in the southeastern U.S., so it remains to be seen if the fungus will spread to other species or areas.

Frog: 3, Fungus: 4

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