OCS Study

BOEM 2020-022

U.S. Department of the Interior

Bureau of Ocean Energy Management

New Orleans Office

Continuing and Expanding a Deepwater

Biological Observation System in the

Northern Gulf of Mexico
OCS Study

BOEM 2020-022

Published by

U.S. Department of the Interior

Bureau of Ocean Energy Management

New Orleans Office

New Orleans, LA

April 2020 

Continuing and Expanding a Deepwater

Biological Observation System in the

Northern Gulf of Mexico

Authors

Mark C. Benfield

Matthew J. Kupchik

Prepared under BOEM Cooperative Agreement

M13AC00010

by

Louisiana State University

College of the Coast and Environment

Department of Oceanography and Coastal Sciences

Baton Rouge, LA 70803
DISCLAIMER

Study collaboration and funding were provided by the US Department of the Interior, Bureau of Ocean 

Energy Management (BOEM), Environmental Studies Program, Washington, DC, under Agreement 

Number M13AC00010. This report has been technically reviewed by BOEM, and it has been approved 

for publication. The views and conclusions contained in this document are those of the authors and should 

not be interpreted as representing the opinions or policies of the US Government, nor does mention of 

trade names or commercial products constitute endorsement or recommendation for use.

REPORT AVAILABILITY

To download a PDF file of this report, go to the US Department of the Interior, Bureau of Ocean Energy 

Management Data and Information Systems webpage (http://www.boem.gov/Environmental-StudiesEnvData/), click on the link for the Environmental Studies Program Information System (ESPIS), and 

search on 2020-022. The report is also available at the National Technical Reports Library at 

https://ntrl.ntis.gov/NTRL/.

CITATION

Benfield MC, Kupchik MJ. 2020. Continuing and expanding a deepwater biological observation system 

in the Northern Gulf of Mexico. New Orleans (LA): US Department of the Interior, Bureau of Ocean 

Energy Management. 255 p. Cooperative agreement No.: M13AC00010. OCS Study BOEM 2020-

022. 

ABOUT THE COVER

ROV image of a great barracuda swimming with almaco jacks beneath a platform in the Northern Gulf of 

Mexico. 

ACKNOWLEDGMENTS

The authors are grateful for the cooperation of Shell, BP, Petrobras America, Anadarko and Oceaneering. 

Dr. Ruth Perry (Shell) was instrumental in enabling access to Shell observations and inspection data. Mr. 

Joe Gelpi (Oceaneering) provided valuable assistance in securing observations from their ROV systems. 

Taxonomic identification was crucial and we appreciate the help of Dr. John Caruso, Dr. Kenneth Sulak, 

Dr. Michael Vecchione, Dr. Steve Haddock, Dr. Erik Cordes, Dr. Mary Wicksten, Dr. Dave Pawson, Dr. 

Morgan Kilgour, and Dr. Jose Castro.
i

Contents

List of Figures................................................................................................................................................iii

List of Tables................................................................................................................................................. v

List of Abbreviations and Acronyms............................................................................................................. vi

Introduction.................................................................................................................................................... 7

Objectives.................................................................................................................................................. 9

2. Operations...............................................................................................................................................10

2.1 Shell Oil .............................................................................................................................................10

2.2 BP 10

2.3 Petrobras America ............................................................................................................................10

2.4 Anadarko Petroleum .........................................................................................................................10

3. Biological Observations 2013–2016 .......................................................................................................11

3.1 Alaminos Canyon ..............................................................................................................................12

3.1.1 AC857A......................................................................................................................................12

3.2 De Soto Canyon................................................................................................................................35

3.2.1 DC398 ........................................................................................................................................35

3.2.2 DC843 ........................................................................................................................................37

3.3 Garden Banks ...................................................................................................................................39

3.3.1 GB385 ........................................................................................................................................39

3.4 Green Canyon...................................................................................................................................40

3.4.1 GC200........................................................................................................................................40

3.4.2 GC237........................................................................................................................................41

3.4.3 GC653........................................................................................................................................42

3.4.4 GC743........................................................................................................................................44

3.4.5 GC782........................................................................................................................................71

3.5 Keathley Canyon...............................................................................................................................78

3.5.1 KC147 ........................................................................................................................................78

3.6 Mississippi Canyon .........................................................................................................................123

3.6.1 MC118......................................................................................................................................123

3.6.2 MC383......................................................................................................................................125

3.6.3 MC451......................................................................................................................................144

3.6.4 MC525......................................................................................................................................145

3.6.5 MC762......................................................................................................................................150
ii

3.6.6 MC806......................................................................................................................................151

3.6.7 MC809......................................................................................................................................163

3.6.8 MC811......................................................................................................................................170

3.6.9 MC822......................................................................................................................................183

3.7 Walker Ridge...................................................................................................................................199

3.7.1 WR467 .....................................................................................................................................199

3.7.2 WR469 .....................................................................................................................................214

4. Vertical Distribution Patterns of Selected Organisms ...........................................................................219

4.1 Introduction......................................................................................................................................219

4.2 Target Organisms ...........................................................................................................................220

4.2.1 Tuna Vertical Migration Patterns..............................................................................................220

4.2.2 Great Barracuda Sphyraena barracuda...................................................................................224

4.2.1 Juvenile Caribbean Moonfish Selene brownii..........................................................................227

4.2.2 Coldwater Coral Lophelia pertusa ...........................................................................................229

4.2.1 Deepwater Soft Coral Anthomastus sp....................................................................................237

4.2.2 Other Potential Candidate Organisms for Assessment ...........................................................239

Works Cited...............................................................................................................................................252
iii

List of Figures

Figure 1. An example of a seafloor survey.. ................................................................................................. 3

Figure 1. An example of a seafloor survey. .................................................................................................. 9

Figure 2. Gulf SERPENT observation locations from 2013 to 2018...........................................................10

Figure 3. Part of the riser field below Shell’s Mars (MC807A) platform....................................................219

Figure 4. Example frames showing tunas imaged during riser inspections below Shell’s Mars platform.222

Figure 5. Observations of yellowfin tuna () superimposed on acoustic backscatter from the Mars ADCP 

from June 5–10, 2017. ..............................................................................................................................223

Figure 6. An average acoustic day below the Mars platform for the period June 5–10, 2017. ................223

Figure 7. Small fish observed in aggregations near, and coincident with foraging yellowfin tuna............224

Figure 8. Examples of great barracuda Sphyraena barracuda below Shell’s Ursa platform in 2018.......225

Figure 9. Vertical distribution of great barracuda Sphyraena barracuda beneath Shell’s Ursa platform..226

Figure 10. Vertical distribution of great barracuda Sphyraena barracuda beneath Shell’s Auger platform.

..................................................................................................................................................................227

Figure 11. Example frame grabs of Caribbean moonfish Selene brownii on risers below Shell’s Ursa 

platform. ....................................................................................................................................................228

Figure 12. Vertical distribution patterns of juvenile Caribbean moonfish on six risers below Shell’s Ursa 

platform in August 2018. ...........................................................................................................................229

Figure 13. Example frame grabs of Lophelia pertusa colonies on risers below the Mars platform..........232

Figure 14. Lophelia pertusa colony abundance on risers below Shell’s Mars platform in October 2013. 233

Figure 15. Percent coverage of risers below Shell’s Mars platform by Lophelia pertusa in October 2013.

234

Figure 16. Vertical distribution of Lophelia pertusa colonies below Shell’s Ursa platform in December 

2018. .........................................................................................................................................................235

Figure 17. Examples of Lophelia pertusa colonies on risers and tendons below Shell’s Ursa platform in 

2018. .........................................................................................................................................................236

Figure 18. Images of the deepwater soft coral Anthomastus sp. imaged during an inspection of the 

Crosby West Import riser at MC809A. ......................................................................................................237

Figure 19. Distributions of Anthomastus sp. colonies on six risers below Shell’s Ursa platform in 2018. 238

Figure 20. Average vertical distribution pattern of Anthomastus colonies for the six Ursa risers.............239

Figure 21. Examples of coldwater corals on risers below Shell’s Auger (GB426A) platform. ..................240

Figure 22. Examples of brisingid sea stars on risers and tendons below Shell’s Ursa platform. .............241
iv

Figure 23. A lionfish observed by an industrial ROV operating in Walker Ridge 29 during May 2019.....248

Figure 24. Orange cup coral Tubastrea coccinia at different depths on various Auger platform (GB426) 

structures during a 2018 survey................................................................................................................249

Figure 25. Deepest observations of aggregations of Tubastrea coccinia polyps on 18 production risers 

below Shell’s Mars platform. .....................................................................................................................250

Figure 26. Flytrap-like anemones at different depths on an Ursa platform (MC809) riser during a 2018 

survey........................................................................................................................................................251
v

List of Tables

Table 1. Biological Observations from AC857A..........................................................................................12

Table 2. Biological Observations from DC398............................................................................................35

Table 3. Biological Observations from DC843............................................................................................37

Table 4. Biological Observations from GB385............................................................................................39

Table 5. Biological Observations from GC200............................................................................................40

Table 6. Biological Observations from GC237............................................................................................41

Table 7. Biological Observations from GC653............................................................................................42

Table 8. Biological Observations from GC743............................................................................................44

Table 9. Biological Observations from GC782............................................................................................71

Table 10. Biological Observations from KC147 ..........................................................................................78

Table 11. Biological Observations from MC118........................................................................................123

Table 12. Biological Observations from MC383........................................................................................125

Table 13. Biological Observations from MC451........................................................................................144

Table 14. Biological Observations from MC525........................................................................................145

Table 15. Biological Observations from MC762........................................................................................150

Table 16. Biological Observations from MC806........................................................................................151

Table 17. Biological Observations from MC809........................................................................................163

Table 18. Biological Observations from MC811........................................................................................170

Table 19. Biological Observations from MC822........................................................................................183

Table 20. Biological observations from WR467........................................................................................199

Table 21. Biological Observations from WR469 .......................................................................................214

Table 22. Locations, Depths, Survey Dates And Construction Dates of 14 Well Risers..........................230

Table 23. Locations of Lionfish Pterois sp. Observed by ROVs...............................................................242
vi

List of Abbreviations and Acronyms

Short Form Long Form

AC Alaminos Canyon

ADCP acoustic doppler current profiler

BOEM Bureau of Ocean Energy Management

BOP blow-out preventer

CTD conductivity, temperature, depth recoder

DC De Soto Canyon

DSC digital stills camera

DOI US Department of the Interior

ESP Environmental Studies Program

ESPIS Environmental Studies Program Information System

GB Flower Garden Banks

GC Green Canyon

KC Keathley Canyon

MC Mississippi Canyon

MODU mobile offshore drilling unit

NOAA National Oceanic and Atmospheric Administration

ROV remotely-operated vehicle

SERPENT Scientific ROV Partnership using Existing iNdustrial 

Technology

SS Ship Shoal

WR Walker Ridge
7

Introduction

SERPENT (Scientific [remotely-operated vehicle] ROV Partnership using Existing iNdustrial 

Technology) is a global scientific collaboration between the oil and gas industry and academia. It affords 

scientific access to industrial vessels and the remotely-operated vehicles (ROVs) that are deployed in 

support of petroleum exploration and production. SERPENT operates in the Northeast Atlantic, off West 

Africa, Australia, and in the Gulf of Mexico (Gulf SERPENT). Gulf SERPENT was initiated in 2005 with 

a grant from NOAA’s Office of Ocean Exploration. BP was the first industrial partner and the success of 

that project led to funding from the Bureau of Ocean Energy Management (BOEM) in 2007 until 2016. 

