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

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.

Stable isotopes reveal niche segregation between native and non‐native Hoplias in a Neotropical floodplain

“…Contrasting results were found by Philippsen et al (2015) while studying the isotopic niche of the same Hoplias species in the same floodplain, showing high isotopic niche overlap between them. One explanation might be related to environmental conditions since their study was conducted during the high-water season, which implies in a greater availability of food from terrestrial energy sources, and the homogenisation of resource supply (e.g.…”

“…In the past few years, studies using an isotopic approach to assess trophic relationships between native and non-native species have demonstrated different outcomes, with a low, moderate and/or high degree of trophic niche overlap between the species (Alves, Figueiredo, et al, 2017;Córdova-Tapia, Contreras, & Zambrano, 2015;Haubrock, Azzini, Balzani, Inghilesi, & Tricarico, 2019;Mercado-Silva, Helmus, & Vander Zanden, 2009;Monroy, Maceda-Veiga, Caiola, & Sestoa, 2014;Pacioglu, Zubrod, Schulz, Jones, & Pârvulescu, 2019;Philippsen et al, 2015). Here, we found evidence of divergence in food resource use between native and non-native Hoplias species in the Upper Paraná River floodplain, supporting the prediction that they assimilate distinct energy sources and occupy different trophic positions in the food web.…”

Feeding interaction of exotic Oreochromis niloticus (Linnaeus, 1758) versus native Coptodon rendalli (Boulenger, 1896) in the upper Kabompo River, northwest of Zambia.

“…In certain cases, native species can also be affected indirectly by exotic species. For example, in the northern most of North America where exotic Lake trout is generalist feeder and overlapping the natural distribution of the native Arctic charr through dietary competition, this seems to have displaced the native species from several habitats (Ke et al, 2008;Kırankaya & Ekmekçi, 2013;Philippsen et al, 2015). Such negative impacts on the population of native species may become more common if other effects such as climate change and other anthropogenic activates that may limit availability of food resources (Agostinho et al, 2015;Figueredo & Giani, 2005;Scheffer et al, 2006;Zengeya et al, 2015).…”