Food webs of the Paraná River floodplain: assessing basal sources using stable carbon and nitrogen isotopes

MARCHESE M.R. , ; SAIGO M., ; ZILLI F.L.; CAPELLO S.; DEVERCELLI, M.; MONTALTO, M.; PAPORELLO DE AMSLER, G.; WANTZEN, K.M.

LIMNOLOGICA

ELSEVIER GMBH

Año: 2014 vol. 46 p. 22 - 30

0075-9511

Foodwebs in floodplain ecosystems may be based on a variety of aquatic, terrestrial or amphibious food sources. Studying isotopic composition of C and N (¦Ä13C and ¦Ä15N) of potential food sources in the Paran¨¢ floodplain, Argentina, we hypothesized that C3 macrophytes would be the most important sources for herbivorous and biofilms for detritivores. To estimate the contribution of different sources of carbon to consumers, we measured the stable isotopic compositions of bottom sediment organic matter, coarse particulate organic matter, biofilm, suspended particulate organic matter, epiphyton, phytoplankton, C3 and C4 macrophytes and riparian tree leaves, benthic macroinvertebrates, aquatic orthopterans and fishes in dry and flooding seasons. The package Stable Isotope Analysis in R and the Stable Isotope Bayesian Ellipses algorhythm in R were calculated to compare the C and N isotopic variability between the primary consumers and their sources. The energy sources available for benthic organisms mainly originated from autochthonous sources based on the C3 photosynthesis pathway. The mollusk Pomacea canaliculata and the orthopteran Cornops aquaticum proved to be an adequate baseline for primary production pathways, whereas the oligochaetes and the fish Prochilodus lineatus were shown to be an adequate baseline for detritivore foodwebs.