Seasonality and episodic variation in picoeukaryote diversity and structure reveal community resilience to disturbances in the North Pacific Subtropical Gyre

We examined variability in the euphotic zone (0–175 m) picoeukaryotic community based on time-series observations (2011–2013) at Station ALOHA in the North Pacific Subtropical Gyre. By sampling over scales ranging from daily to approximately monthly over 2.25 years, we evaluated the resilience of the picoeukaryotic community to seasonal- to episodic-scale physical disturbances, such as convective mixing and mesoscale processes, respectively. We quantified the frequency and intensity of disturbances that altered upper ocean light and nutrients in the context of the Hawaii Ocean Time-series program climatology, and evaluated picoeukaryotic community resilience based on shifts in dissimilarity in community structure at different depths in the euphotic zone. Our results suggest that in this stratified habitat, picoeukaryote communities are resilient on timescales of days to weeks in response to these physical disturbances, and that the juxtaposition of mesoscale and submesoscale disturbances on more predictable seasonality requires spatially and temporally resolved assessment of community response and resilience. We highlight the value of examining recent (days to weeks) physical forcing of the upper ocean for insight into the influences of physical habitat alterations that structure the contemporaneous plankton community.