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SEDIMENT AND PLANT PHOSPHORUS IN TWO THALASSIA TESTUDINUM SEAGRASS BEDS OF SANTA ROSA SOUND, NW FLORIDA
Citation:
Stanley, R S., J. Cherry, J.S., III, D F. Yates, AND R D. Devereux. SEDIMENT AND PLANT PHOSPHORUS IN TWO THALASSIA TESTUDINUM SEAGRASS BEDS OF SANTA ROSA SOUND, NW FLORIDA. Presented at Joint Meeting of GERS and SWS: Communication and Collaboration: Coastal Systems of the Gulf of Mexico and Southeastern United States, Pensacola Beach, FL, March 30 - April 02, 2005.
Impact/Purpose:
Conference abstract
Description:
We investigated phosphorus concentrations in the seagrass, Thalassia testudinum, and the supporting quartz sediments of two meadows in Santa Rosa Sound. One meadow was sampled during 2002, and the other during 2003. Triplicate sediment and biomass cores were obtained from beneath three water depths at six week intervals during the growing season. Dried, ground sediments were analyzed for total and inorganic ortho-phosphate by the colorimetric ascorbic acid method. Profiles of solid-phase total elemental phosphorus concentration varied moderately from the sediment surface down to 16 cm, the maximum core depth, during 2003. Phosphorus in these sediments ranged from 10 to 50 mg/kg. However, profiles during 2002 had marked peaks in phosphorus reaching 40, 55, 80 and 100 mg/kg in June, July, September and November, respectively. Organic phosphorus profiles, calculated as the difference between total and inorganic phosphorus, generally paralleled total phosphorus profiles. Dried, ground seagrass tissues were analyzed for total ortho-phosphate. Leaf phosphorus concentrations of 1.4 mg/g (0.7-1.9 mg/g), were consistently higher than concentrations in rhizomes and roots (0.2-2.0 mg/g) within any sampling date. Plants from the deep water (1.5 m) cores in both years had higher concentrations of phosphorus in leaves and rhizomes than in the corresponding tissues of plants collected at the shallower depths (0.5 m and 1 m). This suggests that plants growing in the deeper water were not limited by phosphorus