Aquatic food web of Zinav Lake

Stable isotope analysis was used to determine which basal sources are important in supporting native and invasive carp fishes in a dimictic-eutrophic lake (Zinav Lake, Turkey). Potential primary producers (littoral, pelagic sources and detritus), fish and macroinvertebrates were sampled from the coastal and pelagic zones of the lake during spring and summer 2013. The relative importance of basal resources assimilated by invasive (Carassius spp.) and native fishes (Squalius cephalus, Capoeta banarescui and Cyprinus carpio) was estimated using the SIAR mixing model. Forager-accumulator (1) (-35.33‰) and S. cephalus, Carassius spp. and consumers such as C. carpio had more ¹³C depletion (-32.12, -31.09, -31.54 ‰, respectively), while C. banarescui, forager-gatherer (2) etc. had more ¹³C enriched values (-25.03, -26.55 ‰, respectively). SIAR and gut contents showed that the main energy sources were highly variable among fish, with three main sources contributing to invasive fish, but coastal resources were more important for C. banarescui, pelagic resources and detritus for S. cephalus and pelagic resources for C. carpio. The biomass of the consumer was also partially linked to detritus. Our study revealed that all species promote the merging of pelagic and coastal zones and that competition for resources between invasive and native fish may lead to resource partitioning and shifts towards suboptimal resources.