Ventilatory and locomotory activities in anoxia and subsequent recovery of epigean and hypogean crustaceans.

Locomotory and ventilatory responses to severe hypoxia and subsequent recovery were investigated in 3 amphipod crustaceans: 2 hypogean species (1 interstitial species Niphargus rhenorhodanensis and 1 karstic species N. virei) and 1 epigean species (Gammarus fossarum), and in an epigean population of 1 isopod crustacean (Asellus aquaticus). These species displayed respectively 46.7 h, 52.1 h, 6.3 h and 19.7 h lethal times for 50% of the population (LT50) values for anoxic survival. The aim of this study was to determine why the hypogean species displayed a survival time during severe hypoxia longer than that of Gammarus, Asellus and most other epigean crustaceans, and to better understand the ecological problems concerning Niphargus survival and perennation modalities in subterranean habitats which very often present hypoxic conditions during a hydrological cycle. The high resistance to severe hypoxia of hypogean animals partly results from an adaptation to the limitation of energetic expenditure linked to locomotion and ventilation in anaerobiosis, and from a decrease of general metabolism in severe hypoxia.