The stress response of the gilthead sea bream (Sparus aurata L.) to air exposure and confinement

Abstract

We investigated short-term effects (up to 24 h) of air exposure and confinement, and long-term effects (up to 11 days) of confinement, to elucidate signalling pathways in the stress response of gilthead sea bream Sparus aurata L. Plasma glucose and lactate were taken as indicators of sympathetic activation, and -melanocyte stimulating hormone ( -MSH), adrenocorticotrophic hormone (ACTH) and cortisol as indicators of activation of the brainpituitary-interrenal (BPI) axis. Air exposure for 3 min resulted, within 30 min, in an increase in plasma concentrations of cortisol, -MSH, glucose, lactate, osmolality and plasma Na, Cl and Mg. Plasma ACTH and -endorphin and plasma K, Ca and P did not change. We conclude that air exposure mainly activates the brainsympathetic-chromaffin cell (BSC) axis. In fish confined at a density of 70 kg/m 3 (compared with 4 kg/m 3 in controls), cortisol, ACTH and -MSH increased within 1 h, indicating activation of the BPI axis. Plasma glucose, Na, Cl and Mg increased with an 8 h delay compared with the response to air exposure. No changes in plasma lactate, osmolality, K, Ca and P were observed. Long-term confinement induced a biphasic cortisol response with peaks at 1 h and at 2 and 3 days. A gradual increase in plasma -endorphin concentrations peaked at 7 days; the concentration of -MSH increased rapidly within 1 h and then declined to control values 4 days after the onset of confinement. No changes in ACTH were detected. Our data provide evidence that a stressor-specific activation of the BSC and BPI axes may occur in Sparus aurata.

Biological indicators of stress in pacu (Piaractus mesopotamicus) after capture

“…the chasing and swimming of fish, physical injury provoked by the contact among fish and with the net and anoxia by air exposure (Mugnier et al, 1998;Arends et al, 1999;Ross and Ross, 1999;Barcellos et al, 2001;Morales et al, 2005). Confirming the literature regarding fish stress, elevated circulating cortisol and glucose of pacu were short-term responses in both air-exposed fish after capture and the recovery occurred within 24 hours.…”

“…Air exposure of Sparus aurata for 3 minutes resulted, within 30 minutes, in an increase in plasma concentrations of cortisol and glucose. After 2 hours, plasma cortisol and after 12 hours plasma glucose had returned to control concentrations (Arends et al, 1999). On the other hand, netting and exposure of juvenile turbot to air for 1-4 minutes had no immediate effect on plasma cortisol concentrations (Mugnier et al, 1998).…”

“…Various stressors, including fish capture (Mugnier et al, 1998;Arends et al, 1999;Barcellos et al, 2001;Rocha et al, 2004;Morales et al, 2005), are necessary components of modern intensive aquaculture (Wendelaar Bonga, 1997). The fish response to such stressors involves a series of physiological changes in an attempt to compensate for the challenge imposed upon it and, thereby cope with the stress.…”

“…The majority of international research effort has gone into the stress responses of salmonids (McCormick et al, 1998;Ackerman et al, 2000;Barton, 2000), but other species such as carp (Cyprinus carpio L.) (Vianen et al, 2001), tilapia (Oreochromis niloticus L.) ( Van der Salm et al, 2005), turbot (Scophthalmus maximus L.) (Van Ham et al, 2003) and sea bream (Sparus aurata L.) (Arends et al, 1999) have gained attention due to their potential for aquaculture in many countries. However, little research has been done on native South American fishes.…”

Divergence of endocrine and metabolic responses to stress in two rainbow trout lines selected for differing cortisol responsiveness to stress

“…The cortisol response is slower and is therefore more easily quantified. Consequently, cortisol has been widely employed as an indicator of stress in actinopterygian fishes (Pickering, 1992;Sumpter, 1997;Arends et al, 1999;Belanger et al, 2001). Cortisol release is mediated by activation of the hypothalamicpituitary-interrenal (HPI) axis (Wendelaar Bonga, 1997;Rotllant, et al, 2000) in response to a stressor.…”