The effects of total ammonia nitrogen and nitrite concentrations on mouting and the surviving of white leg shrimp (Litopenaeus vannamei)

Abstract

White leg shrimp (Litopenaeus vannamei) or Pacific white leg shrimp is presently the most important cultivated shrimp species in the world. They can tolerate in low salinity waters, growth faster than other species. However, in low salinity condition, the toxicity of total ammonia nitrogen (TAN) and nitrite (NO2--N) concentration is increased. In this study, Litopenaeus vannemei (4.54±0.58cm; 0.77±0.17g) was exposed to TAN (0 mg/L, 2.21 mg/L, 6.63 mg/L, 11.04 mg/L) and NO2--N (0 mg/L, 9.33 mg/L, 27.95 mg/L, 46.59 mg/L) corresponding with 0% (control), 5%, 15% and 25% of 48h LC50 at 15ppt salinity waters. The experiment was carried out in two culture volume, 1.5 liter beaker and 30 liter aquaria. The density in individual test is 1 shrimp and 15 shrimps in population test. Total of each test have 16 treatments and each of which is triplicated. The result experimental after 30 days showed that Litopenaeus vannamei were sensitive to high TAN and NO2--N concentration, specially high mortality at 6.63 mg/L of TAN and 46.59 mg/L of NO2--N concentrations. Nitrite was more toxic than TAN at low salinity condition which was water quality resulting in high mortality and slow growth. The moulting cycle was observed and dead shrimps have soft shell and incomplete moulting.