Invertebrates and their dormant eggs transported in ballast sediments of ships arriving to the Canadian coasts and the Laurentian Great Lakes

Abstract

The most effective strategy for managing nonindigenous species (NIS) is through prevention of their transport via regulation of introduction vectors. We sampled 135 ships arriving to three different regions of Canada to assess abundance and species richness of invertebrates and their dormant eggs transported in ballast sediments. By sampling ships that followed particular pathways, we were able to compare vector strength to different regions, the invasion risk of transoceanic vs. coastal vessels, and the effect of midocean exchange, length of voyage, and amount of sediment on the richness and abundance of species inside ballast tanks. Although standardized ballast management regulations have been implemented across Canada, the resulting invasion risk is not uniform across regions. Ships arriving to the Atlantic region carried a greater sediment load with correspondingly higher abundance and species richness than those arriving to the Pacific and Great Lakes regions. Abundance and species richness of invertebrates and their dormant eggs associated with transoceanic ships did not differ from that of ships operating along coastal areas of North America. Similarly, midocean exchange did not reduce either abundance or species richness of invertebrate dormant eggs in ships. Finally, the length of voyage did not influence taxonomic composition or abundance of invertebrate dormant eggs but was directly related to survival of active macroinvertebrates. Ballast sediments could introduce new NIS to some regions of Canada despite requirements to manage ships' ballast by midocean exchange. Minimizing sediment accumulation may be the only effective management option for this vector.

Using the critical salinity (S crit) concept to predict invasion potential of the anemone Diadumene lineata in the Baltic Sea

“…Another possibility is the introduction via ballast water. Unidentified actiniaria have been found in ship ballast tanks before (Briski et al 2011). Especially for locations nearby Kiel Canal, where deballasting water is a typical ship operation before entering the lock, this could be a significant vector.…”

Dormancy in metacommunities

“…Dormancy can also affect the distribution of species across the metacommunity by 258 modifying colonization rates and patch invasibility (Gillespie et al 2012;Gioria et al 2012) as illustrated, for example, by the spread of exotic species by the transport of dormant propagules 260 (e.g., in the ballast water of ships, Briski et al 2011). Dormancy could allow colonizers that arrive during unfavorable environmental conditions to persist until conditions improve, 262 increasing the probability of successful establishment (Gioria et al 2012).…”

Separation strategies for invertebrate dormant stages contained in sediment

“…The ability to determine invasion risk based on identification, abundance and viability of transported taxa can be extremely problematic (Bailey et al 2003, 2005, Briski et al 2010, 2011a. Recent studies assessing invasion risk have used 2 different methods, the colloidal silica sol Ludox HS 40 and sugar flotation (i.e.…”

“…Recent studies assessing invasion risk have used 2 different methods, the colloidal silica sol Ludox HS 40 and sugar flotation (i.e. the Onbé-Marcus method; Onbé 1978, Marcus 1990, for separation of dormant stages from sediment (Bailey et al 2003, Duggan et al 2006, Briski et al 2010, 2011a; the assumptions were that colloidal silica sol Ludox HS 40 separates biota and dormant stages from sediment more effectively than does sugar flotation, providing more accurate abundance estimates (Persmark et al 1992, Burgess 2001, but reduces hatching rates, thereby underestimating the viability of taxa (Schwing hamer 1981). Furthermore, different methods may produce an array of morphological damages on separated organisms, limiting an accurate morphological identification.…”