LOCOMOTORY, VENTILATORY AND METABOLIC RESPONSES OF THE SUBTERRANEAN STENASELLUS-VIREI (CRUSTACEA, ISOPODA) TO SEVERE HYPOXIA AND SUBSEQUENTRECOVERY

The locomotory and ventilatory activities and the intermediary and ene rgy metabolism modifications of the hypogean aquatic isopod crustacean Stenasellus virei were investigated in severe hypoxia (Po-2 < 0.03 kP a) and subsequent recovery. The aims of this study were i) to determin e why the subterranean species displayed a greater tolerance of hypoxi a than numerous other epigean crustaceans, ii) to confirm previous res ults obtained with four hypogean and epigean crustaceans, iii) to comp are the responses to severe hypoxia in hypogean amphipods and isopods, and iv) to better understand the ecological problems of the hypogean organisms survival in subterranean habitats. S. virei responded to exp erimental long-term, severe hypoxia with classical anaerobic metabolis m mainly characterized by a decrease in adenosine triphosphate (ATP) a nd phosphagen, utilization of glycogen and glutamate, and accumulation of lactate and alanine. Lactate was also largely excreted by this org anism, which is unusual for crustaceans in general. Compared to most o ther epigean crustaceans, the isopod S. virei showed high amounts of s tored glycogen and arginine phosphate. These differences in glycogen a nd phosphagen stores, and the ability to reduced energetic expenditure s linked to locomotion and ventilation, extended the survival of S. vi rei under experimental anaerobiosis. During recovery, the isopod S. vi rei showed a higher capacity for glyconeogenesis from lactate and a fa ster and total replenishment of ATP and arginine phosphate levels than epigean crustaceans. Data concerning responses to hypoxia and subsequ ent recovery in S. virei are similar to those previously obtained with two other hypogean amphipods, except that this isopod did not synthes ize succinate in anaerobiosis.