In early October 2016, a tropical storm named Nicole formed in the middle of the Atlantic Ocean. It roamed for six days, intensifying to a powerful hurricane with 140 mph winds, before hitting the island of Bermuda as a Category 3 storm.
Hurricanes like Nicole can cause significant damage to human structures on land, and often permanently alter terrestrial landscapes. But these powerful storms also affect the ocean, and while we have some idea of their surface effects, we didn’t know much about how hurricanes impact the deep ocean.
A new study by researchers at the UChicago-affiliated Marine Biological Laboratory and the Bermuda Institute of Ocean Sciences has provided novel insight on those impacts. Nicole had a significant effect on the ocean’s carbon cycle and deep-sea ecosystems, the team reports.
Studying the deep ocean
Scientists have a good understanding of how hurricanes impact the surface layer of the ocean, the sunlit zone, where photosynthesis can occur. Hurricanes’ strong winds churn colder water up from below, bringing nutrients such as nitrogen and phosphorus to the surface and stimulating short-lived algae blooms. But effects lower down have been hard to track.
The Oceanic Flux Program has been continuously measuring sinking particles, known as marine snow, in the deep Sargasso Sea since 1978. It’s the longest-running time series of its kind. Before hitting Bermuda, Hurricane Nicole passed right through the OFP site, about 50 miles southeast of Bermuda. This gave the scientists a unique opportunity to study how hurricanes impact the deep ocean.
To study the deep ocean, the program strings scientific equipment, including sediment traps, at various depths on a mooring line that extends up from a 2,000-pound anchor situated on the seafloor, 2.8 miles below the surface.
—Prof. Jacqueline Stewart
