Temporal and Spatial Scales of Correlation in Marine Phytoplankton Communities

Ocean circulation shapes marine phytoplankton communities by setting environmental conditions and dispersing organisms. In addition, processes acting on the water column (e.g., heat fluxes and mixing) affect the community structure by modulating environmental variables that determine in situ growth and loss rates. Understanding the scales over which phytoplankton communities vary in time and space is key to elucidate the relative contributions of local processes and ocean circulation on phytoplankton distributions. Using a global ocean ecosystem model, we quantify temporal and spatial correlation scales for phytoplankton phenotypes with diverse functional traits and cell sizes. Through this analysis, we address these questions: (1) Over what timescales do perturbations in phytoplankton populations persist? and (2) over what distances are variations in phytoplankton populations synchronous? We find that correlation timescales are short in regions of strong currents, such as the Gulf Stream and Antarctic Circumpolar Current. Conversely, in the subtropical gyres, phytoplankton population anomalies persist for relatively long periods. Spatial correlation length scales are elongated near ocean fronts and narrow boundary currents, reflecting flow paths and frontal patterns. In contrast, we find nearly isotropic spatial correlation fields where current speeds are small, or where mixing acts roughly equally in all directions. Phytoplankton timescales and length scales also vary coherently with phytoplankton body size. In addition to aiding understanding of phytoplankton population dynamics, our results provide global insights to guide the design of biological ocean observing networks and to better interpret data collected at long‐term monitoring stations. Plain Language Summary Using a global model of the marine planktonic ecosystem, we quantify the temporal and spatial correlation scales of diverse types of phytoplankton. The timescales reflect the persistence of anomalies in time and the stability of the planktonic system. The spatial scales measure over what distances variations in phytoplankton populations are synchronous. We find that timescales and length scales vary with cell size and that global patterns of correlation are shaped by ocean currents. These results provide valuable insights for the design of ocean observing systems with a unique ecological perspective. We also discuss how regional differences in phytoplankton community correlation scales are