Sivrisinek Balığı (Gambusia Holbrooki)'nin Yerli Dişlisazancık Türleri Üzerindeki Etkisi: Taksonomik ve Tehlike Kategorileri Bağlamında Fonksiyonel Cevabın Kullanımı

Abstract

The global spread of invasive species, particularly in aquatic ecosystems, has been rapidly increasing. The records of the introduction of non-native fish species into natural freshwater ecosystems in Turkey date back more than 100 years, and one of the most common species is Gambusia holbrooki, which has been used for mosquito control. Due to its reproductive success and tolerance to different environmental conditions, this species has spread to almost all river basins in Turkey. Gambusia holbrooki may adversely affect native species, particularly trophic analogues which share the same habitat. In this regard, G. holbrooki has the potential to have serious individual and population-level effects on the endemic Aphaniidae, an endangered group of species in Turkey, but the extent of this interaction has not been well studied. This thesis aims to experimentally investigate this impact. The study utilizes functional response (FR) comparisons, which are defined as the predator’s consumption rate as a function of prey density. The research also tests whether phylogenetically closer species exhibit similar functional responses in terms of resource use efficiency and whether the FR curves of native killifish species, classified as endangered on the IUCN Red List, differ from those of species classified as of Least Concern. In experiments involving two Anatolichthys and two Paraphanius species, it was observed that G. holbrooki exhibited a higher attack rate but a longer prey handling time compared to native species. Contrary to expectations, no functional response similarity was found among closely related species. However, the study suggests that Paraphanius species may be more effective predators compared to Anatolichthys species. The functional response curves of species classified as endangered on the IUCN Red List were generally found to be lower than those of species classified as of Least Concern, although exceptions were observed.