Bafra Balık Gölleri'nde (Balık Gölü ve Uzungöl) Yaşayan Bazı Balık Türlerinin Trofik Seviyesinin Belirlenmesi

Abstract

This thesis study focus on Balık Lake and UzunGöl and carried out between date of September 2015 and September 2016, it was aimed to determine the trophic level of 5 fish species (Cyprinus carpio, Carassius gibelio, Vimba vimba, Sander lucioperca ve Gambusia holbrooki). In this context, stomach contents of all individuals were examined and numerical, volume and frequency values were calculated. Along with that, some of the samples were selected from the individuals belonging to the species hunted from the lakes were analyzed statistically and biologically by performing a stable nitrogen isotope(δ15N) analysis in muscle tissue. In addition, some physical and chemical properties of Balık Lake and Uzungöl’s lake water were measured in place. In addition, growth characteristics such as age distribution, age-length, age-weight, length-weight relationship, condition factor and sex ratio were determined. As a result of this study, it has been determined that the lake waters obtained from the physical and chemical measurements provides a suitable environment for the fishes to carry on their vital activities. As a result of this research, it was determined that the growth characteristics of C. carpio, C. gibelio, V. vimba, S. lucioperca and G. holbrooki living in Balık Lake and Uzungöl were in expected values in normal fish populations. According to the results obtained from stomach contents, C. carpio and C. gibelio were fed through similar foods and predominantly plankton. According to this data, C. gibelio was found to be in food competition with C. carpio. V. vimba preferred more animal nutrients than the other two omnivorous species. Individuals belonging to S. lucioperca were fed on fish in general, whereas those belonging to G. holbrooki were predominantly fed on aquatic insects. When the stable nitrogen isotope (δ15N) values obtained from muscular tissues of fish are examined, it is determined that the highest mean value belongs to G. holbrooki with 11.5 ‰ and C. gibelio with the lowest value of 6.5‰. In this study, the data obtained from analyzes of stomach contents and the stable nitrogen isotope values obtained from muscles of fishes were evaluated together and the trophic level of 5 fish species living in Balık Lake and Uzungöl was determined. According to the obtained data, it was determined that trophic level of C. carpio and C. gibelio species living in Balık Lake and Uzungöl was at the lowest level, V. vimba and S. lucioperca species were at the upper level and G. holbrooki was at the top level of trophic level.