THE EFFECTS OF LONG TERM HYPOXIA ON ASPECTS OF THE BIOLOGY OF GAMMARUS CHEVREUXI (SEXTON, 1913)

Areas of hypoxia are becoming more frequent throughout the world’s oceans as a result of climate change and increased eutrophication and, although it is becoming clear that hypoxia has significant impacts on a range of aquatic organisms, there are few studies examining the response of such organisms to long term exposure to hypoxic conditions. As such this investigation aims to assess some of the key responses of an organism to long term hypoxia, taking an integrative approach covering physiology, gene expression and reproductive output. To achieve this, Gammarus chevreuxi were cultured under hypoxic (40% air saturation) and normoxic (100% air saturation) conditions at Plymouth University’s marine biology and ecology research centre. Measurements on their metabolism, ventilation and heart rate were taken under declining PO2 after 1 week exposure for the F0 adults and upon reaching the juvenile stage for F1 generation (9 weeks after hatching). Critical oxygen tensions (Pc) were determined for individuals from both conditions. Expression levels of superoxide dismutase (SOD), catalase (CAT) and hypoxia-inducible factor 1 (HIF-1) were also measured in the adults. No significant difference was found between Pc in normoxia and hypoxia in either adults or juveniles (p=0.799 and 0.456 respectively), but the Pc for juveniles was found to be significantly higher to that of the adults (p=0.013), meaning they were not able to regulate their oxygen uptake for as long as the adults under declining PO2. Both heart rate and ventilation were also significantly increased in hypoxic G. chevreuxi (p=