Marine Institute
SeaRover Dive Video

D483A Transect 29 Bedrock cliffs with Solenosmilia colonies, terraced carbonate cliffs and mixed corals, areas of sloping bedrock with a rich sponge aggregation (Aphrocallistes beatrix). Features of Interest: canyon, escarpment, carbonate mound Water Depth: 1523-1145 m

Highlights: Yellow sea fan, brisingid starfish & Anthomastus octocoral Hexactinellid sponge Acesta excavata file shell and anemones Cable Anthomastus octocoral Line Hexactinellid sponge with yellow zoanthid anemone Hexactinellid sponge reef

The soft sediment floor of the canyon contains burrows, presumed to be those of galatheids; echinoids and holothurians are also present here. A large rock cliff with block-like boulders at right angles to each other occurs at the base of the mound. The boulders are colonised by the stony coral Solenosmilia variabilis and the bivalve Acesta excavata. These bivalves are particularly dense in crevices and overhangs. The terrain is terraced with soft sediment on the horizontal steps. Cliff and rock are colonised by a variety of corals, including black, bamboo, gorgonian and soft corals. The smooth column hormathiid anemone is common here. Fish species include grenadiers, oreos and numerous orange roughy, some very small in size.

At 1370 m the seafloor is comprised of carbonate sediment and cliffs of carbonate substrate approximately 10 m in height. These carbonate areas are interspersed with fine, dark grey to black sediment. The carbonate is sparsely colonised with encrusting sponges but diverse fauna are found where hard rock occurs and includes, the glass sponge Aphrocallistes sp., cup sponges and black and bamboo corals. Oreos, including a juvenile, are very common. Numerous white sponge covered with yellow zoanthids are frequent on the mound slope while white hydrozoan coral is very plentiful on the mound top. The variety and density of sponges implies this location is a sponge field. Discarded rope/fishing line was observed at this site.

START VIDEO A [00:00:00]/21:48 [1] Transect starts on mud with some burrows, white Benthogone sp. (OTU574) Holothurians dominate the epifauna. [00:08:00] [2] Low vertical bedrock cliffs (c [00:02:00]) with sparse encrusting fauna (some signs of barnacles but few look to be living at present) and a couple of larger sponges. [00:14:00] [3] back to mud and holothurians along with sparse cup corals. [00:18:00] [4] both protruding carbonate and bedrock cliffs, mixed corals initially, with an area dominated by discrete Solenosmilia variabilis. [00:33:00]-[00:45:00] Sampling. 54-[01:01:00] Sampling. [01:10:00] [5] up over cliffs to mud with sparse cup corals, occasionally with small carbonate protrusions. [01:28:24] [6] terraced carbonate cliffs with mixed corals and light mud/sand veneer. [01:44:00] CTD recordings stop. [01:49:00] [7] epifaunally rich mud at top of cliffs similar to in T26 hosts xenophyophores (Syringammina fragilissima), cup corals and Acanella arbuscula together (labelled as mosaicked Cup coral/Xenophyophore communities, but may be more appropriate to create new combination community. [01:58:00] [8] relatively smooth sloping bedrock with light mud/sand veneer hosting sparse mixed corals and xenophyophores (not usually seen on bedrock!). END VIDEO A 23:58.

START VIDEO B [02:09:00]/00:02: continued until [02:12:00] [9] Bedrock less smooth here, hosting lamellate/lobose (especially Aphrocallistes sp.) sponge aggregation with large stylasterid hydrocorals (assemblage usually associated with the upper bathyal). [00:06:00]-[02:29:00] two sampling events. [02:38:00] [10] proceed up slope and to top of slope where rock is again smooth and large stylasterids & sponges persist in isolated patches while xenophyophores dominate intermediate areas. The current appears stronger up here. [02:59:00] [11] Top of slope, the landscape is rolling, video poor due to being too zoomed in outside of the light pool. Here there is a thicker sand/mud veneer hosting patchy xenophyophores, while scattered pebbles and rare cobbles are dominated by barnacles. Just as landsape starts sloping downhill again, navigation ends two minutes before ENDVIDEO B in same spot at [03:14:00]/01:08.

