Project Report

Microhabitat Use Differences among Life Stages of the Japanese Giant Salamander William Bradley Sutton Current Address: Department of Forestry, Wildlife, and Fisheries The University of Tennessee Knoxville, TN 37996 The major focus of this research was to determine microhabitat use patterns among larval, juvenile, and adult Japanese Giant Salamanders (Andrias japonicus) within the Ikuridani River, Hiroshima Prefecture. Increasing evidence of worldwide amphibian declines has made it necessary to evaluate basic life history requirements for many amphibian species Data from this study are important because they represent the first examination of habitat use for A. japonicus, which will provide essential data for developing informed conservation plans. Andrias japonicus is one of the largest amphibian species in the world, and due to its endemicity, it is a species of high conservation concern (IUCN status: Near Threatened). I completed this research at Tottori University located in Tottori Prefecture, Japan. Drs. Nobuo Tsurusaki and Sumio Okada served as host researchers during this project period. This research location was chosen as a means to collaborate with Dr. Okada, who is one of the world’s leading experts on A. japonicus biology. Additional research collaborators included Dr. Zach Felix, who is currently an assistant professor of Biology at Reinhardt University. I used radiotelemetry to monitor short-term movement and microhabitat site selection of A. japonicus. I captured salamanders by turning over cover objects and completing night surveys within the stream area. After recording size-class data (i.e., total length, snout-vent length, and mass) I attached a transmitter (Holohil systems, ltd.) externally to the middle portion of the tail of each study animal. I recorded salamander locations daily and compared habitat (i.e., rock substrate percent cover, space availability, distance to streambank, rock size class, and rock embededness) and stream (i.e., velocity [m/s], temperature [°C], pH, depth [cm] and dissolved oxygen) features at used and randomly determined locations. I completed a maximum of three microhabitat plots for each salamander, and used a multivariate data analysis approach to compare overall microhabitat differences between used and random sites. I radiotracked 20 total salamanders (7 adults [4 males and 3 females], 6 juveniles, and 7 larvae) and completed 72 total habitat plots during this research. Overall, I found that each salamander size class selected used sites differently than random locations, and adult salamanders selected different microhabitat features compared to juvenile and larval salamanders. Specifically, adult salamanders used sites with greater percent boulder cover (> 25.0 cm) and greater space availability, whereas juvenile and larval salamanders selected sites closer to the streambank possessing greater cobble cover (6.5 – 25.0 cm) and shallower water. My research findings represent the first comparison of microhabitat use patterns among different life stages of aquatic salamanders. I was also able to evaluate the success of using external transmitter attachment methods for monitoring large aquatic salamanders. This method of transmitter attachment is essential when surgical transmitter implantation is not feasible. Most importantly, this research will lead to a greater understanding of essential habitat features for A. japonicus. My future research directions include developing a research lab focused on evaluating wildlife responses to anthropogenic disturbances. Specifically, I plan to develop research that will evaluate the impacts of landscape and streamside disturbances on Hellbender Salamanders (Cryptobranchus alleganiensis), which are large, fully aquatic salamanders native to the United States, closely related to A. japonicus.

National Science Foundation (NSF)
Office of International and Integrative Activities (IIA)
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Carter Kimsey
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Sutton William B
United States
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