Trophic niche differences between two congeneric goby species: evidence for ontogenetic diet shift and habitat use

Abstract

Food partitioning is one of the primary mechanisms facilitating the stable cooccurrence of competing species, but very few studies have investigated how food resource use of competing and closely related species varies with life-history stages and habitats. In Lake Erhai (China), the trophic niche of 2 congeneric and co-occurring invasive goby species (Rhinogobius cliffordpopei and R. giurinus) was examined to test the existence of an ontogenetic diet shift and to determine potential differences in trophic niche between species within a habitat and between habitats (i.e. littoral and profundal) within species. Results obtained from gut content and stable isotope analyses revealed a strong trophic niche shift during ontogeny, whereby juveniles mainly consumed macrozooplankton while sub-adults and adults increasingly consumed aquatic insects and Tubificidae. The trophic niche of juveniles was similar between species in each of the 2 habitats but significantly different for sub-adults and adults, notably in littoral habitat. Moreover, the trophic niche was similar between habitats for juveniles of each species, whereas it differed significantly between habitats for sub-adults and adults. This study demonstrates the importance of ontogeny and shows that habitat use can significantly affect food resource use and trophic relationships between 2 co-occurring fish species.KEY WORDS: Species co-occurrence · Niche differentiation · Ontogenetic niche shift · Stable isotope analyses · Rhinogobius · Gut content analysis Resale or republication not permitted without written consent of the publisher

Stable isotope signatures and trophic-step fractionation factors of fish tissues collected as non-lethal surrogates of dorsal muscle

“…By contrast, the application of stable isotope data from focal fish species and their putative food resources to Bayesian mixing models tends to use relatively small sample sizes to predict diet composition . This approach has a higher resolution and can, for example, indicate important dietary differences between species, locations and seasons . The models are based on isotopic fractionation factors and so require accurate estimates of diet‐tissue fractionation .…”

Spatiotemporal ecology of juvenile Muskellunge (Esox masquinongy) and Northern Pike (Esox lucius) in upper St. Lawrence River nursery bays during their inaugural fall and winter

“…To this end, fisheries managers may wish to work with riparian landowners to appropriately manage canopy‐forming SAV and mitigate its loss when juvenile fish are experiencing ontogenetic changes, which are known to play a crucial role in habitat segregation and existence of sympatry between juveniles and adult fish (e.g. Rhinogobius spp; Guo et al, ; Sone, Inoue, & Yanagisawa, ). Considering subadult Muskellunge are rarely observed, despite significant sampling effort (J. M. Farrell, personal communications), it is clear that spatiotemporal research on juvenile Muskellunge throughout the Great Lakes basin is a critical, yet understudied link.…”

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“…The high portion of such low-energy foods in diets of these fish taxa may be indicative for a competition induced niche shift to suboptimal food sources (Didenko&Kruzhylina, 2015). Specialization in habitat resources and food partitioning is one of the primary mechanism to reduce interspecific competition, and facilitate the co-occurrence of related species (Guo et al, 2014). Increased competition for resources among invasive and native fishes could cause to shift to suboptimal resources in order to meet energy requirements.…”