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Early Detection Monitoring Approaches for Exotic Aquatic Species in Great Lakes Harbors and Embayments
Citation:
TREBITZ, A. S., J. R. KELLY, J. HOFFMAN, G. S. PETERSON, AND C. W. WEST. Early Detection Monitoring Approaches for Exotic Aquatic Species in Great Lakes Harbors and Embayments. Presented at Western Great Lakes Research Conference, Ashland, WI, April 01 - 02, 2009.
Impact/Purpose:
Aquatic invasive species pose a significant ecological and economic threat in the Great Lakes basin. Early detection of invaders is desirable so as to allow for a timely management response, raising the question of how to accomplish this detection in a consistent, cost-effective manner. To that end, we have been conducting intensive sampling of benthic macroinvertebrates and fish in the Duluth-Superior harbor/St. Louis River estuary on Lake Superior.
Description:
Aquatic invasive species pose a significant ecological and economic threat in the Great Lakes basin. Early detection of invaders is desirable so as to allow for a timely management response, raising the question of how to accomplish this detection in a consistent, cost-effective manner. To that end, we have been conducting intensive sampling of benthic macroinvertebrates and fish in the Duluth-Superior harbor/St. Louis River estuary on Lake Superior. This water body is subject to heavy propagule pressure from international shipping and other introduction vectors, and our sampling detected a variety of both “old” and “new” invaders (e.g., common carp, rainbow smelt, tubenose goby, zebra mussel, New Zealand mud snail, quagga mussel). Our deliberately oversampled data set provides the basis with which to evaluate sampling strategies (gear types, spatio-temporal distribution, use of ancillary environmental predictors, etc.). Analyses confirm that early detection of invaders is inherently an inefficient process, with increasing amounts of effort required to detect the next new or rare species. Detection probability depends not only on species abundance, but also on spatial distribution and vulnerability to sampling gear. Species acquisition curves, species ordinations, and species composition metrics differed substantially among the types of sampling gear used, and the gears catching the largest numbers of individuals were not necessarily the ones that most rapidly detected invasive species. Since the identity, introduction vector, and habitat preference of the next exotic species cannot be known, monitoring should cover a diversity of locations and habitats. While all habitat types should receive some level of sampling effort, our analyses suggest that the most efficient strategies bias benthic invertebrate sampling towards shallow vegetated habitats and away from deep and bare habitats; and bias fish sampling towards fyke and electrofish samples and away from trawl samples.