Deep-sea Corals and Sponges

In the fall of 2011, GFNMS in partnership with US Geological Survey (USGS) and NOAA's National Centers for Coastal Ocean Science (NCCOS), conducted multibeam surveys to better define the bottom habitats of the sanctuary. The multibeam data revealed highly detailed images of several significant underwater geologic features off San Francisco and Marin counties in NOAA's Gulf of the Farallones National Marine Sanctuary. These underwater features can now be seen for the first time ever through the release of an animated 3-D "flythrough" which can be viewed below.

This "flythrough" was produced by NOAA's National Centers for Coastal Ocean Science, USGS, and GFNMS. Highly detailed maps of topography and substrate type for Rittenburg Bank, Farallon Escarpment and an unnamed bank are now revealed for the first time. The newly explored bank is currently labeled as "West Fanny Shoal" in the 3-dimensonal, high-resolution video. This is the first time Rittenburg Bank and Farallon Escarpment have been mapped in this level of detail.

In October 2012, the sanctuary will explore these areas in greater depth to determine the presence of deep-sea corals and sponges and the importance of these animals to fish and other invertebrates in the marine sanctuary. Deep-sea coral and sponge communities are believed to form key "living habitats" for other sea life in the marine ecosystem. The October research cruise will use a remotely operated vehicle (ROV) with cameras to explore the target areas most likely to support communities of deep-sea corals and sponges. In deep, cold oceanic waters, complex habitats are most often formed by species of corals and/or sponges already adapted to environmental conditions such as high pressure and little to no sunlight. They form remarkably complex and fragile ecosystems throughout the world's oceans. The 2012 expedition will also document any marine debris and establish baseline water quality conditions as they relate to potential impacts of ocean acidification on deep-sea corals.

A red urchin hides behind the California hydrocoral
Rittenburg Bank is a likely to have corals and sponges similar to species found on Cordell Bank and Davidson Seamount, such as this coral, Stylaster sp

Rittenburg Bank, approximately 50 kilometers (31 mi) off the Marin county coast, lies at depths ranging from approximately 50 to 150 meters (165-490 ft); the unnamed bank, labeled 'West Fanny Shoal', lies at depths ranging from 70 to 150 meters (230-490 ft) is 68 kilometers (42 mi) off San Francisco and just west of Fanny Shoal; and the Farallon Escarpment, around 45 miles west of San Francisco, plunges from approximately 150 meters deep (490 ft) at the edge of the continental shelf to the seafloor at around 2,000 meters (6560 ft).

In addition to the 2011 discovery of new geologic features, the 2012 expedition may yield more information on canyons along the Farallon Escarpment and prove to be the key to finding new deep-sea corals and sponges. According to USGS's Guy Cochrane, "The canyons are active erosional features and numerous slump debris masses, and slump scarps can be seen in the data on the upper slope of the Farallon escarpment. The slumping may have exposed hard bottom on the scarp faces. These areas will be explored to determine if they provide habitat for corals."