The introduction of non-native species can lead to biodiversity loss and disruption of ecological functions, with cascading impacts on ecosystem services, especially in intensively exploited socio-ecological systems. Among these species, the Atlantic blue crab (Callinectes sapidus) has gained widespread attention due to its recent invasion of the Northern Adriatic coast since 2023.

This study aims to document the upstream expansion of the blue crab along the Po River and assess its impact on provisioning services in the Sacca di Goro lagoon, an internationally recognized brackish coastal system known for aquaculture. Field observations along the river were obtained through targeted sampling and reports from local anglers. Impacts on provisioning services (i.e. fishing and aquaculture) were quantified by comparing 2023–2024 data with previous years. Revenues from blue crab sales and associated disposal costs were also assessed to estimate the net economic impact.

The results showed that male blue crabs migrated over 100 km upstream. This unprecedented dispersal capacity has not been observed in other invaded regions and is likely due to overcrowding in the Po Delta lagoons and the absence of predators of large sizes. Fishing impacts primarily involved grey mullets (Liza ramada, Liza aurata), the sand smelt (Atherina boyeri), the golden shrimps (Penaeus spp) and native crab (Carcinus aestuarii). Clam (Ruditapes philippinarum) aquaculture biomass dropped by 71.36% in 2024 compared to the 2013–2023 average, resulting in a monetary loss of 51.2 million € yr⁻¹. Net revenue from blue crab harvesting was positive in 2023 (+408,000 € yr⁻¹) but turned negative in 2024 (-714,000 € yr⁻¹) due to rising disposal costs and declining market value.

To date, not only are the revenues from blue crab sales negligible, but they are also outweighed by the high costs of disposal. This case highlights how invasive species can profoundly alter ecosystem service flows, threatening both ecological balance and economic sustainability.