Stress indicators in conservative tissues of Humboldt penguin under captivity.

Humboldt penguins (Spheniscus humboldti) from the Barcelona zoo (n=9) were followed to assess their physiological stress status using conservative protocols. Corticosterone levels were measured in feathers and plasma as indicative of chronic and acute physiological stress, respectively. Other markers: B-esterases, potentially indicative of xenobiotic exposure were measured in plasma of these same individuals and reported for the first time in this species. The sensitivity to chemicals of environmental concern, employed as plastic additives, was assessed in vitro with plasma of this species using the inhibition of carboxylesterase (CE) and acetylcholinesterase enzymatic measurements. Among the tested additives, the organophosphorus flame retardants displayed the highest in vitro inhibitory potential on basal CE activity, suggesting their potential utility as biomarkers of this particular chemical class. Additionally, enzymatic measurements in plasma are determined for the first time in Humboldt penguin and can be regarded as baseline values for a potential field monitoring application.