Abstract
The vast majority of the Posidonia oceanica seagrass meadows in the Mediterranean Sea are threatened and have demonstrated large-scale declines in the last several decades (Telesca et al. 2015). These delicate habitats provide services to humans and many other organisms, and are subject to stressors, such as reduced water clarity, climate change, and direct physical damage from boating activities (Telesca et al. 2015). Acquiring spatial information is an important tool for the conservation of these habitats and has been encouraged by international and national legislation and agreements. In Greece, however, such data is lacking and only a small portion (~ 8%) of the nation’s coastal regions have been mapped for P. oceanica (Telesca et al. 2015). To effectively conserve this valuable ecosystem, the distribution of P. oceanica must first be spatially identified, which will result in the ability to create informed management and conservation plans. P. oceanica distribution data was collected through kayak-based surveys (sidescan sonar) and satellite imagery (Sentinel-2A) around the island of Lipsi, Greece, in the southeast Aegean Sea, contributing to the overall mapping effort of P. oceanica in Greece and the Mediterranean. The sidescan sonar data was used as training data to optimize accuracy of satellite imagery mapping. This data was used to create habitat distribution models using ArcGIS, ReefMaster 2.0, and Sentinel Application Platform (SNAP) software. The results indicated substantial P. oceanica coverage around Lipsi island, and the methodology produced outcomes with adequate accuracy. The results of this study can continue to be used for further mapping, but may benefit from adjustments or improvements to the methodology. Overall, growing contributions and developments in high resolution habitat mapping in the Mediterranean may provide the necessary foundation for improved management, conservation, and enforcement actions not only in Greece, but potentially on a larger scale, as well.