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Invasion of the Upper Mississippi River System by Saltwater Amphipods
Citation:
GRIGOROVICH, I. A., T. R. ANGRADI, E. B. EMERY, AND M. S. WOOTEN. Invasion of the Upper Mississippi River System by Saltwater Amphipods. Fundamental and Applied Limnology. E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany, 173(1):67-77, (2008).
Impact/Purpose:
The establishment of nonindigenous amphipods will likely contribute to alterations of food webs and native faunal diversity in the invaded rivers
Description:
Zoobenthos surveys of the Great Rivers of the Upper Mississippi River basin (Missouri, Mississippi, and Ohio Rivers) provided an opportunity for documenting a series of invasions by euryhaline amphipods. The corophiid amphipod Apocorophium lacustre was first found in the Ohio River in 1996, and the gammarid amphipods Echinogammarus ischnus and Gammarus tigrinus were discovered in the Ohio and Upper Mississippi in 2004. None of these invaders were present in the Missouri River. The geographical range of A. lacustre has increased in the Ohio between 1996 and 2006, and expanded to the Illinois in 2003 and the Upper Mississippi in 2005. The spatial distribution and occurrence of E. ischnus and G. tigrinus in the Ohio and Mississippi also increased from 2004 through 2006. Of the three species, E. ischnus has the widest distribution in the Ohio and Upper Mississippi, and G. tigrinus has the smallest. The existence of breeding populations of all three species indicate that they are permanently established in these rivers. The collective contribution of the three invaders to total amphipod catch in the Upper Mississippi increased from 0.8% in 2004, to 5.4% in 2005, and 15.2% in 2006, and in the Ohio changed from 4.8% in 2004, to 27.8% in 2005, and 23.5% in 2006. The establishment of nonindigenous amphipods will likely contribute to alterations of food webs and native faunal diversity in the invaded rivers.