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Tuesday, April 10 • 11:00am - 11:15am
INVASIVE SPECIES: Network Centrality as a Method for Identifying High Priority Ports for Aquatic Invasive Species Management on the Laurentian Great Lakes

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AUTHORS: Jake Kvistad*, University of Toledo; Jonathan Bossenbroek, University of Toledo; Lindsay Chadderton, The Nature Conservancy

ABSTRACT: Ballast water is a major vector for aquatic invasive species (AIS) introduction and spread on the Laurentian Great Lakes. Understanding inter-lake patterns of domestic ballast water exchanges on the Great Lakes will aid in designing effective ballast water management plans that can either slow or prohibit secondary spread of potentially harmful AIS. Graph theoretic analysis techniques were used to identify central ports in a network of 151 Great Lakes ports that should be considered for increased management efforts. Twenty-seven ports which scored high for several network centrality metrics were identified for hypothetical management focus. Aquatic invasive species secondary spread patterns were simulated for 1000 trials of both 3 and 10 time-steps using a stochastic model of basin-wide ballast water exchanges between ports under a continuum of management scenarios ranging from “no management” to “100% management” at 10% incremental increases of potential management effort. Infestation probabilities resulting from 10 time-steps of simulated spread in both 100% managed and unmanaged scenarios differed significantly (p < 0.05), and average basin-wide infestation probabilities reduced by 75.6%. Average basin-wide infestation probabilities after 10 time-steps decreased exponentially as management effort increased, with the greatest reductions in infestation probabilities occurring between 70 and 100% management effort. Average basin-wide infestation probabilities after 3 time-steps decreased approximately linearly. Differences in average infestation probabilities after 3 time-steps 10 time-steps across management scenarios suggest that management loses effectiveness the longer an organism is allowed to spread. Some ports within the Great Lakes basin, specifically in northern Lakes Michigan and Huron, did not show any appreciable reduction in infestation probabilities, suggesting additional scrutiny is required for AIS management in these areas. These simulations show that targeted management at central ports within the Great Lakes basin have the potential to dramatically reduce and slow AIS secondary spread through ballast water exchange.

Tuesday April 10, 2018 11:00am - 11:15am CDT
Spire Parlor

Attendees (6)