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Invasive Macroinvertebrates in the Upper Mississippi River system: Recent Findings
Citation:
ANGRADI, T. R. AND I. GRIGOROVICH. Invasive Macroinvertebrates in the Upper Mississippi River system: Recent Findings. Presented at Minnesota Invasive Species Conference, Duluth, MN, October 26 - 29, 2008.
Impact/Purpose:
Further monitoring is necessary to determine whether the qu-agga mussel will become established in the Mississippi River system.
Description:
Zoobenthos surveys of the great rivers of the Upper Mississippi River basin (Missouri, Upper Mississippi, and Ohio Rivers) in 2004-2006 revealed new invasions by marine and estuarine amphipods. The gammarid amphipods Echinogammarus ischnus and Gammarus tigrinus were discovered in the Ohio and Upper Mississippi Rivers in 2004. The corophiid amphipod Apocorophium lacustre was first found in the Ohio River in 1996, and first detected in the Upper Mississippi River in 2005. None of these invaders was collected in the Missouri River. The presence of breeding adults of all three species suggests they are permanently established in the Ohio and Upper Mississippi. The range and occurrence of all three species increased in the basin from 2004 through 2006. The quagga mussel Dreissena bugensis was first found in the Ohio and Upper Mississippi Rivers in the mid-1990s. It has since gone unreported in the Mississippi River system possibly due in part to its phenotypic variability and close morphological resemblance to the more commonly occurring zebra mussel Dreissena polymorpha. Sampling of the great rivers during 2004-2006 revealed that the quagga mussel occurs at several localities outside its previously reported distribution in the Ohio and Upper Mississippi Rivers. Few zebra and no quagga mussels were found in the Missouri River. Quagga were nowhere abundant in our survey, comprising less than 1% of identifiable Dreissena specimens. Further monitoring is necessary to determine whether the qu-agga mussel will become established in the Mississippi River system.