Marine Institute
SeaRover Dive Video

D492 Transect 50 Hydrozoan/bryozoan community on cobbles/boulders/bedrock, some escarpment Desmophyllum/Lophelia community on overhangs, area of dense unknown yellow anthozoans (octocorals?), encrusting globose sponge patch. Features of interest: escarpment Water Depth: 670-484 m

Highlights: Crab - Cancer sp. Pink & white Lophelia & cup coral - Desmophyllum dianthus Spectacular Lophelia reef

This site has an escarpment which appears to run for 100 m. Extensive Lophelia reef is found on vertical cliffs. The feature contains a series of ridges with high diversity of fauna including anemones, ophiuroids, crinoids, brisingids, asteroids, crabs, galatheids and hermit crabs. In some areas the echinoid Cidaris cidaris occurs in large numbers. Fish species include oreos, grenadiers, monkfish, blackbelly rosefish and black scabbard.

START VIDEO A [00:00:00]/10:55 [1] The dive starts on sand/mud with Cidaris cidaris urchins. [00:07:00] the ROV laterals left, then turns ~90 and stops. [00:08:00] continue forwards. [00:24:00] [2] increasing pebbles and gravel with mixed urchins (particularly C. cidaris, and Araeosoma fenestratum) and the burrowing Bolocera-like Actiniidae sp. (OTU41). [00:41:00] [3] clumps of boulders followed by dense cobbles and boulders host a community most obviously dominated by Pliobothrus sp. and Reteporella sp. interspersed by urchins. [00:56:00] sloping sand veneered carbonate begins, cobbles and boulders persist. [00:57:00] a carbonate ledge feature is encountered and the ROV starts traversing along it to the right. [01:04:00] ROV starts moving forward up over sloping layered broken carbonate crust. [01:05:00] [4] A small (~2m high) vertical carbonate cliff is met, colonised by an escarpment/overhang community, mainly Desmophyllum cf. dianthus and some small colonies of Lophelia pertusa. [01:06:00] the ROV starts tracking along the course of a snagged fishing line until [01:09:00] the ROV leaves the rope and continues along the vertical carbonate face. [01:18:25] [5] The carbonate is now only sparsely encrusted but coral rubble and broken framework (some fresh) can be seen at the base of cliff suggesting Lophelia pertusa colonies somewhere above. [01:26:00] [6] Discrete Lophelia pertusa colonies start appearing then become dense, along with abundant D. cf. dianthus [01:41:00] Encrusting globose porifera (OTU75) is also abundant. [01:42:00]-[01:50:00] stop for sampling L. pertusa from vertical cliff with scoop then continue traversing along. END VIDEO A 10:54.

START VIDEO B [01:56:00]/10:55. Cliff and discrete L. pertusa escarpment community continues. [02:02:00] [7] the cliff ends and more layered sloping carbonate crust with sand veneer continues with C. cidaris. [02:07:00] [8] A small cave is encountered under the carbonate. Unknown yellow anthozoans (OTU1028, possibly juvenile Paramuricea sp. , but unsure) are abundant here, yet patchy, together with C. cidaris. [02:15:00] [9] The carbonate crust and broken protrusions start to be colonised by Pliobothrus sp and Reteporella sp. Patchy occurrence of the yellow anthozoans (OTU1028, possibly juvenile Paramuricea sp . ) continues allows this to be termed more of a mixed coral community mosaicked with the Hydrozoan/Bryozoan community seen earlier. The ROV tracks along another fishing line leading to more tangled line. C. cidaris is also abundant. [02:13:00] [10] The Hydrozoan/Bryozoan community continues with sometimes abundant bushy hydrozoans (OTU50) now with broken carbonate boulders also being encountered. [02:14:00] [11] Again the Hydrozoan/Bryozoan community is mosaicked with patchy yellow anthozoans. Several more fishing lines are encountered. [02:22:00] [12] The sand deepens and cobbles of decreasing density host the Hydrozoan/Bryozoan community (which is increasingly sparse) with C. cidaris. [02:25:00] [13] C. cidaris is now the only dominant fauna and the cobbles are sparse. The ROV stops to take a pushcore and attempt to rearrange the scoop/ Lophelia sample before the END VIDEO B [02:41:00]/11:40.

