Dive 02: “Escarpment Canyon”
December 1, 2017
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Dive 02: Wall of Life

During Dive 02 of the expedition, after traversing an area with a lot of sediment and not a lot of life, the team came upon this canyon wall covered with glass sponges belonging to the family Euplectellidae, as well as many large coral colonies. Video courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2017. Download larger version (mp4, 28.8 MB).

During Dive 02, we explored a canyon feature along the West Florida Escarpment, southwest of Pulley Ridge, starting at a depth of 2,319 meters (7,608 feet) and working up the canyon wall. The slope of the canyon wall varied throughout the dive, with less steep areas covered in sediment and generally harboring less life than steeper areas with hard, exposed carbonate substrates. Along a particularly steep section of the wall, we encountered an area of exposed hard substrate covered with thousands of glass sponges belonging to the family Euplectellidae. Large coral colonies (Isididae spp., Chrysogorgiidae spp., and Corallium sp.) also appeared in high numbers here, but only on corners and promontories that projected outward from the wall. Many of these coral colonies had commensals such as shrimp, brisingid sea stars, scalpellid barnacles, chirostylid squat lobsters, and featherstars. Other notable observations during the dive included a live larvacean (Bathochordaeus? sp.), an argonaut shell, and a polychaete worm, which had incorporated a number of pteropod shells into its tube. We also collected a bathycrinid sea lily or stalked crinoid that is likely a depth record for its family in the western Atlantic. The geology along the upper edge of the wall was particularly dramatic and consisted of several large, heavily pitted carbonate outcrops. Unfortunately, we encountered a large amount of marine debris throughout the dive, from gaskets and plastic bags to a bucket, glass bottles, and even a fluorescent light bulb.