An Automated Biogeochemical Observatory on a Ship of Opportunity: Biweekly Assessment of the Carbon Cycle in the Northwest Atlantic



Each year an intense phytoplankton bloom sweeps across the subarctic North Atlantic Ocean.  The spatial extent, timing and composition of this bloom regulate the photosynthetic assimilation of carbon and its subsequent export to depth.  The bloom also supports higher trophic levels and North Atlantic fisheries.  Variability in the dynamics of the bloom is linked to primary modes of North Atlantic climate variability, including the North Atlantic Oscillation (NAO), which dictates physical preconditioning such as deep mixing by winter storms, shifting currents and the availability of light and nutrients.  Monitoring the resulting variability not only for the peak spring bloom, but over the entire annual cycle is an essential part of understanding the carbon cycle in this ocean region.

We propose to take advantage of a unique opportunity to establish a time-series of measurements critical to characterizing ocean primary production and carbon cycle dynamics in the northwest Atlantic Ocean by installing a system of sensors on a commercial ship of opportunity that transits between Iceland and New England.  This ship’s route passes through two important regions of the Subarctic North Atlantic: the Irminger Basin and the Gulf of Maine, and we propose to outfit this ship with a basic suite of sensors for nitrate, dissolved oxygen, photosynthetically active radiation (PAR), and phytoplankton chlorophyll and photosynthetic physiology.  What makes this ocean observing project unique is the exceptional temporal and spatial resolution provided by the commercial route, which makes twelve return trips between Reykjavik and Portland ME annually.  Such frequent transits allows us to characterize the seasonal and spatial dynamics of connections between climate variability, phytoplankton communities and biogeochemical cycles in two important North Atlantic pelagic ecosystems.  We are partnering with NOAA scientists, thus benefiting from existing measurements made on this leg (surface pCO2, XBT Temperature profiles, surface T and S, towed continuous plankton recorder).

This goal of this one-year project is to establish the infrastructure to leverage future opportunities to outfit this specific route with more sophisticated autonomous instrumentation (e.g., underway mass spectrometry for measuring net community production, ocean pH, and algal cell imaging to  characterize phytoplankton community structure).  This pilot project will solidify critical partnerships with NOAA researchers who have a decade-plus relationship with this Icelandic shipping company.  This first year of preliminary data that we will collect with our system will represent an important demonstration of new autonomous, near-real-time approaches for collecting ecological and biogeochemical data with minimal user interaction.