An island under siege: origin, fate and impacts of non-indigenous aquatic fauna in coastal wetlands of a large Mediterranean island (Sardinia, Tyrrhenian Sea)
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Department of Life and Environmental Sciences, University of Cagliari, T. Fiorelli 1, Cagliari, CA - 09126, Italia
Coastal wetlands are hotspots for biological invasions, yet comprehensive assessments of non-indigenous species (NIS) across Mediterranean islands remain scarce. Here, we present the first systematic list and analysis of aquatic NIS in 31 coastal wetlands across Sardinia, Italy. We identified 34 aquatic NIS spanning multiple taxonomic groups, with Mollusca, Chordata, and Annelida accounting for 82% of the total records. We reveal a sharp rise in introductions since the 1970s, with most species introduced via aquaculture, shipping, or recreational pathways. Reported NIS are mostly of Indo-Pacific and North Atlantic origin, with estuaries and hydraulically interconnected wetlands hosting the greatest NIS diversity. The most frequent impact mechanisms of NIS include chemical, physical, or structural alteration of ecosystems (35%), followed by predation (26%) and competition (12%). Impacts severity varies a lot from major to minor, though several species lacked sufficient impact data. Spatial analyses revealed that Santa Gilla Lagoon and the Flumendosa River wetlands harbored the highest NIS richness. The blue crab Callinectes sapidus, the fish Gambusia holbrooki, and the polychaetae Ficopomatus enigmaticus were the most widespread, reflecting their high ecological adaptability. Using a novel Invasiveness Risk Score (IRS), integrating species mobility and establishment success, we ranked wetlands by their cumulative invasion risk. Santa Gilla and the Flumendosa river wetlands emerged as the highest-risk sites. While this study provides a baseline for invasion risk assessment, limitations include its regional scope, potential underreporting due to uneven research effort, and data gaps regarding species-specific ecological impacts.
This work has been developed within the framework of the project e.INS www.einsardinia.eu (Next Generation EU- PNRR - M4 C2 I1.5 CUP F53C22000430001.
Effetti del disturbo sui sistemi ecologici