Differences in 13C and 15N stable isotopes in the pearly razorfish Xyrichtys novacula related to the sex, location and spawning period
In the present study, Xyrichtys novacula (Labridae) were sampled at five locations around the islands of Ibiza and Formentera (western Mediterranean Sea). Isotopic signatures of 13C, 15N and the C:N ratio were analysed in relation to locality, sex and size differences. 13C and 15N partitioning was also studied in the reproductive spawning period. There were significant differences in the 13C signature between localities for both sexes, but not for 15N. Sex differences were also found with a mean ±s.e. value of −17·38 ± 0·06‰13C and 8·36 ± 0·05‰15N for females and −17·17 ± 0·07‰13C and 8·80 ± 0·06‰15N for males. Increasing total length in both sexes was positively correlated with 15N enrichment and a significant positive linear regression was established for both variables. During the reproductive spawning period, there were changes in 13C fractioning with enrichment in postspawning females and males (with respect to prespawning and spawning periods) and 15N impoverishment in postspawning females (with respect to prespawning and spawning periods). Xyrichtys novacula uses local food sources, as confirmed by 13C and 15N, and females and males use different food sources, thus avoiding intraspecific competition. This was confirmed by 15N enrichment as size increased. Spawning leads to special requirements for gonad maturation, which is reflected in the isotopic signatures for both sexes.
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Document Type: Regular Paper
Laboratorio de Biología Marina, Universidad de las Islas Baleares, Ctra Valldemossa Km 7.5, CP 07122, Balearic Islands, Spain
Direcció General de Pesca, Govern de les Illes Balears, C/ Foners 10, 07006, Palma, Balearic Islands, Spain
Publication date: 2010-06-01