Ballast tank biofilms resist water exchange but distribute dominant species

Shipping in the Laurentian Great Lakes includes numerous “lakers” and a group of international vessels arriving via the St. Lawrence Seaway. It was expected that ballast water exchange techniques, or eventual volumetric ballast water treatment, would eliminate the risks of transfer of ballast tank nuisance aquatic and aerosol organisms to Great Lakes ports and other parts of the world. New and important information is that ballast water exchanges and current ballast water treatments are not effective in destroying biofilms on tank walls and sediments that provide living micro-organisms for new biofilms and bioaerosols. Our Ballast Organic Biofilm (BOB) studies of around-the-world ships associated with multiple ballasting events in the continuous presence of BOB samplers showed that dominant microorganisms are acquired and persist, and can be spontaneously transferred to fresh surfaces and also delivered as bioaerosols from discharged ballast water plumes. This communication uses such studies to infer that a port-based ballast tank water-exchange and cleaning procedure can mitigate such biofilm risks to health and existing biodiversity. A useful site would be the Port of Buffalo, just opposite the Welland Canal entrance for international shipping to the upper Great Lakes.