The effect of pre-exposure ammonia on survival and ammonia resistant of macrobrachium lanchesteri (de man, 1911)

Abstract

This study was conducted in a lab at University Malaysia Terengganu. Acute toxicity test and pre-exposure test with the ammonia were conducted to examine the effect on survival of Macrobrachium lanchesteri. Shrimp were submitted for various concentration of ammonia for 96 h on acute toxicity test. 96 h LC50 is 13.5 mg.r1 and the safety level for Macrobrachium lanchesteri is l .35mg.r1 • Mortalitiy increase with the ammonia concentration in acute toxicity test. Pre-exposure test was conducted by exposing the shrimps to low concentration of ammonia (0.5 mg.r1 , 1.0 mg.r1 and a control test for 7days before increasing into 20 mgS1 ammonia concentrations for 96 h. Shrimp that was exposed under low concentration ammonia (0.5 mg.r1 and 1.0 mgS1 ) sensitive to higher concentration of ammonia rather than shrimp in the control test. The shrimp were stressed due to the pre-exposure ammonia compared to the control test that has higher survival rate than the pre-exposure test.