Dive 15: Pichincho Wall East

Date: November 15, 2018
Location: Lat: 18.37005°, Lon: -67.75489°
Dive Depth Range: 250-366 meters (820-1,200 feet)

Roughtongue bass Pronotogrammus martinicensis seen next to to stylasterid corals during Dive 15. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (jpg, 1.1 MB).
A highlight of Dive 15 was the sighting of a translucent egg case with a catshark embryo actively swimming inside. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (jpg, 746 KB).
Yellowfish flagfish Aulopus filametosus seen next to patch of small stylasterid corals. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (jpg, 1.3 MB).
Stylaterid corals were by far the most abundant corals on today’s dive. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (jpg, 1.5 MB).
The terrain explored during Dive 15 included a lot of overhangs and crevices, which provided great habitat for a wide diversity of organisms. Image courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (jpg, 1.5 MB).

Today’s dive explored a steep ridge at 250-366 meters depth (820-1,200 feet), which provided habitat for the highest biodiversity we have encountered on this expedition so far. The structural relief at this site was very impressive with a lot of overhangs, crevices, and large boulder-like features, which provided great habitat for a wide diversity of fishes, corals, sponges, and other invertebrates. We observed a total of 12 different species of fish during the dive, with the bigeye soldierfish (Ositchtys trachypoma) being the most abundant throughout the dive, followed by silk snappers (Lutjanus vivanus). A highlight of this dive was a translucent egg case, which was attached to a coral branch. Upon zooming in on this egg case, we were able to clearly see the embryo of a catshark actively swimming within the case.

Corals and sponges were particularly abundant at the site. Sponges consisted primarily of encrusting demosponges, but also included numerous glass sponges. Deep-sea corals included black corals, scleractinian corals, octocorals, and stylaterids, the latter of which were by far the most abundant group and frequently seen underneath overhangs. We also saw Linkia sp. and Plinthaster dentatus sea stars on the faces of ledges, as well as Cidocidaris micans, one of which looked like it was eating a sponge. Other organisms observed included squids (Doryteuthis sp.) and more crabs (Mithrax sp.) than we have seen on any previous dive of this expedition. Crinoids and sea cucumbers were consciously absent on today’s dive.

Sharks that are oviparous lay eggs outside the mother’s body and provide no parental care to the next generation. A yolk sac inside the egg case provides the embryo with all the nutrients necessary for its development. Egg cases are attached to invertebrates or algae via long strands that coil around a solid base during the few months until hatching. After completing its development, the shark pup will emerge from the case and will be ready to swim in order to maximize its survival chances. Benthic shark species belonging to the families Scyliorhinidae, Hemiscylliidae, and Heterodontidae and all skates reproduce in this manner. This egg case was seen during Dive 15 of the Océano Profundo 2018 expedition.

Text contributed by Michelle T Scharer Umpierre, University of Puerto Rico.

Video courtesy of the NOAA Office of Ocean Exploration and Research, Exploring Deep-sea Habitats off Puerto Rico and the U.S. Virgin Islands. Download larger version (mp4, 79.1 MB).

Location of Dive 15 on November 15, 2018. Download larger version (jpg, 2.2 MB).

The remotely operated vehicle track for Dive 15, shown as a white line. Scale is water depth in meters. Download larger version (jpg, 668 KB).