Our colleague Barney Balch recently led a study that revealed some pretty shocking discoveries about our Southern Ocean. This area has been critical in combating climate change by sequestering atmospheric carbon. The research, published in the journal Global Biogeochemical Cycles, highlights how coccolithophores, a type of phytoplankton, thrive in this cold environment. The broader impacts of these discoveries reach beyond ecology, helping to inform our knowledge of carbon cycling and its effects on the global climate.
The Southern Ocean has long been considered one of the planet’s most important sinks for atmospheric carbon. In the early 2000s, Balch and his colleagues discovered a unique area of seawater encircling Antarctica called the Great Calcite Belt. This area is an important hotspot for the cycling of carbon in the Southern Ocean. That far-reaching impact requires a deep dive into its biological and geochemical dynamics.
Study Overview and Methodology
This team was made up of scientists from Bigelow Laboratory for Ocean Sciences, Woods Hole Oceanographic Institute, Arizona State University, Texas A&M University and the Bermuda Institute of Ocean Sciences. They traveled from Hawaii to 60 degrees latitude, where they collected data along a transect located at 150°W longitude.
Armstrong and her co-authors used high-tech remote sensing instruments to calculate ocean color, calcification and photosynthesis rates. They examined concentrations of inorganic carbon and silica. These different measurements gave a holistic picture of the environment in the Southern Ocean.
Despite the challenges, the study found measurable concentrations of inorganic carbon and evidence of calcification taking place in these largely inaccessible far southern waters. Scientists had long thought coccolithophores to be abundant in cooler waters. This finding indicates that these organisms are capable of persisting in conditions once thought to be uninhabitable by them.
“This work takes a broad brush to understand the biological and geochemical dynamics of this far-flung body of water in ways that haven’t been previously possible.”
We had expected to find coccolithophores within a very narrow geographic range. This otherwise unaccounted-for player may have a significant impact on how carbon flows through the Southern Ocean. Balch herself mentioned that this broader conceptualization will help inform climate models that are based on precise projections of carbon cycling.
Implications for Carbon Cycling
One of their other major findings was that eddies from the south could function as “seed populations.” These eddies reliably transport coccolithophores into the Great Calcite Belt. This discovery opens exciting new opportunities for exploring the important role these organisms play in carbon sequestration.
Balch and his colleagues used multiple approaches to enhance their understanding of the Southern Ocean’s ecology. They employed both traditional sampling techniques and remote sensing capabilities to obtain a more nuanced view of this remote area.
“We’ve never had such a complete suite of integrated measurements through the water column in this part of the ocean.”
He explained the significance of measuring oceanic conditions through multiple approaches:
Advancements in Oceanographic Research
This multiscale lens equipped researchers to gather quantitative and qualitative data at varying depths. Such nuanced observations are typically not feasible with satellite data alone. Balch stated:
This massive data haul is the proverbial “smoking gun,” as Balch put it. It creates pointed linkages between how and why we see coccolithophores, to how important they are to carbon dynamics.
“There’s nothing like measuring something multiple ways to tell a more complete story.”
This multifaceted approach allowed researchers to gather data at various depths, which is often not possible with satellite observations alone. Balch stated:
“Satellites only see the top several meters of the ocean, but we were able to drill down with multiple measurements at multiple depths.”
Such comprehensive data collection provides what Balch referred to as a “smoking gun,” establishing clear connections between coccolithophores’ presence and their role in carbon dynamics.