Global ports are hubs for industrial activities and trade. In consequence, sediments and water in these areas are often contaminated by an array of chemicals. Sediments also harbour both living, active stages and various diapausing or resting stages of biota. International shipping activities move sediments containing these biotic stages around the world, possibly resulting in biological contamination of port areas. In this study we assess active and resting stages of invertebrates contained in ballast sediment of transoceanic vessels operating on the North American Great Lakes to determine if ballast sediments could serve as a vector of nonindigenous species. A cumulative total of 160 species were identified, including 22 freshwater species not recorded from the Great Lakes! basin. Hatch rates of resting stages are affected by thermal conditions, thereby affecting invasion success. Total abundance and species diversity of freshwater invertebrate animals hatched from resting stages were negatively related to salinity of residual water in ballast tanks from which the sediments were obtained, suggesting that ballasting a shallow lens of saltwater may provide some degree of risk reduction from freshwater species invasions.

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