Tolerance for ammonia by early stage spiny lobster (Jasus edwardsii) phyllosoma larvae

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 provide the basis for the design and management of systems for the culture of larval J. edwardsii.