The effects of drying-induced trophic cascades on larval salamander development and wetland function

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Authors
Burkhead, Shania E. M.
Advisors
Luhring, Thomas M.
Issue Date
2024-05
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Thesis
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Abstract

Many studies have been conducted on the effects of active drying on amphibian development, however, not much is known on what carry-over effects there may be from previous drying events. Previous drying and density have an interaction effect, with density determining body size of anurans following a drying event. By combining factors of previous drying and densities of the larval salamander, Ambystoma texanum, we will attempt to identify how drought-induced trophic cascades affect the overall development of salamanders and wetland trophic structures. Using mesocosms, we combined 4 density treatments (10, 20, 40, and 80 individuals) with 2 drying treatments (Non-dried and Dried-Refilled) to create 8 treatment combinations (n=64). We recorded larval A. texanum vital rates (e.g., growth, development, survival), (2) odonate abundance and size and (3) gross primary productivity. Previous drying significantly increased survival of larval A. texanum due to the loss of top predators, with only one survivor in the non-dried mesocosms. In dried-refilled tanks, growth and development rate, time to metamorphosis, and size at metamorphosis were negatively correlated with density. Odonates (larval dragonflies) were much smaller following refill and less abundant. GPP was also lower following a refill, however, higher larval salamander densities accelerated GPP recovery and more quickly surpassed GPP of non-dry mesocosms due to top-down control of zooplankton. We found supporting evidence that drying and refilling leads to loss of top-level predators and increasingly strong density-dependent responses of vital rates. Our findings suggest that larval A. texanum require intermittent pools for successful reproduction, and that the carryover effects of drying are not the same for all amphibians. This study highlights the need to understand taxa-specific responses to previously dried pools.

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Thesis (M.S.)-- Wichita State University, College of Liberal Arts and Sciences, Dept. of Biological Sciences
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Wichita State University
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