01105179

Component

http://onlinepubs.trb.org...nepubs/sr/sr291_kelly2.pdf

The Laurentian Great Lakes have an extensive history of human-mediated biological invasions, beginning at least 150 years ago. During this interval, a number of transitions have occurred both with respect to the types of non-indigenous species (NIS) that established and in the mechanisms that vectored them to the lakes. The number of reported invaders established in the lakes has increased from the early nineteenth century to modern times. Fish and plants were the most common invaders prior to the 20th century, with most introductions resulting from human releases. Algae and invertebrates became more common invaders to the lakes after transoceanic shipping converted to use of liquid ballast prior to 1900. Although the ship ballast vector appears to have become dominant during much of the 20th century, alternative vectors have received less attention. The author reassessed the vectors and pathways for all species that unequivocally invaded the Great Lakes since the expanded seaway was opened in 1959. He utilized a conservative approach that required that NIS meet at least 3 of the ten criteria proposed for introduced status by Chapman and Carlton (1991). Fifty-nine species were confirmed as NIS, with an additional 21 species (mainly algae) classified as cryptogenic. Of the confirmed NIS, ships' ballast water was the leading vector for 55% of species, and remained the dominant (47% of species) when alternative vectors were prioritized. Deliberate releases, unauthorized introductions, range extensions, hull fouling and recreational boating were all of lesser importance (<10% of species). A clear vector could not be established for 11% of NIS. Eurasia was the source of 67% of established NIS, followed by North America (14%) and Palearctic/Nearctic (7%). Europe was the source of 94% of ballast-mediated invasions, including 15 species from western and central Europe, 12 from the Ponto-Caspian region, and 3 from the Baltic Sea. Invasions continued to be reported in the basin as recently as 2006, despite implementation of regulations requiring mandatory ballast water exchange (BWE) in 1993. Determination of the efficacy of BWE is encumbered by time lags between introduction and reports of establishment, and by possible contributions by similar vectors, including no-ballast-on-board and coastal domestic shipping, which could introduce NIS.

This paper was commissioned by the Committee on the St. Lawrence Seaway: Options to Eliminate Introduction of Nonindigenous Species into the Great Lakes, Phase 2, which was convened by the Transportation Research Board and the Division on Earth and Life Studies, both of which are divisions of the National Academies. This paper is published in conjunction with Transportation Research Board Special Report 291, "Great Lakes Shipping, Trade, and Aquatic Invasive Species." Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

English

27p

2007-6

Web

Appendices (1) ; Figures (6) ; References; Tables (2)

Ballast (Ships); History; Regulations

Invasive species

Great Lakes; Saint Lawrence Seaway

Environment; Highways; History; Law; Marine Transportation

TRIS, TRB

Jul 24 2008 2:10PM