Understanding variation in salamander ionomes: A nutrient balance approach

• Published in: Freshwater biology Vol. 64; no. 2
• Main Authors: Prater, Clay, Scott, David E., Lance, Stacey L., Nunziata, Schyler O., Sherman, Ryan, Tomczyk, Nathan, Capps, Krista A., Jeyasingh, Punidan D.
• Format: Journal Article
• Language: English
• Published: United States Wiley 10.12.2018
• Subjects: ambystoma; amphibians; BASIC BIOLOGICAL SCIENCES; ecological stoichiometry; ionomics; ontogeny
• ISSN: 0046-5070; 1365-2427

1. Ecological stoichiometry uses information on three key elements (C, N, and P), which are abundant in biomass to explain ecological patterns. Comparatively less is known however about dynamics of the other essential elements comprising biological tissues (i.e., the ionome) or their roles in growth and development of vertebrate consumers, especially ecologically sensitive taxa such as amphibians. 2. In this paper, we report observations of ionomic variation in two species of salamander (Ambystoma opacum and A. talpoideum) across ontogenic stages using specimens from biological collections from two wetlands sampled over a 30-year period. This unique data set allowed us to explore the extent of ionomic variation between species and through space and time. 3. We found species- and to a lesser extent site-specific differences in traditionally studied stoichiometric elements along with 13 other elements forming salamander ionomes but saw no evidence of temporal changes. Salamander ionomic composition was most strongly related to ontogeny with relatively higher concentrations of many elements in adult males (i.e., Ca, P, S, Mg, Zn, and Cu) compared to metamorphic juveniles, which had greater amounts of C, Fe, and Mn. 4. In addition to patterns in individual elements, covariance among elements was used to construct multi-elemental nutrient balances, which revealed differences in salamander elemental composition between species and sites and showed systematic changes in elemental proportions across ontogenic development. These multi-elemental balances along with traditional stoichiometric balances also better distinguished among species-site-ontogenic groups than stoichiometric balances only. 5. Overall, this study highlights the responsiveness of consumer ionomes to life-history and environmental variation, while reflecting underlying relationships among elements tied to biological function. As such, ionomic studies can provide important insights into factors shaping consumer elemental composition and for predicting how these changes might affect higher-order ecological processes.