RhizoDiazo

The proposed research is designed to capture the composition, activity, and symbiotic nature of Rhizosolenia mat communities, as well as determine the significance of these communities to the N inventory in the North Pacific Subtropical Gyre. Specifically, we propose to test the following hypotheses: H 1) The composition of Rhizosolenia species creating the matrix of a mat and the associated diazotroph containing microbiome varies within and between mat fields throughout the NPSG; H2) Rhizosolenia mats obtain diazotroph-derived N; and H3) Diazotrophy within Rhizosolenia mats are a significant source of new N in the NPSG. A research cruise in the subtropical North Pacific Subtropical Gyre (NPSG) is planned where Rhizosolenia mat distribution, composition, and activity (both C/N 2 fixation) will be sampled integrating a rigorous blue water SCUBA program . We will combine traditional microscopy (light, fluorescence, electron) and molecular and 'omics techniques with stable isotopic measures at both whole mat and sub-mat scales to address these questions. The proposed research will result in the first detailed characterization of mat-forming Rhizosolenia and their associated diazotroph communities using modern molecular techniques and isotope techniques to significantly advance our understanding of these potentially important components of the biogeochemistry of the NPSG.