Mintz, Molly , Major, Kelly , Boettcher, Anne .
Effects of Salinity and Herbicide Exposure on Photosynthetic Physiology and Protein Expression in Aquatic Plants.
AQUATIC “grasses” constitute a group of angiosperms with a worldwide distribution among estuarine and shallow marine ecosystems. These plants occupy nearshore environments affected by anthropogenic disturbance, including exposure to high nutrient loads and agricultural herbicides. Because these populations represent a threatened and endangered habitat, the potential impact of chemical exposure coincident with other environmental stressors (e.g., high salt, low light, high nutrients, etc.) could be severe. This study examined how well Thalassia testudinum (turtle grass), a marine species, and Vallisneria americana (tape grass), an estuarine species, tolerate increased salinity and herbicide (dichlorophenyl dimethylurea – DCMU) exposure using Chlorophyll-a (Chl-a) fluorescence and pigment content as indicators of plant health. Measurements of fluorescence yield (Fv/Fm) indicated that both increased salinity and herbicide exposure resulted in low photosynthetic efficiency in both T. testudinum and V. americana; v/Fm ratios were 53% lower in stressed than non-stressed plants. Low fluorescence yields were attributed to 1) damage to PSII as indicated by high values for initial fluorescence (Fo) upon DCMU exposure (ca. 734) and 2) reduction in pigment content under increased salt conditions (T. testudinum only). Values for maximum fluorescence (Fm) did not vary as a function of salinity or herbicide. Preliminary data suggest that increased salinity, when combined with herbicide exposure, acts synergistically to negatively impact photosynthetic efficiency in Thalassia and Vallisneria. In conjunction with photosynthetic measurements, future experiments will examine the roles of heat shock protein (HSP) 70 and antioxidant enzymes as they relate to stress in aquatic plants.
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1 - University of South Alabama, Biological Sciences, Life Sciences Bldg. #124, 307 University Blvd. North, Mobile, Alabama, 36688, USA
Presentation Type: Poster:Posters for Topics
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM