Zoom Meeting ID: 91433095773
Several existing studies suggest that lateral export of nutrients, organic matter, and organisms connects nearshore upwelling regions to offshore oligotrophic environments in the California Current Ecosystem (CCE). Using data from cruises conducted in the CCE between 2006-2017, the trophic state of the surface ocean determined from traditional (grazing) and microbial food webs were compared. The results support a nearshore, net autotrophic region that can transition to an offshore, net oligotrophic region. A small overall net primary production surplus of roughly 42 mmol C m-2 d-1 remained after supporting zooplankton grazing but estimated dissolved organic carbon released by phytoplankton and zooplankton processes was insufficient to support bacterial carbon demand in much of the CCE. Close examination of a westward propagating filament supports the hypothesis that the transport of excess organic matter laterally in mesoscale features may differentially support bacterioplankton and zooplankton communities and explain the observed imbalance in the offshore. Additionally, microbial community composition from amplicon sequencing suggests community progression within the filament. Interactions between members were identified and visualized via microbial correlation networks. These relationships were further evaluated in the context of regional chemotypes as detected by environmental metabolomics. The integration of biogeochemical measurements with community composition enabled us to examine how relationships between primary and secondary producers shifted across gradients in nutrient status and carbon production as the filament was propagated offshore.