Hellbenders falling off Highland Rim of Tennessee

Written by
downloadDr. Brian MIller
 

MTSU researchers document hellbender's accelerating decline in Middle Tennessee

(Author’s note: I was aware of the hellbender before interviewing Brian Miller, but did not know the giant salamanders were present on the Highland Rim of Tennessee. Subsequent reading and interviews with other researchers, including Dr. Bill Sutton at Tennessee State University, Nashville, confirm Miller’s statements that hellbenders are vanishing from large portions of Tennessee, and Missouri. The healthy populations in portions of the Great Smoky Mountains and Cherokee National Forest may be an exception to a general trend toward extirpation and, ultimately, extinction).

Brian Miller has been researching hellbenders for decades. He serves on the faculty of Middle Tennessee State University where he teaches in the biology department and mentors younger researchers, many of whom publish their research.

He has even developed a digital "Guide to the Reptiles and Amphibians of Middle Tennessee." The guide began more than 30 years ago as a dichotomous key for students in his vertebrate zoology class and now includes hundreds of photographs and exceeds 400 pages.

Dr. Miller researches the hellbenders of the Highland Rim, the upland that surrounds Nashville and the Great Basin. Populations of hellbenders in streams of this region are perhaps Tennessee's most endangered.

QUESTION: I noticed that you specialize in herpetofauna. Most of the research listed on your faculty page is focused on amphibians, but with some papers on snakes. Can you comment about your research?

ANSWER: You are correct that amphibians are my primary research interest, particularly salamanders. However, I also have strong interests in reptiles, and my students and I have conducted research on various species of snakes and turtles.

When did you become interested in hellbenders?

Hellbenders have been of interest to me since I first encountered them while enrolled in a course on herpetology at the University of Missouri in 1977. I was fortunate that the professor of that course, Dean Metter, was involved with research on hellbenders and I began to assist with his research in 1978, in collaboration with Robert Wilkinson at Southwest Missouri State University in Springfield, Missouri.

Chris Petersen was working on his master's degree with Dr. Wilkinson at that time and he matriculated to the University of Missouri a couple of years later to start on his Ph.D, which was also with hellbenders. Chris and I spent time in the field gathering data for his Ph.D. project until I moved to Washington State to work on my Ph.D.

I was hired into the biology department at Middle Tennessee State University in 1989 and began working with hellbenders in this state in 1990. At that time, I was able to locate populations in several rivers in Middle Tennessee, including a large population in the Collins River. I decided to concentrate my efforts on this population and one in the Buffalo River.

Of note, the population I worked with in the Collins River was dominated by large adults, whereas the population in the Buffalo River consisted of many age classes, including young individuals.

The Collins River situation was like what I was familiar with in Missouri and Arkansas populations. Unfortunately, by the early 2000s the population I was working with in the Collins River was gone; however, populations remain in the Buffalo River. My research with hellbenders during the past decade has been concentrated in streams in the Western Highland Rim.

Do you work with both subspecies, the Ozark, and the Eastern hellbender?

I worked with both subspecies while a student at the University of Missouri when assisting with projects in the Metter lab, but since I moved to Tennessee, I have worked only with Tennessee populations.

What do you perceive as the greatest threats to hellbender populations?

I am not certain why most populations of hellbenders are in decline rangewide, but suspect that habitat alteration, including sedimentation, and disease are involved in many if not all areas where declines are occurring. Lack of recruitment of young is a common theme of populations that decline. 

Populations dominated by large adults, which was my experience for two decades and what was thought to be normal, is a sign of trouble. Exactly why recruitment of young into adulthood is not occurring is the focus of research of many people who study hellbenders throughout their range.

Do you think that the hellbenders need further habitat protection or other protective measures?

I do. I think that any protection that can be given to protect streams and their watersheds will not only benefit hellbenders but all species that inhabit the streams.

Organizations in many states are developing head-start programs that will release 3– to 4-year-old hellbenders into the wild. The St. Louis Zoo has been the leader in these efforts and have successfully reared thousands of hellbenders, I think a few thousand annually for many years. The Nashville Zoo is developing a head start program but is not yet raising as many hellbenders as the St. Louis Zoo.

Are industrial or mining chemicals in the water a threat to this species?

Any contaminants dumped into streams can present problems for the inhabitants, including hellbenders. Although I know of no studies that causally link a specific industry or mining activity with hellbender declines, certain types of mining activities severely alter stream water quality and present a clear threat to all aquatic life, including hellbenders.

For example, increased sedimentation can destroy habitat used by hellbenders, including their breeding sites.

I noticed a paper in your publications list that described the demography of Cryptobranchus alleganiensis in the Ozarks. What can you tell us about your research on Eastern hellbenders in Missouri?

This manuscript was one of several that stemmed from the Ph.D. research of Chris Peterson. 

This manuscript, and all the work I was involved with in Missouri and Arkansas, was published prior to noticeable declines rangewide.

Populations discussed were all dominated by large sexually mature adults. Sadly, these populations crashed several years after the paper was published.

You are the sole author of a 2017 paper describing the hellbender demography in the Little Buffalo River at Laurel Hill Wildlife Management Area. What did you discover about that population?

The report is one of several that I wrote for the Tennessee Wildlife Resources Agency. It described my projects conducted in the Little Buffalo River. Rather than summarizing the report, I will summarize my efforts on populations in the river.

I first discovered populations of hellbenders on the Little Buffalo river in 2012 and began examining population structure in 2015. My student assistants and I could locate hellbenders easily early on (2012, 2015, 2016), but numbers of hellbenders that we find in a day has decreased significantly over the years. Although I have documented some young hellbenders in the river, the population is skewed to older adults.

My data suggests that, as happened with populations in streams I studied in the Eastern Highland Rim, populations in the Western Highland Rim are in jeopardy of being extirpated.

What is the one most important thing you would like our readers to remember about the hellbender?

I am often asked, "Why should anyone care about the hellbender," or some other species of salamander or seldom-seen animal. I assume that most readers are unaware of the occurrence of the hellbender or have never seen one in the wild. Certainly, most have not seen very many or handled any. 

I guess that is the problem. Most of us who care about wild places and the wildlife that inhabit those places are concerned about the loss of both the places and the life.

Based on early accounts, hellbenders were common and abundant in many streams throughout the eastern United States through the middle portion of the 20th century.

Populations have crashed during the past 40 years, and few knew. It is difficult to care about a species if you are not aware of its existence, or that it is in jeopardy of extirpation or extinction.

My take-home message is that hellbenders are interesting inhabitants of streams in our area. Healthy populations are important components of the stream ecosystem as they can compose a large component of the vertebrate biomass in those streams.

They are certainly an important component of the natural history of our region and as such are worthy of our attention and protection.

Just as society recognizes the value of conserving aspects of American history, such as buildings, we should recognize the value in conserving aspects of our natural history. Too often people look for an economic value of a species, such as pharmaceuticals that can be derived from glands or other organs. I have never cared much for that approach.  

I think the hellbender is worthy of protection simply because of its inherent value to a healthy ecosystem and as a component of our natural history.

Unfortunately, without an improvement in stream water quality, hellbender populations are likely to continue their precipitous decline that has been occurring for decades.

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