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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Record number 401661
Title Intra-lake stable isotope ratio variation in selected fish species and their possible carbon sources in Lake Kyoga (Uganda): implications for aquatic food web studies
Author(s) Mbabazi, D.; Makanga, B.; Orach-Meza, F.; Hecky, R.E.; Balirwa, J.S.; Ogutu-Ohwayo, R.; Verburg, P.H.; Chapman, L.; Muhumuza, E.
Source African Journal of Ecology 48 (2010)3. - ISSN 0141-6707 - p. 667 - 675.
Department(s) Land Dynamics
Publication type Refereed Article in a scientific journal
Publication year 2010
Keyword(s) trophic structure - east-africa - mwanza gulf - nitrogen - diet - delta-n-15 - victoria - ecosystem - specialization - delta-c-13
Abstract The stable isotopes of nitrogen (delta 15N) and carbon (delta 13C) provide powerful tools for quantifying trophic relationships and carbon flow to consumers in food webs; however, the isotopic signatures of organisms vary within a lake. Assessment of carbon and nitrogen isotopic signatures in a suite of plants, invertebrates, and fishes in Lake Kyoga, indicated significant variation between two sites for delta 13C (paired t = 6.305; df = 14, P <0.001 and delta 15N paired t = 1.292; df = 14; P <0.05). The fish fauna in Bukungu was generally more 13C enriched (mean delta 13C = -16.37 +/- 1.64 parts per thousand) than in Iyingo (mean delta 13C = -20.80 +/- 2.41 parts per thousand) but more delta 15N depleted (mean delta 15N = 5.57 +/- 0.71 parts per thousand) than in Iyingo (mean delta 15N = 6.92 +/- 0.83 parts per thousand). The simultaneous shifts in phytoplankton and consumer signatures confirmed phytoplankton as the major source of carbon for the food chain leading to fish. Limited sampling coverage within lakes may affect lake wide stable isotope signatures, and the same error is transferred into trophic position estimation. Consideration of potential intra-lake spatial variability in isotope ratios and size is essential in evaluating the spatial and trophic structure of fish assemblages.Resume Les isotopes stables d'azote (delta 15N) et de carbone (delta 13C) sont des outils interessants pour quantifier les relations trophiques et le flux de carbone vers les consommateurs de chaines alimentaires; cependant, la signature isotopique des organismes varie au sein d'un meme lac. L'evaluation des signatures isotopiques du carbone et de l'azote dans une suite de plantes, d'invertebres et de poissons du lac Kyoga indiquait une variation significative entre deux sites pour delta 13C (test t apparie = 6.305; df = 14; P <0.05). La faune piscicole de Bukungu etait generalement plus enrichie en delta 13C (moyenne de delta 13C = -16.37 +/- 1.64 parts per thousand) qu'a Iyingo (moyenne de delta 13C = -20.80 +/- 2.41 parts per thousand) mais plus depourvue de delta 15N (moyenne de delta 15N = 5.57 +/- 0.71 parts per thousand) qu'Inyingo (moyenne de delta 15N = 6.92 +/- 0.83 parts per thousand). Les glissements simultanes des signatures du phytoplancton et des consommateurs confirmaient que le phytoplancton est la source principale de carbone de la chaine alimentaire qui aboutit aux poissons. Une couverture limitee de l'echantillonnage dans les lacs peut affecter la signature des isotopes stables de tout le lac, et cette meme erreur est reportee dans l'estimation de la situation trophique. Il est essentiel de tenir compte de la variabilite spatiale possible des taux et de la taille des isotopes dans les lacs lorsque l'on evalue la structure spatiale et trophique des assemblages de poissons.
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