The decline of biodiversity and the degradation of marine habitats are pressing challenges in the current context of climate change and growing anthropogenic pressures.

Posidonia oceanica meadows are key ecosystems in the coastal waters of the Mediterranean, due to their ecological value and the multiple services they provide. However, these meadows face serious threats such as rising sea temperatures, increased sedimentation and turbidity, anchoring, and coastal development. Understanding their long-term responses is thus essential to develop effective, science-based conservation strategies.

The P. oceanica meadow off Lacco Ameno (northern Ischia Island, Italy) provides a remarkable case study. Systematically investigated since the 1980s, and integrated as site IT13-002-M in the Italian Long-Term Ecological Research Network (LTER-IT), this meadow has been the focus of a unique coastal benthic long-term monitoring. This monitoring integrates data on meadow structure (shoot density at a small spatial scale), spatial patterns of genetic diversity, plant phenology, and influence of environmental variables (mainly temperature), enabling the study of meadow dynamics, the detection of regression/recovery patterns, and the assessment of impacts due to climate changes and human activities.

Data recorded so far show clear signs of structural alterations increasing with time, including reduced shoot density and altered spatial integrity. Plant and animal associated communities are consequently impacted. This case study is an example of how continuous ecological observations reveal ecosystemic changes that, if analysed in time, may provide early warning signals of degradation and can be used to inform management and define strategies for targeted conservation efforts.