The concept behind Gulf SERPENT is simple: use industrial ROV operational standby time for scientific 

observations. Most deepwater vessels are equipped with one or two ROV systems capable of operating to 

3000 or 4000 m depth. These ROVs serve as the eyes and hands of the vessel in the deep sea. Many 

deepwater vessels are drillships or mobile offshore drilling units (MODU) tasked with drilling 

exploratory wells in search of hydrocarbons at sites where seismic data suggest the presence of oil or gas. 

These exploration vessels are connected to the subsea well by a narrow pipe called a riser. The riser may 

extend for several thousand meters and contains the drill, conductors for drilling fluids, and power and/or 

telemetry feeds. At the seabed the riser is connected to the blowout preventer (BOP), a smaller device 

designed to prevent any hydrocarbons from leaving the subsea well in the event of an emergency. The 

ROVs are tasked with inspecting the integrity of the riser and BOP at intervals of one to three days and to 

monitor the condition of the BOP as well as to deploy/recover/inspect other subsea instrumentation (e.g.,

ADCPs, pipelines). The ROVs are tasked with various subsea work but on average, they are operational 

and on standby about 30–40% of the time. This is time when they can potentially be devoted to science.

Drilling a well takes approximately three months. This affords a much more complete picture of 

conditions in the ocean than would be provided by a scientific research cruise of a few weeks’ duration. 

Moreover, the narrow riser and the small BOP mean that the drilling operation has a very low impact on 

the abundances and behaviors of marine organisms. Animals drifting through the water column have little 

to no advance warning of the presence of the riser. Animals on the seabed experience anthropogenic 

signals in the form of drilling cuttings and drilling muds only in a narrow zone extending within a narrow 

zone around the BOP. Thus, deepwater drilling operations provide excellent opportunities to document 

the biodiversity and vertical distributions of deep-sea marine life for an extended period.

Once oil or gas has been discovered, the well is completed and capped. Then, if economical, a more 

permanent structure is deployed at the site and wells are connected by a production riser to this moored 

structure (often called a platform or a spar). Hydrocarbons are then extracted from the well by a series of 

production risers, subjected to some initial processing, and then routed to shore-based refineries through

subsea pipelines. These platforms or spars are usually also equipped with an ROV, which inspects the 

integrity of the production risers and the subsea infrastructure. These production facilities are usually in 

place for decadal time periods. Again, the ROVs are sometimes available to collect observations of both 

water column and seafloor marine life. If an ROV is not based at a production facility, periodic visits by 

vessels equipped with ROVs are undertaken to inspect the condition and integrity of the subsea 

equipment and risers. These periodic inspection videos are archived and represent a unique time-series of 

biological observations in the deep Gulf of Mexico.
8

Using industrial ROVs for scientific data collection requires special training because the pilots are not 

typically trained in collecting scientifically useful data with the vehicles. Before 2010, Gulf SERPENT 

conducted hands-on training at deepwater exploration and production sites. After acquiring all necessary 

deepwater safety and security certifications, a Gulf SERPENT representative would fly by helicopter out 

to each rig and spend several days (often accompanied by a qualified student or postdoctoral assistant) to 

familiarize offshore management with the project and to train the ROV pilots in the specifics of our water 

column and seafloor surveys. We would also recommend modifications of lighting and vehicle power, 

and video recording settings to optimize the quality of the observations. Once these training site visits 

were completed, the ROV pilots collected regular video observations, which were burned to DVD, SD 

cards, or hard drives, which were then sent to Louisiana State University (LSU) for analysis. Return visits 

to the vessels were conducted when possible and were based on factors such as when the ROV was likely 

to be available for extended periods, availability of space on board, substantial changes in the 

composition of the ROV crew, or occurrence of data quality issues.

In the aftermath of the 2010 Deepwater Horizon spill, it has become more difficult, though not impossible 

(depending on the company) to conduct training by direct offshore site visits. As an alternative, we have 

developed Microsoft® PowerPoint® and/or Adobe PDF® training packages that can be sent to the ROV 

teams. Data are still sent back by hard drives and feedback on data quality can be provided to improve the 

quality of the data. This process isn’t as optimal as before but it still works effectively. This latter 

approach continues to use two survey strategies and two other observation approaches. Water Column 

Surveys consist of horizontal transects separated by ~150 m, flown into the prevailing current at constant 

velocity, depth, and speed for defined times or distances. On the return transect the ROV is free to collect 

close-up videos of organisms to enable better taxonomic discrimination. These surveys yield estimates of 

numbers of different taxa per unit time or distance. Seafloor surveys use a radial transect design centered 

on the BOP (Fig. 1). The ROV flies a series of 12 linear transects on primary compass headings (N, E, S, 

W) for a distance that depends on the length of the tether (electro-optical cable connecting the ROV to its 

vertical umbilical). On each compass heading, the ROV flies three parallel transects offset by a few 

meters to avoid overlap. The outbound transects are flown at an altitude of ~ 1 m while the vehicle moves 

at a constant speed with the camera aimed obliquely down at ~30°. On the return transect the vehicle can 

deviate to get high-resolution close-ups of marine life. If the ROV is equipped with laser-scalers then the 

field of view can be quantified and numbers of each taxa per m2

. Otherwise, numbers per unit distance 

can be calculated and then averaged over all transects to estimate the site mean abundance. Opportunistic 

encounters occur when during the course of normal industrial taskings, an interesting organism appears. If 

time and safety permit, the ROV records as much video as possible. Some of our most interesting

encounters have resulted from these chance observations. Finally, most ROV pilots keep past encounters 

with unusual marine life on personal computers. We are often able to secure copies of these videos, which 

often include metadata. Where possible, and with the cooperation of industry, we are able to add these 

data to our database. 
9

Figure 1. An example of a seafloor survey. 

Three parallel transects are flown outbound from the BOP in each cardinal compass direction at constant speed, 

altitude, and heading. During the return, the ROV is free to deviate to obtain close-up images of representative 

marine life.

During the period covered in this report, we also made substantial use of inspection videos provided by 

Shell. These observations, recently collected and archived in full HD (1080p), provide an excellent 

opportunity to study the vertical distribution patterns of invertebrates and some fishes in relation to hard 

structure that extends throughout the water column.

Objectives

The objectives of Gulf SERPENT were to use video observations–collected by ROVs operating in the 

oceanic waters of the Gulf of Mexico–to assemble a picture of: 

(1) what organisms were present; 

(2) where did they occur in terms of season, time of day, and depth; and 

(3) to document behavior and inter- and intra-species associations. 

This report covers Gulf SERPENT activities from September 2013 through December 2018 conducted 

under the cooperative agreement M13AC00010 titled “Gulf SERPENT: Continuing and Expanding a 

Deepwater Biological Observation System in the Northern Gulf of Mexico.” Also included are some

observations from 2012 that were collected after this initial Gulf SERPENT report (Benfield and Kupchik 

2017) (Cooperative Agreement No. M07AC12468) was published.
10

2. Operations

2.1 Shell Oil

Shell was one of the first Gulf SERPENT partners. Shell began operations in 2009 and continues to the 

present day. Observations from Shell (Fig. 2) were obtained from production facilities: Ursa (MC809A); 

Mars (MC807A); Olympus (MC806/MC807B); Auger (GB426); Ram Powell (VK956); and Perdido 

(AC857A). Shell exploration facilities that also contributed observations included: GC200; GC247; 

GC248; MD525; and MC762. 

2.2 BP

BP was the first petroleum company to partner with Gulf SERPENT and they have provided data since 

2006. After the Deepwater Horizon spill, fewer observations were obtained from BP facilities; however, 

they provided data from DC32; DC33; DC801; KC57; KC147; GC743; GC787; MC778; and MC822 

(Fig. 2). 

2.3 Petrobras America

Petrobras America partnered with Gulf SERPENT from 2012 to 2015 and contributed observations from 

the drillship Titanium Explorer and ENSCO Deep Ocean Medocino operating in WR206 and WR426 

(Fig. 2). Petrobras America ended exploration operations in the Gulf of Mexico in 2016.

2.4 Anadarko Petroleum

Anadarko Petroleum is the newest Gulf SERPENT partner. Thus far they have provided a few 

observations from Ocean Black Hornet operating in KC875 (Fig. 2).

Figure 2. Gulf SERPENT observation locations from 2013 to 2018.
11

3. Biological Observations 2013–2016

Gulf SERPENT relies on directed surveys of the water column and seabed, opportunistic encounters with 

marine life, and retrospective encounters that were in the possession of interested remotely-operated 

vehicle (ROV) personnel. The ROVs used by the oil and gas industry are sophisticated vehicles capable 

of operating to the full depth of the Gulf of Mexico. Unlike scientific ROVs, they generally lack 

instrumentation, such as laser scalers, a conductivity, temperature, and depth recorder (CTD), digital stills 

cameras (DSC), and collection and/or sampling systems. Without laser scalers, measurement of the sizes 

of organisms and the width of the field of view on the seabed cannot be undertaken. A CTD provides a 

continuous record of hydrographic parameters including at a minimum, temperature and salinity. The 

Oceaneering ROVs are equipped with a temperature sensor that can collect spot measurements; however, 

these data are not often recorded. The resolution of most DSCs is 18–24 megapixels. The frame grabs 

collected from high density (HD) video are approximately 2 MP. Consequently, the image quality and 

resolution of frame grabs is substantially lower than would be obtained from a dedicated DSC. The 

limitations on image resolution mean that taxonomic identifications are often much coarser than might be 

possible with high quality images from a DSC. The absence of sampling systems means that organisms 

can only be identified on the basis of information within the images. Despite these limitations, an 

industrial ROV in the hands of a skilled pilot can collect some remarkably useful images. During this 

project, data were collected from a variety of locations spanning the Northern Gulf of Mexico (Fig. 2). 

