PARENT SESSION
Poster Session # 17: Aquatic Systems.
Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Steady-state fluorescence sensing of wetland vegetation.
Corp, Lawrence*,1, Middleton, Elizabeth1, McMurtrey, James2, Carter, Jacoby3, Campbell, Petya1, Butcher, Maryn1, 1 Biospheric Sciences Branch, Greenbelt, MD2 Hydrology & Remote Sensing Laboratory, Beltsville, MD3 Biological Resources Division, Lafayette, LA
ABSTRACT- The disappearance and degradation of wetlands, and the means of restoration is a problem of great national importance and concern. In coastal areas the distribution of submerged aquatic vegetation (SAV) communities are controlled by a variety of abiotic factors that will be affected by global change processes. These processes range from global changes in climate due to anthropogenic factors, to changes in regional biophysical regimes such as nutrient regimes and hydrology because of human modifications of the landscape. Since the aquatic environmental gradient spans fresh, brackish, and high salinity, changes such as sea level rise and precipitation patterns can locally affect nutrients, salinity, and light availability. These factors determine which species of SAV, including exotic and invasive species, can potentially grow and establish in an area. Several wetland species, Scheonoplectus robustus, S. californicus, Phragmites australis and Distichlis spicata, were investigated with respect to their fluorescence spectral properties. On plants acquired from natural settings, characterizations were performed within the visible emission spectrum (400 - 760 nm) with ultraviolet excitation at 355 nm. We were able to identify spectral characteristics that differed among the three genera, and to separate the two species of the genus Scheonoplectus, based on spectral characteristics. To assess the responses of SAV communities in changing micro-environments, a salinity experiment was conducted with potted plants placed in large fiberglass tanks. The experiment was conducted as a 3 x 2 factorial design, with three levels of salinity and two water depths. The most definitive results were obtained with Phragmites australis, for which the red and far-red chlorophyll fluorescence bands produced significant interactions between water depth and salinity. Plants grown at a salinity of 10 ppt had significantly higher fluorescence intensity (p < 0.05) than those grown at 0 ppt. Additionally, a significant increase in red fluorescence emission intensity occurred for plants placed in deep water vs. shallow water conditions.
Key words: Wetland Vegetation, Fluorescence, Vegetation Stress, Species Identification