감성돔(Acanthopagrus schlegelii) 순환여과양식 시스템 내 수질환경 개선을 위한 이산화염소 유효 처리 요구량 평가

Abstract

Disease outbreak in aquaculture is an important factor affecting productivity, and therefore disease prevention is one of the most important culture management regimes. There are various disinfection and sterilization methods for disease prevention, and chlorine dioxide is considered a promising material for this purpose. For the use of the material in aquaculture, it is important to obtain basic and practical information, such as the effective doses that can control the microbial community in aquaculture systems but have no harmful side effects on aquatic organisms. In this study, short-term and long-term experiments were conducted to investigate the effects of chlorine dioxide on the growth and survival of blackhead seabream (Acanthopagrus schlegelii) and to determine the safe concentration in recirculating aquaculture systems. The first short-term experiment was conducted to determine the 96-hour lethal concentration (96hrLC50), which determines the theoretical safe concentration of chlorine dioxide at a given fish weight. The second experiment tested the demand effect of fish weight on the theoretically safe concentration. Based on the results of these short-term experiments, a long-term experiment was conducted that lasted 8 weeks and confirmed a long-term effective and safe concentration. The experiment was conducted in a laboratory-scale recirculating aquaculture system. The total volume of the experimental system was 360 L/hr and the systems were set to 24 turnovers per day. In the first experiment, the chlorine dioxide concentration was set to 0 (control), 5, 10, 20, 30, and 40 mg ClO2/L, and the same biomass of fish (501 g) was stocked for each concentration. In the second experiment, different biomasses (322 g, 618 g, and 941 g) were applied to two concentrations (20 and 30 mg ClO2/L). In the long-term culture experiment, the chlorine dioxide concentration was adjusted to 0 (control), 1.5, 3.0, 6.0, 12.0, and 24.0 mg ClO2/L, and the total fish biomass of fish was 695 g. The result of the short-term experiment showed that the survival rate decreased with increasing chlorine dioxide concentration and decreasing biomass, displaying 96hrLC50 of 17.20~17.50 mg. The long-term culture experiment showed the highest survival rate at 12 mg ClO2/L. A comprehensive analysis of the results of this experiment showed that when only the water quality environment was considered, the best water quality improvement effect was obtained at 24 mg ClO2/L. However, when interacting with fish growth, the optimal concentration was 12 mg ClO2/L. In terms of demand, the best effect of chlorine dioxide was obtained at 1.27 mg ClO2/g total fish weight × day-1., while it was 0.58 mg ClO2/g feed consumption × day-1.