The observations that follow were collected by participating ROV teams between 2013–2016. Data 

collected at Petrobras sites in Walker Ridge are summarized in Chapter 3.
12

3.1 Alaminos Canyon

3.1.1 AC857A

Alaminos Canyon 857A is the location of Shell’s Perdido Spar and is the westernmost site in Gulf SERPENT’s network. The depth of the site 

(~2400 m) makes it an interesting study area and the dedicated ROV team of Oceaneering’s MIL57 system have provided some very high quality 

observations. The site is notable for its abundance of holothurians. The bigfin squid Magnapinna sp. has been observed on numerous occasions at 

this site, usually just above the seabed. Highfin lizardfish Bathysaurus mollis were common.

Table 1. Biological Observations from AC857A

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

08:36:56

26.13 N

94.88 W 2402

Cydippid 

ctenophore 

Aulacoctena sp.
13

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

09:55:58

26.13 N

94.88 W 2391

Holothurian

Enypniastes 

eximia

11/14/13

09:59:06

26.13 N

94.88 W 2426

Holothurian

Benthodytes 

typica
14

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

10:22:33

26.13 N

94.88 W 2395 Coldwater coral 

Unidentified

11/14/13

10:25:12

26.13 N

94.88 W 2392

Highfin 

lizardfish

Bathysauridae

Bathysaurus 

mollis
15

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

10:42:26

26.13 N

94.88 W 2389 HormathiidAnemone

11/14/13

10:43:20

26.13 N

94.88 W 2389 Unidentified coral
16

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

10:43:51

26.13 N

94.88 W 2389 Unidentified coral

11/14/13

10:44:30

26.13 N

94.88 W 2389

Unidentified squat 

lobster at base of 

sea pen.
17

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

10:44:43

26.13 N

94.88 W 2389

Flytrap anemone 

Actinoscyphia sp. 

on sea pen

11/14/13

12:28:56

26.13 N

94.88 W 2389 Fish Macrouridae 

Unidentified
18

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

12:31:09

26.13 N

94.88 W 2388

Bigfin squid

Magnapinnidae

Magnapinna sp.

11/14/13

12:31:59

26.13 N

94.88 W 2388

Bigfin squid

Magnapinnidae

Magnapinna sp.

(same individual as 

12:31:09)
19

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

12:35:20

26.13 N

94.88 W 2391

Highfin lizardfish

Bathysauridae

Bathysaurus mollis

11/14/13

12:43:34

26.13 N

94.88 W 2388

Fish

Alepocephalidae

Unidentified
20

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

12:56:57

26.13 N

94.88 W 2394 Holothurian 

Enypniastes eximia

11/14/13

12:59:47

26.13 N

94.88 W 2395

Highfin lizardfish

Bathysauridae

Bathysaurus mollis
21

Date/

Time Location Depth (m) Likely Identity Image

11/14/13

13:02:58

26.13 N

94.88 W 2388

Ophidiidae

Bony-eared assfish

Acanthonus 

armatus

11/14/13

13:03:36

26.13 N

94.88 W 2387 Unidentified shrimp
22

Date/

Time Location Depth (m) Likely Identity Image

11/17/13

10:11:09

26.13 N

94.88 W 2385

Fish

Inopiidae

Bathypterois 

grallator

11/17/13

10:12:40

26.13 N

94.88 W 2386

Fish

Macrouridae

Coryphaenoides 

mexicanus?
23

Date/

Time Location Depth (m) Likely Identity Image

11/17/13

10:24:56

26.13 N

94.88 W 2388

Notacanthidae

Polyacanthonotus 

challengeri

12/11/13

15:46:51

26.13 N

94.88 W 460

Fish

Sternoptychidae

Unidentified
24

Date/

Time Location Depth (m) Likely Identity Image

12/11/13

16:05:03

26.13 N

94.88 W 344 MedusaUnidentified

12/13/13

10:27:29

26.13 N

94.88 W 2405

Brittle star

Bathypectinura 

heros
25

Date/

Time Location Depth (m) Likely Identity Image

12/13/13

10:55:09

26.13 N

94.88 W 2313 Unidentified anemone

12/28/13

08:24:28

26.13 N

94.88 W 1181

Scyphomedusa

Periphyllopsis 

braueri
26

Date/

Time Location Depth (m) Likely Identity Image

01/21/14

02:46:44

26.13 N

94.88 W 2409 Holothurian

Benthodytes typica

01/21/14

02:56:52

26.13 N

94.88 W 2406 Holothurian

Benthodytes typica
27

Date/

Time Location Depth (m) Likely Identity Image

01/21/14

02:58:21

26.13 N

94.88 W 2408 Holothurian

Benthodytes typica

01/21/14

02:58:37

26.13 N

94.88 W 2409 Holothurian

Benthodytes typica
28

Date/

Time Location Depth (m) Likely Identity Image

01/21/14

03:04:39

26.13 N

94.88 W 2405

Unidentified squat 

lobster and shrimps

Nematocarcinus sp.

01/21/14

03:04:45

26.13 N

94.88 W 2405 Shrimps 

Nematocarcinus sp.
29

Date/

Time Location Depth (m) Likely Identity Image

01/21/14

03:07:50

26.13 N

94.88 W 2405 Holothurian

Benthodytes typica

01/21/14

03:18:15

26.13 N

94.88 W 2404 Unidentified squat 

lobsters
30

Date/

Time Location Depth (m) Likely Identity Image

01/21/14

03:40:22

26.13 N

94.88 W 2403

Highfin lizardfish

Bathysauridae

Bathysaurus mollis

11/22/14

10:12:11

26.13 N

94.88 W 2398

Fish

Macrouridae

Bathygadus sp. 

(B. arcuatus?)
31

Date/

Time Location Depth (m) Likely Identity Image

11/22/14

13:03:16

26.13 N

94.88 W 2405 Gastropod 

Unidentified

11/22/14

13:14:55

26.13 N

94.88 W 2406

Holothurian

Chiridotidae

Chirodota sp.
32

Date/

Time Location Depth (m) Likely Identity Image

11/22/14

13:16:30

26.13 N

94.88 W 2406

Holothurian

Chiridotidae

Chirodota sp.

11/22/14

13:28:26

26.13 N

94.88 W 2406 Hermit crabUnidentified
33

Date/

Time Location Depth (m) Likely Identity Image

11/22/14

13:46:18

26.13 N

94.88 W 2406 Anemones

Unidentified

03/07/15

14:40:00

26.13 N

94.88 W 2400

Highfin lizardfish

Bathysauridae

Bathysaurus mollis
34

Date/

Time Location Depth (m) Likely Identity Image

03/07/15

14:40:02

26.13 N

94.88 W 2400

Highfin lizardfish

Bathysauridae

Bathysaurus mollis

(same individual as 

14:40:00)

03/20/15

13:33:28

26.13 N

94.88 W 2393 HolothurianBenthodytes typica
35

3.2 De Soto Canyon

3.2.1 DC398

Observations at DC398 were collected by Oceaneering’s Millennium 115 ROV. This is a deep site (~2300 m). Near bottom encounters from the 

summer and fall of 2014 revealed the presence of bigfin squid (Magnapinna sp.) and a large sleeper shark (Somniosus sp.). 

Table 2. Biological Observations from DC398

Date/

Time Location Depth (m) Likely Identity Image

07/16/14

03:40:51

28.59 N

87.84 W 1220 Unidentified larvacean 

house

07/16/14

04:08:30

28.59 N

87.84 W 613

Lobate ctenophore 

Thalassocalyce 

inconstans
36

Date/

Time Location Depth (m) Likely Identity Image

08/14/14

15:33:22

28.59 N

87.84 W 2318 Sleeper shark

Somniosus sp.

11/02/14

09:45:55

28.59 N

87.84 W 2317 Bigfin squid

Magnapinna sp.

11/02/14

09:46:56

28.59 N

87.84 W 2317

Bigfin squid

Magnapinna sp. (same 

individual as 09:45:55)
37

Date/

Time Location Depth (m) Likely Identity Image

11/02/14

09:48:35

28.59 N

87.84 W 2316

Bigfin squid

Magnapinna sp. (same 

individual as 09:45:55)

3.2.2 DC843

These observations were collected by Oceaneering’s Millennium 115 system operating from Noble’s Globetrotter 1 drillship working under 

contract for Shell. This is an extremely deep site with a bottom depth in excess of 2275 m. A bigfin squid was observed near the seabed. 

Table 3. Biological Observations from DC843

Date/

Time Location Depth (m) Likely Identity Image

01/13/14

11:48:49

Unavailable

Reported as 

DC843

2596 Bony-eared assfish

Acanthonus armatus
38

Date/

Time Location Depth (m) Likely Identity Image

06/12/14

09:39:25

28.15 N

87.60 W 2278 Bigfin squid

Magnapinna sp.

06/12/14

09:41:19

28.15 N

87.60 W 2278

Bigfin squid

Magnapinna sp. (same 

individual as 09:39:25)

06/12/14

09:42:08

28.15 N

87.60 W 2278

Bigfin squid

Magnapinna sp. (same 

individual as 09:39:25)
39

Date/

Time Location Depth (m) Likely Identity Image

06/12/14

09:42:52

28.15 N

87.60 W 2279

Bigfin squid

Magnapinna sp. (same 

individual as 09:39:25)

3.3 Garden Banks

3.3.1 GB385

One observation of a squid Mastigoteuthis sp. was provided by an Oceaneering ROV working aboard the multiservice vessel (MV) Ocean 

Intervention IV under contract for Shell. This observation is included because it occurred a few days before the onset of this project.

Table 4. Biological Observations from GB385

Date/

Time Location Depth (m) Likely Identity Image

08/29/13

07:10:21

27.60 N

92.30 W 799 Squid

Mastigoteuthis sp.
40

3.4 Green Canyon

3.4.1 GC200

One observation of swordfish Xiphias gladius in the mesopelagic zone was provided by an Oceaneering ROV working aboard the multiservice 

vessel (MV) Ocean Intervention IV under contract for Shell.

Table 5. Biological Observations from GC200

Date/

Time Location Depth (m) Likely Identity Image

06/15/13

14:54:57

27.76 N

90.74 W 490 Swordfish 

Xiphias gladius
41

3.4.2 GC237

One observation of an unidentified ray was provided by an Oceaneering ROV working aboard the multiservice vessel (MV) Ocean Intervention IV

under contract for Shell.

