Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: December 10, 2008
Publication Date: February 15, 2009
Citation: Ott, B.D., Torrans, E.L. 2009. Routine Metabolic Rate and Limiting Oxygen Concentration of Freshwater Prawn Macrobrachium rosenbergii Larvae [Abstract]. In: Book of Abstracts. Aquaculture America, February 15-19, 2009, Seattle, Washington. p. 255. Technical Abstract: Malaysian prawns, Macrobrachium rosenbergii, are hatched and raised indoors in small tanks. Prawns may be raised and shipped at high densities which could result in low dissolved oxygen (DO) conditions. Because DO may play an important role in prawn development and survival, we measured routine metabolic rate (RMR) and limiting oxygen concentration (Pcrit; the presumed hypometabolic transition zone) of prawns at four different ages. Measurements were taken in a closed respirometer consisting of a 300mL BOD bottle fitted with a Hach BOD overflow funnel. Oxygen consumption (Vo2) and temperature were measured using a Hach HQ10 luminescent DO meter equipped with a spin bar on the tip of the probe. Prawn larvae were collected either from hatching or rearing troughs at Lauren Farms, Inc., Leland, MS. Vo2 was measured initially after they hatched (0 days post hatch [dph]), at 15 dph and 29 dph, and immediately after the prawns transformed into post-larvae (31 dph). For each measurement, a prawn sample was collected in a dip net, patted dry and weighed (1.0 – 1.2g, n=6,000-120), and placed in a respirometer where DO and temperature were measured every minute for 30-100 minutes at an average water temperature of 26.0°C. The Pcrit was determined as the DO concentration at which prawn Vo2 decreased from a linear rate. Individual prawn Vo2 was lowest at 0 dph (0.00023 ± 0.00003 mg O2 n-1 h-1) and was 11-, 30-, and 49-fold higher than intial rates at 15 dph, 29 dph, and 31 dph, respectively. Mass-specific Vo2 remained unchanged over the four sampling periods and ranged from 1216 ± 144 mg O2 kg-1 h-1 on 0 dph to 1300 ± 49 mg O2 kg-1 h-1 on 31 dph. Limiting O2 concentration was lowest at 0 dph (53 ± 1% saturation), peaked at 29 dph (74 ± 1%), and decreased once they became post-larvae (69 ± 1%). Oxygen consumption and limiting O2 concentration are factors to consider when raising and shipping prawns and become more critical issues as they age and grow.