HR: 0830h
AN: B31D-0341    [PDF]
TI: A Time Series Investigation of the Oxygen Isotopic Composition of Dissolved Inorganic Phosphate in Monterey Bay Seawater
AU: * McLaughlin, K
EM: karenmcl@pangea.stanford.edu
AF: Stanford University Department of Geological & Environmental Sciences, Building 320, Room 118, Stanford, CA 94305-2115 United States
AU: Paytan, A
EM: apaytan@pangea.stanford.edu
AF: Stanford University Department of Geological & Environmental Sciences, Building 320, Room 118, Stanford, CA 94305-2115 United States
AU: Kendall, C
EM: ckendall@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Road, MS 434, Menlo Park, CA 94025 United States
AU: Silva, S
EM: srsilva@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Road, MS 434, Menlo Park, CA 94025 United States
AU: Chavez, F
EM: chfr@mbari.org
AF: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039-9644 United States
AU: Pennington, T
EM: peti@mbari.org
AF: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039-9644 United States
AB: Phosphorous is an essential and limiting macro-nutrient for productivity in marine ecosystems. Because the P-O bond in phosphate is resistant to inorganic hydrolysis and the fractionation and exchange of oxygen isotopes will only occur due to intracellular biological cycling, the oxygen isotopic composition of dissolved inorganic phosphate (DIP) in seawater may be used as a tracer for modern phosphate recycling in aquatic ecosystems. The degree of disequilibrium between the d18O of DIP and that of the surrounding water will act as a proxy for the extent of phosphate recycling through the biomass in a particular system. A time series investigation of a dynamic system such as the Monterey Bay could indicate how ecosystems vary the extent of phosphate turnover as the system becomes nutrient stressed following a bloom period. The nutrient dynamics in the Monterey Bay vary temporally and are characterized by seasonal upwelling from March to September which supplies nutrients to the surface waters and sustains high productivity during these months. We conducted monthly depth profiles for a year at MBARI stations C1, M1 and M2 to assess the variation in d18O of DIP over the course of the onset of the upwelling season and less productive seasons which follow. The results of this time series investigation were compared to estimates of primary productivity, chlorophyll concentrations, temperature, salinity, and nutrient concentrations to determine if phosphate turnover varies with these seasonal ecosystem changes and if during periods of higher nutrient availability phosphate is utilized less efficiently than during periods of lower nutrient availability.
DE: 4805 Biogeochemical cycles (1615)
DE: 4815 Ecosystems, structure and dynamics
DE: 4845 Nutrients and nutrient cycling
DE: 4870 Stable isotopes
SC: Biogeosciences [B]
MN: 2003 Fall Meeting