Trophic niche overlap and abundance reveal potential impact of interspecific interactions on a reintroduced fish1

Document Type

Article

Publication Date

1-1-2021

Publication Title

Canadian Journal of Fisheries and Aquatic Sciences

Volume

78

Issue

6

First Page

765

Last Page

774

Abstract

Conceptually, trophic niche overlap and species abundance can describe the strength and number of interspecific trophic interactions to determine the competitive impact on reintroduced species or other ecosystem changes. We use an example with young-of-year (YOY) Atlantic salmon (Salmo salar) reintroductions to determine whether trophic niche overlaps and abundances limit restoration success. Using seasonal stable isotopes and abundance estimates for invertivorous fishes in three Lake Ontario tributaries, we assessed community isotopic structure, trophic niche overlap, and the impact of the niche overlap by incorporating relative abundance. Brown trout (Salmo trutta) YOY could be a strong competitor with a high trophic niche overlap with Atlantic salmon YOY, but at lower abundances relative to Atlantic salmon there is minimal impact. Stream resident fish communities appeared to partition resources across seasons such that abundant species had low trophic niche overlap to minimize overall competition with Atlantic salmon YOY given available resources, indicating niche complementarity. Through joint consideration of trophic overlap and abundance using our conceptual model, the competitive impact of community composition on a reintroduced species could be assessed.

DOI

10.1139/cjfas-2020-0204

ISSN

0706652X

E-ISSN

12057533

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