<p><strong>Fig. 8.45.</strong> The zebra mussel (<em>Dreissena</em> <em>polymorpha</em>), an invasive freshwater species, was introduced to the North American Great Lakes through ballast water.</p>

Fig. 8.45. The zebra mussel (Dreissena polymorpha), an invasive freshwater species, was introduced to the North American Great Lakes through ballast water.

Image courtesy of US Geological Survey (USGS)