Effect of nitrite on growth and oxygen consumption for juvenile greenlip abalone, Haliotis laevigata Donovan

Juvenile greenlip abalone, Haliotis laevigata Donovan (mean whole weight, 5.61 g) were grown for 2-3 mo in bioassay tanks. Specific growth rate (SGR), measured on a whole-weight (p < 0.05) or shell length (p < 0.01) basis, was significantly affected by nitrite (NaNO₂). Modeling of the whole weight indicated relatively uniform growth depression (average SGR weight of 67.2% relative to the control, 0.024 mg of NO₂-N L^-1), regardless of concentration in the range of 0.56-7.80 mg of NO₂-N L^-1. This pattern of growth depression, which is independent of nitrite concentration once growth is reduced relative to controls, has been recorded by other researchers for penaeid shrimp and freshwater crayfish. SGR data for shell length exhibited a similar pattern, except that much more severe growth depression (average SGR length of 17.7% relative to the control) was recorded for the highest concentration (7.80 mg NO₂-N L^-1). Compared with several aquatic species studied by other authors, greenlip abalone are sensitive to nitrite on a growth basis. Oxygen consumption declined sharply with increasing nitrite concentration (y = 82.452.e(-0.154-x); range, 0.025-7.72 mg of NO₂-N L^-1). However, neither food consumption (as a percentage of initial biomass, corrected for mortality) nor survival was significantly affected by nitrite concentration (p > 0.05).