Seagrass-epibiont interactions in Mediterranean coastal lagoon ecosystems: biotic relationships in a changing environment

This thesis presents a comprehensive investigation of seagrass-epibiont interactions in Mediterranean coastal ecosystems, with a particular focus on the Stagnone of Marsala lagoon (Sicily, Italy). Through a multi-faceted approach combining global analysis, long-term ecological studies, experimental research, and field observations, the work provides crucial insights into the dynamics and resilience of these important marine habitats in the face of environmental change. The research begins with a global perspective on the ecological roles of epibionts and epiphytes in seagrass ecosystems, establishing a broad context for understanding these interactions. It then narrows its focus to the Mediterranean, presenting an in-depth examination of long-term ecological and structural changes in the Stagnone of Marsala lagoon. This case study reveals valuable information about the temporal dynamics of seagrass-dominated lagoon ecosystems and the factors driving changes in biodiversity and ecosystem structure. The thesis further explores the physiological responses of key species to environmental stressors through an investigation of the thermal performance and biotic interactions of Cymodocea nodosa, Paranemonia cinerea, and its symbiont. This experimental approach provides insights into the potential impacts of warming on important Mediterranean coastal species. Finally, the research examines the spatial and temporal dynamics of seagrass-epibiont interactions within the Stagnone of Marsala, combining field observations with ecological modeling to understand the factors influencing the distribution and abundance of epibionts on seagrasses in a lagoon setting.By integrating these diverse approaches, the thesis offers a holistic understanding of seagrass-epibiont ecology in the Mediterranean context, identifies critical knowledge gaps, and provides valuable insights for the conservation and management of these vital coastal ecosystems in an era of rapid environmental change.