Using Biophysical modelling and marine connectivity to assess the risk of natural dispersal of non-indigenous species to comply with the Ballast Water Management Convention

Abstract

Abstract Marine Non-Indigenous Species (NIS) are considered a major threat to biodiversity as well as ecosystem functioning and services worldwide, and ballast water has been considered one of the main pathways for transferring NIS between regions. The Ballast Water Management Convention (BWMC) aims at reducing the risk of both primary and secondary introduction of NIS via take-up and discharge of ballast water by de facto requirements for ballast water on-board treatment. However, the BWMC allows for national authorities to grant exemptions from this requirement for shipping routes operating within a geographical area, known as a Same-Risk-Area (SRA). An SRA can be established in areas where a risk assessment (RA) concludes a low risk of NIS spreading via ballast water relative to their predicted natural dispersal. According to the BWMC this risk assessment should be based on modelling of the natural dispersal of NIS, but to date no standard procedures have been proposed. In this paper we present a methodology for how to apply biophysical modelling and analyses of marine connectivity of NIS as a basis for SRA RA and delineation. This work is intended to provide a standardised procedure and a benchmark for future SRA studies.