Date of Graduation

Summer 2020

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Day Ligon

Keywords

Macrochelys temminckii, reintroduction, detection, side-scan sonar, remote-sensing, habitat suitability

Subject Categories

Other Ecology and Evolutionary Biology | Research Methods in Life Sciences

Abstract

Reintroduction has been employed as a management strategy to combat population declines of the Alligator Snapping Turtle. The suitability of previous reintroduction sites was determined by researchers with years of experience in Alligator Snapping Turtle biology, following detection surveys and a visual habitat assessment. I developed methods that will facilitate the assessment of suitable release sites. First, I investigated the amount of effort needed to detect Alligator Snapping Turtles during surveys, then I compared methods to quantify submerged deadwood (a key habitat feature), and finally, I developed a standardized field survey and habitat suitability model that can be used to determine suitability of potential release sites. Following permutations, I determined that surveys for Alligator Snapping Turtles have a high risk of falsely concluding absence of small populations when survey effort is limited, and at least 100 net nights should be conducted to detect populations representing a catch-per-unit-effort of at least 0.02 turtles per net night. When quantifying deadwood density within long stretches rivers, sonar was found to be more useful compared to point-count methods because it provides the most exhaustive measure of deadwood. The accuracy of point counts was variable on a small scale, but the method may be viable following a transformation if sonar cannot be used. When using sonar, it may be beneficial to shorten processing time by sub-sampling sonar data. In which case, I recommend dividing sonar data into segments of 40 meters and counting pieces of deadwood within a random selection of segments comprising 40–60% of the river’s length. Finally, the use of raw field data in a habitat suitability model was an effective way to determine suitability of rivers for Alligator Snapping Turtles. Sonar-based scores correctly predicted the presence of suitability habitat at sites with current populations of Alligator Snapping Turtles and deadwood density and human disturbance were the main drivers in determining score. The application of the methods I developed will aid in the identification of future reintroduction sites, contributing to continued recovery of this declining turtle

Copyright

© Kameron C. Voves

Open Access

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