EFFECT OF MOLT STAGE AND HYPOXIA ON OSMOREGULATORY CAPACITY IN THE PENEID SHRIMP PENAEUS-VANNAMEI

The osmoregulatory capacity (OC) was used to study the effects of hypoxia in Penaeus vannamei. Since OC varied with molt stages with a tendency for animals to show a reduced OC before and after ecdysis, only shrimps a stages C-D(o) were consequently used. Hyper-OC and hypo-OC, respectively, measured at low salinity and in seawater, were both depressed after 1-2 days exposure to low oxygen tension (PO2) ranging from 4 to 8 kPa. Low PO, effect was time-dependent. OC recovered fully after 24 h in an O2 saturated medium. OC measurement is confirmed as a convenient tool to monitor the physiological condition and the effect of stress in crustaceans.