Tolerance for Ammonia in Early Stage Spiny Lobster (Jasus Edwardsii) Phyllosoma Larvae

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Abstract The tolerance of spiny lobster J. edwardsii phyllosoma to the effects of increasing levels of ammonia was assessed at Stages I to IV of larval development. The median lethal concentration (96-h LC50) for total ammonia (and corresponding NH3-N) were 31.6 (0.97) mg l−1, 45.7 (1.40) mg l−1, 52.1 (1.59) mg l−1, and 35.5 (1.01) mg l−1 at Stage I, II, III and IV, respectively. When Stage II larvae were cultured through to Stage III at total ammonia concentrations of 0.5 (control), 1.4, 3.8, 6.3 and 9.5 mg l−1, the intermoult period increased significantly at and above 6.3 mg l−1 (from 11.2 days in controls to 13.2 days at 9.5 mg l−1). Thus, the no-observable-effect-concentration (NOEC) of total ammonia (and corresponding NH3-N) at Stage II of 3.8 mg l−1 (0.12 mg l−1) was used as the divisor in the acute:chronic ratio (i.e., 96-h LC50 ÷ NOEC) to estimate the concentrations at Stages I, III, and IV, which were 2.7 (0.08) mg l−1, 4.4 (0.14) mg l−1, and 3.0 (0.09) mg l−1, respectively. These results provid...