The California Current Ecosystem (CCE) is a coastal ecosystem that has been impacted by warming and other climate-change associated phenomena in past years. The CCE is oceanographically complex, with northerly currents contributing waters from the North Pacific and Subarctic, an undercurrent carrying tropical waters north, and seasonal upwelling leading to a strong cross-shore gradient in productivity. Though zooplankton play important ecological roles, much of their diversity is understudied, and traditional taxonomic methods can require extensive resources and expertise. Here we used DNA metabarcoding of the cytochrome oxidase I (COI) and 18S rRNA on size separated plankton tissue samples, to investigate diversity patterns across a longitudinal gradient spanning a large range of abiotic factors from coastal upwelling to 800 km offshore. The two markers presented compositionally distinct, yet complementary, perspectives of total plankton diversity, thus demonstrating the value of using multiple primers for broader views of pelagic diversity. Results revealed a cross-shore shift in mesozooplankton community composition correlated with temperature, nutrient concentrations, and primarily characterized by differences in size. Larger key arthropods were most abundant in nearshore communities, with greater richness of small zooplankton further offshore. This study forms a unique size-structured baseline characterizing zooplankton communities across a large environmental gradient that will enhance our ability to detect ecosystem shifts in response to global climate change.

Primary Presenter: Hannah Budroe, UC San Diego (budroe.hannah@gmail.com)

Authors:

Hannah Budroe, University of California, San Diego  (hbudroe@ucsd.edu)

Dante Capone, Scripps Institution of Oceanography, UCSD  (dcapone@ucsd.edu)

Stephanie Matthews, Scripps Institution of Oceanography, UCSD  (samatthews@ucsd.edu)

Jeff Bowman, Scripps Institution of Oceanography, UCSD  (jsbowman@ucsd.edu)

Ramón Gallego, Universidad Autonoma de Madrid  (ramongallego@gmail.com)

Moira Décima, Scripps Institution of Oceanography, UCSD  (mdecima@ucsd.edu)