Phytoplankton Community Structure across a Distributed Biological Observatory in the Pacific Arctic Region

Declining sea ice conditions in the Arctic can change phytoplankton composition and community structure impacting marine food webs, fisheries and human health (i.e. harmful algal blooms). With continued record-breaking warming events in the region, it is critical to understand how phytoplankton species will adapt or shift to the rapid changes in their environment. While satellite analysis can provide some information on how phytoplankton abundances change through time, current sensors are limited in their capacity to see deep into the water column as well as identify taxa-specific shifts. Here we present abundance and genus level identification of phytoplankton assemblages over a latitudinal gradient of “hotspot” sites in the Bering and Chukchi Seas as part of the Distributed Biological Observatory (DBO) monitoring program. Discrete seawater samples at various depths were collected during the July 2019 field season and analyzed using an Imaging FlowCytobot (IFCB) which takes high-resolution images of suspended particles in water ranging in size from 2 to 150 μm. Phytoplankton were classified at the genus level using a random forest machine learning algorithm and the spatial variability of drivers in community composition were analyzed. Ongoing work will be to develop a more robust and representative training sample for the Arctic region, as well as to link these high taxonomic resolution data sets with synoptic satellite data in preparation for future earth observing missions.