Integrating Ontogenetic Shift,Growth and Mortality to Determine a Species' Ecological Role from Isotopic Signatures |
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| Authors: | Nelson F Fontoura Lúcia R Rodrigues Cibele B Batista Tanilene S P Persch Mariola E Janowicz |
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| Institution: | 1Faculdade de Biociências; Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil;2Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil;3Department of Biology and Environmental Sciences, Concordia University College of Alberta, Edmonton, Alberta, Canada;University of Otago, NEW ZEALAND |
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| Abstract: | Understanding species linkages and energy transfer is a basic goal underlying any attempt at ecosystem analysis. Although the first food-web studies were based on gut contents of captured specimens, the assessment of stable isotopes, mainly δ13C and δ15N, has become a standard methodology for wide-range analyses in the last 30 years. Stable isotopes provide information on the trophic level of species, food-web length, and origin of organic matter ingested by consumers. In this study, we analyzed the ontogenetic variability of δ13C and δ15N obtained from samples of three Neotropical fish species: silver sardine (Lycengraulis grossidens, n=46), white lambari (Cyanocharax alburnus, n= 26), and the red-tail lambari (Astyanax fasciatus, n=23) in Pinguela Lagoon, southern Brazil. We developed a new metric, called the Weighted Isotopic Signature (φ 15N or φ 13C, ‰), that incorporates ontogenetic variability, body growth, and natural mortality into a single number. |
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