Zooplankton communities in Canadian ports: Composition, relative abundance and occurrence of invasive species

Aquatic invasive species (AIS) cause significant damage to their host ecosystems, altering habitats and native species dynamics. Initiatives to improve our understanding and management of leading stressors of ecosystems like AIS are being developed through collaborative research within the Canadian Aquatic Invasive Species Network (CAISN). This thesis was developed in the context of preventing or reducing dispersal of AIS, facilitating early detection tools to rapidly and effectively identify AIS. In fact, one of the priorities of CAISN aimed at comparing results of several different approaches using traditional and molecular taxonomy to support the development of a national surveillance program. The overarching objective of this thesis was to identify zooplankton species from 16 "high risk ports" based on shipping traffic and ballast water discharges across Canada, four in each of the four coastal regions (Atlantic, Pacific, Arctic, Great Lakes). Zooplankton collections were conducted by four different CAISN teams, one for each region. 250μm mesh plankton net was used by means of oblique tows during summer periods of 2011 and 2012. The zooplankton was immediately preserved in 95% ethanol and fractioned for parallel projects including traditional and molecular taxonomy. A target taxonomic group (crustaceans) with a global invasion history was studied using a dissecting microscopic. As a result, approximately 14,400 specimens and 86 different taxa, 81 of which were crustaceans, have been identified to their lowest taxonomic level and reference list are provided. Among those, 13 NIS were identified, including Carcinus maenas, the green crab and Cercopagis pengoi, the fishhook waterflea. The number of NIS identified was fairly conservative considering the number of known NIS in each coastal region of Canada. Ordination tests were used to assess the similarities and dissimilarities among ports and regions, and regression analyses were used to assess the relationship between propagule pressure and NIS occurrence. Considerable variation was found among and within regions and significant relationships (albeit modest) between propagule pressure (measured as ship traffic) and the number of NIS were found. Overall, the Artic and Atlantic Oceans were the most different and the Pacific and Atlantic Oceans were the most similar in terms of zooplankton composition. No significant relationships existed when the relative abundance of zooplankton were analysed but significant relationships existed when the number of NIS were analyzed. A separate analysis focused on the comparison among samples and ports of the Atlantic region. A first inventory list of plankton communities associated to ports in this region was developed and ordination analyses were used to assess their level of similarity. Overall, Port Hawkesbury and Halifax Harbour were the most similar and Bayside and Sept-Iles were the most different in terms of zooplankton composition. The data from the 16 ports included in this thesis will be deposited in a National AIS database providing baseline information to support future policy development, and studies on vectors and environmental assessments.