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Öğe Acoustic effects of underwater drilling and piling noise on growth and physiological response of Nile tilapia (Oreochromis niloticus)(Wiley, 2020) Kusku, Halit; Yigit, Umut; Yılmaz, Sevdan; Yigit, Murat; Ergün, SebahattinHuman-generated noises are considered as underwater sound pollution with potential short- or long-term impacts on behavioural responses and physiological reaction of aquatic living organisms. Few investigations are available so far on long-term influences of impulsive and continuous sound sources on physiological response of fish. In the present study, opercula beat rates and pectoral wing rates were monitored as a physiological stress response of ventilation in Nile tilapia (Oreochromis niloticus) exposed to long-term repeated and continued sounds generated from underwater construction work. Fish responded to underwater sound treatment with significantly increased opercula beat-and pectoral wing movements. Maximum ventilation rate was observed as a startle response of fish at initial exposure to underwater sound. The ventilation rates remained at high levels over the first 4 weeks and showed a declining trend thereafter. Fish growth was almost stable for the first 4 weeks, but shifted forward from day 45 onwards. We found strong evidence that fish could attune to repeated playbacks of underwater noise exposures since we found higher specific growth rates for the sound exposed fish from day 45 onwards until day 120, a so-called 'catch-up growth endeavour'.Öğe Bio-economic efficiency of copper alloy mesh technology in offshore cage systems for sustainable aquaculture(Natl Inst Science Communication-Niscair, 2017) Yigit, Umut; Ergün, Sebahattin; Bulut, Musa; Celikkol, Barbaros; Yigit, MuratIn the present study, innovative and environment friendly copper alloy mesh material was used in an offshore cage system to compare with traditional nylon nets, in a one-year grow-out cycle of European seabass (Dicentrarchuslabrax). Based on combined indicators such as growth performance, feed utilization with bio-economic assessment of initial investment costs, it was observed that copper alloy mesh performed higher productivity indices and economic benefits compared to those in the antifouling coated traditional nylon net pens. Results showed that copper alloy mesh is a promising alternative material that could be used in offshore cage aquaculture with an improved economic return.Öğe Biofouling Control of Invasive Zebra Mussel (Dreissena polymorpha) Using Acoustic Energy(Hard, 2022) Kusku, Halit; Yigit, Murat; Yılmaz, Sevdan; Yigit, Umut; Ergün, SebahattinEffects of increasing levels of audible sound energy (500, 1000, 5000 Hz frequency) on attachment strength and mortality rates of zebra mussels were investigated in a long-term study for the control and deterrence of zebra mussel infestation. All groups exposed to sound treatments presented weight loss by 1.09, 1.44 and 2.07% in the 500 Hz, 1.000 Hz, and 5.000 Hz frequency groups, respectively, while mussels receiving no sound showed an increasing trend in weight gain by 1.37%. The mortality rate increased with both increasing levels of sound frequency, and the time-length of exposure duration within the same frequency level. Attachment strength declined with induced mortality of zebra mussel after 20 days of sound exposure, and nearly 50% of zebra mussels died by sound treatment of 5000 Hz frequency after 100-days of exposure. The findings in this study demonstrate that sound energy is a potential tool and a practical option for preventive management and control of zebra mussel biofouling in freshwater ecosystems.Öğe Effects of dietary lipid levels on growth performance and feed utilization in juvenile Black Sea turbot (Psetta maxima) with reference to nitrogen excretion(Adem Yavuz SÖNMEZ, 2014) Harmantepe, Fatma Burcu; Yigit, Murat; Dogan, Gaye; Karsli, Zafer; Yigit, Umut; Uyan, OrhanIn the present study, iso-nitrogenous test diets were formulated to contain two different levels of lipid (9% and 12%) with dietary energy ranging from 19 kJ/g to 20 kJ/g diet. White fish meal was the main protein source of the diet and the protein level was 55% in all diets offered to triplicate groups of juvenile Black Sea turbot (mean initial weight of 24.5±0.3 g) for a period of 70 days. Specific growth rates were significantly better (P < 0.05) in high lipid diet group compared to the groups fed low lipid diets. Feed conversion rates (FCR) were influenced by the lipid levels and the best FCR was obtained in fish given the diet with high lipid content. Similarly, protein efficiency was also significantly better (P < 0.05) in fish fed diets with high lipid level. The better utilization of protein in the diet with high lipid content resulted in a significantly higher (P < 0.05) nitrogen retention as percent of intake when compared to the other group with lower lipid level. The amount of nitrogen loss into the water environment was significantly reduced (P < 0.05) to the same extent in the group fed diets with high lipid level. The lipid retention values calculated based on the intake rates were also better in the high lipid diets compared to the other group with low lipid level, however the difference was not significant (P > 0.05) among the experimental groups. The results in the present study indicate that the use of high lipid level with a protein to energy ratio of 27 mg/kJ (12% lipid, 55% protein, 20 kJ/g gross energy) performed best. Increasing the dietary lipid to 20 kJ/g diet has reduced the total nitrogen excretion from Black Sea turbot by 23%.