Marine Institute
SeaRover Dive Video

D453 Transect 5 Deep sponge and coral aggregation, unusual fauna, elasmobranch egg cases. Features of Interest: carbonate mound Water Depth: 2280-2026 m

Highlights: Sponges & stalked crinoids Antipatharian Large hexactinellid sponge Large hexactinellid sponge Antipatharian Sponges & bamboo coral Hexactinellid Asconema Stalked crinoids & sponges Sponges: hexactinellids and Geodia sp. Sponges: hexactinellids and Geodia sp. Yellow zoanthid anemone Hexactinellid sponges, bamboo coral, Geodia sp. & chimaerid Hexactinellid sponges including Asconema Chimaerid

This site is distinguished by fields of large glass sponges and bamboo coral which predominate along the sides and top of the mound. With the exception of some chimerids, few fish are recorded here.

Soft ground transitioned from sand with pebbles and dropstones to rippled sand at the base of the mound. Here the fauna is generally sparse except for a variety of sea pens species and dense aggregations of xenophyophores. Elsewhere on the mound the obvious fauna on the soft ground is a sea pen species and a holothurian.

Lower down on the slope stalked crinoids, sponges (including glass, large globular varieties and encrusting forms) and cup corals are evident while black corals (Parantipathes sp. and Bathypathes sp.) occur on harder ground. The upper half of the mound is dominated by extensive fields of large glass sponges and thin white bamboo coral (cf. Isididae sp. from Howell & Davies 2010). The variety of corals includes chrysogorgiid sp., Euplectella sp. and very long specimens of the bamboo coral Lepidisis sp. Among these sponge and coral fields a number of elasmobranch egg cases were noted.

START VIDEO A [00:00:00]/11:51 [1] The transect starts on relatively flat mixed mud/sand and gravel/increasing pebbles with sparse cf. Anthoptilum sp. (OTU1107) sea pens. [00:17:00] [2] protruding bedrock hosts mixed stalked crinoids and a geodiid sponge (OTU601) which at [00:22:00] is sampled. [00:25:00] [3] the ROV continues uphill over mud and pebbles until [00:27:00] [4] encountering more flat/sloping protruding bedrock with stalked crinoids and sparse sponge and coral fauna. [00:28:00]-[00:32:00] stopped for imagery. [00:39:00]-[00:52:00] stopped for imagery, aborted sampling, and sampling of “bubble” lamellate sponge (OTU1156). [00:54:00] [5] ROV continues up mud slope with pebbles and cobbles and occasional boulders colonised by Anachalypsicrinus nefertiti. [00:55:00] [6] more protruding bedrock and cobbles/boulders colonised by stalked crinoids, sponges, and corals. [00:55:00]-[01:00:00] ROV stops for imagery of a large (>1 m) lamellate glass sponge (cf. Hexactinosida, OTU1151), [01:02:00]-[01:03:00] ROV stopped for imagery of a large branching Parantipathes black coral. [01:04:00]-[01:06:00] ROV stopped for imagery of a Rhabdodictyum cf. delicatum (OTU611) glass sponge and stalked crinoids. [01:07:00] [7] more mud slope with sparse cobbles, the pebble/gravel overlay often forming rings around “mud mounds”, presumably highlighting rock protrusions beneath the sediment. [01:10:00] [8] ROV skirts the edge of flat bedrock protrusions with pebble overlaid mud with stalked crinoids, and sparse corals/sponges. [01:11:00]-[01:14:00] stopped for imagery before proceeding uphill diagonally right towards more bedrock protrusions, here Anachalypsicrinus nefertiti and Rhabdodictyum cf. delicatum dominate the bedrock islands, interspersed with pebbles/mud. [01:17:00] [9] and extended upslope of mud with pebbles, mud mounds and sparse mixed sea pens. [01:19:00] [10] bedrock protrusions with large Rhabdodictyum cf. delicatum and A. nefertiti. [01:20:00] [11] mud/pebbles/mud mounds, and sparse cobbles and sea pens. [01:21:00] [12] Rhabdodictyum cf. delicatum / A. nefertiti /mixed corals on bedrock. [01:22:00] [13] pebbles/mud/mud mounds and sparse seapens. [01:23:00] [14] Rhabdodictyum cf. delicatum / A. nefertiti /mixed corals on bedrock and now also with fine branching bamboo corals (possibly Keratoisis sp. , OTU1157) in increasing density. [01:24:00]-[01:26:00] stopped for imagery, [01:27:00] ROV turns left then continues, [01:32:00]-[01:35:00] stopped for imagery. [01:35:00]-[01:39:00] sampling Keratoisis (OTU1157), [01:41:00]-[01:46:00] stopped for imagery and sampling zoanthids. [01:50:00] [15] mud/pebble slope, mud mounds, some patchy sea pens and xenophyophores, and a couple of boulders dominated by stalked crinoids. [01:52:00]-[01:57:00] stopped for imagery of boulders. END VIDEO A 13:49.

