title: Integrating ontogenetic shift, growth and mortality to determine a species' ecological role from isotopic signatures.
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.
authors.affiliation: Faculdade de Biociências; Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Nelson F
authors.initials: NF
authors.lastname: Fontoura
authors.affiliation: Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Lúcia R
authors.initials: LR
authors.lastname: Rodrigues
authors.affiliation: Faculdade de Biociências; Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Cibele B
authors.initials: CB
authors.lastname: Batista
authors.affiliation: Faculdade de Biociências; Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Tanilene S P
authors.initials: TS
authors.lastname: Persch
authors.affiliation: Department of Biology and Environmental Sciences, Concordia University College of Alberta, Edmonton, Alberta, Canada.
authors.forename: Mariola E
authors.initials: ME
authors.lastname: Janowicz
mesh_terms: D000818:Animals; D044822:Biodiversity; D001938:Brazil; D017753:Ecosystem; D005399:Fishes; D008962:Models, Theoretical