Progression Start Duration Code Name
1[00:00:00]00:08:02M.AtUA.Mu.HolComHolothurian dominated community on Atlantic upper abyssal mud
8[00:00:00]02:09:45M.AtLB.Ro.MixCorMixed cold water coral community on Atlantic lower bathyal coarse sediment
9[00:03:37]00:25:42M.AtUB.Ro.DeeSpo.SpoStyLobose sponge and stylasterid assemblage on Atlantic upper bathyal rock and other hard substrata
2[00:08:03]00:06:16M.AtMB.Ro.SpaEncSparse encrusting community on Atlantic mid bathyal rock and other hard substrata
3[00:14:20]00:04:36M.AtUA.Mu.HolComHolothurian dominated community on Atlantic upper abyssal mud
4[00:18:57]00:52:00M.AtLB.Ro.MixCor.DisSolDiscrete Solenosmilia variabilis colonies on Atlantic lower bathyal rock and other hard substrata
10[00:29:20]00:20:40M.AtLB.Mx.XenCom.SyrFraSyringammina fragilissima field on Atlantic lower bathyal mixed sediment
11[00:50:01]00:13:45M.AtMB.Ro.BarComBarnacle dominated community on Atlantic mid bathyal rock and other hard substrata
5[01:10:58]00:17:27M.AtUA.Mu.HolComHolothurian dominated community on Atlantic upper abyssal mud
6[01:28:26]00:20:53M.AtLB.Ro.MixCorMixed cold water coral community on Atlantic lower bathyal coarse sediment
7[01:49:20]00:08:59M.AtLB.Mu.SolSclSolitary scleractinian field on Atlantic lower bathyal mud

Foraminifera
Syringammina fragilissima : 261 : O
Porifera
Hyalonema sp. 1 : 917 : O
Aphrocallistes beatrix : 264 : F
Geodia cf. atlantica (Porifera massive lobose sp. 6) : 83 : O
Porifera cup 2 : 535 : O
Porifera encrusting (blue) : 532 : O
Porifera encrusting globose (pale) : 75 : O
Porifera encrusting sp. 1 (white) : 1 : R
Porifera encrusting sp. 10 (yellow) : 30 : R
Porifera globose (muddy) : 1128 : O
Porifera globose (spiky Loofah) : 1127 : R
Porifera lamellate sp. 10 : 1010 : O
Porifera lamellate sp. 10 (Yellow Solenosmilia assoc.) : 623 : O
Porifera lamellate sp. 7 : 422 : O
Porifera lamellate sp. 9 : 606 : F
Porifera massive globose sp. 6 : 137 : R
Porifera massive globose sp. 9 : 380 : O
Porifera massive lobose sp. 18 (cf. Farrea sp. ) : 576 : O
Porifera massive lobose sp. 32 : 1090 : R
Blue Porifera encrusting : 800 : R
Cnidaria
Cerianthidae sp. 1 : 2 : R
Actiniaria sp. 20 : 605 : R
Sagartidae sp. (wide oral disc) : 1118 : O
Actiniidae sp. (sand Bolocera) : 41 : R
Actinoscyphiidae sp. 1 (pink) : 1047 : R
Actinostolidae sp. 1 : 132 : R
Phelliactis sp. 1 : 255 : R
Stichopathes sp. : 560 : O
Chrysopathes sp. Trissopathes sp. : 540 : R
Leiopathes sp. : 305 : R
Bathypathes sp. (brown) : 284 : R
Dendrobathypathes ( prev. Stauropathes sp. 1) : 1015 : R
Parantipathes sp. : 1042 : O
Stauropathes arctica : 547 : O
Corallimorphidae sp. 1 : 39 : R
Caryophyllidae sp. (tentative) : 1057 : R
Caryophyllia sp. 2 : 6 : F
Caryophyllia sp. 5 (bullseye) : 584 : R
Solenosmilia variabilis : 700 : F

