Divergence in energy sources for Prochilodus lineatus (Characiformes: Prochilodontidae) in Neotropical floodplains

Evanilde Benedito,Martin Werth,Ana Rute A Santana

doi:10.1590/1982-0224-20160130

Evanilde Benedito, Martin Werth + Show 1 more

Open Access

https://doi.org/10.1590/1982-0224-20160130

Copy DOI

Abstract

ABSTRACT The stable carbon isotopic variability and the contributions of autochthonous (sediment microbial biomass, phytoplankton, and periphyton) and allochthonous (soil microbial biomass) sources available to the detritivorous fish Prochilodus lineatus were investigated in three environments of the floodplain of the Upper Paraná River. The isotopic composition of carbon sources and fish varied significantly among the studied environments. The autochthonous resources, represented by the phytoplankton, were the most assimilated by the species, followed by periphyton and sediment microbial biomass. The species used the sources differently in each environment. This study suggests that the inherent characteristics of this area, as well as the size of the watershed, the dry season, anthropogenic actions, and phytoplankton productivity, favor the use of autochthonous resources by the species studied. Therefore, studies in the floodplain should employ an eco-hydrological approach that quantifies the magnitude of energy subsidies, as well as an access route to consumers, knowledge about the selectivity of detritivorous species and the effects of different land uses.

Highlights

Freshwater aquatic food chains are maintained by autochthonous sources of detritus, derived from phytoplankton, periphyton, sediment, macrophytes, and microorganisms, as well as by allochthonous sources (Cole et al, 2011)
The values of the isotope ratios were expressed in delta notation (d) and in parts per thousand (‰) (Bond, Hobson, 2012) relative to the international standard Viena Pee Dee Belemnite (VPDB)
All biological material prepared was sent to the UC Davis Stable Isotope Facility, USA, for analysis of δ13C (‰) in the isotope ratio mass spectrometer (PDZ Europa ANCA-GSL, Sercon Ltd., Cheshire, UK), according to the expression: d13C = [(Rsample/Rstandard) -1] x 103 where: R = carbon isotope ratios = 13C/12C For the microbial biomass carbon (C) an extraction coefficient (KEC) of 0.45 was used (Wu et al, 1990)

Summary

Introduction

Freshwater aquatic food chains are maintained by autochthonous sources of detritus, derived from phytoplankton, periphyton, sediment, macrophytes, and microorganisms, as well as by allochthonous sources (i.e., material originating from terrestrial vegetation) (Cole et al, 2011). It has been assumed that autochthonous carbon is responsible for the maintenance of aquatic consumers, especially carbon derived from the phytoplankton. Studies on feeding interactions have reported the relevance of bacteria due to their importance in the transformation of matter and energy (Torsvik et al, 1996), being responsible for much of the energy flow in ecosystems (Wagener et al, 1998). Due to constant interaction between aquatic and terrestrial systems, these resources are essential in floodplains (Winemiller et al, 2010). Many fish species of wetland areas have adaptive features that facilitate the exploitation of resources during seasonal flood pulses, allowing e160130[1]

Methods

Results

Conclusion