Integration of in situ and satellite observations of the Northeast U.S. Continental Shelf: From microscopic plankton to ecosystem assessment

Abstract:

The challenges inherent in observing and understanding patterns of biodiversity change and related ecosystem impacts in the ocean are multi-faceted and demand innovative approaches. Organisms comprising the base of marine food web are microscopic, with rapid turnover times (~daily) and other adaptations for success in a fluid habitat that is subject to high levels of spatial and temporal variability at scales from micrometers to 1000s of kilometers. Satellite remote sensing approaches are valuable for assessing large-scale patterns in surface ocean environmental properties and chlorophyll concentration, but cannot provide sufficient biodiversity detail for many objectives. To complement the strengths of remote sensing observations, we have undertaken an extensive field program to characterize plankton biomass and composition in situ. Leveraging the NSF-supported NES-LTER and NOAA-supported EcoMon programs has enabled ship-based continuous sampling of surface waters and vertical profile sampling at strategic locations across the Northeast U.S. continental shelf over multiple years and across seasons. On board the ships, we use automated imaging and cytometry for high-throughput characterization of plankton, with taxonomic resolution and across space and time. We highlight case studies showing the power of the integration of satellite and in situ observations to assess spatial and temporal patterns plankton diversity. Conditions that favor communities dominated by microplankton, such as chain- forming diatoms, are expected to structure food webs that support production at higher trophic levels, including commercially important fish species. The combination of satellite and in situ observations can provide input to bottom-up food web approaches to estimate ecosystem production and fisheries exploitation rate potentials. Going forward these approaches can support both near term management of sustainable harvests, as well as predictions of possible ecosystem responses to on-going climate change.