Thursday, June 13
The Great Lakes have a long history of biological invasions mediated by human introductions. This presentation will explore the nature of these invasions, including different phases during which invasions rates seemingly changed as did the taxonomic composition of the invaders. These patterns relate directly to the prevailing vectors of introduction. During the latter 40 years of the 21st century, international shipping dominated introduction vectors, as vessels transported and discharged large volumes of untreated ballast water into the system. Policy changes enacted by the USA and Canada in the early 1990s and mid 2000s were intended to reduce invasion rates by requiring vessels to discharge only oceanic ballast water into the system. Invasions continued to be discovered well after the initial effort, though reported introductions appear to have declined. Four recent discoveries in Lake Erie—the copepod Thermocyclops crassus (2016), the rotifer Brachionus leydigii (2017), the cladoceran Diaphanosoma fluviatile (2108) and the Mesocyclops pehpeiensis (2018)—suggest that the system continues to sustain new invasions. While the vector for these introductions is not known, one possibility is that ballast water exchange may not have been as effective as desired. However, time lags between introduction and discovery, and development of new diagnostic tools for species detection, make it very difficult to determine when these newly found invaders actually colonized the system. Implementation of the International Maritime Organization’s ballast water convention will eventually require all large foreign vessels (i.e., those thought responsible for Great Lakes invasions) to treat ballast water to ensure they only release low densities of viable organisms. This should reduce invasions as discharged organisms would have reduced propagule pressure, although species richness is not addressed and might not be affected. It is essential to curtail invasions of the Great Lakes considering that they in turn serve as the source for many inland lake invasions.
HUGH MACISAAC is a professor and senior Canada Research Chair in Aquatic Invasive Species at the Great Lakes Institute for Environmental Research, University of Windsor (Windsor ON). From 2006 to 2016 he served as director of the NSERC Canadian Aquatic Invasive Species Network. Hugh’s research includes collaborative investigations with European researchers working on the Baltic, North, Black, and Caspian Seas. Recently, he became a Distinguished Research Fellow of the Sino-Canada Research Center on Plateau Lakes, Yunnan University, China. His editorships include a period as an associate editor of the Journal of Aquatic Ecosystem Health and Diversity and Distributions. He is a former member of the Great Lakes Invasive Species Task Force and the International Joint Commission’s Science Advisory Board. Hugh has authored over 207 peer-reviewed papers and books and was honored with the Frank H. Rigler Award from the Society of Canadian Limnologists and the Premier’s Research Excellence Award.
Hugh is interested in a variety of issues pertaining to invasive species. His interests include analyses of pathways and vectors of introduction, including risk assessment, genetic characterization and evolution, impacts and mitigation, and, more recently, identifying factors affecting establishment success. He developed conceptual and empirical models describing how alien invasive species colonize the Great Lakes and other aquatic ecosystems. Recent work addresses use of genetic markers to identify source and destination patterns and problems that may arise with this approach. He also uses a variety of approaches to predict impact of invasive species. Hugh earned a B.Sc. from the University of Windsor, M.Sc. from the University of Toronto, and a Ph.D. from Dartmouth College.
