Date of Award
Great Lakes Institute for Environmental Research
Biological sciences, Ballast water, Dormant eggs, Invasive species
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This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
The shipping industry has been a leading mechanism for introducing nonindigenous species (NIS) into aquatic ecosystems. Two different ballast water regulations, mid-ocean exchange (MOE) and saltwater flushing, were implemented as management practices to reduce the likelihood of new biological invasions in the Pacific, Great Lakes and Atlantic regions of Canada. There has, however, been no formal assessment of the efficacy of these regulations on invertebrates and their dormant eggs transported in the ballast sediment of ships, and current invasion risk posed by these taxa to different regions of Canada. To determine the potential risk of invasion associated with this vector after the implementation of ballast water regulations, I collected sediment samples from 135 ships entering the Pacific, Great Lakes and Atlantic ports and measured density and diversity of invertebrates as well as viability of their dormant eggs. To accurately identify dormant eggs I tested the application of DNA barcoding using mitochondrial cytochrome c oxidase subunit I and 16S rDNA. Further, I explored survival of invertebrate dormant eggs in collected ballast sediment over a one year period to determine if they accumulate inside of ballast tanks. Subsequently, to test efficacy of saltwater flushing, I compared the results of samples I collected in the Great Lakes with the results of similar samples collected prior to the implementation of saltwater flushing regulations, and to test efficacy of MOE I compared voyages with MOE vs. voyages without MOE. Finally, I compared vector strength in different regions in Canada. Overall results show DNA barcoding to be a rapid and accurate approach to identification of invertebrate dormant eggs, and the results indicate possible accumulation of dormant eggs of onychopods and bryozoans inside ballast tanks. This comparative analysis suggests that vector strength varies among different regions in Canada with the Atlantic region being under the highest risk. The two ballast management regulations differently influence the probability of introductions of NIS via dormant eggs. Finally, the amount of sediment is the single, most important factor for management of invertebrates and their dormant eggs in ballast sediment and should be treated beyond current ballast management regulations.
Briski, Elizabeta, "Invasion risk associated with invertebrates and their dormant stages in ships entering Canadian ports" (2011). Electronic Theses and Dissertations. 7885.