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Meta-analysis of stable carbon and nitrogen isotopic enrichment factors for aquatic animals.

GUO Liang, SUN Cui-ping, REN Wei-zheng, ZHANG Jian, TANG Jian-jun, HU Liang-liang*, CHEN Xin   

  1. (College of Life Sciences, Zhejiang University, Hangzhou 310058, China).
  • Online:2016-02-18 Published:2016-02-18

Abstract: Isotopic enrichment factor (Δ, the difference between the δ value of food and a consumer tissue) is an important parameter in using stable isotope analysis (SIA) to reconstruct diets, characterize trophic relationships, elucidate patterns of resource allocation, and construct food webs. Isotopic enrichment factor has been considered as a constancy value across a broad range of animals. However, recent studies showed that the isotopic enrichment factor differed among various types of animals although the magnitude of variation was not clear. Here, we conducted a metaanalysis to synthesize and compare Δ13C and Δ15N among four types of aquatic animals (teleosts, crustaceans, reptiles and molluscs). We searched for papers published before 2014 on Web of Science  and CNKI  using the key words “stable isotope or isotopic fractionation or fractionation factor or isotopic enrichment or trophic enrichment”. Fortytwo publications that contain 140 studies on Δ13C and 159 studies on Δ15N were obtained. We conducted three parallel metaanalyses by using three types of weights (the reciprocal of variance as weights, the sample size as weights, and equal weights). The results showed that no significant difference in Δ13C among different animal types (teleosts 1.0‰, crustaceans 1.3‰, reptiles 0.5‰, and molluscs 1.5‰), while Δ15N values were significantly different (teleosts 2.4‰, crustaceans 3.6‰, reptiles 1.0‰ and molluscs 2.5‰).Our results suggested that the overall mean of Δ13C could be used as a general enrichment factor, but Δ15N should be chosen according to the type of aquatic animals in using SIA to analyze trophic relationships, patterns of resource allocation and food webs.