Located off of North America’s Pacific coast lies the Cascadia Subduction Zone. Here, The E/V Nautilus conducted the first comprehensive study of the region, studying methane seep habitats. Methane (CH4) is a hydrocarbon that is a primary component of the natural gas we burn for energy. With 23 times the global warming potential of carbon dioxide, it is also a powerful greenhouse gas. The E/V Nautilus used its hull-mounted Kongsberg multibeam sonar to search for methane bubble plumes in the water column and used remotely-operated vehicles (ROVs) to further investigate the seep ecosystems. The bubble plumes are given off by methane deposits and methane hydrate, a solid, ice-like form of methane that fuels these unique ecosystems.
During the 2015 expedition, The E/V Nautilus discovered extensive white, orange, and gray chemosynthetic bacterial mats within the Cascadia Subduction Zone. Chemosynthesis is similar to photosynthesis in that the microbes use methane, sulfide, and/or other compounds (instead of sunlight) to generate energy. The bacteria consume about 80% of the methane given off by the seeps, and produce carbon as a byproduct. By making carbon readily available, these microbes make the seep sites habitable to other organisms such as tube worms, shrimp, mussels, and clams, which use carbon as an energy source.
Recent studies suggest that ocean warming could change the stability of seep sites by overwhelming microbial communities. The seeps could emit methane at a rate faster than the bacteria can consume it. The result is increased methane emissions into the atmosphere, leading to an increased rate of global warming. By studying the seepage sites of the Cascadia Subduction Zone, The E/V Nautilus Corp of Exploration hopes to gather baseline data on methane seep ecosystems. A better understanding of these unique ecosystems will help us to monitor and manage potential community changes as global temperatures continue to increase.
Check out the links below for some awesome footage of the life surrounding these underwater seeps!
E/V Nautilus, “Expedition Overview: Cold Seeps in 60 Seconds”
E/V Nautilus, “Life at Extremes: Biology of Brine Pools and Methane Seeps”
Featured image courtesy of Ocean Exploration Trust.