Immune responses to combined effect of hypoxia and high temperature in the green-lipped mussel Perna viridis

Flow cytometry was used to examine immune responses in haemocytes of the green-lipped mussel Perna viridis under six combinations of oxygen level (1.5mg O₂l^-1, 6.0mg O₂l^-1) and temperature (20°C, 25°C and 30°C) at 24h, 48h, 96h and 168h. The mussels were then transferred to normoxic condition (6.0mg O₂l^-1) at 20°C for further 24h to study their recovery from the combined hypoxic and temperature stress. Esterase (Est), reactive oxygen species (ROS), lysosome content (Lyso) and phagocytosis (Pha) were reduced at high temperatures, whereas hypoxia resulted in higher haemocyte mortality (HM) and reduced phagocytosis. For HM and Pha, changes were observed after being exposed to the stresses for 96h, whereas only a 24h period was required for ROS and Lyso, and a 48h one for Est. Recovery from the stresses was observed for HM and Pha but not other immune responses. © 2011 Elsevier Ltd.