Table 6. Biological Observations from GC237

Date/

Time Location Depth (m) Likely Identity Image

03/23/14

11:36:00

27.75 N

91.09 W 732 Unidentified ray
42

3.4.3 GC653

An Oceaneering ROV operating near the Shenzi TLP provided observations of a manta ray. The original video was from a 3D camera system and 

lacked an overlay.

Table 7. Biological Observations from GC653

Date/

Time Location Depth (m) Likely Identity Image

05/04/14

07:53:01

27.30 N

90.14 W 61

Manta ray

Manta birostris with 

remoras

05/04/14

07:53:02

27.30 N

90.14 W 61

Manta ray

Manta birostris with 

remoras

(same individual as 

07:53:01)
43

Date/

Time Location Depth (m) Likely Identity Image

05/04/14

07:53:03

27.30 N

90.14 W 61

Manta ray

Manta birostris with 

remoras

(same individual as 

07:53:01)
44

3.4.4 GC743

Green Canyon 743 observations were provided by an Oceaneering system Millennium 82 operating from the Development Driller III rig under 

contract to BP. Additional observations were collected by a C-Innovation ROV (UHD69). This soft-bottom site contained a diverse invertebrate 

and fish community. Invertebrates included holothurians (Enypniastes eximia, Benthodytes typica, Benthothuria sp.). At least three species of sea 

stars (Zoroaster fulgens, Nymphaster arenatus, and possibly Plutonaster sp.) were observed along with unidentified brittle stars. Sea pens were 

common. Shrimps included Nematocarcinus sp., Cerataspis monstrosa, and other unidentified taxa. The hermit crab Sympagurus pictus carrying 

an anemone Adamsia obvolva was common. This was one of only two locations where the flatback lobster Polycheles was recorded. Fishes were 

predominantly halosaurs, macrourids, the tripodfish Bathypterois quadrifilis, cutthroat eels Synaphobranchus sp., and the skate Rajella 

purpuriventralis.

Table 8. Biological Observations from GC743

Date/

Time Location Depth (m) Likely Identity Image

06/19/15

05:40:06

27.22 N

90.05 W 305 Salp chain 

Helicosalpa virgula (right)
45

Date/

Time Location Depth (m) Likely Identity Image

06/19/15

05:42:11

27.22 N

90.05 W 305 Salp chain 

Unidentified

11/03/15

13:38:52

27.22 N

90.05 W 2097

Hermit crab 

Sympagurus pictus

with anemone 

Adamsia obvolva
46

Date/

Time Location Depth (m) Likely Identity Image

11/03/15

13:55:14

27.22 N

90.05 W 2091 Holothurian 

Benthodytes typica
47

Date/

Time Location Depth (m) Likely Identity Image

11/03/15

13:55:14

27.22 N

90.05 W 2099

Fish

Halosauridae

Unidentified

11/07/15

13:55:14

27.22 N

90.05 W 2080 Holothurian

Enypniastes eximia
48

Date/

Time Location Depth (m) Likely Identity Image

11/07/15

16:12:10

27.22 N

90.05 W 624

Fish 

Trichiuridae

Possibly Aphanopus 

intermedius

11/07/15

16:13:35

27.22 N

90.05 W 621 Dinner plate jellyfish

Solmissus sp.

12/22/15

12:35:47

27.22 N

90.05 W 2098

Hermit crab 

Sympagurus pictus

with anemone 

Adamsia obvolva
49

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

12:35:47

27.22 N

90.05 W 2098 Unidentified anemone

12/22/15

12:35:47

27.22 N

90.05 W 2098 Hormathiid anemone 

Unidentified

12/22/15

12:48:56

27.22 N

90.05 W 2098

Fish

Ipnopidae

Bathypterois quadrifilis
50

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

12:49:35

27.22 N

90.05 W 2098 Stalked crinoid

Bathycrinidae

12/22/15

12:54:39

27.22 N

90.05 W 2098 Sea pen 

Unidentified
51

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

13:11:24

27.22 N

90.05 W 2097 Sponge 

Unidentified

12/22/15

13:33:55

27.22 N

90.05 W 2099 Brittle star 

Unidentified

12/22/15

13:35:27

27.22 N

90.05 W 2099 Sea star

Zoroaster fulgens
52

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

13:48:57

27.22 N

90.05 W 2099 Sea pen 

Unidentified

12/22/15

13:52:24

27.22 N

90.05 W 2099 HolothurianBenthothuria sp.

12/22/15

13:58:37

27.22 N

90.05 W 2098 Shrimp cerataspis 

monstrosa
53

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

14:57:59

27.22 N

90.05 W 2098

Fish

Synaphobranchidae

Synaphobranchus sp.

12/22/15

15:02:55

27.22 N

90.05 W 2097

Fish

Halosauridae

Unidentified

12/22/15

15:05:09

27.22 N

90.05 W 2099 Unidentified
54

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

15:07:29

27.22 N

90.05 W 2097

Sea star 

Astropectinidae

Plutonaster sp.?

12/22/15

18:17:45

27.22 N

90.05 W 2102

Fish

Halosauridae

Unidentified

12/22/15

18:19:57

27.22 N

90.05 W 2099 Unidentified shrimp
55

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

18:38:39

27.22 N

90.05 W 2102

Fish

Ipnopidae

Bathypterois quadrifilis

12/22/15

18:39:15

27.22 N

90.05 W 2102

Fish

Ipnopidae

Bathypterois quadrifilis

12/22/15

18:42:22

27.22 N

90.05 W 2102 Skate

Rajella purpuriventralis
56

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

18:43:10

27.22 N

90.05 W 2102

Shrimp

Cerataspis monstrosa 

(formerly Plesiopenaeus 

armatus)

12/22/15

18:55:32

27.22 N

90.05 W 2101 Shrimp

Nematocarcinus sp.

12/22/15

19:48:56

27.22 N

90.05 W 2097 Holothurian 

Benthodytes typica
57

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

19:48:56

27.22 N

90.05 W 2099 Unidentified 

(holothurian?)

12/22/15

20:02:08

27.22 N

90.05 W 2098

Fish

Ipnopidae

Bathypterois quadrifilis

12/22/15

20:08:50

27.22 N

90.05 W 2097 Shrimp 

Nematocarcinus sp.
58

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

20:20:34

27.22 N

90.05 W 2099

Notacanthidae

Polyacanthonotus 

challengeri

12/22/15

20:23:41

27.22 N

90.05 W 2098 Sea star 

Nymphaster arenatus

12/22/15

21:02:36

27.22 N

90.05 W 2091 Holothurian

Benthodytes abyssicola
59

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

21:04:18

27.22 N

90.05 W 2094 Sea star

Nymphaster arenatus

12/22/15

21:11:51

27.22 N

90.05 W 2095 Sea pen 

Unidentified

12/22/15

21:14:13

27.22 N

90.05 W 2095 Coral 

Unidentified
60

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

21:27:14

27.22 N

90.05 W 2096 Stalked crinoid

Bathycrinidae

12/22/15

21:33:50

27.22 N

90.05 W 2097 Feather star

Atelecrinidae

12/22/15

21:34:23

27.22 N

90.05 W 2096 Shrimp 

Nematocarcinus sp.
61

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

21:35:23

27.22 N

90.05 W 2096

Flatback lobster

Polycheles sp. 

possibly P. sculptus

12/22/15

22:02:47

27.22 N

90.05 W 2093

Sea pen 

Umbellula sp. 

Same individual as 

22:02:39

12/22/15

22:03:07

27.22 N

90.05 W 2093

Sea pen 

Umbellula sp. 

Same individual as 

22:02:39
62

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

22:06:11

27.22 N

90.05 W 2094 Unidentified crab beneath 

pteropod shell.

12/22/15

22:23:54

27.22 N

90.05 W 2096 Stalked crinoid

Bathycrinidae

12/22/15

22:29:45

27.22 N

90.05 W 2096 Unidentifed cerianthid anemone
63

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

22:29:12

27.22 N

90.05 W 2096 Unidentified sea pen

12/22/15

22:44:37

27.22 N

90.05 W 2095 Unidentified sea pen

12/22/15

22:45:06

27.22 N

90.05 W 2095 Unidentified crinoid
64

Date/

Time Location Depth (m) Likely Identity Image

12/22/15

22:50:12

27.22 N

90.05 W 2096

Macrouridae

Coryphaenoides 

(mexicanus?)

12/22/15

22:50:16

27.22 N

90.05 W 2096

Macrouridae

Coryphaenoides 

(mexicanus?) 

Same individual as 

22:50:12

12/22/15

22:51:19

27.22 N

90.05 W 2096 Unidentified brittle star
65

Date/

Time Location Depth (m) Likely Identity Image

12/23/15

08:31:42

27.22 N

90.05 W 2101 Sea pen 

Umbellula sp.

12/23/15

08:41:10

27.22 N

90.05 W 2100 Unidentified sea pen

12/23/15

09:04:05

27.22 N

90.05 W 2100 Hormathiid anemone 

Unidentified
66

Date/

Time Location Depth (m) Likely Identity Image

12/23/15

09:48:02

27.22 N

90.05 W 2099 Holothurian

Benthothuria sp.

12/23/15

10:18:02

27.22 N

90.05 W 2103 Sea star

Zoroaster fulgens?

12/23/15

10:23:18

27.22 N

90.05 W 2101

Shrimp 

Possibly Aristeus 

antillensis
67

Date/

Time Location Depth (m) Likely Identity Image

12/23/15

10:25:35

27.22 N

90.05 W 2098 Eel Synaphobranchidae

12/23/15

10:34:56

27.22 N

90.05 W 2099 HolothurianBenthodytes sp.
68

Date/

Time Location Depth (m) Likely Identity Image

12/23/15

10:37:32

27.22 N

90.05 W 2102

Skate

Unidentified

Rajella purpuriventralis?

12/23/15

11:23:35

27.22 N

90.05 W 1156 Larvacean house 

Unidentified
69

Date/

Time Location Depth (m) Likely Identity Image

12/23/15

12:17:00

27.22 N

90.05 W 1921 Holothurian

Enypniastes eximia

12/23/15

13:12:01

27.22 N

90.05 W 1611 Lobate ctenophore 

Bathocyroe fosteri
70

Date/

Time Location Depth (m) Likely Identity Image

12/23/15

14:26:25

27.22 N

90.05 W 1011 Midwater shrimp 

Unidentified

12/23/15

14:47:01

27.22 N

90.05 W 855

Medusa 

Crossota millsae

12/23/15

15:14:05

27.22 N

90.05 W 549

Calycophoran 

siphonophore 

Prayidae
71

3.4.5 GC782

GC782 is the location of BP’s Mad Dog Spar. This was a frequent contributor to Gulf SERPENT during the period 2008–2010, when a SaipemAmerica Innovator ROV was on board. That ROV has been upgraded to an Oceaneering system, which provided some observations from 2015. 

