In-water and dry-dock hull fouling assessments reveal high risk for regional translocation of nonindigenous species in the southwestern Atlantic

To assess the potential of domestic traffic for the regional spread of nonindigenous species (NIS), we surveyed the hull of an oceanographic vessel serving routes in the southwestern Atlantic and Southern Ocean. Sampling was performed while the vessel was in the water and in dry-dock in the Port of Mar del Plata, Argentina. We found 120 taxa belonging to 14 different invertebrate groups, including 53 species, 47 morphospecies, and 20 taxa identified at higher taxonomic levels. Ten of these species have not been reported for the Port of Mar del Plata and adjacent areas prior to the present study, and eight are new records for the entire Argentine coast. While both in-water and dry-dock sampling allowed for the detection of native, non-native, and cryptogenic fauna, more samples and species were obtained in dry-dock. Dry-dock richness estimates amounted to up to ~ 110 hull fouling species. Despite specific logistic challenges, dry-dock sampling should be considered by managers assessing vector strength due to its greater species detection power. The present results highlight the potential for domestic vessel spread of hull fouling marine NIS, and pinpoint likely future additions to the non-native fauna inventory in the southwestern Atlantic.