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ASSESSING ROOT DEMOGRAPHY AND CARBOHYDRATE DYNAMICS OF ZOSTERA MARINA
Citation:
Johnson, M G. AND C P. Andersen. ASSESSING ROOT DEMOGRAPHY AND CARBOHYDRATE DYNAMICS OF ZOSTERA MARINA. Presented at Estuarine Research Federation, Seattle, WA, September 14-18, 2003.
Description:
To help establish protective criteria for Zostera marina a more complete understanding of the factors affecting the status, condition, distribution and ecophysiology of Z. marina is needed. While Z. marina shoots are readily observed, assessing growth and carbon dynamics of roots and rhizomes is more problematic. Our goals are to use minirhizotrons to quantify the seasonal standing crop, production and mortality of Z. marina roots and to couple this data with shoot, rhizome and root biochemistry to assess concurrent carbohydrate dynamics. Minirhizotrons are round plastic tubes (I.D. ~ 5 cm) inserted into sediment beneath Z. marina. At low tide a miniature color video camera is inserted into the minirhizotron tubes and images of Z. marina roots in contact with the tubes are recorded on videotape. While minirhizotrons have been used successfully in terrestrial systems to investigate the demography (production, lifespan and mortality) of fine roots (< 2 mm in diameter), adapting this technology to the estuarine environment poses a number of technical and logistical problems. In May, 2002, we installed 3 minirhizotron tubes at three different elevations across a Z. marina bed located in Yaquina Bay, Oregon. Beginning in August, 2002, we collected root images and sampled shoot, rhizome and root tissue proximal to each of the tubes at approximately 4 ?6 week intervals. Roots were observed at each image collection. Minirhizotron data were extracted from the videotapes and an HPLC was used for tissue carbohydrate analyses. This paper details our application of minirhizotrons to investigate the demography of Z. marina roots and presents preliminary root growth and carbohydrate data on seasonal changes in Z. marina.