Figure 1.
Eurasian Ruffe presences from 1986 to 2011.
Ruffe data were obtained from the Nonindigenous Aquatic Species (NAS) database (USGS 2009).
Figure 2.
Zebra mussel presences from 1986 to 1992.
Zebra mussel data were obtained from the Nonindigenous Aquatic Species (NAS) database (USGS 2009).
Figure 3.
Mean number of discharging ship visits per year for each discharge location.
Means between 0 and 1 were rounded up to 1. Ship visit data were obtained for ships visiting U.S. ports between 2004 and 2010 from the National Ballast Information Clearinghouse (Smithsonian Environmental Research Center and USCG 2009).
Table 1.
Model runs conducted in backcasting the spread of Eurasian Ruffe and zebra mussels.
Table 2.
Ports identified as having received ballast water from killer shrimp and golden mussel infested locations.
Figure 4.
Backcasting results for Eurasian Ruffe and zebra mussel.
Graphs A–C illustrate the results for Eurasian Ruffe, and graphs D–E illustrate the results for zebra mussel. Graphs A and D depict the overall accuracy of the models tested. Graphs B and E depict the presence accuracy, or ability to correctly identify presences correctly. Graphs C and F display the absence accuracy, or ability to correctly identify absences correctly. Error bars represent standard deviations.
Figure 5.
Eurasian Ruffe prediction results.
The maps illustrate the results of the Eurasian Ruffe prediction models with Figure 5A dispersal distance = 10-km and probability of infestation = 0.01 and Figure 5B dispersal distance = 25-km and probability of infestation = 0.0001. The maps depict the next likely invaded locations from estimated presences.
Table 3.
Prediction results for the top 25 U.S. ports receiving the most visits by de-ballasting ships.
Figure 6.
Killer shrimp prediction results.
The maps illustrate the results of the killer shrimp prediction models with probability of infestation = 0.50 and no dispersal distance. Invasions were started from Figure 6A Duluth, Minnesota, USA and Figure 6B Toledo, Ohio, USA. The maps depict the next likely invaded locations from current observed presences.
Figure 7.
Golden mussel prediction results.
The maps illustrate the results of the golden mussel prediction models with dispersal distance = 20-km and probability of infestation = 0.50. Invasions were started from Figure 7A Duluth, Minnesota, USA and Figure7B Bay City, Michigan, USA. The maps depict the next likely invaded locations from estimated presences.