Posidonia oceanica meadows play several ecological roles and provide essential ecosystem services in the Mediterranean Sea. However, increasing anthropogenic pressures and climate-driven stressors are accelerating their decline, highlighting the need for more sensitive and integrative monitoring approaches. Microbial communities associated with seagrass regulate key biogeochemical processes and contribute to host resistance and resilience. Due to their rapid response to environmental changes, seagrass microbiomes can provide early indicators of ecosystem degradation.

The METIS PhD project aims to identify microbial descriptors of the health of Posidonia oceanica meadows and provide a new predictive tool for the management and conservation of coastal marine ecosystems. The project aims to answer three questions: i) how do bacterial communities vary along gradients of thermal stress and anthropogenic impact? ii) which taxa and functional pathways are most sensitive to disturbance? and iii) can specific microbial signatures reliably indicate ecological status? To address these questions, three objectives are defined: i) characterize bacterial diversity and composition associated with leaves and sediments; ii) identify changes in community structure and functional traits related to the biogeochemical nitrogen cycling, which is critical for seagrass survival and iii) link microbial patterns with environmental conditions, host status and epiphytic community. Sampling will be conducted seasonally at three sites along the Calabrian coasts, representing a gradient of anthropic pressure: a low-impact site (Cirella), a moderately impacted site (Capo Rizzuto), and a highly impacted site (Calopezzati). Microbial communities will be characterized using an integrated approach combining traditional and innovative molecular techniques, including DNA metabarcoding and eDNA. The resulting data will be correlated with environmental parameters to assess thermal stress and anthropogenic impacts.

Developing this integrated approach, METIS aims to identify microbial descriptors of seagrass health and contribute to the development of innovative monitoring tools, such as a microbial-based index, to support conservation and management strategies.