PARENT SESSION
Oral Session #37: Aquatic Ecology: Macrophytes. Presiding: J. Titus.
Tuesday, August 7, 2001. 1:00 PM to 5:00 PM. Hall of Ideas I.
Functions of submersed vegetation in the Hudson River.
Findlay, Stuart 1, Caraco, Nina1, Cole, Jon1, Strayer, David1, Nieder, Chuck2, 1 2
ABSTRACT- Patches of submersed aquatic vegetation (SAV) are a conspicuous feature of most aquatic ecosystems and have been shown to serve a variety of quantitatively important functions ranging from habitat to sediment trapping. In the tidal freshwater Hudson River SAV can occupy as much as 20% of the river bottom area and plant biomass is as high as 500 g dry mass/m2. In a 60 km stretch there are nearly 400 plant beds ranging in size from 20 to 1.2 million m2. We have evaluated several of the ecological functions including primary productivity, sediment trapping, and habitat for invertebrates and fishes. We are exploring the extent to which patch characteristics or landscape variables help explain among-patch variability in these functions. Maintenance of super-saturated oxygen concentrations in the water column appear to be a simple function of patch size suggesting larger patches are buffered from exchange with the generally under-saturated water in the rivers main channel. In contrast, suspended sediment concentrations are higher in the patches than in the main channel and were not related to patch size. This suggests that even large patches are incapable of decreasing water velocities sufficiently to enhance sediment trapping. Our ability to extrapolate from site-specific studies to the whole ecosystem depends upon finding relationships between function and simple predictor variables such as patch size, shape or landscape position. Such tools would also help efforts to manage and preserve these important habitats.
KEY WORDS: Submerged macrophytes, Vallisneria americana, Primary production, Habitat