This video serves as a preview for an upcoming E/V Nautilus expedition to the Cascadia Margin, off the coasts of Oregon and Washington. Lead scientists Tamara Baumberger and Susan Merle discuss the expedition's primary focus on exploring and characterizing methane seeps created by the Cascadia Subduction Zone. The scientists explain how modern multibeam sonar technology, which maps both the seafloor and the water column, is used to detect the bubble plumes that signify active seeps. The expedition aims to visit various seep sites at different depths and latitudes to collect a diverse range of samples, including gas bubbles, sediment cores, biological specimens, and water column samples. Key objectives include mapping unexplored areas, understanding the unique chemosynthetic ecosystems that thrive on these seeps, quantifying the carbon release, and establishing a scientific baseline to monitor future changes related to tectonic activity and climate change.
Exploring the Methane Seeps of the Cascadia Margin
0:02:46 The Cascadia Subduction Zone: The expedition will explore the Cascadia Margin, an area off the coasts of Oregon and Washington where one tectonic plate is subducting under another. This geological activity squeezes out fluids and gases, primarily methane, from deep sea sediments, creating bubble streams known as methane seeps.
0:04:24 Thriving Ecosystems: These methane seeps support unique chemosynthetic ecosystems. Microbes consume the methane and produce sulfide, which in turn provides the energy source for a diverse food web of clams, tube worms, and other organisms that live without sunlight.
0:07:54 Mapping with Modern Technology: Scientists use advanced multibeam sonar on the E/V Nautilus to find these seeps. This technology simultaneously maps the seafloor topography and scans the water column, allowing researchers to visualize the bubble plumes rising from the seafloor.
0:11:01 Thousands of Seeps Discovered: Over 3,500 individual bubble streams have been identified so far along the Cascadia Margin. However, a significant portion of the margin, especially in shallower waters, remains unmapped, suggesting many more seeps are yet to be discovered.
0:12:38 Climate Change Implications: A major focus is mapping along the 500-meter depth contour, which marks the edge of the methane hydrate stability zone. Scientists are studying these seeps to establish a baseline and monitor how warming ocean temperatures could destabilize these frozen methane deposits, potentially releasing large amounts of greenhouse gas.
0:16:49 Sophisticated Sampling Techniques: The team will use a Remotely Operated Vehicle (ROV) for daily dives to collect samples. This includes using specially designed, evacuated, gas-tight bottles with funnels to capture pure bubble samples, as well as taking push cores of sediment, biological specimens, and water samples to study the system's geochemistry and biology.
0:20:56 Primary Expedition Goals: The core objectives are to map unexplored regions, characterize the diversity of seep ecosystems, understand the role of these seeps in the global carbon cycle, and create a baseline to track environmental changes over time.
0:25:58 Dynamic and Unpredictable Seeps: The scientists note that methane seeps are highly dynamic. They can turn on and off, shift location, and be influenced by tides, which adds a layer of challenge to locating and sampling them.
0:37:03 Watch the Expedition Live: The entire expedition, including ROV dives and mapping, will be streamed live 24/7 on NautilusLive.org, where viewers can follow the exploration and ask the scientists questions in real-time.