Dissolved Organic Phosphorus Cycling in the Coastal Ocean

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ABSTRACTOCE-0119134A researcher from Woods Hole Oceanographic Institution will participate in the cruises and field experiments of the Coastal Ocean Advances in Shelf Transport (COAST) project funded by the Coastal Oceans Processes (CoOP) program. The participation of this PI in the study will add a phosphorus component to the project thereby allowing the coupled dynamics of carbon, nitrogen and phosphorus cycling in the coastal system off Oregon to be resolved. Taking advantage of the high temporal and spatial resolution provided by the COAST sampling plan, the PI plans to carry out the following research: (1) determine the 3-dimensional distributions of dissolved organic phosphorus (DOP) and particulate organic phosphorus (POP), and how they relate to distributions of dissolved organic carbon (DOC), particulate organic carbon, dissolved organic nitrogen (DON), particulate organic nitrogen and other biological parameters; (2) ascertain the dynamic variability of the C:N:P ratios of the dissolved and particulate organic pools; (3) assess the short term (during transect re-sampling on each 21-day cruise) versus seasonal variations in coupled DOC, DON, DOP; and (4) evaluate the effects that topography has on DOP and POP cycling and cross-shelf transport. In addition, DOP bioavailability will be evaluated by monitoring the extent of enzymatic DOP hydrolysis in field samples. The nutritional status of in-situ phytoplankton with regard to phosphate stress will be determined by bulk and cell-specific Enzyme Labeled Fluorescence (ELF) Alkaline phosphatase (APase) and the species-specific response of phytoplankton to induced or alleviated P-limitation will be assessed using ELF-APase in shipboard nutrient amendment incubations.