Water cortisol is a reliable indicator of stress in European sea bass, Dicentrarchus labrax

Abstract

[This study examined cortisol release into the water by European sea bass, Dicentrarchus labrax . The time-course of plasma and water cortisol concentrations were determined in adult fish subjected to acute stress, by sampling blood and water at 0 h (before stress) and 0.5, 1, 2, 4, 8 and 24 h after stress. Sea bass showed a typical stress response, with plasma glucose and lactate concentrations peaking at 2 h, and plasma cortisol levels peaking at 1 h. Cortisol release rate into the water increased in response to stress and was positively correlated with plasma cortisol concentrations. In a further trial, juvenile fish were confined at densities of 20 and 50 kg/m 3 and water cortisol was evaluated over a 24 h period. Cortisol release rates peaked between 0–1 h in the high and 1–2 h in the low density group. In conclusion, these results provide strong evidence that cortisol release rate into the water can be used as a non-invasive method for the assessment of the stress response and that although sea bass presents a high blood stress response after exposure to acute husbandry stressors, it is releasing less cortisol into the water compared to other species previously examined., This study examined cortisol release into the water by European sea bass, Dicentrarchus labrax . The time-course of plasma and water cortisol concentrations were determined in adult fish subjected to acute stress, by sampling blood and water at 0 h (before stress) and 0.5, 1, 2, 4, 8 and 24 h after stress. Sea bass showed a typical stress response, with plasma glucose and lactate concentrations peaking at 2 h, and plasma cortisol levels peaking at 1 h. Cortisol release rate into the water increased in response to stress and was positively correlated with plasma cortisol concentrations. In a further trial, juvenile fish were confined at densities of 20 and 50 kg/m 3 and water cortisol was evaluated over a 24 h period. Cortisol release rates peaked between 0–1 h in the high and 1–2 h in the low density group. In conclusion, these results provide strong evidence that cortisol release rate into the water can be used as a non-invasive method for the assessment of the stress response and that although sea bass presents a high blood stress response after exposure to acute husbandry stressors, it is releasing less cortisol into the water compared to other species previously examined.]