Avis de soutenance - doctorat - Ian BOUYOUCOS

Myriad anthropogenic impacts drive declines in global shark populations; yet, the consequences of a newly recognised threat, global climate change, are poorly understood. This thesis tested the hypothesis that global change stressors (ocean acidification and warming) reduce fitness in tropical reef sharks via effects on physiological performance. My specific objectives were to define thermal performance in fitness-enhancing nursery areas, physiological performance in situ, associations between thermal performance, preference, and tolerance, and physiological performance under multiple global change stressors. I found that neonatal blacktip reef sharks (Carcharhinus melanopterus) have superior growth efficiency in nursery areas relative to other habitats, but ocean acidification and warming synergistically reduce performance. This thesis suggests that global change stressors reduce fitness in tropical reef sharks by acting on physiological traits that are associated with nursery areas.