One of the most interesting things they recorded was a large aggregation of juvenile lithodid Neolithodes agassizii crabs at the base of the Spar. 

The aggregation was unusual because this species normally forages on soft sediments and is not known for its ability to climb up on structures, yet 

all these juveniles had scaled the base of the Spar.

Table 9. Biological Observations from GC782

Date/

Time Location Depth (m) Likely Identity Image

10/22/15

11:46:39

27.19 N

90.27 W 1346 Shrimp 

Heterocarpus sp.

10/22/15

13:11:48

27.19 N

90.27 W 1346 Flytrap anemone 

Actinoscyphia sp.
72

Date/

Time Location Depth (m) Likely Identity Image

10/22/15

13:13:08

27.19 N

90.27 W 1346 Flytrap anemone 

Actinoscyphia sp.

10/22/15

13:13:22

27.19 N

90.27 W 1346 Flytrap anemone 

Actinoscyphia sp.

10/22/15

13:17:36

27.19 N

90.27 W 1346 Hydroids

Unidentified
73

Date/

Time Location Depth (m) Likely Identity Image

10/22/15

13:18:03

27.19 N

90.27 W 1346 Flytrap anemone Actinoscyphia sp.

10/22/15

13:18:03

27.19 N

90.27 W 1349 Lithodid crab

Neolithodes agassizii

10/22/15

13:25:59

27.19 N

90.27 W 1349

Lithodid crab

Neolithodes agassizii 

(same individual as 

13:18:03)
74

Date/

Time Location Depth (m) Likely Identity Image

10/22/15

13:30:40

27.19 N

90.27 W 1350

Cutthroat eel

Synaphobranchidae

Synaphobranchus sp.

10/22/15

13:31:55

27.19 N

90.27 W 1350

Cutthroat eel

Synaphobranchidae

Synaphobranchus sp.

10/24/15

10:59:20

27.19 N

90.27 W 1346 Unidentified 

Chaetognath?
75

Date/

Time Location Depth (m) Likely Identity Image

10/24/15

11:36:33

27.19 N

90.27 W 1346 Shrimp 

Glyphocrangon sp.

10/24/15

11:01:38

27.19 N

90.27 W 1359 Lithodid crabs
76

Date/

Time Location Depth (m) Likely Identity Image

10/24/15

11:02:20

27.19 N

90.27 W 1359 Lithodid crabs

10/24/15

11:02:48

27.19 N

90.27 W 1359 Lithodid crabs
77

Date/

Time Location Depth (m) Likely Identity Image

10/24/15

11:07:22

27.19 N

90.27 W 1349 Fish 

Macrouridae

10/24/15

11:24:42

27.19 N

90.27 W 1350

Fish 

Ophidiidae

Bassogigas gilli 
78

3.5 Keathley Canyon

3.5.1 KC147

These observations were provided by ROVs (UHD70, UHD71) operated by C-Innovations working under contract for BP. Glass sponges were the 

dominant sessile invertebrates on the soft sediments. A variety of fishes including cusk eels, cutthroat eels, and macrourids occurred near the 

seabed. A notable feature of this site was the presence of a large asphalt seep containing a brine pool. Dead giant isopods Bathynomus giganteus

carcasses were observed floating on the surface of the brine pool.

Table 10. Biological Observations from KC147

Date/

Time Location Depth (m) Likely Identity Image

02/06/15

23:09:37

26.84 N

93.20 W 1292

Eel

Nettastomatidae?

Unidentified
79

Date/

Time Location Depth (m) Likely Identity Image

02/06/15

23:11:10

26.84 N

93.20 W 1292

Glass sponge 

Hexactinellidae

Hyalonema sp.

02/06/15

23:12:06

26.84 N

93.20 W 1292

Glass sponge 

Hexactinellidae

Hyalonema sp.
80

Date/

Time Location Depth (m) Likely Identity Image

02/06/15

23:14:45

26.84 N

93.20 W 1293 Holothurian

Benthodytes sp.

02/06/15

23:15:41

26.84 N

93.20 W 1293

Glass sponge 

Hexactinellidae

Hyalonema sp.
81

Date/

Time Location Depth (m) Likely Identity Image

02/06/15

23:17:21

26.84 N

93.20 W 1294

Glass sponges 

Hexactinellidae

Hyalonema sp.

02/06/15

23:26:39

26.84 N

93.20 W 1297 Lithodid crab

Neolithodes agassizii
82

Date/

Time Location Depth (m) Likely Identity Image

02/06/15

23:28:42

26.84 N

93.20 W 1297 Red crab

Chaceon quinquidens

02/07/15

00:14:27

26.84 N

93.20 W 1293 Fish

Unidentified
83

Date/

Time Location Depth (m) Likely Identity Image

02/07/15

00:17:41

26.84 N

93.20 W 1291

Eel

Synaphobranchidae?

Unidentified

02/07/15

00:38:40

26.84 N

93.20 W 1296

Eel

Synaphobranchidae

Synaphobranchus sp.
84

Date/

Time Location Depth (m) Likely Identity Image

02/07/15

00:39:41

26.84 N

93.20 W 1296 Sea pen

Unidentified

02/07/15

00:40:25

26.84 N

93.20 W 1295 Red crab

Chaceon quinquedens
85

Date/

Time Location Depth (m) Likely Identity Image

02/07/15

00:40:35

26.84 N

93.20 W 1294

Glass sponge

Hexactinellidae

Unidentified

02/07/15

00:52:26

26.84 N

93.20 W 1290

Glass sponge

Hexactinellidae

Hyalonema sp.
86

Date/

Time Location Depth (m) Likely Identity Image

02/07/15

01:00:51

26.84 N

93.20 W 1297 Holothurian

Enypniastes eximia

02/07/15

01/12/28

26.84 N

93.20 W 1290 Holothurian

Unidentified

02/07/15

01/13/49

26.84 N

93.20 W 1289

Eel

Synaphobranchidae?

Unidentified
87

Date/

Time Location Depth (m) Likely Identity Image

02/07/15

01/16/51

26.84 N

93.20 W 1286

Glass sponge

Hexactinellidae

Unidentified

02/07/15

01/19/42

26.84 N

93.20 W 1295

Fish

Ophiidae?

Unidentified

02/10/15

19/07/59

26.84 N

93.20 W 1068 Fish

Unidentified
88

Date/

Time Location Depth (m) Likely Identity Image

02/10/15

19/14/49

26.84 N

93.20 W 1068 Large marine aggregate

02/10/15

19/21/39

26.84 N

93.20 W 1068 Lobate ctenophore

Bathocyroe fosteri

02/10/15

20/30/00

26.84 N

93.20 W 914 Undescribed cydippid 

ctenophore
89

Date/

Time Location Depth (m) Likely Identity Image

02/10/15

20/39/15

26.84 N

93.20 W 914 Unidentified

02/10/15

21/12/54

26.84 N

93.20 W 765 Medusa

Halitrephes valdiviae

02/10/15

21/15/16

26.84 N

93.20 W 764

Fish

Gonostomatidae

Cyclothone sp.
90

Date/

Time Location Depth (m) Likely Identity Image

02/10/15

21/28/53

26.84 N

93.20 W 763 Midwater shrimpUnidentified

02/10/15

21/29/51

26.84 N

93.20 W 763 Undescribed cydippid 

ctenophore
91

Date/

Time Location Depth (m) Likely Identity Image

02/10/15

21/35/06

26.84 N

93.20 W 764 Physonect siphonophoreUnidentified

02/10/15

21/42/24

26.84 N

93.20 W 582 Chaetognath

Unidentified

02/10/15

21/52/03

26.84 N

93.20 W 603 Larvacean

Unidentified
92

Date/

Time Location Depth (m) Likely Identity Image

02/10/15

21/52/11

26.84 N

93.20 W 603 Physonect siphonophore

Unidentified

02/10/15

21/55/27

26.84 N

93.20 W 611

Calycophoran 

siphonophore

Praya sp.
93

Date/

Time Location Depth (m) Likely Identity Image

02/10/15

21/58/39

26.84 N

93.20 W 612

Hatchetfish

Sternoptychidae

Unidentified

02/10/15

22/03/47

26.84 N

93.20 W 611 Medusa

Rhopalonema sp.
94

Date/

Time Location Depth (m) Likely Identity Image

02/10/15

22/09/20

26.84 N

93.20 W 611 Dinner plate jellyfish

Solmissus sp.

02/10/15

22/13/06

26.84 N

93.20 W 610 Medusa

Unidentified
95

Date/

Time Location Depth (m) Likely Identity Image

02/10/15

22/19/16

26.84 N

93.20 W 610 Tentacle

Unidentified

02/10/15

22/41/40

26.84 N

93.20 W 459 Salp chain

Unidentified
96

Date/

Time Location Depth (m) Likely Identity Image

02/11/15

00/37/15

26.84 N

93.20 W 153 Shrimp

Unidentified

02/11/15

00/39/12

26.84 N

93.20 W 153 Amphipod

Phronima sp.

02/28/15

06:59:56

26.84 N

93.20 W 1297 Undescribed demersal cydippid ctenophore
97

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

07:06:25

26.84 N

93.20 W 1297

Glass sponge 

Hexactinellidae

Hyalonema sp.

02/28/15

07:08:01

26.84 N

93.20 W 1297 Shrimps

Nematocarcinus sp.

02/28/15

07:16:39

26.84 N

93.20 W 1296 ShrimpGlyphocrangon sp.
98

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

07:18:32

26.84 N

93.20 W 1296 Brittle starUnidentified

02/28/15

07:24:09

26.84 N

93.20 W 1296 Squat lobster

Unidentified on soft coral
99

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

07:34:40

26.84 N

93.20 W 1291 Red crab

Chaceon quinquedens

02/28/15

07:42:48

26.84 N

93.20 W 1288 Giant isopod

Bathynomus giganteus
100

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

07:46:05

26.84 N

93.20 W 1288 Holothurian

Benthodytes sp.

02/28/15

14:33:45

26.84 N

93.20 W 1297 Sea penUnidentified
101

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

14:34:43

26.84 N

93.20 W 1297

Eel

Synaphobranchidae

Synaphobranchus sp.

02/28/15

14:39:42

26.84 N

93.20 W 1295

Eel

Synaphobranchidae

Synaphobranchus sp.

