Low dissolved oxygen reduces growth rate and oxygen consumption rate of juvenile greenlip abalone, Haliotis laevigata Donovan

Juvenile greentip abalone, Haliotis laevigata, (whole weight 10.8 ± 3.0 g, mean ± SD, n = 603) were grown for 57-77 days in bioassay tanks at a range of dissolved oxygen (DO) concentrations (4.2-8.9 mg DO l ^-1 ; 55-117% oxygen saturation). Specific growth rate (SGR) was significantly affected by hypoxia whether measured on a length (P < 0.01) or whole weight (P < 0.001) basis. For growth expressed on a whole weight basis, the EC ₅ and EC ₅₀ values (5 and 50% reductions in growth rate) were 7.36 and 5.91 mg DO l ^-1 (96 and 77% saturation), respectively. Shell growth rates declined over the entire experimental range. At the end of the bioassay, groups of abalone were transferred to respiratory chambers. Oxygen consumption by juvenile greenlip abalone was significantly affected by the external oxygen concentration (P < 0.01). The EC ₅ and EC ₅₀ values (5 and 50% reductions in respiration rate) were 6.16 and 5.19 mg DO l ^-1 (80 and 68% saturation), respectively. Oxygen consumption was estimated to be independent of external oxygen concentration in the range 6.25 mg-8.9 DO 1 ^-1 (81-117% oxygen saturation).