Isotopic niches of sympatric native and exotic fish species in a Neotropical floodplain.

Juliana S Philippsen,Evanilde Benedito,Marília Hauser

doi:10.1590/0001-3765201520140266

Juliana S Philippsen, Evanilde Benedito + Show 1 more

Open Access

https://doi.org/10.1590/0001-3765201520140266

Copy DOI

Abstract

This study investigated the isotopic niches of two fish species, one exotic and one native. It was hypothesized that these species would show little or no isotopic niche overlap. This hypothesis was tested with the isotopic niche concept and the trophic Layman's metrics. A considerable isotopic niche overlap was observed between the species, mainly for the exotic that showed the greater percentage of overlapping, indicating an interspecific competition for food resources. Layman's metrics also showed this species probably exploits a more specific array of food resources when compared with the native species. The native species probably has the ability to exploit a wider array of resources, highlighted by the higher values given for the Layman's metrics. The juveniles and adults of native species showed minor overlapping between the isotopic niches. This indicates that they have probably adopted different foraging strategies, minimizing intraspecific competition. Evidences that the exotic species explores a narrower range of resources and that the native species has a greater isotopic niche and possibly suffer less intraspecific competition, indicates that the native species can tolerate the presence of the exotic species and promote survival and maintenance of its population even under possible competition effects imposed by the exotic species.

Highlights

The introduction of a non-native species in an ecosystem has great potential for presenting ecological risks if it is able to establish its population in the environment successfully (Gozlan and Newton 2009), resulting in possible harmful relationships with native species (Gozlan et al 2010)
Considering the need for a comprehensive analysis on patterns of use and partitioning of food resources in order to clarify how exotic species interact with native species (Vitule et al 2012), this study aimed to characterize the isotopic niches of one exotic thraira Hoplias sp1 and one native thraira Hoplias sp2, fish species co-occurring in a Neotropical floodplain
Jackson et al (2012) suggest that there is an inverse relationship between the isotopic niche space occupied by one species and the degree of interspecific competition that it experiences

Summary

Introduction

The introduction of a non-native species in an ecosystem has great potential for presenting ecological risks if it is able to establish its population in the environment successfully (Gozlan and Newton 2009), resulting in possible harmful relationships with native species (Gozlan et al 2010). Non-native species have been introduced intentionally or not, through various human activities (Gozlan et al 2010).The coexistence and interactions between species have been investigated by means of the niche concepts postulated by Grinnell, Elton and Hutchinson (Newsome et al 2007, Colwell and Rangel 2009). PHILIPPSEN, MARÍLIA HAUSER and EVANILDE BENEDITO niche space (Bearhop et al 2004) and is of essential importance to understanding food web structure, resource use and trophic interactions in aquatic ecosystems (Chen et al 2011). These studies have practical applications when assessing possible impacts of exotic species on native species (Clarke et al 2005, Pound et al 2011)

Objectives

Methods

Results

Conclusion