Is Zooplankton Community Structure Spatially and Temporally Persistent in the Eastern North Pacific?

Two decades of Continuous Plankton Recorder (CPR) surveys in the Northeast Pacific now enable characterization of spatial and temporal variation in zooplankton community structure under wide ranging environmental conditions, including the marine heatwave in 2014-2016 when the pelagic environment warmed 2-4 standard deviations above average. Using summer CPR collections over 17 years (2000-2016), we tested the hypothesis that zooplankton communities are spatially persistent across years of varying conditions. Using 16 abundant taxa, we used spatial ordinations and hierarchical clustering to: i) identify and characterize the “typical” community structures associated with particular regions of the NEP, and ii) describe how regional community structure changed with sea surface temperature, current flow, and bathymetry. We identified 7 regional communities, each representing distinct combinations of zooplankton taxa. This approach illustrated coastal clusters off the shelf near Vancouver Island; a single cluster southeast of Unimak Pass associated with strong currents; a cluster of generally low abundance located along the eastern arm of the subarctic gyre where ocean conditions are dominated by eddy activity; and a set of clusters in the pelagic Gulf of Alaska (GoA) that are associated with stable temperature and current conditions. We observed spatial shifts in communities along the Aleutian and North American shelfs, but spatial persistence in the central GoA. These results suggest greater variability in coastal food webs than in the central portion of the eastern subarctic gyre, which may be important to the trophic ecology of upper trophic level consumers.