Date: July 9, 2019
Location: Lat: 38.3169°, Lon: -74.4284°
Dive Depth Range: 1,395 - 1,533 meters ( 4,993 - 5,030 feet)
Today we dove along the south facing wall in Wilmington Canyon. Wilmington Canyon is one of the major mid-Atlantic canyons that remains relatively unexplored. The remotely operated vehicles (ROVs) reached the bottom in the trough of the canyon around 1,533 meters (5,030 feet). This area was sedimented and had a high abundance of very small (about one centimeter) swimming holothurians, pancake urchins, a few large pycnogonid sea spiders, a number of different sea pens, the proboscis of a few spoon worms extended out of seafloor holes, and a number of different types of fish including Synaphobranchus eels, deep-sea lizardfish, juvenile cusk eels sheltering in the spines of urchins, and a halosaur (Halosauropsis macrochir).
As we encountered the hard rock substrate around 1,494 meters (4,902 feet) we started to observe brisingid sea stars; octocorals; giant solitary hydroids (Monocaulus sp.); and two species of octopods – warty octopods (Graneledone verrucosa) and a Muusoctopus johnsonianus, including the first of what would become many sightings of a warty octopus under a rock ledge in a poster guarding her eggs that were attached onto the rock surface. As the dive progressed, we observed over 20 individuals of warty octopods in a brooding poster in crevices and small cave-like areas in the rock surface. At least half of the octopods had eggs that were visible and the others could have had eggs hidden by their arms. Various color variations were observed across the individual brooding octopods and it was suggested to be due to various levels of senescence, or gradual deterioration, since the mother likely stays and guards the eggs until they hatch. A similar species of warty octopod has been observed in the Pacific in the same brooding poster over a four-year period.
This dive had very interesting geology with the rock features having imbedded fossilized fluid burrows whose formation is unknown. In the rubble/sedimented area around the rocks, we observed a number of corals, including octocorals and cup corals and various species of sea pens. We collected two octocoral and a black coral during the dive, with it ending around 1,395 meters (4,577 feet).