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EFFECTS OF MICROTOPOGRAPHIC VARIATION ON MORPHOMETRICS AND SURVIVAL OF THE ANNUAL FORM OF THE EELGRASS, ZOSTERA MARINA
Citation:
Nelson, W G. AND G. Sullivan. EFFECTS OF MICROTOPOGRAPHIC VARIATION ON MORPHOMETRICS AND SURVIVAL OF THE ANNUAL FORM OF THE EELGRASS, ZOSTERA MARINA. Presented at Pacific Estuarine Research Society, Tacoma, WA, May 18-19, 2001.
Description:
We sampled a disjunct population of the annual form of the seagrass Zostera marina occurring in the upper intertidal zone of Yaquina Bay, Oregon to determine whether there are differences in recruitment, growth, survivorship and morphology associated with microtopographic location on the sand flat. Population responses of seagrass found in topographic high and low areas differing by only a few cm in vertical elevation were compared using both random and fixed quadrat samples. Both random and fixed quadrant data indicated higher abundance, greater survivorship, and higher number of shoots per plant in topographic low areas. Plants in lower areas had significantly longer shoots, greater total above ground biomass, greater biomass per shoot, and greater biomass of reproductive spathes than plants growing in immediately adjacent topographic high areas. While relative exposure to dessication is likely as a main cause of these differences, green macroalgal cover was higher in early summer in topographic high areas as compared to low areas. Macroalgal accumulation may have further stressed annual Zostera plants occupying the topographic high areas.