Development and metabolic rate of stage I spiny lobster (Jasus edwardsii) larvae under constant and fluctuating salinities

The effects of fluctuating salinity on the development and metabolic rate of stage I Jasus edwardsii larvae were investigated. J. edwardsii larvae were reared from hatching through to stage II under continuous salinity regimes at 28, 31, 34, and 37 psu, and under repeated exposure to 28, 31, and 37 psu from a salinity of 34 psu. Continuous exposure to salinities between 28 and 37 psu did not affect the duration of larval development. In the repeated exposure treatments, only larvae subjected to 28 psu developed slower than those in the 34 psu continuous exposure group. Although post-moult growth to stage II was not suppressed by fluctuating salinity in the 31 and 37 psu groups, larvae repeatedly exposed to 28 psu and larvae under continuous salinities of 28, 31, and 37 psu were significantly smaller than those from the 34 psu continuous treatment. The effect of salinity acclimation on the respiratory response of mid-stage I larvae was examined in a second experiment. The reduced oxygen consumption of acclimated larvae at subnormal salinities (i.e., 28 psu) was characteristic of stenohaline organisms, and overall there was little relationship between metabolic rate and larval growth performance. From the results obtained in this study we recommend the monitoring and control of environmental salinity for the propagation of J. edwardsii larvae to prevent prolonged exposure to suboptimal salinities. © The Royal Society of New Zealand 2005.