Effects of short-term crowding stress on the gilthead seabream (Sparus aurata L.) innate immune response

Gilthead seabream specimens were subjected to an intense short-term crowdin g stress of 100 kg m(-3) for 2 h. After 0, 1, 2, 3 and 4 days, blood glucos e and serum cortisol levels, serum complement activity, phagocytic and resp iratory burst activities of head-kidney leucocytes, and the percentage of m onocyte/macrophages and granulocytes in head-kidney and circulating blood w ere determined. An immediate effect of the stress was a depression in compl ement and phagocytic activities, both of which recovered after 3 or 2 days, respectively, while respiratory burst remained unaffected. The depression of phagocytosis in head-kidney leucocytes seemed to correlate with stress-i nduced migration of active cells from the organ to circulating blood. The p resent results point to the importance of minimising intense short-term cro wding stress in order to reduce possible states of immunodepression in farm ed fish. (C) 2001 Academic Press.