1277 Behavioral, Ventilatory, and Metabolic Responses of the Hypogean Amphipod Niphargus vire/ and the Epigean lsopod Ase/lus aquatlcus to Severe Hypoxia and Subsequent Recovery Fr édéric Hervant 1 Jacques Mathieu 1 Daniel Garin 2 Alain Freminet2 'Hydrobiologie et Ecologie Souterraines, ESA CNRS 5023, Université Claude Bernard-Lyon 1, 43 boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France; 2 Service de Physiologie du Métabolisme Intermédi aire et Energétique, Université Claude Bernard-Lyon 1, 43 boulevard du 11 novembre 1918, F-69622 Villeurbanne Cedex, France Accepted 1/24/96 Abstract Tbe locomotory and ventilatory activities and the intermediary and energy me· tabolism modifications of the hypogean amphipod Niphargus virei and the epi- gea11 isopod Ase li us aquaticus were compared during severe hypoxia ( <0. 03 kPa) and subsequent recovery. The aims of this study were (1) to determine why the subterranean species displayed a greater tolerance of hypoxia than A. aquaticus and 1111merous other epigean crustaceans, (2) to conjîrm previous results ob- tai11ed with the hypogean amphipod Niphargus rhenor hodanensis and the epi- gean amphipod Gammarus fossarum, (3) to provide an interspecific comparison of epigean species in order to see if responses showed by epigean amphipods dur- ing hypoxia and recovery can be exte1zded to epigean isopods, and (4) to better understand the ecological problems of the hypogean organism '.5 surviva/ and per· ennati on in subterranean habitats. Botb organisms responded to long-term ex· perimental severe hypoxia with classical anaerobic metabolism, characterized by a decrease in ATP and phospbagen, the use of glycogen and glutamate, and the accumulation of lactate (witb some alanine). ln addition, some accumulation of s11cci11ate wasfo1md in N. virei. Lactate (and succilzate for N. virei) was also large/y excreted by both ampbipods, which is u11us11alfor the crustacea in gen- eral. Compared with A. aquaticus and most other epigean crustaceans, N. virei showed large amou11ts of stored glycogen and arginine phosphate. These differ- e 11 ces i11 glycogen and pbosphagen stores, and the ability to redu ce gl ycolytic flux 011d energet ic expenditures linked to locomotion and ventilatio11, extended the surviva l of hypogea11 crustaceans under experimental anaerobiosfs (l T 50 was 52 .1 h for N. virei and 19. 7 b for A. aquaticus du ring severe hypoxia at 11° C). Du ring recovery, both species displayed characteristic hyperventilation, slow Io· Physiolog1cal loology 69(6) :1277- 1300 . 1996. © 1996 by The University of Chicago. Ali nghts reserved. 0031 -935X/96/6906-9552$02. 00