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Research Interests « Michael Freake

Research Interests

Population study of eastern hellbenders (Cryptobranchus alleganiensis)

The hellbender is one of the largest salamander found in North America. Unfortunately hellbenders have suffered severe declines across much of their range. Of the 17 states with hellbender populations, most classify the species as endangered, rare, or a species of concern, and are implementing tracking programs to monitor populations. These salamanders are found only in large, fast-flowing, highly oxygenated streams, and are extremely sensitive to siltation, dam construction, and acid mine drainage. In Tennessee, hellbenders are currently classified “in need of management”. This is a stop-gap designation given to species where there is concern over the status of populations, however insufficient data has been collected to determine whether state protection is required. It is believed that hellbenders may be locally abundant in some Tennessee river systems, but absent in most. Unfortunately current presence/absence data is particularly scarce in Tennessee, so the true distribution of hellbenders in the state’s river systems is not known, and there is even less information on the long-term viability of any populations.

Much of the best potential aquatic habitat for hellbenders in Tennessee is found in the eastern part of the state, in the Smoky Mountains National Park and the north and south sections of the Cherokee National Forest. With the support of the US Forest Service and National Park Service, we are conducting population surveys in river systems in the southern Cherokee National Forest, and in the Great Smoky Mountains National Park. This is an important first step in gaining sufficient data to determine an appropriate level of state protection for hellbenders in Tennessee.

Pesticide residues in salamanders in the Great Smoky Mountains National Park

We have found low levels of pesticides in the tissues of black-belly salamanders (Desmognathus quadramaculatus), including pesticides banned in the 1970’s and 1980’s (e.g. DDT and Chlordane), as well as pesticides that are still in use (e.g. Chlorpyrifos, Endosulfan and Atrazine). The pesticide likely originate from crop applications outside the park and are delivered by prevailing winds and precipitation. We hope to identify seasonal and geographic patterns of exposure in amphibians within the Great Smoky Mountains NP, and determine whether there are any significant biological effects.