02/28/15

15:05:07

26.84 N

93.20 W 1284 Lobate ctenophore

Lampocteis cruentiventer
102

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

15:08:40

26.84 N

93.20 W 1294 Lithodid crab

Neolithodes agassizii

02/28/15

15:11:34

26.84 N

93.20 W 1296 Sea pen?

Unidentified
103

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

15:24:27

26.84 N

93.20 W 1291 Lobate ctenophore

Bathocyroe fosteri

02/28/15

15:24:41

26.84 N

93.20 W 1293

Glass sponge

Hexactinellidae

Hyalonema sp.
104

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

15:49:30

26.84 N

93.20 W 1299 Holothurian

Benthodytes sp.

02/28/15

15:51:20

26.84 N

93.20 W 1300 ShrimpGlyphocrangon sp.
105

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

16:03:56

26.84 N

93.20 W 1300

Flatback lobster

Polycheles sp. possibly P. 

sculptus

02/28/15

16:05:18

26.84 N

93.20 W 1300

Fish 

Ophidiidae

Bassogigas gilli

02/28/15

16:09:50

26.84 N

93.20 W 1299

Fish

Macrouridae

Coryphaenoides sp.
106

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

16:19:56

26.84 N

93.20 W 1299

Fish (upper left)

Macrouridae

Coryphaenoides sp.

02/28/15

16:20:32

26.84 N

93.20 W 1299

Fish

Ophidiidae

Dicrolene introniger
107

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

16:26:06

26.84 N

93.20 W 1299

Eel

Synaphobranchidae

Synaphobranchus sp.

02/28/15

16:55:36

26.84 N

93.20 W 1301

Shrimps

Nematocarcinus sp. next 

to asphalt

02/28/15

16:57:20

26.84 N

93.20 W 1301

Eel

Synaphobranchidae

Illyophis sp.?
108

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

16:57:36

26.84 N

93.20 W 1301 Asphalt seep with brine 

pool

02/28/15

16:58:52

26.84 N

93.20 W 1301

Dead isopod Bathynomus 

giganteus floating on 

surface of brine pool

02/28/15

16:59:54

26.84 N

93.20 W 1301

Dead isopod Bathynomus 

giganteus floating on 

surface of brine pool
109

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

17:00:05

26.84 N

93.20 W 1301

Dead isopod Bathynomus 

giganteus floating on 

surface of brine pool

02/28/15

17:03:02

26.84 N

93.20 W 1301

Dead isopod Bathynomus 

giganteus floating on 

surface of brine pool
110

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

17:04:52

26.84 N

93.20 W 1302 Edge of asphalt seep

02/28/15

17:07:12

26.84 N

93.20 W 1301 Lithodid crabNeolithodes agassizii
111

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

17:11:02

26.84 N

93.20 W 1301 Holothurian

Benthodytes sp.

02/28/15

17:17:06

26.84 N

93.20 W 1299

Eel

Synaphobranchidae

Unidentified
112

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

17:24:57

26.84 N

93.20 W 1298

Eel

Synaphobranchidae

Unidentified

02/28/15

17:29:11

26.84 N

93.20 W 1300

Fish

Ophidiidae

Dicrolene introniger
113

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

17:32:06

26.84 N

93.20 W 1301 Squat lobsters

Unidentified

02/28/15

17:33:01

26.84 N

93.20 W 1301

Shrimp

Glyphocrangon above 

unidentified squat lobster
114

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

17:34:51

26.84 N

93.20 W 1302 Brine pool

02/28/15

17:35:57

26.84 N

93.20 W 1301 Brine pool
115

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

17:36:14

26.84 N

93.20 W 1301 Brine pool

02/28/15

20:01:06

26.84 N

93.20 W 1295 Holothurian

Benthodytes sp.
116

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

20:29:22

26.84 N

93.20 W 1294

Eel

Synaphobranchidae

Synaphobranchus sp.

02/28/15

20:30:49

26.84 N

93.20 W 1294 Fish

Unidentified
117

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

20:43:08

26.84 N

93.20 W 1295 Holothurian

Benthodytes sp.

02/28/15

21:14:41

26.84 N

93.20 W 1291 Lobate ctenophore

Bathocyroe fosteri?
118

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

21:36:00

26.84 N

93.20 W 1300

Eel

Synaphobranchidae

Unidentified

02/28/15

21:37:32

26.84 N

93.20 W 1295

Fish

Macrouridae

Unidentified
119

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

21:50:39

26.84 N

93.20 W 1299 Asphalt seeps

02/28/15

21:51:04

26.84 N

93.20 W 1299 Asphalt seeps
120

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

21:51:41

26.84 N

93.20 W 1300 Shoreline of brine pool

02/28/15

21:52:13

26.84 N

93.20 W 1300 Shoreline of brine pool
121

Date/

Time Location Depth (m) Likely Identity Image

02/28/15

22:00:00

26.84 N

93.20 W 1300

Eel

Synaphobranchidae

Unidentified

02/28/15

22:17:55

26.84 N

93.20 W 1281

Fish

Ophidiidae?

Bassogigas gilli

02/28/15

22:17:55

26.84 N

93.20 W 1287

Fish

Ophidiidae?

Bassogigas gilli
122

Date/

Time Location Depth (m) Likely Identity Image

03/09/15

18:07:37

26.84 N

93.20 W 1298 Lithodid crab

Neolithodes agassizii
123

3.6 Mississippi Canyon

3.6.1 MC118

This single observation of the piglet squid Helicocranchia sp. was provided by an Oceaneering ROV (Millennium 160). No further information 

was available.

Table 11. Biological Observations from MC118

Date/

Time Location Depth (m) Likely Identity Image

03/06/15

22:01:05

28.85 N

88.48 W 933 Piglet squid

Helicocranchia sp.

03/06/15

22:01:45

28.85 N

88.48 W 933

Piglet squid

Helicocranchia sp. (same 

individual as 22:01:05)
124

Date/

Time Location Depth (m) Likely Identity Image

03/06/15

22:03:36

28.85 N

88.48 W 933

Piglet squid

Helicocranchia sp. (same 

individual as 22:01:05)
125

3.6.2 MC383

A C-Innovation ROV (UHD48), operating from the Transocean Development Driller III working under contract for BP, provided a large number 

of observations during 2015. This soft-bottom site is located in the upper bathypelagic zone with a bottom depth of approximately 1435 m. 

Visibility near the seabed was often reduced by suspended sediment. This, combined with the altitude of the ROV, often reduced image quality. 

The site had a diverse invertebrate and fish community. Invertebrates included seastars Nymphaster arenatus, cerianthid anemones, shrimps 

Nematocarcinus sp. and Glyphocrangon sp. Red crabs Chaceon quinquedens were abundant and the lithodid crab Neolithodes agassizii was 

present. Fishes included several species of macrouridae, cutthroat eels Synaphobranchus sp., halosaurs, and cusk eels Dicrolene introniger and 

Bassogigas gilli.

Table 12. Biological Observations from MC383

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

15:31:10

28.62 N

88.43 W 1437

Cutthroat eel

Synaphobranchidae

Synaphobranchus sp.

11/13/15

15:32:43

28.62 N

88.43 W 1437 Fish

Unidentified
126

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

15:38:28

28.62 N

88.43 W 1437 Shrimp

Nematocarcinus sp.

11/13/15

15:42:02

28.62 N

88.43 W 1437 Shrimp

Cerataspis monstrosa

11/13/15

16:34:20

28.62 N

88.43 W 1466 Red crab 

Chaceon quinquedens
127

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

16:43:09

28.62 N

88.43 W 1466

Fish

Macrouridae

Coelorinchus?

11/13/15

16:47:10

28.62 N

88.43 W 1466

Fish

Ophidiidae

Dicrolene introniger
128

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

17:05:48

28.62 N

88.43 W 1469

Fish

Halosauridae

Unidentified

11/13/15

17:09:09

28.62 N

88.43 W 1470 Shrimp

Nematocarcinus sp.
129

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

17:09:42

28.62 N

88.43 W 1470

Fish

Halosauridae

Unidentified

11/13/15

17:23:29

28.62 N

88.43 W 1449

Fish

Ipnopidae

Bathypterois quadrifilis
130

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

17:28:01

28.62 N

88.43 W 1449 Red crab

Chaceon quinquedens

11/13/15

17:42:21

28.62 N

88.43 W 1445

Fish

Ophidiidae

Bassogigas gilli

11/13/15

19:00:53

28.62 N

88.43 W 1447

Fish

Halosauridae

Unidentified
131

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

19:06:04

28.62 N

88.43 W 1447 Sea star

Nymphaster arenatus

11/13/15

19:09:45

28.62 N

88.43 W 1447

Fish

Ophidiidae?

Unidentified
132

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

19:28:50

28.62 N

88.43 W 1445 Red crab

Chaceon quinquedens

11/13/15

20:27:24

28.62 N

88.43 W 1434 Cerianthid anemone

Unidentified
133

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

20:30:36

28.62 N

88.43 W 1433 Fish

Unidentified

11/13/15

20:34:46

28.62 N

88.43 W 1434

Fish

Halosauridae

Unidentified
134

Date/

Time Location Depth (m) Likely Identity Image

11/13/15

20:57:29

28.62 N

88.43 W 1428

Fish

Ipnopidae

Bathypterois quadrifilis

11/13/15

21:07:53

28.62 N

88.43 W 1436 Sea star

Nymphaster arenatus

11/13/15

22:24:43

28.62 N

88.43 W 1451 Fish

Unidentified
135

Date/

Time Location Depth (m) Likely Identity Image

11/14/15

00:14:20

28.62 N

88.43 W 1446 Red crab

Chaceon quinquedens

11/14/15

00:19:25

28.62 N

88.43 W 1446

Fish

Ophidiidae

Bassogigas gilli
136

Date/

Time Location Depth (m) Likely Identity Image

11/14/15

12:57:49

28.62 N

88.43 W 1448 Shrimp

Cerataspis monstrosa?

11/14/15

13:55:45

28.62 N

88.43 W 1449

Fish

Stephanoberycidae?