Flabellum sp. : 1056 : R
Zoanthidea sp. 3 (Hyalonema assoc.) : 925 : R
Zoanthidae sp. 2 : 586 : R
Acanthogorgia cf. armata : 608 : O
Anthomastus grandiflorus : 278 : R
Pseudoanthomastus sp. : 1080 : O
Anthothela grandiflora : 311 : R
Acanella arbuscula : 585 : O
Isididae sp. (fine branching) : 1064 : R
Gersemia sp. 3 : 1022 : R
Paramuricea sp. : 1050 : R
Gorgonacea sp. 7 (pink) cf. Isidella : 307 : O
Pennatulacea (indet.) : 1114 : R
Anthoptilum grandiflorum : 594 : R
Pennatula aculeata : 1046 : R
Umbellula sp. : 581 : O
Unknown Hydrozoa/Bryozoa : 1088 : R
Branchiocerianthus norvegicus : 1069 : R
Stylaster sp. 1 : 361 : O
Annelida
Aphroditidae sp. 1 : 146 : R
Serpulidae sp. 1 : 106 : R
Arthropoda
Chirostylidae sp. 2 (indet.) : 1054 : R
Munida tenuimana : 339 : R
Paguridae sp. : 205 : R
Caridea (indet.) : 1077 : O
Munidopsis sp. : 1126 : R
Colossendeis sp. 1 : 1059 : O
Cirripedia sp. 1 : 82 : F
Mollusca
Acesta excavata : 1062 : R
Opisthoteuthis extensa : 918 : R
Octopoda (indet.) : 659 : R
Bryozoa
Reteporella sp. : 204 : R
Echinodermata
Bathycrinidae sp. 1 : 1041 : R
Pentametrocrinus atlanticus : 436 : R
Crinoidea sp. : 1072 : O
Crinoidea sp. 1 : 131 : R
Asteronyx loveni : 471 : R

Gorgonocephalus sp. 1 : 214 : R
Ophiomusa lymani : 551 : O
Ophiuroidea (indet.) : 1076 : R
Ophiuroidea sp. (orange deep) : 646 : R
Ophiuroidea sp. 7 - yellow : 340 : R
Brisingidae sp. : 274 : O
Stichastrella rosea : 198 : R
Zoroaster fulgens : 988 : O
Henricia sanguinolenta : 208 : R
Goniasteridae sp. : 1002 : R
Ceramaster/Peltaster/Plinthaster sp. 1 : 234 : R
Porania sp. : 263 : O
Lophaster furcifer : 1089 : R
Hymenaster cf. pellucidus : 1110 : R
cf. Echinus (deep pink spine) : 1129 : R
Echinidae sp. (pink) : 194 : R
Cidaris cidaris : 211 : R
Phormosoma placenta : 555 : R
Elpidiidae (indet.) : 1122 : R
cf. Amperima sp. : 628 : R
cf. Benthogone sp. (white) : 574 : O
Mesothuria intestinalis : 536 : R
Chordata
Ascidiacea sp. 2 : 20 : O
Galeus melastomus : 1005 : R
Squaliformes sp. : 569 : O
Chimaera opalescens : 653 : O
Synaphobranchus kaupii : 440 : F
Hoplostethus atlantica : 651 : F
Brosme brosme : 258 : R
Molva dypterygia : 245 : R
Nezumia aequalis : 1003 : R
Coryphaenoides guentheri : 577 : O
Coryphaenoides rupestris : 566 : O
Trachyrincus sp. : 446 : O
Lepidion eques : 249 : R
Polyacanthonotus rissoanus : 552 : R
cf. Rouleina attrita : 1074 : R
Zoarcidae sp. 1 : 259 : R
Neocyttus helgae : 563 : R
Actinopterygii sp. 3 : 930 : R

Number of species = 116

© Marine Institute, MERC Consultants, Bernard Picton 2022