As part of a study to develop recommendations for non-indigenous species (NIS) monitoring in Great Lakes areas at risk of invasion, we conducted intensive sampling in the Duluth-Superior Harbor and lower St. Louis River in 2005 and 2006. Of the ~. 240 benthic invertebrate taxa identified, 19 were non-indigenous, including 8 first detection records for this system: New Zealand mud snail Potamopyrgus antipodarum; African/Asian-origin cladoceran Daphnia lumholtzi; Eurasian-origin amphipod Echinogammarus ischnus; Eurasian-origin bivalves Dreissena bugensis, Pisidium henslowanum and Pisidium supinum; and possibly range expanding oligochaetes Paranais frici and Pristina acuminata. Dreissenids were by far the most abundant NIS. Several other NIS were also common, but others were detected in only a few of the > 200 samples taken. Non-indigenous amphipods and Dreissena were most frequently detected in sweep net and colonization plate samples of littoral vegetation, while NIS oligochaetes, gastropods, and non-dreissenid bivalves were most frequently detected in ponar and bottom sled samples of sediments. Our findings confirm that this major shipping port remains a NIS "hotspot" and emphasize that regular surveys covering a range of habitats with multiple sampling gears and thorough taxonomic effort are needed to detect and monitor non-indigenous species.
Bibliographical noteFunding Information:
Charlie Butterworth, Tim Corry, Sam Miller, Mario Picinich, Brian Sederberg, and Jon Van Alstine assisted with the field work. The map was produced by Matthew Starry. We thank Tim Dawson and staff at Wilson Environmental Laboratories for conducting sample picking and counting; staff taxonomists were Kevin Stroom and John Sandberg in addition to co-author Grigorovich. Outside taxonomic experts consulted for quality assurance checks and difficult specimens were Dr. Gerry Mackie (University of Guelph) and Drs. Mary Balcer and Kurt Schmude (University of Wisconsin — Superior). Although this work was fully funded by the U.S. Environmental Protection Agency, the views expressed in this article are those of the authors and do not necessarily reflect the views or policies of the Agency.
Copyright 2010 Elsevier B.V., All rights reserved.
- First detection
- Gear effects
- Non-native species