ALBERT

Description: Invasions by non-indigenous macroinvertebrates often cause ecological and economic problems, and commercial ships have been implicated as a principal mechanism for their dispersal. We explored the presence and species diversity of adult macroinvertebrates transported by transoceanic and coastal vessels arriving to ports on the Atlantic coast of Canada. We sampled 67 ballast tanks from 62 ships operating along discrete geographic pathways and tested whether mid-ocean exchange or voyage length affects the probability for translocation of macroinvertebrates. Additionally, we assessed the relationship between macroinvertebrate presence and the amount of sediment in ballast tanks. We document the presence of highly invasive European green crab (Carcinus maenas), mud crab (Rhithropanopeus harrisii), common periwinkle (Littorina littorea), soft shell clam (Mya arenaria) and blue mussel (Mytilus galloprovincialis) in ballast tanks of surveyed ships. Mid-ocean exchange did not affect macroinvertebrate occurrence, suggesting that current ballast water management regulations are ineffective for this taxonomic group. Viable individuals were recorded in vessels undertaking shorter voyages (average and maximum of 4.5 and 15 days, respectively) and presence was not related to the amount of sediment in tanks. While presence and densities of macroinvertebrates were low, invasion risk may nonetheless be significant during reproductive seasons owing to high fecundity of some taxa. The highest risk may be posed by decapods since gravid females may carry thousands to several million eggs per clutch, and after several weeks of brooding, two or more subsequent clutches may be fertilized by retained sperm from an earlier mating.

Description: The global transhipment of ballast water and associated flora and fauna by cargo vessels has increased dramatically in recent decades. Invertebrate species are frequently carried in ballast water and sediment, although identification of diapausing eggs can be extremely problematic. Here we test the application of DNA barcoding using mitochondrial cytochrome c oxidase subunit I and 16S rDNA to identify species from diapausing eggs collected in ballast sediment of ships. The accuracy of DNA barcoding identification was tested by comparing results from the molecular markers against each other, and by comparing barcoding results to traditional morphological identification of individuals hatched from diapausing eggs. Further, we explored two public genetic databases to determine the broader applicability of DNA barcodes. Of 289 diapausing eggs surveyed, sufficient DNA for barcoding was obtained from 96 individuals (33%). Unsuccessful DNA extractions from 67% of eggs in our study were most likely due to degraded condition of eggs. Of 96 eggs with successful DNA extraction, 61 (64%) were identified to species level, while 36% were identified to possible family/order level. Species level identifications were always consistent between methodologies. DNA barcoding was suitable for a wide range of taxa, including Branchiopoda, Copepoda, Rotifera, Bryozoa and Ascidia. Branchiopoda and Copepoda were respectively the best and worst represented groups in genetic databases. Though genetic databases remain incomplete, DNA barcoding resolved nearly double the number of species identified by traditional taxonomy (19 vs. 10). Notorious invaders are well represented in existing databases, rendering these NIS detectable using molecular methods. DNA barcoding provides a rapid and accurate approach to identification of invertebrate diapausing eggs that otherwise would be very difficult to identify.

Description: onindigenous species (NIS) cause global biotic homogenization and extinctions, with commercial shipping being a leading vector for spread of aquatic NIS. To reduce transport of NIS by ships, regulations requiring ballast water exchange (BWE) have been implemented by numerous countries. BWE appears to effectively reduce risk for freshwater ports, but provides only moderate protection of marine ports. In the near future, ships may be required to undertake ballast water treatment (BWT) to meet numeric performance standards, and BWE may be phased out of use. However, there are concerns that BWT systems may not operate reliably in fresh or turbid water, or both. Consequently, it has been proposed that BWE could be used in combination with BWT to maximize the positive benefits of both management strategies for protection of freshwater ports. We compared the biological efficacy of "BWE plus BWT" against "BWT alone" at a ballast water treatment experimental test facility. Our comparative evaluation showed that even though BWT alone significantly reduced abundances of all tested organism groups except total heterotrophic bacteria, the BWE plus BWT strategy significantly reduced abundances for all groups and furthermore resulted in significantly lower abundances of most groups when compared to BWT alone. Our study clearly demonstrates potential benefits of combining BWE with BWT to reduce invasion risk of freshwater organisms transported in ships' ballast water, and it should be of interest to policy makers and environmental managers.