The conservation of marine biodiversity requires tools capable of detecting functional alterations in trophic networks before they result in potentially irreversible structural changes in ecosystems. In this context, the study proposes an integrated index to assess the continuity of the ecological processes that support marine biodiversity, applicable within the framework of the Marine Strategy Framework Directive, with particular reference to Descriptor 4 on food-web integrity.

The index stems from the need to integrate results from different types of monitoring, providing an overall assessment of the functional status of trophic networks. The model is based on the joint analysis of physico-chemical, biological and ecotoxicological indicators, considering dissolved nutrients, chlorophyll-a, phytoplankton community structure, and the responses of organisms belonging to different trophic levels, such as Aliivibrio fischeri, Phaeodactylum tricornutum and Paracentrotus lividus.

The composition and diversity of phytoplankton make it possible to characterize the quality of the ecosystem’s food base, while ecotoxicological endpoints allow the identification of sub-lethal effects and biological alterations that may potentially propagate to higher trophic levels. In particular, the sensitivity of Paracentrotus lividus embryos and marine microalgae is useful for the early detection of stress conditions that are not always detectable through traditional environmental indicators alone.

The calculation model was developed using public datasets from Tuscany and was subsequently tested in different national geographic areas in order to assess its robustness and applicability across different environmental contexts.

The results show that the integrated approach describes the functional status of local trophic networks more reliably than individual indicators considered in isolation. The proposed index therefore provides a synthetic framework of the functional stability of the trophic network and represents a useful tool for defining intervention thresholds in the environmental monitoring of maritime works and dredging activities.