Unidentified
137

Date/

Time Location Depth (m) Likely Identity Image

11/14/15

13:56:04

28.62 N

88.43 W 1448 Red crabChaceon quinquedens

11/14/15

14:02:21

28.62 N

88.43 W 1448 Shrimp

Nematocarcinus sp.
138

Date/

Time Location Depth (m) Likely Identity Image

11/14/15

14:04:00

28.62 N

88.43 W 1449 Sea star

Nymphaster arenatus

11/14/15

13:33:31

28.62 N

88.43 W 1421 Red crab

Chaceon quinquedens
139

Date/

Time Location Depth (m) Likely Identity Image

11/14/15

13:35:20

28.62 N

88.43 W 1421 Sea starUnidentified

11/14/15

13:36:00

28.62 N

88.43 W 1421 Shrimp

Cerataspis monstrosa?
140

Date/

Time Location Depth (m) Likely Identity Image

11/14/15

13:38:32

28.62 N

88.43 W 1421

Fish

Macrouridae

Unidentified

11/14/15

13:39:37

28.62 N

88.43 W 1420 Fish Macrouridae

Gadomus longifilis

11/14/15

15:52:11

28.62 N

88.43 W 1418 Sea star

Nymphaster arenatus
141

Date/

Time Location Depth (m) Likely Identity Image

11/14/15

15:55:11

28.62 N

88.43 W 1418 Cerianthid anemoneUnidentified

11/14/15

16:01:02

28.62 N

88.43 W 1421 Sea star

Unidentified
142

Date/

Time Location Depth (m) Likely Identity Image

11/14/15

16:09:12

28.62 N

88.43 W 1432 Shrimp

Glyphocrangon sp.

11/14/15

16:18:10

28.62 N

88.43 W 1438 Lithodid crab

Neolithodes agassizii
143

Date/

Time Location Depth (m) Likely Identity Image

11/14/15

16:21:26

28.62 N

88.43 W 1443 Fish

Unidentified
144

3.6.3 MC451

A single observation of a seldom-seen deepwater shark, the ragged-tooth shark Odontaspis ferox was provided by an Oceaneering ROV from 

Ocean Intervention IV. The location of this observation was provided as MC451; however, latitude and longitude data were not available.

Table 13. Biological Observations from MC451

Date/

Time Location Depth (m) Likely Identity Image

10/17/13

09:14:15 Unavailable 462 Ragged-tooth shark

Odontaspis ferox
145

3.6.4 MC525

MC525 is a deep site with a bottom depth in excess of 2275 m. An Oceaneering ROV Millennium 115 provided observations of holothurians: 

Benthodytes typica, Benthothuria funebris, and Enypniastes eximia swimming above the seabed. The sea urchin Phormosoma sp. was observed

here. Fishes typically observed only in deep locations included the bony-eared assfish Acanthonus armatus and a sleeper shark Somniosus sp.

Table 14. Biological Observations from MC525

Date/

Time Location Depth (m) Likely Identity Image

01/28/14

15:51:31

28.46 N

87.96 W 2283 Holothurian 

Benthodytes typica

02/08/14

16:44:36

28.46 N

87.96 W 2281 Holothurian

Benthothuria funebris
146

Date/

Time Location Depth (m) Likely Identity Image

02/11/14

04:09:52

28.46 N

87.96 W 2290 Sea urchin

Phormosoma sp.

02/11/14

07:03:20

28.46 N

87.96 W 2281 Holothurian

Benthothuria funebris
147

Date/

Time Location Depth (m) Likely Identity Image

02/16/14

00:48:00

28.46 N

87.96 W 2290 Sea urchinPhormosoma sp.

Date/

Time Location Depth (m) Likely Identity Image

02/19/14

12:38:29

28.46 N

87.96 W 2278

Holothurian

Enypniastes eximia 

juvenile

02/24/14

13:20:25

28.46 N

87.96 W 2280

Witch eel

Nettastomatidae

Venefica procera
148

Date/

Time Location Depth (m) Likely Identity Image

03/06/14

08:45:42

28.46 N

87.96 W 2281 Sleeper shark

Somniosus sp.

03/06/14

17:05:04

28.46 N

87.96 W 2286 Bony-eared assfish

Acanthonus armatus

05/30/14

08:21:07

28.46 N

87.96 W 2283 Crab

Neolithodes agassizii
149

Date/

Time Location Depth (m) Likely Identity Image

05/30/14

08:23:54

28.46 N

87.96 W 2281 Penaeoid shrimp 

Aristaeidae
150

3.6.5 MC762

A few observations of great barracuda and a chimaera Rhinochimaera atlantica were provided by an Oceaneering ROV deployed from the 

multiservice vessel (MV) Ocean Intervention IV.

Table 15. Biological Observations from MC762

Date/

Time Location Depth (m) Likely Identity Image

09/28/18

09:53:10

28.16 N

89.24 W 91 Great barracuda

Sphyraena barracuda

10/10/13

07:46:03

28.18 N

89.29 W 956 Fish

Rhinochimaera atlantica

10/10/13

07:46:03

28.18 N

89.29 W 956

Fish

Rhinochimaera atlantica

(same individual as 

07:46:03)
151

3.6.6 MC806

Shell’s Mars platform provided a large number of interesting observations collected by Oceaneering ROVs working from ROV support vessels.

This site is relatively shallow (~920 m) and has soft sediments that show evidence of abundant marine life. Invertebrates included sea stars 

Nymphaster arenatus, holothurians Enypniastes eximia, Pseudostichopus, Psychropotes sp., shrimps Nematocarcinus sp., a large scaled squid 

Pholidoteuthis adami, and red crabs Chaceon quinquedens. The latter were abundant and the ROV collected an observation of large numbers 

consuming a carcass of indeterminate origin. Fishes near the seabed consisted of chimaeras Rhinochimaera atlantica, a catshark Apristurus sp, 

synaphobranchid eels, cusk eels, and macrourids. Near the surface, great barracudas Sphyraena barracuda and tunas were common. The ROV also 

imaged a silky shark Carcharhinus falciformis that had what appeared to be a plastic ring or cord entangled around its head. Water column surveys 

recorded a large pyrosome Pyrosoma spinifera, a relatively uncommon genus of cydippid ctenophore Aulacoctena sp., and several different 

physonect siphonophores.

Table 16. Biological Observations from MC806

Date/

Time Location Depth (m) Likely Identity Image

10/13/13

15:50:57

28.17 N

89.22 W 927 Sea star 

Nymphaster arenatus

10/13/13

15:53:28

28.17 N

89.22 W 926 Sea star 

Nymphaster arenatus
152

Date/

Time Location Depth (m) Likely Identity Image

10/13/13

15:57:18

28.17 N

89.22 W 925 Shrimp 

Nematocarcinus sp.

10/13/13

15:58:25

28.17 N

89.22 W 925 Fish Macrouridae

Gadomus longifilis

10/13/13

16:17:35

28.17 N

89.22 W 925 Holothurian

Pseudostichopus sp.
153

Date/

Time Location Depth (m) Likely Identity Image

10/13/13

16:20:05

28.17 N

89.22 W 925 Synaphobranchidae

Illyophis sp.?

10/14/13

10:32:16

28.17 N

89.22 W 944 Holothurian 

Enypniastes eximia

10/14/13

16:21:52

28.17 N

89.22 W 924 Red crabs matingChaceon quinquedens
154

Date/

Time Location Depth (m) Likely Identity Image

10/14/13

16:54:15

28.17 N

89.22 W 924 Cutthroat eel Synaphobranchus sp.

10/14/13

16:54:51

28.17 N

89.22 W 924 Unidentified squat lobster

10/15/13

08:01:05

28.17 N

89.22 W 960

Fish 

Ophidiidae

Bassogigas gilli
155

Date/

Time Location Depth (m) Likely Identity Image

10/16/13

01:25:36

28.17 N

89.22 W 874

Aggregation of red crabs 

Chaceon quinquedens

feeding on unidentified 

material. Approximately 

14 crabs. 

10/16/13

01:26:48

28.17 N

89.22 W 874

Aggregation of red crabs 

Chaceon quinquedens

feeding on unidentified 

material. Approximately 

14 crabs. 

10/25/13

18:04:36

28.17 N

89.22 W 954 Unidentified shrimp
156

Date/

Time Location Depth (m) Likely Identity Image

10/26/13

02:47:24

28.17 N

89.22 W 958 Holothurian

Psychropotes sp.

10/26/13

18:11:56

28.17 N

89.22 W 954 Unidentified shrimp

10/27/13

04:55:11

28.17 N

89.22 W 393 School of unidentified tunas
157

Date/

Time Location Depth (m) Likely Identity Image

11/01/13

16:06:38

28.17 N

89.22 W 935 Ctenophore 

Kiyohimea sp. 

11/07/13

10:35:58

28.17 N

89.22 W 907 Holothurian

Enypniastes eximia

11/09/13

12:39:35

28.17 N

89.22 W 920 Ctenophore 

Aulacoctena sp
158

Date/

Time Location Depth (m) Likely Identity Image

11/10/13

08:53:08

28.17 N

89.22 W 22 Great barracuda

Sphyraena barracuda

11/10/13

11:02:00

28.17 N

89.22 W 922 Unidentified physonect 

siphonophore fishing

11/10/13

11:02:10

28.17 N

89.22 W 922

Unidentified physonect 

siphonophore fishing 

(same colony as 

11:02:00)
159

Date/

Time Location Depth (m) Likely Identity Image

11/11/13

21:59:29

28.17 N

89.22 W 944 Rhinochimaera atlantica

11/11/13

21:38:08

28.17 N

89.22 W 23 Juvenile queen angelfish

Holacanthis ciliaris

11/12/13

11:06:34

28.17 N

89.22 W 943 Holothurian 

Enypniastes eximia
160

Date/

Time Location Depth (m) Likely Identity Image

11/15/13

10:06:22

28.17 N

89.22 W 34 Great barracuda

Sphyraena barracuda

11/20/13

16:08:05

28.17 N

89.22 W 41

Silky shark Carcharhinus 

falciformis with plastic line 

or bag wrapped around its 

head.

11/20/13

16:08:08

28.17 N

89.22 W 41

Silky shark Carcharhinus 

falciformis with plastic line 

or bag wrapped around its 

head. 

(Same individual as 

16:08:06)
161

Date/

Time Location Depth (m) Likely Identity Image

11/20/13

18:34:29

28.17 N

89.22 W 804 Pyrosome

Pyrosoma spinosum

11/20/13

20:15:42

28.17 N

89.22 W 912 Catshark

Apristurus sp.

11/21/13

12:21:55

28.17 N

89.22 W 911 Unidentified physonect 

siphonophore
162

Date/

Time Location Depth (m) Likely Identity Image

11/22/13

06:49:08

28.17 N

89.22 W 943 Squid

Pholidoteuthis adami
163

3.6.7 MC809

In June 2014, an Oceaneering ROV, Millennium 111, operating from the drillship Noble Don Taylor under contract to Shell, was able to image the 

abundant fishes beneath the site. Macrourids were predominant; however, a pair of chimaeras Rhinochimaera atlantica and a catshark Apristurus

sp. were also observed. Red crabs Chaceon quinquedens and lithodid crabs Neolithodes agassizii were present. Opportunistic encounters included 

large tunas at over 1000 m depth.

