Dive 01: “South Reed”
November 30, 2017
Access Dive Summary and ROV Data
Loading the player...

Dive 01: Giant Isopod

During the first dive of the expedition, we saw this giant deep-sea isopod, Bathynomus giganteus. While we often see these giant underwater 'pill bugs' resting on the seafloor, we don't always get to see them swim, so seeing this isopod, which measured nearly 30 centimeters (almost one foot) long, come in for a landing was exciting! Video courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2017. Download larger version (mp4, 24.0 MB).

Today’s dive took place at “South Reed,” a site southwest of Florida located in an area proposed as a Habitat Area of Particular Concern by the Gulf of Mexico Fishery Management Council. The remotely operated vehicle (ROV) Deep Discoverer touched down at a depth of 816 meters (2,677 feet) on a fine muddy bottom and immediately encountered large numbers of shortfin squid (Illex sp.). We saw these squid throughout the dive. Their aggregation may have been associated with breeding, because we saw many dead specimens; squid often die after reproducing. We also saw the giant deep-sea isopod pill bug, Bathynomus giganteus, as well as several species of decapod crustaceans, including Chaceon fenneri (golden crab), C. quinquedens (red crab), royal red shrimp (Pleoticus robustus), and Nematocarcinus sp. shrimp. These decapods highlight the importance of the area, as all are commercially fished species. Some of the most extraordinary organisms encountered were several species of sponge in the family Cladorhizidae – extraordinary because, unlike all other sponges, which feed on extremely small suspended particles, members of this family are carnivorous and trap small crustaceans on their hook-like skeletal spicules. Moving up the first escarpment, we encountered several species of bryozoans (moss animals), octocorals, and black corals with zoanthids and sponges. Many of them harbored commensals, including squat lobsters, shrimps, and scale worms. Continuing up slope, coral rubble appeared in increasing abundance and transitioned into an area of lightly sedimented hard substrate with patches of dead colonies of the branching stony coral, Lophelia pertusa. On the second escarpment, the bottom community became more diverse and dense, and included the stony corals Lophelia pertusa, Madrepora occulata, and solitary cup corals, as well as the octocorals Acanthogorgia sp., Paramuricea sp., and Pseudoanthomastus sp. Many of these also hosted commensals. The geology along the upper edge of the second escarpment was particularly dramatic, consisting of several small walls of limestone. The dive ended at the local high of the escarpment (645 meters; 2,116 feet), a flat terrace dominated by a high density of three species of black corals (Antipatharia).