Abstract:
The role of consumers in aquatic ecosystems has gained substantial recognition due to their potential contributions to ecosystem processes such as decomposition, primary production, and nutrient availability. Our understanding of consumer roles in these processes has been heavily influenced by the development of ecological stoichiometry as a framework for studying consumer-driven nutrient dynamics. The effects of consumer-driven nutrient dynamics result from complex food web and environmental interactions as well as consumer life history traits. My study sought to determine how larval anuran (tadpole) tissue stoichiometry varies across developmental stages, and whether this variation drives patterns of excretion and egestion as predicted by ecological stoichiometry. I also examined how developmental traits and variation in larval anuran community biomass drives variation in areal excretion and egestion at the wetland scale. GIWs dry down seasonally, and are particularly important breeding habitats for many species of invertebrates and amphibians due to the (general) lack of fish predators. Anurans are a particularly interesting species group to study in GIWs given their potentially high density and diversity, as well as their developmental cycle from aquatic larvae, through metamorphosis, to terrestrial juvenile and adult frogs. A major component of the metamorphic process in larval anurans is the development of bones, which are rich in phosphorus. I found that across developmental stages, the body phosphorus content of larval anurans increased significantly during times in which bone was being developed. Excretion and egestion by larvae were also strongly linked to developmental stage (i.e. changing tissue stoichiometry) as predicted by ecological stoichiometry. This suggests that nutrient dynamics at the wetland scale may be influenced by the developmental demands in individual larvae. I found that production of the larval anurans was driven by temperature and resource quality and that these factors, as well as tissue nutrient stoichiometry explained the patterns in excretion and egestion by larval anurans throughout development. Lastly, I found that combined effects of species presence (influencing total anuran biomass) and development (influencing storage stoichiometry) played the most important roles in driving patterns in storage, excretion and egestion by the anuran community during larval development.