START VIDEO B [01:58:00]/13:50. Continue diagonally up slope until [02:00:00] [16] bedrock protrusions and boulders with Rhabdodictyum cf. delicatum / A. nefertiti. [02:05:00] a large ray is encountered. Continue up slope, fairly steep until flattens out at [02:12:00]. [02:14:00] [17] mud/pebbles, some ripples, with sparse cobbles/boulders, xenophyophores on the mixed sediment and stalked crinoids on hard substrate. [02:20:00] [18] increasingly dense corals and sponges on bedrock/boulders, at first Rhabdodictyum cf. delicatum and Keratoisis sp. dominate. [02:34:00]-[02:37:00] ledge feature, stopped for imagery. [00:42:00] dense mixed corals and sponges, ([02:40:00]-[02:51:00] many elasmobranch egg cases visible lying on the seabed between corals and sponges). [00:45:00] still dense mixed corals and sponges, now chrysogorgiid corals (OTU1008) and Geodia cf. barretti (OTU601) sponges dominate. [02:44:00] [19] another patch of pebbles/mud before [02:45:00] [20] again dense mixed corals and sponges. This is the summit of the mound. [02:51:00] ROV proceeds over ledge feature with obscured/partial seabed views as going downhill. Continued dense sponges and corals apparent (especially Rhabdodictyum cf. delicatum and Keratoisis sp.). [02:54:00] now gentler downhill slope, mud veneered but rock protrusions many corals/sponges still present. [03:08:00] proceed over small ledge feature to soft sediment where vision becomes obscured and ROV turns ~90+° and tries to escape mud cloud. [03:13:00] ROV heading up hill, too high off seabed, substrate sloping bedrock with mud veneer and some pebbles. Sparse corals and sponges. [03:15:00] vision again obscured by mud cloud, ROV turns 180° and continues downhill with vision obscured until [03:19:00] [21] relatively flat mud bottom with scattered pebbles and sparse sea pens. [03:26:00] ROV stops. END VIDEO B [03:28:00]/15:20.

Progression Start Duration Code Name
1[00:00:00]00:17:45M.AtMB.Mu.SpnMegSea pens and burrowing megafauna on Atlantic mid bathyal mud
15[00:00:00]01:59:13M.AtUA.MxAtlantic upper abyssal mixed sediment
16[00:02:32]00:13:41M.AtUA.RoAtlantic upper abyssal rock and other hard substrata
17[00:16:14]00:06:27M.AtLB.Mx.XenCom.SyrFraSyringammina fragilissima field on Atlantic lower bathyal mixed sediment
2[00:17:46]00:08:07M.AtUA.RoAtlantic upper abyssal rock and other hard substrata
18[00:22:42]00:24:05M.AtUA.RoAtlantic upper abyssal rock and other hard substrata
3[00:25:54]00:01:27M.AtUA.MxAtlantic upper abyssal mixed sediment
4[00:27:22]00:27:13M.AtUA.RoAtlantic upper abyssal rock and other hard substrata
19[00:46:48]00:00:53M.AtUA.MxAtlantic upper abyssal mixed sediment
20[00:47:42]00:33:45M.AtUA.RoAtlantic upper abyssal rock and other hard substrata
5[00:54:36]00:00:59M.AtUA.MxAtlantic upper abyssal mixed sediment
6[00:55:36]00:12:22M.AtUA.RoAtlantic upper abyssal rock and other hard substrata
7[01:07:59]00:02:52M.AtUA.MxAtlantic upper abyssal mixed sediment
8[01:10:52]00:06:48M.AtUA.RoAtlantic upper abyssal rock and other hard substrata
9[01:17:41]00:01:42M.AtMB.Mu.SpnMegSea pens and burrowing megafauna on Atlantic mid bathyal mud
10[01:19:24]00:01:30M.AtUA.RoAtlantic upper abyssal rock and other hard substrata
11[01:20:55]00:00:47M.AtMB.Mu.SpnMegSea pens and burrowing megafauna on Atlantic mid bathyal mud
21[01:21:28]00:09:05M.AtMB.Mu.SpnMegSea pens and burrowing megafauna on Atlantic mid bathyal mud
12[01:21:43]00:00:44M.AtUA.RoAtlantic upper abyssal rock and other hard substrata
13[01:22:28]00:00:55M.AtMB.Mu.SpnMegSea pens and burrowing megafauna on Atlantic mid bathyal mud
14[01:23:24]00:27:10M.AtUA.RoAtlantic upper abyssal rock and other hard substrata

