Larval anurans follow predictions of stoichiometric theory: implications for nutrient storage in wetlands

Abstract

AbstractEcological stoichiometry provides a framework to predict how animals regulate nutritional balances within their tissue and, as a result, how animal biomass affects ecosystem processes through nutrient cycling. However, most interspecific and developmental stoichiometric studies in animals focus on invertebrates, and the few vertebrate studies are largely fish‐centric. Larval anurans are ideal vertebrates to test predictions of developmental and interspecific stoichiometry as they undergo a complex development, exhibit broad arrays of life‐history traits, and can constitute high animal biomass in wetlands, implying major roles in wetland nutrient storage and cycling. We examined (1) patterns of body stoichiometry across larval developmental stages within multiple anuran species, (2) whether key predictors of stoichiometric change, specifically body size, developmental period, and breeding season, influence interspecific stoichiometric variation, and (3) natural magnitudes and fluctuations of larval anuran nutrient storage in geographically isolated wetlands (GIWs). We measured carbon (C), nitrogen (N), and phosphorus (P) tissue content in larval anurans across five developmental stages within 11 species collected from four GIWs to examine patterns of developmental and interspecific stoichiometry. Within species, we found broad developmental stoichiometric patterns in which later developmental stages were lower in %N, but higher in %P than earlier stages. Patterns in %C were inconsistent but were generally lower in later stages, while tissue C:N ratios increased, and C:P and N:P decreased in later developmental stages. Interspecific stoichiometric variation was partially explained by body size and developmental period which positively affected %C and C:N ratios. We observed spatial and temporal fluctuations in species‐specific biomass which dictated nutrient storage patterns within larval anuran assemblages, though stoichiometric identity played a major role. Our estimated magnitudes of larval anuran areal nutrient storage also greatly exceeded that of other wetland fauna with the maximum estimated areal P storage reaching over 200 times that of a similar‐density co‐occurring invertebrate group. These results highlight stoichiometric patterns of development and interspecific variation in a diverse group of amphibians while providing critical baseline information for elucidating the role of anurans in wetland nutrient dynamics.