Automated observations of phytoplankton communities from open water moorings

The composition of marine phytoplankton communities changes on a broad range of spatial and temporal scales, from fleeting turbulent eddies the size of single plankton to low-frequency, hemispheric scale variations in climate. Observing the full spectrum of variability in a diverse community can be difficult and expensive, particularly in the remote ocean. Recent advances in autonomous underwater imaging and machine learning now make it possible to image and identify phytoplankton in the environment on a less expensive and nearly continuous basis. To date, however, few of these observing systems have been deployed continuously and autonomously in the remote ocean. Here we describe the technical challenges and initial successes of deploying an Imaging FlowCytobot (IFCB) at a mooring in the Southern California Bight near Del Mar, CA for trial periods in spring 2018 (~1 month) and winter 2018-2019 (~3 months). The mooring was equipped with solar power, mobile phone internet connectivity, and remote control to allow for extended deployment. Over the two deployments, we observed high frequency changes in phytoplankton and microzooplankton assemblages occurring on diel-to-weekly timescales. Another deployment is planned which will demonstrate enhanced solar power and usability in limited band-width connections more typical of satellite internet throughput. This initial proof-of-concept deployment of the IFCB will facilitate future, longer deployments of the IFCB in other open ocean locations.