1995 Annual Status Report: A Summary of Aquatic Vegetation Monitoring at Fixed Transects in Pools 4, 8, 13, and 26 and La Grange Pool of the Upper Mississippi River System.
GEOLOGICAL SURVEY ONALASKA WI ENVIRONMENTAL MANAGEMENT TECHNICAL CENTER
Pagination or Media Count:
Distribution and frequency of aquatic vegetation in the Upper Mississippi River System are monitored as part of the Long Term Resource Monitoring Program. This report summarizes results of sampling aquatic vegetation along fixed transects in Navigation Pools 4, 8, 13, and 26 in the Upper Mississippi River and In Grange Pool of the Illinois River in 1995. Pool 26 includes 12 miles of the Illinois River upstream of its confluence with the Mississippi River all of the backwaters surveyed in this river reach are on the lower Illinois River. Plants were sampled using a modified rake technique along fixed transects. Data from additional qualitative surveys or informals was used to augment species records in each pool. Twenty-three submersed and rooted floating-leaved species were found in 1995. Pools 4 and 8 harbored the most species, including most of the large-leaved pondweeds, and the number of species decreased in the pools to the south. Submersed aquatic vegetation was most widespread in Pools 8 and 13 throughout the growing season frequency of about 60 and least in Pools 4 and 26 less than or equal 30. Sago pondweed Potamogeton pectinatus was the dominant species found along the length of the river followed by coons tail Ceratophyllum demersum. Curly pondweed P. crispus, wild celery Vallisneria americana, and American lotus Nelumbo lutea were generally widespread in the upper three pools, and their presence varied seasonally. The abundance of curly pondweed peaked during the spring, whereas wild celery and American lotus were later season strategists. Aquatic vegetation was generally rare in contiguous areas of Pool 26 and La Grange Pool, and where vegetation was sampled mostly isolated backwaters fewer species were found than in the three northern pools.