plSSN : 0374-8111 | elSSN : 2287-8815
plSSN : 0374-8111 | elSSN : 2287-8815
plSSN : 0374-8111elSSN : 2287-8815
Water Quality Improvement and Acute Toxicity Assessment of ChlorineDioxide in a Recirculating Aquaculture System for Black Sea BreamAcanthopagrus schlegelii
배재현·서형원·운성천·박정환*
부경대학교 수산생물학과
Here, the effects of chlorine dioxide (ClO2) on water quality and acute toxicity were evaluated in a seawater-based recirculating aquaculture system (RAS). In the first phase, six ClO2 concentrations (0, 5, 10, 20, 30, and 40 mg/L) were tested to assess survival rates, water quality parameters, and bacterial abundance over 96 h of exposure. In the second phase, different stocking densities (10, 20, and 30 fish per tank) were evaluated under two fixed ClO2 concentrations (20 and 30 mg/L) to examine biomass effects on toxicity outcomes. The fish exposed to ≥30 mg/L ClO2 showed complete mortality, whereas the 96 h median lethal concentration was calculated as 17.26 mg/L based on fish count and 12.17 mg/L based on total biomass. Higher ClO2 concentrations improved water quality and microbial colonies. However, a sudden increase in turbidity and nitrite concentration was observed at the highest concentration (40 mg/L). This suggests microbial lysis and excessive organic matter release may have overwhelmed the oxidative capacity. Fish survival improved with increasing biomass under identical ClO2 exposure, indicating that elevated organic loads probably consumed more ClO2 and reduced its direct toxicity to fish. This highlights the importance of considering biomass-dependent oxidant demand during disinfectant application in RAS.
Recirculating aquaculture system (RAS), Chlorine dioxide, Acute toxicity, 96LC50, Biomass based toxicity