Stress-induced immune changes in the oyster Crassostrea gigas

Information concerning the effect of stress on invertebrate immune function s are scarce. The present study investigated the consequences of a 15-min m echanical disturbance on immune parameters in oysters Crassostrea gigas. As indicated by noradrenaline and dopamine measurements, the mechanical distu rbance caused a transient state of stress in oysters. The number of circula ting hemocytes, the migratory and phagocytic activities and reactive oxygen species production of hemocytes were measured before, during and after app lication of the stressor. Results show that all immune functions were signi ficantly downregulated during stress and a transient period of immunostimul ation was observed 30-240 min after the end of the disturbance. Taken toget her, these results suggest that stress can exert a profound influence on oy ster immune functions and they may explain why stress and the outbreak of d isease are often linked in shellfish culture. Furthermore, the present stud y strongly suggests that checking the stress status of animals may be neces sary to avoid biases when studying oyster immune responses in vivo. (C) 200 1 Elsevier Science Ltd. All rights reserved.