The tolerance of juvenile stone crabs to hypoxia: Size matters

Over the last fifty years, anthropogenic activities have increased nutrient loading into coastal habitats causing more frequent hypoxic events. Global climate change is expected to increase the frequency and severity of hypoxic conditions as temperatures continue to increase, which will pose physiological and metabolic limits on many coastal species. This study determined the survivorship and tolerance of the commercially important juvenile stone crab (Menippe mercenaria) during short-term hypoxic exposure under laboratory conditions. Small (2.0-3.0 mm carapace width) and large (5.0-18.0 mm carapace width) juveniles were gradually exposed to moderate hypoxic conditions (1.5 mg L-1 oxygen concentration) for 2 h and compared to individuals in normoxic conditions. Smaller juveniles were more sensitive than larger conspecifics and exhibited 80% mortality. Larger juveniles did not exhibit significant mortality (similar to 12% total mortality); however, 35% of the larger crabs displayed immobile by the end of the experiment. These results indicate that juvenile stone crab tolerance to hypoxia is size-dependent and likely changes throughout ontogeny.