Oxygen deficit and
sulfide have been restrictive factors in mariculture zones. However, the adaptive mechanism in aquatic lives is still unclear. The commercial ark shells Anadara broughtonii were selected to test the tolerance and adaptive responses to prolonged and intermittent
hypoxia with or without exogenous
sulfide (mild, moderate, high) by evaluating their behavior, mortality, oxidative level,
antioxidant responses, and the MAPK-mediated apoptosis in gills. The results indicated that the clams were tolerant to
hypoxia and
sulfide exposure but vulnerable during reoxygenation from the challenges. Even so,
sulfide had remarkable effect on attenuating the accumulation of
reactive oxygen species (ROS) and
lipid peroxides caused by reoxygenation from prolonged
hypoxia. The increase of
glutathione level was probably as an early and primary protective response to prevent the expected
reperfusion injury from reoxygenation. The challenges suppressed the oxidative level with a dose-dependent effect of
sulfide, with an exception when exposed to mild
sulfide. Synchronously, biphasic effects of exogenous
sulfide on apoptotic cascade, which was induced by mild
sulfide while it was inhibited by higher
sulfide, were also detected in gills. The induced or inhibited apoptosis by
hypoxia and
sulfide kept to a typical ROS-MAPK-
CASPASE cascade, desiderating further investigation.