Deltaic transitional lagoons are highly productive and ecologically valuable coastal ecosystems, providing multiple ecosystem services. However, they are vulnerable to anthropogenic pressures such as channelization, hydrological alterations and marine intrusion, leading to habitat loss and degradation of ecosystem functions. The study aims to evaluate the effectiveness of hydrological restoration and native aquatic vegetation recovery as a nature-based solution (NbS) to improve ecosystem condition and service provision in the Valle di Gorino lagoon, located in the Po Delta, Italy.

In this complex ecosystem, progressive marine intrusion since the 1990s, driven by hydraulic modifications, caused salinization of inner lagoon areas and loss of characteristic habitats. Between 2016 and 2020, the implementation of hydraulic interventions to restore natural salinity gradients were carried out, and the outcomes in terms of water quality and ecological functioning were experimentally measured.

Monitoring before, during, and after implementation showed that freshwater inputs controlled salinity dynamics. Despite higher nutrient loads deriving from the freshwater intake, eutrophic conditions did not intensify. Since 2016, anoxic and dystrophic events, one occurring with high frequency, have not occurred, as indicated by stable dissolved oxygen. Concurrently, emergent vegetation (Phragmites australis) recovered, while recently established halophytic species regressed.

The restoration of low-salinity conditions and native vegetation enhanced the lagoon’s capacity to regulate nutrients and mitigate eutrophication, improving regulating services, habitat provision and ecosystem resilience. This case demonstrates that combining hydrological management with vegetation recovery is an effective NbS to sustain ecosystem services in deltaic transitional wetlands under anthropogenic pressure.