RESPONSE OF CORALLIGENOUS TO GLOBAL CHANGE: EVIDENCES FROM FIELD AND EXPERIMENTAL STUDIES IN GORGONIAN FORESTS

Global change is one of the major concerns for the conservation of the rich biodiversity of coralligenous assemblages. In the Mediterranean Sea, there is a strong likelihood of increasing frequencies of mass mortality events linked to global warming and the spread of invasive species. Gorgonian forests, one of the most emblematic facies of coralligenous outcrops, are especially vulnerable to global change. The presentation will focus on the study of the responses of gorgonians, mainly the red gorgonian Paramuricea clavata, to warming and exotic algae invasions from observational and experimental approaches in NW Mediterranean Sea. Long-term monitoring of recurrent warming- induced mortalities in marine protected areas such as Cabrera Archipelago and Columbretes Islands showed that warming may act as an important driver for long-term shifts in the bathymetrical distribution of gorgonian forests. Aquaria experiments and field surveys indicate that thermal stress may also have important sublethal effects on the reproduction and the viability of early life stages of gorgonians. Additionally, manipulative experiments demonstrated that invasive algae, such as Caulerpa cylindracea and Womersleyella setacea, have the capacity to reduce gorgonian recruitment and juvenile survival. The final aim of the presentation is to discuss the future consequences of global change on the persistence and recovery of gorgonian forests, in particular, and of coralligenous assemblages in general.