Effect of body mass and activity on the metabolic rate and ammonia-N excretion of the spiny lobster Sagmariasus verreauxi during ontogeny.

Intraspecific analyses of the relationship between metabolic rate and mass have rarely been considered during complete ontogeny. Spiny lobsters are fascinating candidates to examine metabolic changes during ontogeny because their life cycle includes an extended planktonic, nektonic, and benthic life stages. The effect of body mass on metabolic rates, aerobic scope, and ammonia-N excretion of Sagmariasus verreauxi juveniles were examined to determine energetic demands through juvenile development. Mass-independent routine oxygen consumption increased allometrically during juvenile development with a mass scaling exponent of 0.83. The mass scaling exponent of active metabolism (0.81) was reduced compared to standard metabolism (0.91) of juvenile lobsters. The aerobic scope of juvenile lobsters decreased with larger body mass. To examine if the mass scaling exponent varies with ontogeny, we compared our data with previous measurements made with larvae of the same species. Comparison between mass scaling exponents showed they were higher for phyllosoma (0.97) compared to juvenile (0.83) development. Higher scaling exponents for phyllosoma may be attributed to increased growth rates of phyllosoma compared to juveniles, which increase oxygen consumption due to the higher energy cost of growth. The mass scaling exponent for complete ontogeny (0.91) of S. verreauxi was larger than the commonly cited 0.67 (1/3) and 0.75 (3/4) mass scaling exponents, indicating that species-specific differences can be a large factor affecting allometric relationships of animals.