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Introduction

Aquatic vegetation in the Upper Mississippi River System (UMRS) provides food, spawning areas, and shelter to fish, wildlife, and invertebrates. Aquatic vegetation is a vital component of this nationally significant navigation and ecosystem (Public Law 99-662, Upper Mississippi River Management Act of 1986).  The building of locks and dams in the Upper Mississippi and Illinois Rivers during the 1930s for commercial navigation greatly expanded the rivers' backwater areas in which submersed aquatic vegetation flourished for many years.  However, after a severe drought in the basin, aquatic vegetation in the Mississippi River experienced a drastic decline between 1989 and 1994 (Fischer and Claflin 1995; Rogers et al. 1995; Wiener et al. 1998; Tyser et al. 2001).  The causes of this decline are unknown, but may include decreased light availability because of phytoplankton blooms, depletion of nutrients during low flows, herbicides, and grazing by fish (Wiener et al. 1998). Current data indicates that the Upper Mississippi River above Dam 13 has rebounded from the severe declines in aquatic vegetation that occurred during the drought of 1987–89 and the flood of 1993.

Through the Upper Mississippi River Management Act of 1986, Congress established the Environmental Management Program of the UMRS in 1986 to ensure the coordinated development and enhancement of the UMRS.  The Environmental Management Program consists of five elements, including Habitat Rehabilitation and Enhancement Projects (HREP), Long Term Resource Monitoring Program (LTRMP), Recreation Projects, Economic Impacts of Recreation Study, and Navigation Monitoring.  Aquatic vegetation in the UMRS is monitored as a component of the LTRMP, along with fish, water quality, and macroinvertebrate components.  The LTRMP is administered by the U.S. Army Corps of Engineers and implemented by the U.S. Geological Survey Upper Midwest Environmental Sciences Center (UMESC) in partnerships with the Illinois Department of Natural Resources, Iowa Department of Natural Resources, Minnesota Department of Natural Resources, Missouri Department of Conservation, and Wisconsin Department of Natural Resources.  Five key pools have been sampled for aquatic vegetation using a stratified random sampling protocol since 1998 (Yin et al. 2000) including Pools 4, 8, 13, and 26 of the Mississippi River and La Grange Pool of the Illinois River.  In 2001, Pool 11 was sampled as a pilot outpool sampling project.  In 2002, four additional pools were sampled to help determine how representative the five key pools were of the UMRS.  These included Pools 5, 7, and 12 of the Mississippi River and Alton Pool of the Illinois River.

The objective of the sampling was to accumulate data on the distribution, frequency of occurrence, and relative abundance of aquatic vegetation within pools over a long period (>50 years) using a standardized protocol across the system.  Although data on filamentous algae and duckweeds were collected during sampling, they were not reported here because our focus was on submersed, rooted, floating–leaf, and emergent vegetation. The full suite of data (inclusive of submersed, rooted, floating–leaf, emergents, algae, and duckweeds) are archived in the UMESC database and are available online at http://www.umesc.usgs.gov/data_library/vegetation/vegetation_page.html.

From 1998 to 2002, an annual report was written that summarized the data for that year.  In 2003, the format was changed to a Web-based annual update where all years of data are presented in each table. Other vegetation information also is available using the Vegetation SRS Graphical Browser. One can generate graphs depicting status and trend information (e.g., percent frequency, relative abundance, distribution maps) for aquatic vegetation. The downloading of summary statistics also is available.

Yin, Y., H. Langrehr, T. Shay, T. Cook, R. Cosgriff, M. Moore, and J. Petersen. 2007. Vegetation sampling in the Upper Mississippi River System: Annual update. U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, Wisconsin. An LTRMP Web-based report available online at http://www.umesc.usgs.gov/reports_publications/ltrmp/veg/vegetation_update.html. (Accessed May 2007, with 2006 data.)

Content manager: Dr. Yao Yin