Mediterranean marine forests formed by Fucales are key coastal ecosystems supporting high levels of biodiversity.

Cystoseira compressa (Esper) Gerloff & Nizamuddin 1975 habitats are recognised as highly relevant within the framework of the Nature Restoration Regulation, as the enhancement of its distribution can directly contribute to improving habitat quality, biodiversity, and ecological connectivity, thereby contributing to achieve restoration targets in Mediterranean coastal ecosystems.

One of the major challenges for its recovery through ex-situ outplanting is the limited and highly seasonal availability of fertile material, constraining the transition from small-scale interventions to scalable restoration efforts.

Can we anticipate the reproductive period to control and enhance reproductive output? In this study we tested an innovative, restoration-oriented approach for C. compressa: by manipulating temperature and photoperiod, we simulated an accelerated seasonal transition to induce earlier maturation under controlled conditions. In addition, we assessed whether periodic emersion, mimicking natural low-tide exposure, acts as a key ecological trigger to enhance reproductive responses in intertidal species.

The controlled experiment started three months before their reproductive timeframe: we compared natural vs. accelerated scenarios, crossed with emersion treatments, while monitoring donor populations along the Ligurian coast (NW Mediterranean, Italy). We tracked maturity, fertility and gamete release, integrating these measurements with photosynthetic and metabolic performance to elucidate the physiological mechanisms linking environmental cues to fertility.

By identifying key drivers of reproductive outputs, this work provides a physiological and experimental framework to optimize timing and efficiency of ex-situ cultivation and outplanting. Our findings contribute to the development of scalable, climate-informed restoration strategies for Mediterranean macroalgal forests, supporting active restoration interventions.