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Title:Spatial ecology of the smooth softshell turtle (Apalone mutica) in the Kaskaskia River of Illinois
Author(s):Ross, Jason P.
Advisor(s):Dreslik, Michael J.
Department / Program:Natural Res & Env Sci
Discipline:Natural Resources and Environmental Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Abstract:River ecosystems have suffered widespread anthropogenic degradation that threatens their functionality, putting specialized river turtles at risk of population declines. The conservation of such populations requires knowledge of space use including movement rates, home range size, and habitat preference. Spatial ecological information is lacking for many river turtles including the Smooth Softshell Turtle (Apalone mutica), a species inhabiting the Midwestern United States. I investigated the spatial ecology of A. mutica in two reaches of the Kaskaskia River in south-central Illinois from 2013-2014. My objectives were to determine principal components of movement and variables influencing movement rate (m/day), the best estimate of home range size (ha) and variables influencing home range size, and habitat preference at varying spatial scales. I radio-equipped 40 A. mutica and collected location, environmental, and habitat data at every radio-location. Vagility was greater in the higher stream order, whereas sedentary behavior was similar in both stream orders. A mixed-effects model indicated movement rate increased with water temperature except at high temperatures. Movement rate decreased with Julian date and was higher in the larger stream order. Females increased movement during higher water levels. I determined that 95% kernel density estimates clipped to the river channel are the best estimate of home range size. A linear model indicated home range size increased with movement rate and the number of radio-locations and was larger in the higher stream order. I used compositional analysis to determine habitat preference of home range within the study area (2nd order) and radio-locations within the home range (3rd order). Habitat categories were bar, pool, bar-pool transition, run, and channelized. At a large spatial scale, A. mutica established home ranges in the main river channel near meander bends. Within home ranges, males preferred bars over all other habitats and females preferred pools. Mixed models indicated females used deeper waters than males, but neither sex showed an affinity for deadwood. Overall, there were clear sexual differences in habitat preference, but sexual differences in movement rate and home range size were less pronounced. Conservation efforts should focus on reducing effects of fragmentation, maintaining natural flow regimes and restoring river channels to their natural geomorphological state. These conservation actions will benefit A. mutica and increase biodiversity and connectivity of riverine ecosystems.
Issue Date:2016-04-11
Rights Information:Copyright 2016 Jason Patrick Ross
Date Available in IDEALS:2016-07-07
Date Deposited:2016-05

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