Foraminifera
Syringammina fragilissima : 261 : O
Porifera
Asconema sp. (Porifera massive globose 14) : 650 : O
cf. Farreidae : 1142 : O
Poecilosclerida sp. : 1146 : R
cf. Polymastia boletiformis : 1030 : R
Geodia cf. atlantica (Porifera massive lobose sp. 6) : 83 : O
cf. Geodia baretti (Porifera massive globose sp. 11) : 601 : F
Geodia sp. (warty) : 1163 : R
Porifera cup 2 : 535 : O
Porifera cylindrical sp. 2 : 1075 : O
Porifera encrusting sp. 1 (white) : 1 : R
Porifera lamellate (bubbles) : 1156 : O
Porifera lamellate (Hexactinosida) : 1151 : R
Porifera lamellate sp. 9 : 606 : O
Porifera massive lobose sp. 21 (Hertwigia sp. ? yellow) : 1158 : O
Porifera massive lobose sp. 21 (Hertwigia sp. ?) : 611 : C
Cnidaria
Cerianthidae sp. 1 : 2 : R
Actiniaria sp. 20 : 605 : R
Actinernus michaelsarsi : 554 : R
Actinoscyphiidae sp. 1 (pink) : 1047 : R
Actinostolidae sp. 1 : 132 : R
Adamsia sp. : 1066 : R
Leiopathes sp. : 305 : O
Bathypathes sp. (brown) : 284 : R
Parantipathes sp. : 1042 : O
Parantipathes sp. (branched) : 1161 : O

Stauropathes arctica : 547 : O
Telopathes sp. : 1043 : O
Caryophyllidae/Fabellidae (indet.) : 1058 : R
Flabellum sp. : 1056 : R
Zoanthidea sp. : 1149 : O
Anthomastus grandiflorus : 278 : R
Anthothela grandiflora : 311 : R
Chrysogorgidae sp. 1 : 1008 : F
cf. Clavulariidae sp. : 289 : R
Keratoisis sp. (fine branching) : 1157 : C
Keratoisis sp. 2 : 578 : R
Lepidisis sp. : 557 : O
Paramuricea sp. : 1050 : R
Anthoptilum sp. : 1107 : O
Pennatula aculeata : 1046 : R
Umbellula sp. : 581 : R
Annelida
Aphroditidae sp. 1 : 146 : R
Arthropoda
Chirostylidae sp. 2 (indet.) : 1054 : R
Galacantha sp. : 1144 : R
Paguridae sp. : 205 : R
Caridea (indet.) : 1077 : R
Munidopsis sp. : 1126 : R
Colossendeis sp. 1 : 1059 : O
Eucarida sp. (red deep) : 1138 : R
Echinodermata
Bathycrinidae sp. 1 : 1041 : C
Bathycrinidae sp. 2 cf. Porphyrocrinus thalassae : 1045 : O

Anachalypsicrinus nefertiti : 1031 : C
Crinoidea sp. 1 : 131 : F
Ophiomusa lymani : 551 : F
Ophiuroidea (indet.) : 1076 : O
Brisingidae sp. : 274 : O
cf. Henricia sp. (deep) : 1154 : O
Goniasteridae sp. : 1002 : R
Porania sp. : 263 : O
Solaster endeca : 573 : R
Echinidae sp. (white) : 559 : R
Echinoidea sp. 5 : 572 : R
Elpidiidae (indet.) : 1122 : R
cf. Amperima sp. : 628 : R
Benthogone sp. : 432 : R
Mesothuria intestinalis : 536 : R
Oneirophanta mutabilis : 1153 : R
Chordata
Rajiformes (indet.) : 1159 : R
Hydrolagus cf. affinis : 1039 : O
Coryphaenoides armatus : 1105 : O
Coryphaenoides guentheri : 577 : O
Lepidion cf. guentheri : 1160 : O
Polyacanthonotus rissoanus : 552 : O
Notacanthidae sp. 1 : 1009 : R
Actinopterygii sp. 3 : 930 : R

Number of species = 76

© Marine Institute, MERC Consultants, Bernard Picton 2022