Framework underpinning procedures of canopy-forming brown algae restoration in Mediterranean ecosystems in a global change scenario

The restoration of canopy-forming brown algae is a new, rather unexplored, discipline in Mediterranean coastal ecosystems (6 documented studies). In this biogeographic region the genus Cystoseira plays, as marine kelp forests, a key role as an ecosystem engineer. Rapid environmental changes and extreme climatic events are causing unpredictable phenological shifts in these foundation species, leading to their regression or loss. Thenatural recovery is hampered by their limited egg and zygote dispersal. To implement large-scale actions, regulatory frameworks and practice standards are urgently required. Three restoration techniques have been implemented for Cystoseira species so far: i) transplanting juveniles or adults, ii) positioning fertile receptacles in the target area, iii) outplanting along the shore juveniles cultured in the nurseries. We propose an operational work-flow for optimizing: i) prioritization of restoration sites, ii) selection of donor sites and fertile material collection, iii) embryo culturing in the nurseries, iv) juvenile transport to the receiving sites and attachment on the rocky shore, according to bottom features and water depth, v) monitoring the restoration success. The aim is to maximize beneficial outcomes while minimizing costs in terms of time and resource allocation. Financial investments and stakeholder and community engagement, to change the awareness towards macroalgae and their role, are mandatory to achieve substantial restoration goals in marine ecosystems.