Stopping Gobies the Cheap Way
Ann Arbor, MI — Simply changing the time of day when Great Lakes ships take on ballast water may slow or stop invasive species like round gobies from spreading.
Much time, effort, and money has been devoted to stopping invasive species from entering and, once here, being spread around the Great Lakes via ballast water of commercial freighters. Laws have even been enacted to try to solve the problem by forcing ships carrying ballast water into the Great Lakes to exchange their ballast in the open ocean so that saltwater kills unwanted freshwater animals left in the ship's ballast tank. Even with policy regulation, however, invasive animals keep getting into the Great Lakes, where they are spread quickly by ships moving from one Great Lakes port to another.
Some solutions offered by scientists so far have been to attach ballast water treatment devices onto ships or to create ballast water treatment stations where ships must stop to rid water in their tanks of invasive species. These options would be costly to implement and have not yet been regulated into action by policymakers. Two scientists from the University of Michigan, Stephen Hensler, a doctoral student, and David Jude, a Research Scientist and the first person to find gobies in the Great Lakes, suggest a different solution to the problem.
"When I first found round gobies in the Great Lakes, I wondered how they got into ballast water, because they sit right on the bottom, and ships take on ballast water up in the water column to avoid filling up with sediment and sludge," says Jude.
"That question really didn't have an answer until we started finding newly-hatched, or larval, round gobies at the surface," says Hensler. "We learned that larval round gobies come to the surface at night during about a 3-day period after hatching, which probably explains how they end up in ballast water."
The researchers suggest that if ships would take on ballast water only near the surface during daylight hours, they would be less likely to spread invasive species, such as round gobies. If implemented, they believe this relatively inexpensive ballast water practice could reduce effects of invasive species, buying time until better methods become available.
Original Publication Information
Results of this study, "Diel Vertical Migration of Round Goby Larvae in the Great Lakes," are reported by Stephen R. Hensler and David J. Jude in the latest issue (Volume 33, No. 2, pp. 295-302) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2007.
Contacts
For more information about the study, contact Stephen Hensler, School of Natural Resources and Environment, University of Michigan, 440 Church St., Ann Arbor, MI, 48109; shensler@umich.edu, (734) 763-5467.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.
Links
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.
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