Blog: Long Ridge seamount communities - 7, 8 March
8 March 2018The Benthic team have been observing and identifying animals living on the seabed at Long Ridge, north of the Ross Sea.
8 March 2018
The Benthic team have been busy the past few days observing the seafloor video captured by the Deep Towed Imaging System (DTIS) camera in real time to make observations on the seafloor substrate type and to identify any animals living on the seabed at Long Ridge.
A rattail fish (Macrourus sp.), small white hydrocoral, purple anemone Actinernus elongatus, and a dark red shrimp sitting on a substrate of gravel and long-dead barnacle plates on Scott C seamount at 967 m.
Long Ridge is a series of long ridge-like seamounts north of the Ross Sea in the Southern Ocean. The team led by Malcolm Clark, NIWA, are comparing seabed areas inside and outside the new Ross Sea Marine Protected Area to improve knowledge of the composition and structure of seabed communities. On the Iselin Bank in the Ross Sea, highlights seen included a dumbo octopus, boulders covered in snake stars, large patches of seabed covered with rosselid glass sponges and demosponges, and some stylasterid hydrocoral banks.
Transects on Scott C seamount in the Scott Island complex revealed purple anemones, black corals, king crabs and abundant small white bamboo corals. Finally, on Long Ridge in the last two days we have seen numerous bright yellow stalked crinoids, Ptilocrinus amezianeae Eléaume, Hemery, Bowden & Roux, 2011 only recently described from Admiralty seamount, boulders crowded with bright red soft corals, Anthomastus sp., rock pens, and black corals.
The Deep Towed Imaging System (DTIS) camera that will film and take photographs of the seafloor. It can be deployed all the way down to 6000 m deep but on this survey we will use it between 600–1500 m.
AB Bruce McIntyre expertly flies the DTIS 2-3 m above the seafloor as it is towed along by the ship with the CTD winch by watching the seafloor feed and adjusting the depth accordingly.
The midday to midnight DTIS team, concentrating on what is living on top of the rocks on Long Ridge. Nick Eton, NIWA, looks after the DTIS controls, Sadie Mills, NIWA calls out observations of substrate and fauna from the video feed and Aitana Forcén-Vázquez, MetOcean/University of Auckland enters the observations into the Ocean Floor Observation Program (OFOP).
At the summit of a small hill feature on SE Iselin Bank (722m) large boulders covered in soft coral (Alcyoniidae), the snake star Astrotoma agassizii, Ophiacantha pentactis brittle stars, orange zoanthids, barnacles Bathylasma corolliforme and numerous dead barnacle plates forming the substrate.
Rossella sp. vase-shaped glass sponges and thin fan-shaped demosponges attached to cobbles were abundant throughout the transect ~750 m on SE Iselin Bank.
A large black coral with orange polyps, a rock pen, and a red Anthomastus sp. soft coral with its tentacles withdrawn, plus a couple of sponge species on the left of the image, and brittle stars on the gravel. Long Ridge, 850 m.
