FOR IMMEDIATE RELEASE

March 2, 2011

Contacts

Disappearing Diporeia

Ann Arbor, MI — The small, shrimp-like crustacean Diporeia is one of the most important organisms in the Great Lakes food-web, providing a rich source of food to many fish species, including whitefish, as well as smaller fish which are eaten by salmon, trout and walleye. But Diporeia populations have been disappearing at an alarming rate in four of the five lakes.

In a recent summary of 13 years of monitoring data on this bottom-living organism, researchers with the US EPA Great Lakes National Program Office and several collaborating universities have confirmed that Diporeia is now completely absent from Lake Erie, and has almost entirely disappeared from depths less than 90 m in lakes Ontario, Michigan and Huron.

There is some good news, however. Diporeia populations in Lake Superior, while exhibiting some substantial ups and downs over the years, have shown no evidence of overall declines. And in lakes Michigan and Huron, populations in the deeper portions of the lake have remained relatively stable in the past five years.

"It remains to be seen, though," says Rick Barbiero, a contract scientist working with the EPA, "whether deep waters in Lake Michigan and Lake Huron offer a lasting refuge for Diporeia, or whether the relative population stability in recent years merely represents a temporary lull in continuing declines."

Even after decades of research, the cause of the Diporeia declines remains one of the greatest mysteries in the Great Lakes. Data from the current study might offer some new clues, however. In particular, a notable degree of synchrony was seen in population fluctuations between lakes Huron and Michigan, which raises the possibility that regional-scale phenomena, such as climactic influences on primary production, are having an impact on Diporeia populations in those adjacent lakes.

Original Publication Information

Results of this study, "Trends in Diporeia populations across the Laurentian Great Lakes, 1997-2009," are reported by Rick Barbiero, Kurt Schmude, Barry Lesht, Catherine Riseng, Glenn Warren and Marc Tuchman in the latest issue (Volume 37, No. 1, pp. 9-17) of the Journal of Great Lakes Research, published by Elsevier, 2011.

Contacts

For more information about the study, contact Rick Barbiero, CSC 1359 W. Elmdale Ave Suite 2, Chicago, Il, 60660; gloeotri@sbcglobal.net; (773) 878-3661.

For information about the Journal of Great Lakes Research, contact Stephanie Guildford, Scientific Co-Editor, Large Lakes Observatory, University Minnesota Duluth, 2205 East Fifth Street, Duluth, Minnesota, 55812-2401; llo.jglr@gmail.com; (218) 726-8064.


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.