MBARI engineers, led by Alana Sherman, developed a new robotic instrument that was programmed to sink 600 meters (about 2,000 feet) below the ocean surface while a large iceberg drifted overhead, then rise back to the sea surface after the iceberg had passed. This instrument, called a "Lagrangian sediment trap," was used to collect particles of sediment, bits of dead algae, and other debris that drifted down from the waters under and around the iceberg. This device allowed scientists to measure, for the first time, the amount of organic carbon sinking into the deep sea beneath a large (6-kilometers wide, 35-kilometers long, and 28-meters tall), free-floating iceberg.
The researchers compared the amount of carbon sinking down to 600 meters beneath the iceberg with the amount of carbon sinking in the open ocean nearby. They found that about twice as much carbon sank into the deep sea within a 30-kilometer (18.6-mile) radius of the iceberg, compared with an open-ocean "control" area.
Extrapolating their findings to the rest of the Weddell Sea, the researchers concluded that the icebergs (both large and small) were playing an important role in controlling how much carbon from the atmosphere was taken up by algae and ultimately transported into the deep sea. "The role of icebergs in removing carbon from the atmosphere may have implications for global climate models that need to be further studied," said Smith.
In addition to the direct measurements of material sinking beneath the icebergs, the multidisciplinary research team performed a wide variety of physical, chemical, and biological studies around the icebergs. Many of these studies are detailed in the special issue of Deep-Sea Research. The 19 papers in this special issue describe:
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Monterey Bay Aquarium Research Institute