North Atlantic plankton bloom’s secret finally unlocked

North Atlantic plankton bloom’s secret finally unlocked


According to a recent statement, oceanographers from the Woods Hole Oceanographic Institution (or WHOI) in Massachusetts recently published new data concerning the annual diatom bloom—a process that sustains the ocean’s ecosystem and absorbs vast amounts of carbon dioxide—online in the journal Science.

The report describes what is known as the North Atlantic Bloom as “the blooming of countless microscopic plants, or phytoplankton.” WHOI explains the necessity of this “biological pump” to our global climate, saying, “The North Atlantic is critical to this process; it’s responsible for more than 20 percent of the ocean’s uptake of CO2.”

The annual blossoming of phytoplankton not only fills an important environmental function, but the flourishing of the separate species creates colorful swirls and shapes visible from space. MSNBC describes the process as first a “greening” and then ”whitening” as the plants burst into existence in the middle of the chilly North Atlantic.

Don Rice, program director in the National Science Foundation’s Division of Ocean Sciences (the organization funding the study) noted that the North Atlantic bloom is well studied, yet the trigger itself remains somewhat understudied. Previously, the annual blossoming had been largely attributed to an increase of necessary sunlight allowing for photosynthesis.

“Every undergraduate who takes an introductory oceanography course learns about the ecological and climate significance of the North Atlantic Bloom—as well as what causes it,” said researchers.  “This study reminds us that, when it comes to the ocean, the things we know hold some big surprises.”

The diatom blooming process is described in the article by Amala Mahadevan, the author of the study and oceanographer at WHOI, as inextricably linked to the flow of whirlpools circulating the plants through the water and keeping them afloat.

“[The study’s] results show that the bloom starts through eddies, even before the sun begins to warm the ocean,” said Ms. Mahadevan.

This study explains the causation of phytoplankton’s phenology—the reasons behind the annual timing of the microscopic plant’s natural cycle—as it is influenced by the ocean’s conditions.

“Springtime blooms of microscopic plants in the ocean absorb enormous quantities of carbon dioxide, much like our forests, emitting oxygen via photosynthesis. Their growth contributes to the oceanic uptake of carbon dioxide, amounting globally to about one-third of the carbon dioxide we put into the air each year through the burning of fossil fuels. An important question is how this ‘biological pump’ for carbon might change in the future as our climate evolves,” said researchers.

WHOI describes the study as being conducted by a specially designed robot that can float just below the surface like a phytoplankton (only much, much larger). Other robots, referred to by WHOI as “gliders” dove to depths of 1,000 meters to collect data and beam it back to shore. Together, the robots discovered a great deal about the biology and nature of the bloom. Then, using three-dimensional computer modeling to analyze the data, Ms. Mahadevan created a model that corresponded with observation of the natural phenomena.

Co-authors Mary Jane Perry of the University of Maine and Craig Lee of the University of Washington say that annual repetitions of the study could provide a more complete picture of the ocean’s physics, chemistry, and biology— studies that could in turn spark a new understanding of how the ocean’s carbon cycles contribute to the Earth’s climate.

Eric D’Asaro and Mr. Lee, oceanographers in the UW’s Applied Physics Laboratory and School of Oceanography, are among the researchers who discovered that whirlpools, or eddies, that swirl across the North Atlantic sustain phytoplankton in the ocean’s shallower waters, where the plankton can get plenty of sunlight to fuel their growth even before the longer days of spring start.

“We could learn a lot from following its evolution across an entire year with gliders and float outfitted with new sensors to look at the zooplankton that graze on a smorgasbord of phytoplankton. This data could be integrated with a suite of physical-biological models to unfold a more complete story” said the scientists.

It remains unclear exactly what impact this study will have on global climate change. A better understanding of the cause of the massive plankton blooms could allow climate scientists to unravel the mysteries of global warming. Findings also allow for a better understanding of how carbon dioxide, the main source of climate change, impacts local ocean life.