Highlights: 00:48:50 Yellow stalked crinoids - Anachalypsicrinus nefertiti 00:57:00 Hexactinellid sponge 01:16:11 Hexactinellid sponge 01:29:18 Hexactinellid sponge 02:13:20 Demosponge - Polymastia sp. 02:36:12 Hexactinellid sponges & bamboo coral 02:56:29 Hexactinellid sponges & demosponges

The canyon floor contains coarse sediment leading to a series of carbonate cliffs and ledges covered in a thin layer of soft sediment. Very small white echinoids, cf. Echinus sp. are present on the canyon floor; stalked crinoids are very common as are holothurians, Benthogone sp. The white holothurian Mesothuria intestinalis, and Holothuroidea sp. 2 (from Howell & Davies 2010) occur at 2100 m. On hard ground black corals, Bathypathes sp. and Leiopathes sp. are common as are sponges, globular and encrusting forms are recorded as well as glass sponges, including Euplectella sp. Barnacles and cup corals are occasionally present on hard substrate. A delicate chrysogorgiid coral was observed at 2100 m. With the exception of the occasional eel and grenadier there is a paucity of fish species here.

START VIDEO A [00:00:00]/10:45 [1] The transect starts on mixed substrate, gravel and mud, with small white echinoids (OTU559). ROV moves left. [00:02:00] Start encountering sparse boulders with stalked crinoids and sponges. [00:03:00] ROV moves diagonally left then diagonally right, stopping for imagery until [00:04:00] when ROV moves right then forwards away from boulders. [00:05:00] [2] increased cobbles and boulders lead to a large smooth black bedrock protrusion hosting stalked crinoids (especially Anachalypsicrinus nefertiti)/sponges/corals on the hard substrate. ROV moves around protrusion left then right. Proceeds over gravel/mud to another small protrusion, here beige pitted rock. [00:09:00] ROV moves forwards away from protrusions, but encounters several boulders colonised similarly. Echinoids continue on the gravel/mud. [00:17:00] [3] An extended area of gravel/mud with echinoids. Some pull from the ship makes the ROV move slowly and at [00:18:00] get pulled backwards. [00:25:00]-[00:26:00] stop and test sediment with arm, mud is shallow c 10cm before hitting hard substrate and the resistance lifts the ROV. There gravel starts transitioning to pebble size. [00:29:00] [4] pebbles/gravel/mud, there are many small gastropods here (cf . Colus sp.), along with purple holothurians (cf. Benthogone sp. , OTU432). Occasional cobbles until [00:35:00] [5] denser cobbles/boulders with A. nefertiti dominating. [00:37:00] [6] mud/sand and pebbles with occasional cobbles, again purple holothurians (cf. Benthogone sp. . ) are abundant. There is increasing biogenic material in the mixed sediment, especially stick-like forms which may be crinoid stalks or coral skeletons. [00:40:00] one trawl mark was encountered before the slope angles uphill. [00:41:00] [7] Stalked crinoids dominate cobbles and boulders and vertical black rock, with many sponges and corals also present. An extended cliff section is particularly diverse, with chrysogorgiids becoming abundant. [00:55:00]-[01:02:00] stop for sampling Rhabdodictyum cf. delicatum (OTU611), [01:09:00]-[01:11:00] stop for imagery, [01:14:00]-[01:16:00] stop to sample another sponge (may be same species, but unknown). [01:24:00] reach the top of the cliff and proceed over horizontal bedrock. [01:29:12]-[01:36:00] stop for imagery and sampling yellow Rhabdodictyum cf. delicatum (OTU616). [01:39:00] [8] again holothurians on mixed pebbles/mud, some cobbles present. [01:43:00] [9] Area of steep cobbles/ boulders before the base of a small (conglomerate?) bedrock cliff, with cobbles/boulders on top (A. nefertiti). Another cliff feature becomes apparent which the ROV descends over stopping and a ledge at [01:49:00]-[01:54:00] to image and sample a lamellate sponge (possibly OTU1151). The base of the cliff is cobbles and boulders down to a flatter landscape at [01:56:00] [10] Pebbles/mud host holothurians, and a step in the underlying bedrock is identifiable by the presence of large sponges and corals, while scattered boulders continue the hard substrate assemblage (especially A. nefertiti). [01:58:00] Stop for imagery. END VIDEO A 12:49.

START VIDEO B [02:04:00]/12:50. [02:05:00]-[02:10:00] sampling small muddy globose sponge (OTU1128), here the pebble veneer is cleared from using the scoop and leaves only mud behind. Proceed forward over more gravel/mud with scattered boulders. [02:21:00] [11] another conglomerate cliff (black and beige rock) with stalked crinoids and corals [02:23:00]-[02:24:00] stop for imagery of small octopus on cliff. [02:26:00] [12] mud/gravel with bedrock step features. [02:27:00] encounter strange fine grain sedimentary rock boulder (beige, pitted) colonised by stalked crinoids and many Poecilosclerida sp. (OTU1146) sponges, image around boulder. Several more smaller similar boulders/protrusions are encountered, ROV does some zigzagging around these. [02:48:00] Hard sedimentary rock slope up to area of [02:50:00] [13] cobbles and boulders, then cliffs, some sedimentary (sponges especially abundant), some layers of black (conglomerate?) rock (comatulid crinoids abundant). Up to smooth sloping black bedrock to a summit area, with A. nefertiti and chrysogorgiids dominating. This forms a rolling plateau of rock with gullies filled with cobbles/boulders. ROV descends over edge to area of mixed sediment. [03:07:00] stop for pushcore before END VIDEO B [03:12:00]/13:59.