Ontogenetic Diet Shift of Invasive Gibel Carp (Carassius gibelio, Bloch 1782) in Karamenderes River (Turkey)

Abstract

The ontogenetic diet shift of invasive Carassius gibelio (Bloch, 1782) was investigated in Karamenderes River, Turkey. The fieldwork was performed during summer 2012, autumn 2012 and spring 2013. The fishes were caught by electrofishing and using gill nets. Nine fork length groups were used in order to assess the ontogenetic diet shift. The gut contents were assessed by the index of relative importance that was calculated from the frequency of occurrence, numerical abundance, and volumetric analyses. The most abundant length groups of C. gibelio were 18-20 cm, 6-8 cm, and 27-29 cm length groups during summer 2012, autumn 2012 and spring 2013, respectively. The feeding intensity was the lowest in the length groups of 15-17 cm during summer 2012, in 3-5 cm length group in autumn 2012 and in 24-26 cm length group in spring. Seasonal variations were observed in the ontogenetic diet shift of C. gibelio. Large specimens consumed more animal materials during summer and more algae in autumn. There was not any significant niche overlap recorded between small and large specimens except summer. Any niche overlap between small and large specimens might be advantageous for the establishment success of invasive Gibel carp in Karamenderes River.

Inter - and intraspecific phenotypic variation in co-occurring invasive and introduced cyprinid fish species

“…Both the gibel carp and common carp are generalist omnivores, and they particularly consume larger zooplankton and benthic invertebrates (such as Cladocerans, Copepods, Ostracods, Dipterans, etc.) in lakes and reservoirs ( Balık et al, 2003 , Gül et al, 2010 ), and algae, detritus, and small invertebrates in rivers ( Partal and Özdilek, 2019 , Imran et al, 2021 ). Habitat-dependent differences in food preferences can influence operculum and eye size, consequently affecting head width.…”