Comparative analysis of two marine food webs in the Ionian Sea (Central Mediterranean Sea): a standardization-based approach

Characterizing marine food web responses to cumulative anthropogenic and environmental pressures is crucial for advancing ecosystem-based management strategies. This study presents a comparative food web analysis between the fishery exploited Gulf of Taranto (GoT), and the spatially protected Gulf of Corinth (GoC) using standardized 23- functional group Ecopath models. Ecosystem indicators revealed distinct structural patterns: the GoC exhibited a higher System Omnivory Index (SOI = 0.23), indicating a complex, web-like feeding structure, whereas the GoT showed a lower SOI (0.19), a higher Connectance Index (CI = 0.48), and a lower production-to-respiration ratio (TPP/TR = 1.36), signaling a more specialized energy canalization. Furthermore, keystoneness indices highlighted a major functional reorganization. In the GoC, natural top-down regulation remains preserved, with demersal apex predators emerging as primary keystone components. Conversely, in the GoT the keystone roles are represented by mid-trophic intermediate consumers as benthopelagic cephalopods and demersal nonpiscivorous fish and marine mammals. Ultimately, this comparative framework demonstrates the reliability of standardized network indicators as quantitative, robust workflow for marine environmental monitoring and spatial planning.