Effect of Ammonia Nitrogen on Production and Haemolymph of Pacific White Shrimp (Litopenaeus vannamei) Cultured in Low Salinity Ponds in Greene County, Alabama

Abstract

Water temperature, pH, and concentration of total ammonia nitrogen were measured on 12 sampling date in summer 2013 in eight shrimp ponds on an inland, low-salinity shrimp farm in Alabama. Shrimp haemolymph samples also were collected for analysis of total ammonia nitrogen concentration, total hemocyte counts, and phagocytosis activity. The ponds had large inputs of feed (6,100 to 10,377 kg/ha) resulting in large organic nitrogen waste loads. Survival and production were quite variable ranging from 45.5% to 104% and from 3,265 to 6,550 kg/ha, respectively. Total ammonia nitrogen concentration, however, was not particularly great, exceeding 1.0 mg/L only twice. This apparently was the result of good feed management and high rates of aeration that favored ammonia loss to the atmosphere and prevented low dissolved oxygen concentration that can stress nitrifying bacteria. There were no correlations (P>0.05) between total ammonia nitrogen concentration or un-ionized ammonia nitrogen concentration and shrimp survival, production, or feed conversion ration. Moreover, a comparison of ammonia concentration in ponds of this study with data from the literature on the effects of un-ionized ammonia on fish and shrimp also suggested that the ammonia nitrogen concentration measured in the ponds would not likely have adverse impacts on shrimp survival or production. No relationships between ammonia nitrogen concentrations in pond water and concentration of ammonia in shrimp haemolymph, total hemocyte counts or phagocytosis activity was found.