# Mapping Subtidal Marine Forests in the Mediterranean Sea Using Copernicus Contributing Mission
## 5 Conclusions  
Mapping _Cystoseira_ s.l. forests using satellite remote sensing is feasible but requires specific conditions and careful selection of the sites for the replication of the current developments. While several Earth observation platforms offer free or commercial data, sensor selection must be guided by the ecological and spatial characteristics of the target habitat, here the _Cystoseira_ s.l. forests which have been mapped with high accuracy using PlanetLabs imagery. This study outlines a checklist for _Cystoseira_ forest mapping and emphasizes the need for standardized protocols across the Mediterranean Sea, where this habitat still occurs.  
Designing fiducial sites aligned with the pixel size of the selected sensors is essential for long-term monitoring, as such settings will benefit the fractional cover analysis. Establishing these reference sites will facilitate systematic data collection, change detection, and integration of satellite and field observations at matching spatial scales. The availability of level 3 aquatic reflectance products suitable for subtidal seascape mapping is crucial for accurate spatiotemporal analysis and monitoring of key habitats.  
European regulations mandate precise information on habitat distribution and extent to inform restoration strategies, assess carbon stocks, and monitor ecosystem health. High-resolution satellite data, when combined with sound ecological knowledge and field validation, can support member states in meeting these requirements transparently and cost-effectively. This study provides a foundation for advancing satellite-based mapping of _Cystoseira_ forests. Broader adoption and further refinement of this approach will enhance its operational potential, supporting the conservation and management of these critical habitats.  
The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/rs17142398/s1](https://www.mdpi.com/article/10.3390/rs17142398/s1)]([https://www.mdpi.com/article/10.3390/rs17142398/s1](https://www.mdpi.com/article/10.3390/rs17142398/s1)): S1: _Cystoseira_ s.l. view from Skyros island during September 2024 mission, S2: Fraction maps of the seascape habitats.  
Conceptualization, D.P. and S.K.; methodology, D.P.; validation, D.P.; formal analysis, D.P.; data curation, D.P.; writing--original draft preparation, D.P.; writing--review and editing, D.P. and S.K.; visualization, D.P.; project administration, D.P. and S.K.; funding acquisition, D.P. and S.K. All authors have read and agreed to the published version of the manuscript.  
This study was supported by the project NemoTools (next-generation monitoring and mapping tools to assess marine ecosystems and biodiversity) carried out within the framework of the National Recovery and Resilience Plan Greece 2.0, funded by the European Union--NextGenerationEU (implementation body: HFRI)--project No: 16035. DP was supported by the European Union's Horizon Europe research and innovation program (project C-BLUES 101137844). Views and opinions expressed are, however, those of the beneficiaries only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them.  
The products, in the format of GeoTIFF, are available upon request.  
A special thanks to Planet and the Education & Research program ([[https://www.planet.com/markets/education-and-research/](https://www.planet.com/markets/education-and-research/)]([https://www.planet.com/markets/education-and-research/](https://www.planet.com/markets/education-and-research/)), accessed on 20 May 2025) for providing the PlanetScope images for this study.  
The authors declare no conflicts of interest.