Thorhaug, Anitra , Berlyn, Graeme .
The temperature responses measured by spectral reflectance of tropical and temperate 4 seagrasses and 5 macroalgae .
THE temperature tolerances of marine and estuarine plants define their domains as tropical, temperate and arctic. The questions of mechanisms for these important limits has been examined by a series of investigators including membrane transport, primary production , respiration, carbon uptake, and pigment content. Herein we examine the spectral reflectance physiological photosynthetic responses of the seagrasses (higher flowering plants adapted to marine life) and five brown and red macroalgae including Fucus vesiculous. The spectral reflectance and its indices can be expected to measure chlorophyll content changes, changes in ratios of chlorophyll to carotenoid, and photosynthetic efficiency with some detail and accuracy. The testing of spectral reflectance with an UNispec analysis was carried out for each species on 12 plants each measured during 6 tests on various blades or fronds while subjected to each temperature incubation. Randomly selected samples of various temperatures 2 to 40 degrees C were incubated for 60 minutes (simulating a very hot summer or very cold winter day in nearshore shallow water). The results showed intertidal seagrass and algae had appreciably higher tolerances to high and low temperatures than did sublittoral species for both tropical and temperate species. However, there appeared to be an upper limit above which the spectral properties were altered substantially even in these very short time period treatments. The temperature limits will be compared to field tests in thermal effluents of these species, including transplantation into thermal effluents, as well as laboratory whole-plant lethal limit studies. Membrane bioelectric and ion transport studies of high and low temperature relations will also be compared to these results as an attempt to locate mechanisms of temperature lethality.
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1 - Yale University, School of Forestry and Environmental Sciences, Greeley Laboratories 375 Prospect St., New Haven, Connecticut, 06901, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 134/Performing Arts Center
Date: Monday, July 31st, 2006
Time: 9:30 AM