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The general objective of the project has been to conserve gorgonian forests in the face of mass mortality episodes linked to the effects of climate change.

The specific objectives were as follows:

• To know the impact of extreme warming of seawater in summer 2018 on gorgonian forests on the Spanish Mediterranean coast.
• Experimental design and validation of the dead branch pruning technique as a management tool for gorgonian forests.
• Describe the thermal regime of seawater.
• To disseminate the results of research to the scientific community, to the competent Administrations and to the general public.

• Spatio-temporal characterization of the impact of the mortality episode of the summer of 2018 on the populations of gorgonians Eunicella singularis and Paramuricea clavata of the Spanish Mediterranean coast of two marine reserves along a latitudinal gradient.

The two marine reserves and the scientific campaigns carried out are as follows:

– Autonomous Community of Catalonia (El Montgrí Natural Park, the Medes Islands and the Baix Ter

– Region of Murcia (Cabo de Palos-Islas Hormigas Marine Reserve).

• Pruning activities in gorgonians as a tool for the management of gorgonian forests.
• Scientific validation of the effectiveness of the pruning technique as a tool for the management of gorgonian forests.
• Historical analysis of seawater temperature in a bathymetric gradient.
• Dissemination actions: transfer of knowledge to the managers of protected natural areas and to society.

The PODAGORG project has studied the conservation status of gorgonians on the Spanish Mediterranean coast and has carried out an experiment to scientifically validate an innovative management tool for their restoration using the pruning technique of dead gorgonian branches.

The results show an impact of recurrent episodes of mass mortality on gorgonian populations on the Mediterranean coast, caused by the effects of climate change and the consequent warming of seawater. Thus, the populations of red gorgonian (Paramuricea clavata) and white gorgonian (Eunicella singularis) have been severely affected at their surface limit of bathymetric distribution (study of the deep sea).

The experiment has been carried out to evaluate the possible benefits of the pruning technique of dead branches to improve the conservation status of gorgonian populations . The experiment has consisted of installing demographic monitoring plots in which the experimental control (in which there has been no action) has been compared with the pruning treatment (with the application of this technique). After two years of trial, significant differences have been found between the two treatments, so that the pruning technique has proven to be beneficial in improving their population viability.

In the case of red gorgonian (Paramuricea clavata) specimens, the decrease in the incidence of partial mortality in the plots in which pruning technique was applied (24%) was 4 times higher than in the control plots (6%) in which there was no application of technique. On the other hand, in the case of white gorgonian (Eunicella singularis), the decrease in partial mortality in the plots in which pruning technique was applied (16 %) was 5 times higher than in the control plots (3 %).

The reproductive effort of both gorgonian species (P. clavata and E. singularis) showed a significant decrease with the increase in partial mortality of the colonies, so that mass mortality episodes have a long-term impact on the reproductive viability of the colonies and, therefore, on the resilience of the populations through the recruitment of new colonies.

In this sense, the use of the pruning technique does not show significant differences in the reproductive effort of pruned gorgonians compared to control gorgonians, except in male colonies of E. singularis, where an increase in the reproductive effort of pruned gorgonians is observed in relation to control gorgonians. These results have been obtained one year after the pruning action (the pruning technique was applied in 2019 and the reproduction sampling in 2020) and, due to the two-year duration of the gametogenesis cycle of the female colonies, a study is being carried out to evaluate the possible benefits in reproductive effort after two years of the pruning action to obtain more conclusive results.

The results are pending review by the scientific community external to the authors of the study, so the application of the pruning technique by the competent managers must wait for the review process to be completed.

PODAGORG has contributed to the objectives of LIFE Intemares by having actions dedicated to the conservation and recovery of habitats and species of interest studied through this project.