Effect of ammonia on the growth rate and oxygen consumption of juvenile greenlip abalone, Haliotis laevigata Donovan

Juvenile greenlip abalone, Haliotis laevigata, (mean whole weight 4.48 ± 1.9 g, mean ± s.d., n = 953) were highly sensitive to ammonia as indicated by depressed growth rate and food consumption measured over 2-3 months in bioassay tanks. For growth rate expressed on a whole weight basis, the EC₅ and EC₅₀ values (5 and 50% growth reductions) were 0.041 mg FAN l^-1 (Free Ammonia-Nitrogen) and 0.158 mg FAN l^-1, respectively. Shell growth rates declined over the entire experimental range (0.006-0.188 mg FAN l^-1). At the end of the bioassay, groups of abalone were transferred to respiratory chambers. Oxygen consumption rate increased to a maximum of 188% of control values at 0.235 mg FAN l^-1 and decreased slightly at the highest concentration of 0.418 mg FAN l^-1.