Network Centrality for Identifying High Priority Ports for Aquatic Invasive Species Management

Session: 01. - Disease, Parasites, and Pathogens of the Great Lakes and Freshwater Ecosystems

Jake Kvistad, Central Michigan University, [email protected]
Jonathan Bossenbroek, University of Toledo, [email protected]
Lindsay Chadderton, The Nature Conservancy, [email protected]

Abstract

Ballast water is a major vector for aquatic invasive species (AIS) introduction and spread on the Laurentian Great Lakes.  Understanding patterns of domestic ballast water exchanges on the Great Lakes will aid in designing effective ballast water management plans.  Graph theoretic analysis techniques were used to identify central ports in a network of 151 Great Lakes ports that should be considered for focused management efforts.  Twenty-seven ports which scored high for several network centrality metrics were identified.  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 range of management scenarios from “no management” to “100% management”.  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%.  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. 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.        

1. Keyword
invasive species

2. Keyword
ballast

3. Keyword
modeling