UC San Diego

From 2014 to 2019, there was a period of persistent, record-breaking marine heatwaves in the North Pacific that had significant impacts on the California Current Ecosystem (CCE). This thesis first revisited the calculation of the empirical orthogonal functions (EOFs) and principal components (PCs) of sea surface temperature (SST) in this region. We found that since 2014, there were fundamental changes to the dominant EOFs and PCs. A conclusion was that the Pacific Decadal Oscillation (PDO), a measure of variability in the North Pacific, and other EOF-based metrics may not be as useful as climate continues to change. Next, the thesis provided a first look at the anomaly of dissolved oxygen concentration from the annual cycle as measured by the California Underwater Glider Network. We gained new insights on the water masses in the CCE and found that a major contributing factor of oxygen anomalies were changes in source water concentration. Finally, the thesis examined the environmental factors influencing ichthyoplankton abundance in the CCE and suggested new indices to reflect the abundances of several prominent northern and southern mesopelagic species.