Marine Invasion in the Era of Shipping Expansion and Regulation

Shipping is a primary vector for the introduction of non-indigenous species (NIS) into marine ecosystems. Technological advancements and regulatory frameworks, such as the Ballast Water Management (BWM) Convention, have led to the widespread adoption of ballast water management systems. However, growing global shipping intensity along existing routes increases the volume of ballast water discharged and the potential for NIS introductions associated with more shipping arrivals. Moreover, gaps in the compliance of BWM persist, adding uncertainty to future NIS introduction risks. A key contribution of this study is quantifying how realistic compliance levels—not idealized full adherence—interact with global shipping growth to shape future NIS introduction risks. By developing the first globally integrated framework that couples long-term, machine-learning–enhanced projections and compliance-explicit NIS risk modeling, we show that even under widespread adoption of treatment technologies, growing shipping traffic can amplify NIS introduction risk to between 94% and 900% of the 2018 level across Shared Socioeconomic Pathways with current compliance gaps. These results emphasize the importance of compliance and suggest that current BWM regulations may be insufficient to counteract the impacts of global shipping growth, highlighting the need for more stringent or adaptive regulatory frameworks to mitigate future ecological risks.