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Status of Non-indigenous Benthic Invertebrates in the Duluth-Superior Harbor and the Role of Sampling Methods in their Detection
Citation:
TREBITZ, A. S., C. W. WEST, J. HOFFMAN, G. S. PETERSON, AND I. A. GRIGOROVICH. Status of Non-indigenous Benthic Invertebrates in the Duluth-Superior Harbor and the Role of Sampling Methods in their Detection . JOURNAL OF GREAT LAKES RESEARCH. International Association for Great Lakes Research, Ann Arbor, MI, 36(4):747-756, (2010).
Impact/Purpose:
Our findings confirm that this major shipping port is heavily invaded and additional NIS continue to be detected. Regular surveys incorporating varied sampling gear and thorough taxonomic effort are needed to detect and monitor the status of NIS invertebrates in Great Lakes coastal systems.
Description:
As part of a study to develop recommendations for non-indigenous species (NIS) monitoring in Great Lakes areas of risk, we conducted intensive sampling in the Duluth-Superior Harbor and lower St. Louis River in 2005 and 2006. Of the >200 invertebrate taxa recorded, 19 were non-indigenous, including 8 first detection records for this system: the New Zealand mud snail Potamopyrgus antipodarum, the African/south Asian zooplankter Daphnia lumholtzi, several Eurasian species including quagga mussel Dreissena bugensis, pea clams Pisidium henslowanum and P. supinum, and amphipod Echinogammarus ischnus, and North American range expansions by 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 small fraction of the >200 samples taken. Non-indigenous amphipods and dreissenids were best detected by sweep nets and colonization plates deployed in littoral vegetation, while gastropods, oligochaetes and other bivalves were best detected by bottom samplers (ponars, benthic sled). Our findings confirm that this major shipping port is heavily invaded and additional NIS continue to be detected. Regular surveys incorporating varied sampling gear and thorough taxonomic effort are needed to detect and monitor the status of NIS invertebrates in Great Lakes coastal systems.