Larval energy metabolism and physiological variability in the Asian shore crab Hemigrapsus sanguineus

Larvae of the Asian shore crab Hemigrapsus sanguineus were reared in the la boratory during zoeal development (Stages I to V, similar to 15 d at 25 deg reesC and 30 parts per thousand S). Measurements of respiration rates, lact ate dehydrogenase activity (LDH) and total protein content were made daily on individual larvae (n = 181) in order to assess the level of individual v ariance in energy metabolism during development. On average, zoeal developm ent in H. sanguineus was estimated to require 43.8 J of metabolic energy to reach a megalope stage; however, the level of individual variance in metab olic rates resulted in a range of 23.8 to 67.9 J (similar to3-fold differen ce). LDH specific activities also evidenced a wide range in individual valu es during development (12 to 785 muU mug(-1) protein). Although respiration rates were correlated with LDH specific activity (r(2) = 0.628), it is mor e interesting to note the negative correlation between the variance in thes e measurements (r(2) = 0.796), indicating a substantial degree of individua l differences in metabolic activities among these larvae. At present, pheno typic variations in physiological rate processes are not considered in life -history models of larval development, which could be an important variable determining the survival and dispersal of a larval cohort.