Progression Start Duration Code Name
1[00:00:00]00:24:18M.AtUB.Sa.UrcCom.CidUrcCidarid urchin assemblage on Atlantic upper bathyal sand
6[00:00:00]01:56:25M.AtMB.Ro.MixCor.DisLopDiscrete Lophelia pertusa colonies on Atlantic mid bathyal rock and other hard substrata
7[00:06:27]00:04:34M.AtUB.Sa.UrcCom.CidUrcCidarid urchin assemblage on Atlantic upper bathyal sand
8[00:11:02]00:03:20M.AtUB.Ro.MixCorMixed cold water coral community on Atlantic upper bathyal rock and other hard substrata
9[00:14:23]00:02:40M.AtUB.Ro.MixCorMixed cold water coral community on Atlantic upper bathyal rock and other hard substrata
10[00:17:04]00:02:26M.AtUB.Ro.SpaEnc.HydBrySparse encrusting community on Atlantic upper bathyal rock and other hard substrata (dominated by Hydrozoans [e.g. Stylaster/Pliobothrus] and Bryozoans [e.g. Reteporella])
11[00:19:31]00:07:18M.AtUB.Ro.SpaEnc.HydBrySparse encrusting community on Atlantic upper bathyal rock and other hard substrata (dominated by Hydrozoans [e.g. Stylaster/Pliobothrus] and Bryozoans [e.g. Reteporella])
2[00:24:19]00:17:06M.AtUB.Co.UrcComUrchin dominated community on Atlantic upper bathyal coarse sediment
12[00:26:50]00:01:39M.AtUB.Ro.SpaEnc.HydBrySparse encrusting community on Atlantic upper bathyal rock and other hard substrata (dominated by Hydrozoans [e.g. Stylaster/Pliobothrus] and Bryozoans [e.g. Reteporella])
13[00:28:30]00:16:39M.AtUB.Sa.UrcCom.CidUrcCidarid urchin assemblage on Atlantic upper bathyal sand
3[00:41:26]00:17:09M.AtUB.Ro.SpaEnc.HydBrySparse encrusting community on Atlantic upper bathyal rock and other hard substrata (dominated by Hydrozoans [e.g. Stylaster/Pliobothrus] and Bryozoans [e.g. Reteporella])
3[00:58:36]00:06:34M.AtUB.Ro.SpaEnc.HydBrySparse encrusting community on Atlantic upper bathyal rock and other hard substrata (dominated by Hydrozoans [e.g. Stylaster/Pliobothrus] and Bryozoans [e.g. Reteporella])
4[01:05:11]00:09:17M.AtUB.Ro.MixCorMixed cold water coral community on Atlantic upper bathyal rock and other hard substrata
4[01:14:29]00:03:55M.AtUB.Ro.MixCorMixed cold water coral community on Atlantic upper bathyal rock and other hard substrata
5[01:18:25]00:06:49M.AtUB.Ro.SpaEncSparse encrusting community on Atlantic upper bathyal rock and other hard substrata

Porifera
Mycale lingua : 171 : O
Porifera encrusting (black/red) : 118 : R
Porifera encrusting (orange) : 9 : R
Porifera encrusting globose (pale) : 75 : O
Porifera encrusting sp. 1 (white) : 1 : R
Porifera encrusting sp. 10 (yellow) : 30 : R
Blue Porifera encrusting : 800 : R
Cnidaria
Cerianthidae sp. 1 : 2 : R
Pachycerianthus multiplicatus : 458 : R
Unknown Anthozoa (yellow) : 1028 : F
Actiniaria sp. 1 : 4 : R
Actiniaria sp. 13 (pink/purple) : 478 : R
Actiniaria sp. 27 : 976 : R
Actiniidae sp. (sand Bolocera) : 41 : R
Phelliactis sp. 1 : 255 : O
Chrysopathes sp. Trissopathes sp. : 540 : R
Corallimorphidae sp. 2 : 43 : R
Desmophyllum cf. dianthus : 335 : R
Lophelia pertusa : 250 : F
Zoanthidae sp. 2 : 586 : O
Anthomastus grandiflorus : 278 : R
cf. Clavulariidae sp. : 289 : O
Paramuricea sp. : 1050 : O
Hydrozoa (bushy) : 50 : O

Hydrozoa (flat branched) : 56 : R
Pliobothrus sp. : 207 : F
Annelida
Bonellia viridis : 267 : R
Serpulidae sp. 1 : 106 : R
Arthropoda
Chirostylidae sp. 2 (indet.) : 1054 : R
Paromola cuvieri : 304 : F
Munida sarsi : 200 : R
Paguridae sp. : 205 : R
Caridea (indet.) : 1077 : R
Bathynectes sp. : 235 : R
Decapoda sp. 3 : 543 : O
Siphonophora sp. (indet.) : 1135 : O
Mollusca
Octopoda (indet.) : 659 : R
Margarites sp. 1 : 277 : R
Bryozoa
Reteporella sp. : 204 : F
Echinodermata
Brisingidae sp. : 274 : R
Stichastrella rosea : 198 : R
Ceramaster/Peltaster/Plinthaster sp. 2 : 388 : R
Porania sp. : 263 : R
Velatida sp. 1 : 199 : R
Echinus sp. : 445 : R

Cidaris cidaris : 211 : F
Araeosoma fenestratum : 188 : F
Spatangus raschi : 537 : O
Psolus squamatus : 252 : O
Chordata
Apristurus sp. (indet.) : 1131 : R
Leucoraja sp. : 1067 : R
Centrophorus squamosus : 1048 : R
Chimaera monstrosa : 265 : O
Hydrolagus cf. mirabilis : 1024 : R
Conger conger : 1100 : O
Synaphobranchus kaupii : 440 : O
Beryx decadactylus : 1025 : O
Merlangius melangus : 1019 : O
Brosme brosme : 258 : O
Molva molva : 654 : R
Coelorinchus caelorhincus : 303 : O
Lepidion eques : 249 : O
Phycis blennoides : 1020 : O
Epigonus telescopus : 1018 : O
Zoarcidae sp. 1 : 259 : R
Helicolenus dactylopterus : 227 : O
Actinopterygii sp. 3 : 930 : R

Number of species = 67

© Marine Institute, MERC Consultants, Bernard Picton 2022