Effect of disinfection with peracetic acid on the microbial community of a seawater aquaculture recirculation system for Pacific white shrimp (Litopenaeus vannamei).

Abstract

When tropical shrimps are kept in recirculating aquaculture systems (RAS), one of the limiting factors is the maintenance of a sufficient water quality, and therefore, often disinfectants like peracetic acid (PAA) are added to the water either as prophylactic or treatment measure. In this study, PAA in concentrations of 0.1mg/L, 1mg/L and 10mg/L was applied continuously for 56days to small-scale seawater RAS stocked with Litopenaeus vannamei. Treatment with 0.1mg/L did not result in a reduction in the total bacterial amount and therefore was not effective. A concentration of 10mg/L led to significant changes in the chemical water parameters already after 2days and was therefore not recommendable. A concentration of 1mg/L led to increased levels of ammonia and nitrite within 2days and to a significant increase in the bacterial amount in the water, most probably due to an enhanced growth of heterotrophic bacteria. The microflora showed significant fluctuations, and there were indications that the welfare of the shrimps was affected. Using 1mg PAA/L for prophylactic use is therefore also not recommendable but might be an alternative option for short-term treatment in cases of disease outbreaks.