Oxygen supply and the adaptations of animals in groundwater

摘要: 1. The first part of this review focuses on the oxygen status natural groundwater systems (mainly porous aquifers) and hyporheic zones streams. second examines sensitivity organisms, especially crustaceans, to low concentrations (< 3.0 mg L−1 O2). 2. Dissolved (DO) in is spatially heterogeneous at macro- (km), meso- (m) micro- (cm) scales. This heterogeneity, an essential feature environment, reflects changes sediment composition structure, flow velocity, organic matter content, abundance activity micro-organisms. also exhibits strong temporal zone streams as well recharge area aquifers, but these fluctuations should be strongly attenuated with increasing distance from stream zone. 3. gradients along paths vary over several orders magnitude (e.g. declines 9 × 10−5 1.5 ×10−2 mg L−1 O2 m−1 confined aquifers 2 × 10−2 1 mg L−1 O2 m−1 parafluvial water). Several factors explain variation. Where water table close surface, likely consumed rapidly few metres below because incomplete degradation soil-generated labile dissolved carbon (DOC) vadose zone. far depletion vicinity does not occur, DO being then gradually flows down hydraulic gradient. In unconfined systems, consumption may compensated by down-gradient replenishment DO, resulting either ingress atmospheric or through where impossible, removal time varies a years more than 10 000 years, depending mainly content sediment. Comparison between revealed differences length underground pathways for DO. variability among seems related contact sediment. 4. Although macro-crustaceans are much resistant hypoxia epigean species, they cannot survive severe (DO < 0.01 mg L−1 O2) very long (lethal 50% population ranged 46.7 61.7 h). hypoxia, none hypogean crustaceans examined utilized high-ATP yielding metabolic pathway. High survival times result combination three mechanisms: high storage fermentable fuels (glycogen phosphagen), rate normoxia, further reduction reducing locomotion ventilation. It suggested here that many species adaptation necessarily impoverished food supply. 5. An interesting physiological their ability recover anaerobic stress and, specifically, resynthesize glycogen stores during post-hypoxic recovery. A rapid restoration (without feeding) allows exploit moving mosaic suboxic (  3 mg L−1 O2) patches. 6. concluded although animals probably unsuited life extensively permanently groundwater, can found small temporarily patches. Indeed, adaptations clearly suited characterized highly dynamic concentrations. Their capacity days would partly why ecological field studies often reveal occurrence interstitial taxa wide range