Acute toxicity test of four disinfectants on juvenile Apostichopus japonicus

Background Sea cucumber (Apostichopus japonicus) is a significant species in marine aquaculture, valued for its nutritional and medicinal properties. Ensuring the health and vitality of sea cucumber seedlings is crucial for the success of the industry. Water quality and disease prevention are two key factors that directly influence seedling survival and growth rates. Disinfectants play a vital role in preventing and controlling diseases during the seedling cultivation process. When selecting disinfectants for sea cucumber cultivation, it is essential to strike a delicate balance between their efficacy against pathogens and potential toxicity to the target species. Excessive or inappropriate use of disinfectants can lead to adverse effects on seedlings, including mortality, growth retardation, and physiological stress. Therefore, it is imperative to conduct scientific studies to assess the toxicity profiles of various disinfectants and determine their safe concentrations for use.

Objective This research project aims to comprehensively evaluate the acute toxicity effects of four commonly used disinfectants on A. japonicus seedlings, with the primary objective of providing practical and actionable guidance to growers.

Methods Acute toxicity experiments were conducted on four disinfectants commonly used in aquaculture, employing the static water experiment method. Juvenile A. japonicus were used as the experimental subjects. The experiments were taken place in controlled environments, ensuring consistent water quality parameters such as temperature, pH, and dissolved oxygen. Seedlings were exposed to the disinfectants for a specified duration, during which their behavior, survival rates, and any visible signs of toxicity were closely monitored. After the exposure period, data were collected and analyzed to determine the median lethal concentration (LC₅₀) for each disinfectant.

Results The results showed that the 24, 48, 72, and 96 hours median lethal concentrations (LC₅₀) of chlorine dioxide were 2.97, 2.06, 1.56, and 0.96 mg/L, respectively, with a safe concentration of 0.43 mg/L at 48 hours. For potassium hydrogen persulfate, the LC₅₀ values at 24, 48, 72, and 96 hours were 9.66, 6.53, 5.50, and 5.07 mg/L, respectively, with a 48-hour safe concentration of 1.32 mg/L. The LC₅₀ values for dibromohydantoin were 12.80, 7.84, 7.01, and 6.02 mg/L at 24, 48, 72, and 96 hours, respectively, with a 48-hour safe concentration of 1.44 mg/L. For povidone-iodine, the LC₅₀ values were 11.95, 9.30, 8.51, and 8.13 mg/L at the same time intervals, with a 48-hour safe concentration of 2.17 mg/L.

Conclusion The virulence of the disinfectants to A. japonicus manifested as chlorine dioxide > potassium hydrogen persulfate > dibromohydantoin > povidone-iodine. Considering the antibacterial ability of different disinfectants, potassium hydrogen persulfate can be preferred as the disinfectant. The results of this study will offer valuable insights into the safe use of disinfectants in sea cucumber aquaculture.