Investigating the impacts of drought-related drying events following pond refill on the growth, survival, and postmetamorphic fitness of lithobates blairi tadpoles
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Abstract
The incomplete recovery following drying events can have long-lasting impacts on aquatic ecosystems through altered resource availability, changes to water quality and temperature, microhabitat suitability, and community structure. Dynamic impacts of drying events can have detrimental effects on numerous aquatic organisms, but amphibians are particularly susceptible due to their reliance on aquatic environments for reproduction. This study aims to understand how drying events affect amphibian larval communities that recolonize a pond post-refill by investigating the impacts of incomplete recovery on their growth and development. While similar studies have investigated larval amphibian responses to active drying, few have directly assessed the carryover effects of drying events on organisms that recolonize a previously dried pond. Using a 64-mesocosm array, we examined the effects of drying (non-dry vs. dry-rewet) and tadpole density (10, 20, 40, or 80 individuals per tank) on larval amphibian growth, development, and survivorship. We hypothesized that drying and rewetting would decrease growth and development of tadpoles by reducing food resources, and that high larval densities would decrease growth and development through competition. Our results demonstrate strong effects of past drying on larval amphibian growth, time to metamorphosis, and survivorship. Additionally, we observed carryover effects of larval treatments on juvenile jumping performance, which was influenced by body mass at metamorphosis. Larger juveniles were found to jump further distances on average than smaller individuals, which has implications for the terrestrial fitness of these organisms, including predator evasion, foraging, and mating success. These findings emphasize the importance of drying events for amphibian survivorship and developmental plasticity, and that larval history can determine post-metamorphic fitness.