Ecosistemi costieri di transizione: trasformazioni recenti, pressioni antropiche dirette e possibili impatti del cambiamento climatico

Coastal Transitional Ecosystems (CTE), such as estuaries and coastal lagoons, are characterized by composite environmental gradients (e.g., salinity and nutrients) which depend on several factors, such as water residence time and water renewal, riverine input and water mass exchange with the adjacent sea. Due to their characteristics and location, CTE are important as reproduction and nursery areas for several aquatic species, therefore playing a major role in maintaining the biodiversity and productivity of the adjacent marine and fluvial ecosystems. Because of their physical and biological structure, CTE act as natural filters between the land and the sea, which metabolize organic matter and nutrient of continental origin. However, CTE are also exposed to strong anthropogenic and natural pressures and impacts. In this paper, we present the recent evolution and the main physiographic and ecosystemic characteristics of Italian CTE, and identify the main pressures and impacts due to climate change (CC). Two main drivers are discussed: climate and environmental changes (e.g., salinization, oxygenation, confinement) which will likely cause changes in hydrological regime and habitats. From an ecological and biodiversity perspective, CC impacts may lead to changes in the metabolism of aquatic organisms and biotic interactions, with an increase of alien species, as well as cascade effects on food webs and biogeochemical cycles. In order to avoid negative repercussions on the local socio-economic systems, we suggest an adaptive management which include a monitoring system able to catch early signals of change and mitigation measures. The implementation of such as strategy should be bound to the implementation of decision support systems able to tackle changes with prevention, mitigation and adaptive planning measures.