Niche segregation of a newly introduced invasive and co-occurring native fish species in a productive shallow lake (Manyas, NW Anatolia)

Nildeniz Top-Karakuş,Ali Serhan Tarkan,Uğur Karakuş

doi:10.25225/jvb.21043

Abstract

The impacts of aquatic invasive species vary from the population to ecosystem level most strikingly through modifications to native communities, often leading to a decline in native species. A primary impact mechanism is competitive displacement of native by invasive species through resource partitioning. However, the trophic interactions between native and invasive species occupying the same habitat remain poorly understood, particularly at the early stages of invasion. This study used stable isotope analysis of two co-occurring populations of invasive topmouth gudgeon, Pseudorasbora parva and native Caucasian dwarf goby, Knipowitschia caucasica in a highly productive shallow lake to characterize overlap of potential trophic niches. The trophic niches of both species were divergent, with no overlap. Mixing models suggest some inter-specific dietary differences. The trophic niche of the Caucasian dwarf goby was slightly and non-significantly larger than that of topmouth gudgeon. These results suggest that when introduced outside of their natural range, topmouth gudgeon might integrate into new fish communities via the exploitation of resources that are underexploited by native fishes, which could also explain the high invasion success of the species.

Highlights

Introduction of non-native fish species is an important threat to native and to endemic species (Gozlan et al 2010) and is capable of affecting ecosystems directly or indirectly (Gaygusuz et al 2013, Copp et al 2017)
The results of the present study clearly indicated that there was no isotopic niche overlap between the Caucasian dwarf goby and topmouth gudgeon based on stable isotope analysis (Fig. 2)
Our sampling and observations have confirmed that both species were abundant in the lake and seemingly co-exist at a local scale, though no temporal data are available on their abundance. This finding should be considered as questionable due to the short lifespan of both species and as such might be expected to show an unstable population structure, i.e. fluctuations in abundance depending on environmental conditions (Didenko et al 2020)

Summary

Introduction

Introduction of non-native fish species is an important threat to native and to endemic species (Gozlan et al 2010) and is capable of affecting ecosystems directly or indirectly (Gaygusuz et al 2013, Copp et al 2017). One of the main ways for understanding the impact of nonnative fishes is from their trophic interactions with extant native species, such as through convergence or divergence in resource use (Copp et al 2017). These impacts have been reported across a range of families covering different feeding guilds (Crowl et al 1992, Martin et al 2010, Weber & Brown 2011). Niche partitioning has been observed in invasive species which enables their stable coexistence with other community members (Chesson 2000, Kylafis & Loreau 2011). When competition for resources is increased, expansion of trophic niches by invasive species can be observed (Svanbäck & Bolnick 2007)

Methods

Results

Conclusion