Ballast sediment-mediated transport of non-indigenous species of dinoflagellates on the East Coast of Canada

The presence and abundance of non-indigenous, and/or harmful or toxic dinoflagellate species in ballast sediments is examined for 65 cargo ships visiting ports on the East coast of Canada, as part of the Canadian Aquatic Invasive Species Network (CAISN). Ships visiting several ports in the provinces of Quebec, New Brunswick and Nova Scotia were sampled during three summers (2007, 2008, 2009). These ships included general cargo, bulk carriers and oil tankers, and they represented two major categories: ships undergoing continental and trans-oceanic voyages. Our results show that potentially viable dinoflagellate cysts are present in ballast sediments of all the categories of ships arriving to the East coast of Canada. The concentrations of all types of dinoflagellate cysts are higher in continental ships without ballast water exchange (BWE) than in ships with BWE, including trans-oceanic ships, which presented lower risk of introduction of non-indigenous species (NIS) of dinoflagellates. We identified 14 non-indigenous dinoflagellate cyst species not yet reported from Canadian coasts, including 4 potentially harmful/toxic species, representing a possibility of new introductions. These introductions of toxic NIS could represent a problem for marine Canadian ecosystems, with potentially disastrous effects on fish communities, aquaculture and human health. This potential risk may be facilitated with climate change.