Non-Specific Immune Parameters in Some New Candidate Species for Mediterranean Aquaculture: Results of First Studies

The aim of this paper was to describe the distribution of non-specific immune parameters in two fish species considered as new candidates for aquaculture diversification, greater amberjack and blackspot seabream. In particular, haemolysins, haemagglutinins and lysozyme were investigated to monitor their changes induced by two different stressors: 1) an experimental challenge of greater amberjack with the bacterial pathogen Listonella (Vibrio) anguillarum, which simulated an acute stress condition, and 2) a 14-day starvation period in blackspot seabream, which simulated a chronic stress condition. For each experiment, unstressed fish were kept and sacrificed at the same time intervals to be used as controls. In greater amberjack an increase in lysozyme was detected in challenged fish compared to control ones, while haemolytic activity and haemagglutinating titres showed a depressive effect following to the challenge. In blackspot seabream, starvation resulted in a reduction of lysozyme content in the mucus and plasma, as well as of haemolytic activity. The variations measured in non-specific immune parameters suggest their use as indirect markers of stress or altered health conditions.