Spring in the North Atlantic is formidable. Storm-lashed, frigid, gray. The subpolar region is so tumultuous that ever-vigilant space satellites often can’t penetrate the almost perpetual cloud cover, unable to provide a clear view of one of the most important life-sustaining events on the planet — the spring phytoplankton bloom.
That means if researchers ever hope to understand the phenomenon, they have to take to the high seas.
In 2008, an international expedition called the North Atlantic Bloom Experiment, funded by the National Science Foundation, did just that. It was the first to put marine scientists in the North Atlantic to observe the entire progression of the spring bloom over a three-month period, from development to demise.
They did that by using underwater robotic gliders and a float developed by University of Washington researchers that reported conditions between the surface and 1,000 meters several times per day, from early April through late June. High volumes of data were literally “phoned home” by the robots via Iridium satellite.
Now, the discoveries made possible by unprecedented, in situ data collection are being made public. The most recent announcement came in July when the National Science Foundation and the journal Science reported the results of one of the experiment’s studies — the discovery that the spring bloom can begin up to 30 days earlier than previously thought as the result of eddies stratifying the near-surface waters, rather than springtime warming of the ocean surface.
These new contributions to our understanding of the North Atlantic spring bloom, one of the largest in the world, will inform modeling by marine and climate scientists, according to University of Maine biological oceanographer Mary Jane Perry, who was among the 26 researchers from five countries on the expedition. The research findings also have implications for the Gulf of Maine, which is fed by the waters of the North Atlantic and supports similar species.
Major changes in the Gulf of Maine — including the influx of freshwater from accelerated melt in the Arctic and Greenland, and shifts in the marine food web — often occur first in the North Atlantic. But unlike the terrestrial ecosystem, scientists understand much less about North Atlantic phenology, Perry says, including annual variability, patterns and mechanisms.
“The North Atlantic is a really special place — a really important part of the ocean — because what happens there is so important to the atmosphere’s carbon dioxide cycle,” says Perry. “This subpolar region is responsible for more than 20 percent of the entire ocean’s uptake of carbon dioxide, and phytoplankton have an important role in that drawdown.”