NAAMES Summer 2016 Cruise
Think flowers are the only things that bloom in the springtime? In the North Atlantic Ocean, spring also brings large blooms of phytoplankton that span thousands of square kilometers, as light, a limiting factor in phytoplankton growth, becomes more abundant and the nutrient rich surface waters stabilize to conditions that promote rapid growth. This resource driven perspective on what controls the North Atlantic spring bloom has long stood as the accepted hypothesis for what governs phytoplankton accumulation; however, inconsistencies in cell division rates and accumulation have suggested that other factors may control the timing and intensity of the spring bloom. The North Atlantic Aerosol and Marine Ecosystems Study (NAAMES) has set out to identify these factors, suggesting that instead, seasonal changes in predator-prey interactions with grazers and viruses play a key role in controlling phytoplankton accumulation during the annual cycle. The NAAMES project also takes a wider ecosystem perspective, exploring how these microbial processes influence aerosol formation and cloud nucleation in the atmosphere. Professor Kay Bidle, an expert on phytoplankton host-virus interactions, along with PhD graduate student Christien Laber, are exploring a critical component of this study: how do viruses regulate the growth dynamics of phytoplankton throughout the annual cycle of primary production in the North Atlantic and, in turn, impact the ocean ecosystem dynamics and nutrient cycles? Using a suite of diagnostic genetic, lipid, cell biology and optical tools, Bidle and Laber are trying to identify who is being infected, how this contributes to loss terms controlling phytoplankton accumulation, and how viral infection plays a role in broad ecosystem processes and the carbon cycle.
So far, NAAMES has completed two of four field campaigns, November 2015 and May 2016, which consisted of month-long scientific cruises sampling from the southern tip of Greenland down to more southerly sub-tropical waters, accompanied by aircraft sampling and satellite remote sensing of atmospheric and water column properties associated with phytoplankton blooms. With two more campaigns scheduled in summer 2017 and winter 2018, Bidle and his colleagues will be able to weave together data from each season, shedding light on how the annual ecosystem dynamics influence the spring bloom. NAAMES is a lead by Mike Behrenfeld, professor at Oregon State University and is funded by the National Aeronautics and Space Administration’s (NASA) Earth Science Program. It brings together ocean scientists across different disciplines from twenty-one institutions, all of which are working together to tackle this fundamental aspect of how phytoplankton impact ocean ecosystem and atmospheric dynamics and develop a predictive understanding about this process in the face of climate change.