Title

Modeling ships' ballast water as invasion threats to the Great Lakes

Author ORCID Identifier

http://orcid.org/0000-0001-7264-732X

Document Type

Article

Publication Date

2002

Publication Title

Canadian Journal of Fisheries and Aquatic Sciences

Volume

59

Issue

7

First Page

1245

Last Page

1256

DOI

10.1139/f02-090

Abstract

The spread of nonindigenous species (NIS) in aquatic ecosystems provides an opportunity to develop new perspectives on the invasion process. In this paper we review existing invasion models, most of which were developed to describe invasions of terrestrial habitats, and propose an alternative that explores long-distance invasions mediated by discharge of contaminated ballast water by ships inbound to the Great Lakes. Based on current knowledge of shipping traffic to the Great Lakes, our model predicts that mid-ocean exchange of ballast water lowers propagule delivery by approximately three to four orders of magnitude relative to unexchanged ballast water. Propagule pressure of individual ships that enter the Great Lakes loaded with cargo and that declare "no ballast on board" (NOBOB) is typically one to two orders of magnitude higher than that of vessels that exchange ballast. Because NOBOB vessels dominate (∼90%) inbound traffic into the Great Lakes, these vessels collectively appear to pose the greatest risk of new introductions, even though their individual risks are low.

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