Effects of ambient ammonia on ammonia-N and protein concentrations in hemolymph and ammonia-N excretion of Penaeus chinensis

Abstract

Individual Penaeus chinensis adults (26.91 + 4.66 g) were subjected to 0.03, 5.10, 10.11 and 20.04 mg I-' ammonia-N (un-ionized plus ionized ammonia as nitrogen) in 30 ppt seawater and 25 "C. Changes in ammonia-N excretion, hemolymph ammonia-N and hemolymph protein were monitored for 1 to 24 h. Net ammonia-N uptake occurred when shrimp were exposed to 10.11 and 20.04 mg I-' ammonia-N after 4 h. Relationships among ammonia-N excretion rate, hemolymph ammonia-N, hemolymph protein, concentration of ambient ammonia-N and exposure time were determined. An increase of ammonia-N and a decrease of protein in the hemolymph of P chinensis following a 4 h exposure to ambient ammonia-N as high as 10 mg 1-' may cause catabolism of protein and amino a c ~d s to balance the osmoregulation, as well as dysfunction of Na+/NH,+ exchanges.