Risk assessment of biological invasion via ballast water in an Amazonian river port

The International Convention for the Control and Management of Ship's Ballast Water and Sediments plays a crucial role in preserving aquatic ecosystems by aiming to control the introduction of invasive alien species -IAS through ship's ballast water.By exempting ships operating on specific routes from key regulations (D-1 and D-2), the convention allows for a more flexible approach, considering the risk of IES introduction.Risk assessment plays a fundamental role in this context, as it enables the identification and prioritization of ships with a higher likelihood of introducing invasive species into vulnerable ecosystems.We identified risk scenarios as a way to prioritize ships more likely to introduce IAS and for the potential granting of exemptions to ships discharging ballast water at the port of Santarm, in the Tapajs River, Brazil.Risk assessment (RA) included an analysis of environmental similarity followed by a species-specific analysis.In the first step, we identified the environmental similarity between donor and recipient ballast water ports.In the second step, we quantified the species present in estuarine and maritime ports capable of establishing in the Tapajs River.Ships discharged 3,650,018.6tonnes of ballast water at the port of Santarm during the analysis period (2014-2019).Among 74 ports of origin, 6 are riverine, 15 estuarine and 53 maritime.Ships from the estuarine ports of Rotterdam, Cabedelo, Aughinish, Montoir, and maritime ports in the Mediterranean and the West Atlantic pose a high risk of introducing IAS into the Tapajs, therefore, they cannot receive exemption and should be prioritised for inspection.This work presents the first RA for the introduction of IAS in an Amazonian port via ballast water and provides information for the development of effective strategies for the prevention and control of biological invasions in the Amazon rivers.