The species composition, occurrence and temporal stability of submerged aquatic macrophyte patches along the main channel border of pool 5A, Upper Mississippi River

Abstract

Species composition, relative abundance, distribution and physical habitat associations of submerged aquatic macrophytes in the main channel border (MCB) habitat of Pool 5A, Upper Mississippi River (UMR) were investigated during the summers of 1980 and 1983. The submerged aquatic macrophytes in Pool.5A MCB were a small and stable component of the river ecosystem. Submerged plants occurred primarily in small, monospecific clumps. Clumps in close proximity to each other formed plant patches. Plant patches were stable in location and number between 1980 and 1983; 82.5% of the patches first observed in 1980 were present in 1983. Submerged macrophytes covered about lo-12 ha of the 201 ha MCB in Pool 5A. Submerged plants were most common in the lower two-thirds of the pool. Ten species of aquatic macrophytes occurred on rock channel-training structures and eleven occurred on non-rock substrates in the MCB. The most common submerged plants, in order of abundance, were Vallisneria americana Michx., Heteranthra dubia Jacq., Potamogeton pectinatus L., Ceratophyllum demersum L. and Potamogeton americanus C. & S.

Groundwater-surface water ecotones at the upstream part of confluences in former river channels

“…Internal processes act in their maintenance: water flowing through the ecotone is slowed by very dense stands of aquatic plants. The decrease in water velocity, and thereby in its kinetic energy, leads to alluvial deposition within the ecotone which in turn favours the development of particular assemblages of aquatic vegetation (McConville et al, 1986). Through the process of alluvial deposition, those ecotones therefore also act as suspended matter filters between the present-day river and its former channels.…”

Disturbance regimes and vegetation dynamics: role of floods in riverine wetlands

“…The scale of investigation can influence the response observed: disturbance generally affects only some parts of the ecosystem, so resilience is observed in distinct patches, whereas the whole ecosystem remains stable (McConville et al 1986;Wiegleb et al 1989;Brown & Allen 1989). On this basis, White & Pickett (1985) and Townsend (1989) have developed the concept of Patch Dynamics, which supposes the ecosystem to be patchily disturbed, partly because of the intrinsic vulnerability of communities, and supposes that the undisturbed or less disturbed patches provide potential recolonizers for the disturbed ones, thus ensuring the stability of the ecosystem (Trabaud & Lepart 1981;White & Pickett 1985;van der Maarel 1988;Reice et al 1990).…”

WATER LEVEL MANAGEMENT OPPORTUNITIES FOR ECOLOGICAL BENEFIT, POOL 5 MISSISSIPPI RWER1

“…This, combined with an average depth of approximately three feet, facilitates wave action and sediment resuspension. In Mississippi River backwaters, poor light penetration, largely due to suspended sediments (Sullivan, 1991(Sullivan, , 1993, is probably the limiting factor to vegetation establishment and growth in deeper water (Kimber et al, 1995;Owens and Crumpton, 1995;Roseboom et al, 1992;McConville et al, 1986). In 1982, 91 percent of vegetation in the Bottoms occupied areas less than four feet deep (Anderson et al, 1992).…”