Lactate accumulation in the intertidal hermit crab, Pagurus samuelis, in response to burial-induced hypoxia

抄録

We subjected the intertidal hermit crab, Pagurus samuelis (Stimpson, 1857), to various treatments to determine physiological responses of this species to the environmental stress of burial. Hermit crabs were buried with 6 cm of sediment and excavated at 2 h intervals up to a maximum of 12 h. Duration of burial and state (alive or dead) of the crab were analyzed for effects on lactate accumulation in hemolymph. Hermit crab weight, shell weight, weight ratio, lactate, and burial duration were analyzed for their influence on survival. As expected, lactate levels, as well as incidence of death, rose with duration of burial. Significant interaction, however, was also found between burial duration, crab state, and lactate concentration. There was a trend for lactate concentration to be low for surviving crabs, yet higher for dead crabs during shorter burial durations. Conversely and surprisingly, lactate concentrations were very high in surviving crabs, yet lower in dead crabs during long burial durations. Since some surviving crabs were able to develop very high lactate levels, we suggest that lactate buildup itself is unlikely to be the sole cause of death. Further studies are needed to identify factors affecting crab resilience during the stress of burial.