Untitled

Abstract

Several Ponto-Caspian gobiids have expanded from their native distribution ranges to Europe and North America. As knowledge on their bio-ecological features in their native range is still limited, the trophic ecology of monkey goby Neogobius fluviatilis and Western tubenose goby Proterorhinus semilunaris was studied in three natural lakes in the Marmara Region of NW Turkey using the stable isotopes of δ 13 C and δ 15 N. In two of the lakes, the trophic niches (as the isotopic niche) of the gobies were highly divergent with co-existing native fishes, with no overlap. Moreover, mixing models suggests considerable inter-specific dietary differences. In all lakes, the trophic niches of gobies were never significantly larger than those of coexisting fishes. These results suggest that when introduced outside of their natural range, the gobies might integrate into new fish communities via exploiting resources that are underexploited by native fishes or will initially share resources with these species before their niches diverge, perhaps through competitive displacement.

When alien catfish meet—Resource overlap between the North American Ictalurus punctatus and immature European Silurus glanis in the Arno River (Italy)

“…Hence, neither dietary similarity between groups estimated with the overlap of SEAc, SEAb, nor percentual isotopic niche overlap reflected the results gained from direct dietary information. Analyses of diets are very focused and dependable on observable ingested items that can be affected by activity times or responses of species to being caught, while isotope analyses consider previously consumed and assimilated prey, thus a considerably longer time (Tarkan et al, 2018). Additionally, all three groups belong to approximately the same estimated trophic position as expected from I. punctatus and S. glanis (Gido & Franssen, 2007;Syväranta et al, 2010), but "S. glanis" had a slightly wider δ 13 C range than the two life stages of I. punctatus.…”

“…According to the competitive exclusion principle (Hardin, 1960), coexistence can only be possible if utilised resources and occupied dimensions (activity time, habitat use) are different (Chase & Leibold, 2003;Schoener, 1986). Studies investigating dietary and, thus, dietary niche partitioning mostly focused on either mature life stages (Schulze, Dörner, Baade, & Hölker, 2012;Zaia Alves et al, 2017) or ontogenetic variations (Davis, Blanchette, Pusey, Jardine, & Pearson, 2012;Tarkan et al, 2018). However, immature life stages in catfish species can dominate an ecosystem and have a considerable impact on other species as well as the potential to become a target to manifold interaction with other species (Alp, Kara, & Büyükçapar, 2004;Alp, Kara, Üçkardeş, Carol, & García-Berthou, 2011;Elrod, 1974;Persson, 1988).…”

Bio-Ecological Traits of Western Tubenose Goby Proterorhinus semilunaris (Heckel, 1837): A Key to Understand Its Invasion Success

“…The studies on the diet of P. semilunaris [7,10,33,34] recorded that the species is a benthic omnivore, consuming a wide variety of benthic invertebrates (dipterans, ephemeropterans, crustaceans, copepods, ostracods, molluscs, and trichopterans), plants, and occasionally larval fishes. The results of the present study have proved that P. semilunaris has a wide food spectrum; however, Diptera larvae, which are a very common group of zoobenthos, are the most important food item in the diet of P. semilunaris as a food generalist.…”

“…The results of the present study are similar to the results of the studies [7,39] conducted in the non-native distribution range of P. semilunaris (Danube River and Mušov Reservoir); Diptera (mostly chironomids) larvae/pupae are the most dominant food items in the diet of the species. Tarkan et al [10,38] mentioned that this fish has generalist and highly flexible feeding strategies, and would have relatively large trophic niche sizes, with trophic overlap with other native species that indicate high potential for competitive interactions.…”

“…Proterorhinus semilunaris is one of the native gobiid species in the fish fauna of Turkish inland waters [1]. Only a few studies have recently been carried out in Turkish part of its native range to fill the gap in knowledge on its bio-ecology, including the length-weight relationship, diel activity, trophic ecology, age structure, somatic growth, and reproductive characteristics of the species [8][9][10][11].…”