A very high density of bamboo corals and glass sponges were observed towards the end of the dive. To date, these are among the deepest high-density communities recorded in the Gulf of Mexico. Image courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018. Download larger version (jpg, 1.1 MB).
This glass sponge, observed at 2,280 meters (~7,480 feet), was host to many other organisms, including brittle stars, a gooseneck barnacle, an amphipod, a polychete worm, and a squat lobster. Image courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018. Download larger version (jpg, 700 KB).
A yellow crinoid perched on a precious coral (Corallium niobe) that was attached on a topographic high. There was an abundance of bryozoans at the base of this colony. Image courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018. Download larger version (jpg, 675 KB).
Today’s dive surveyed an unexplored narrow ridge feature off a system of canyons on the southern end of the West Florida Escarpment to a depth of ~2,400 meters (~7,875 feet). On the ridge crest, there were several exposed rocks, but no encrusting organisms were seen growing on them. However, moving up the ridge crest, numerous exposed rocks and boulders hosted corals and sponges. For most of the dive, large rock outcrops, separated by sediment patches, were observed. Corals and sponges, as well as densely clumped communities of associated invertebrates, were more common on the rocks than in the sedimented areas. Some rocks displayed clear layering and most had a black oxide crust. In one area, pronounced scour pits around some rocks were observed, indicating excavation by rapid currents. Towards the later part of the dive, the terrain became steeper and vertical rock walls were observed. Additionally, the ridge crest became very narrow – only a few meters across.
The most commonly encountered animals included bamboo corals, black corals, plexaurid corals, and glass sponges. Other animals included chrysogorgid corals, precious coral, stoloniferan corals, anthothelid corals, sea pens, anemones, demosponges, sea stars, zoanthids, crinoids, bryozoans, benthic ctenophores, barnacles, shrimp, and a sea cucumber. Fish included tripod fishes, halosaurs, and a cusk eel. Towards the end of the dive, we observed a very high density of bamboo corals and glass sponges; these are among the deepest high-density communities ever recorded in the Gulf of Mexico.