Table 17. Biological Observations from MC809

Date

Time Location Depth (m) Identity Image

04/07/14

09:01:50

28.17 N

89.12 W 1204

Red crab Chaceon 

quinquedens and cusk eel 

Ophidiidae

04/07/14

09:42:52

28.17 N

89.12 W 1152 Pyrosome 

Pyrosoma spinifera
164

Date

Time Location Depth (m) Identity Image

04/07/14

09:42:52

28.17 N

89.12 W 1174 Lithodid crabsNeolithodes agassizii

04/07/14

09:42:52

28.17 N

89.12 W 1175 Red crab

Chaceon quinquedens

04/07/14

08:42:52

28.17 N

89.12 W 1066 Tuna 

Thunnus sp.
165

Date

Time Location Depth (m) Identity Image

04/07/14

08:44:47

28.17 N

89.12 W 1071 Tuna 

Thunnus sp.

04/07/14

08:44:58

28.17 N

89.12 W 1077 Tuna 

Thunnus sp.

04/07/14

08:45:53

28.17 N

89.12 W 1057 Tuna 

Thunnus sp.
166

Date

Time Location Depth (m) Identity Image

06/21/14

09:41:56

28.17 N

89.12 W 1154 Scyphomedusa

Periphyllopsis braueri

03/12/15

09:00:32

28.17 N

89.12 W 1109

Fish

Macrouridae

Coryphaenoides sp.

03/12/15

09:04:25

28.17 N

89.12 W 1109

Fish

Macrouridae

Coelorinchus sp.
167

Date

Time Location Depth (m) Identity Image

03/12/15

09:05:56

28.17 N

89.12 W 1110 Red crab

Chaceon quinquedens

03/12/15

09:14:38

28.17 N

89.12 W 1110 Shrimp

Glyphocrangon sp.

03/12/15

09:15:35

28.17 N

89.12 W 1110

Eel

Synaphobranchidae

Illyophis sp.
168

Date

Time Location Depth (m) Identity Image

03/12/15

09:16:28

28.17 N

89.12 W 1110

Eel

Synaphobranchidae

Synaphobranchus sp.

03/12/15

09:17:04

28.17 N

89.12 W 1110 Catshark

Apristurus sp.

03/12/15

09:17:14

28.17 N

89.12 W 1110

Catshark

Apristurus sp. 

(Same individual as 

09:17:04)
169

Date

Time Location Depth (m) Identity Image

03/12/15

09:19:18

28.17 N

89.12 W 1110 Shrimp

Glyphocrangon sp.

03/12/15

09:20:40

28.17 N

89.12 W 1110 Abundant fishes at the 

seabed
170

3.6.8 MC811

Oceaneering’s Millennium 115, working under contract for Shell, provided data from this site. MC811 is an intermediate depth site with the 

seabed at approximately 1360 m. Though most surveys were of midwater fauna, the ROV imaged chimaeras Hydrolagus alberti, cutthroat eels

Synaphobranchus sp., nettastomatid eels Venefica procera, and large lithodid crabs Neolithodes agassizii on the seabed. The water column surveys 

provided observations of a diverse fauna including ctenophores, siphonophores and scyphomedusae. The highlight was the observation of a pair of 

telescope fish Gigantura sp. at 1064 m. These fish have been reported to form pair bonds, possibly as a strategy for ensuring access to a mate 

(Kupchik et al. 2018). This observation is the third direct confirmation that Gigantura does form pairs. One of the other observations was from 

Gulf SERPENT observations in Walker Ridge.

Table 18. Biological Observations from MC811

Date

Time Location Depth (m) Identity Image

06/29/14

15:08:40

28.18 N

89.00 W 764 Undescribed red cydippid 

ctenophore

06/29/14

15:08:45

28.18 N

89.00 W 764

Undescribed red cydippid 

ctenophore (same 

individual as 15:08:40)
171

Date

Time Location Depth (m) Identity Image

06/29/14

15:11:05

28.18 N

89.00 W 763

Lobate ctenophore

Ocyropsis sp. with 

unidentified medusa in 

frame.

06/29/14

15:14:52

28.18 N

89.00 W 765 Unidentified shrimp

06/29/14

15:14:52

28.18 N

89.00 W 765 Larvacean house
172

Date

Time Location Depth (m) Identity Image

06/29/14

15:14:52

28.18 N

89.00 W 765 Ctenophore 

Eurhamphaea sp.

06/29/14

15:14:52

28.18 N

89.00 W 765

Physonect 

siphonophore

Apolemia sp.

06/29/14

15:23:05

28.18 N

89.00 W 772 Lobate ctenophore

Ocyropsis sp
173

Date

Time Location Depth (m) Identity Image

06/29/14

15:25:34

28.18 N

89.00 W 777 Lobate ctenophore

Ocyropsis sp.

06/29/14

15:14:52

28.18 N

89.00 W 770

Unidentified 

physonect 

siphonophore

06/29/14

15:14:52

28.18 N

89.00 W 770 Abandoned 

larvacean house
174

Date

Time Location Depth (m) Identity Image

03/08/15

09:55:13

28.18 N

89.00 W 635 Ctenophore 

Eurhamphaea sp.

03/08/15

10:07:19

28.18 N

89.00 W 611

Pyrosome

Pyrosoma 

atlanticum

03/16/15

10:07:31

28.18 N

89.00 W 1063

Medusa

Periphyllopsis 

braueri
175

Date

Time Location Depth (m) Identity Image

03/16/15

10:08:54

28.18 N

89.00 W 1064

A pair of 

Giganturidae

Gigantura chuni

03/16/15

10:09:38

28.18 N

89.00 W 1064

A pair of 

Giganturidae

Gigantura chuni

Same pair as 

10:08:54

03/16/15

10:12:12

28.18 N

89.00 W 1064 Ctenophore

Bathocyroe fosteri
176

Date

Time Location Depth (m) Identity Image

03/16/15

10:13:34

28.18 N

89.00 W 1062 Unidentified 

radiolarian

03/20/15

09:14:37

28.18 N

89.00 W 1362

Fish

Chimaeridae

Hydrolagus alberti

03/28/15

10:25:42

28.18 N

89.00 W 921 Medusa

Poralia rufescens
177

Date

Time Location Depth (m) Identity Image

03/28/15

10:26:27

28.18 N

89.00 W 921

Medusa

Poralia rufescens

Same individual as 

10:25:42

04/03/15

08:14:19

28.18 N

89.00 W 1362

Witch eel

Nettastomatidae

Venefica procera

04/03/15

08:16:56

28.18 N

89.00 W 1362

Cutthroat eel

Synaphobranchidae

Synaphobranchus

sp. (right side)
178

Date

Time Location Depth (m) Identity Image

04/29/15

14:44:09

28.18 N

89.00 W 1362

Fish

Chimaeridae

Hydrolagus alberti

05/08/15

08:36:11

28.18 N

89.00 W 651 Fish

Gonostomatidae

05/08/15

08:37:19

28.18 N

89.00 W 658 Medusa 

Halicreas sp.
179

Date

Time Location Depth (m) Identity Image

05/27/150

6:19:10

28.18 N

89.00 W 1362 Unidentified squat 

lobster

05/27/150

9:16:30

28.18 N

89.00 W 581 Unidentified medusa

05/27/150

9:19:51

28.18 N

89.00 W 579 Squid

Taonius pavo
180

Date

Time Location Depth (m) Identity Image

05/27/150

9:20:06

28.18 N

89.00 W 579

Squid

Taonius pavo

Same individual as 

09:19:51

05/27/150

9:22:45

28.18 N

89.00 W 480 Ctenophore 

Eurhamphaea sp.

05/27/150

9:24:28

28.18 N

89.00 W 570 Physonect 

siphonophore
181

Date

Time Location Depth (m) Identity Image

05/27/150

9:25:14

28.18 N

89.00 W 569 Chaetognath

05/31/15

08:24:43

28.18 N

89.00 W 306

Ctenophore 

Thalassocalyce 

inconstans

06/28/150

8:36:38

28.18 N

89.00 W 1362 Unidentified
182

Date

Time Location Depth (m) Identity Image

06/28/150

8:53:25

28.18 N

89.00 W 1365 Neolithodes agassizi
183

3.6.9 MC822

Data from this location were provided by Oceaneering’s Millennium 80 and 82 ROVs operating from the Transocean Development Driller III rig 

under contract to BP. The seabed at this site is remarkable flat and water clarity was excellent during the surveys. This factor combined with the 

intense lights of the ROV provided some excellent images. A few stalked glass sponges and isolated small corals growing on hard surfaces 

comprised the sessile invertebrate fauna. Nematocarcinus sp. shrimp were abundant along with fewer Cerataspis monstrosa and several other 

unidentified shrimps swimming just above the seabed. A few large lithodid crabs Neolithodes agassizii were present; however, no red crabs 

Chaceon quinquedens were observed. Synaphobranchus eels dominated the fishes along with some tripodfish Bathypterois quadrifilis, halosaurs,

and cusk eels Bassogigas gilli. One notable observation on the seabed was part of the carapace of a sea turtle. In the water column, a nice example 

of the squid Grimalditeuthis bonplandi was imaged along with the fish-eating physonect siphonophore Erenna sp.

Table 19. Biological Observations from MC822

Date

Time Location Depth (m) Identity Image

07/15/16

15:05:09

28.15 N

88.48 W 1912

Shrimp

Cerataspis monstrosa 

(formerly Plesopenaeus 

armatus)
184

Date

Time Location Depth (m) Identity Image

07/15/16

15:13:11

28.15 N

88.48 W 1913 Holothurian

Benthothuria sp.

07/15/16

15:26:40

28.15 N

88.48 W 1912

Fish

Macrouridae

Coryphaenoides 

macrocephalus
185

Date

Time Location Depth (m) Identity Image

07/15/16

15:27:29

28.15 N

88.48 W 1912

Shrimp Nematocarcinus 

sp. and hormathiid 

anemones 

07/16/16

07:43:33

28.15 N

88.48 W 1915

Cutthroat eel

Synaphobranchidae

Synaphobranchus sp.
186

Date

Time Location Depth (m) Identity Image

07/16/16

07:46:44

28.15 N

88.48 W 1915

Cutthroat eel

Synaphobranchidae

Synaphobranchus sp.

07/16/16

07:48:00

28.15 N

88.48 W 1915

Fish

Ipnopidae

Bathypterois quadrifilis 
187

Date

Time Location Depth (m) Identity Image

07/16/16

07:50:02

28.15 N

88.48 W 1915 Red shrimp

Nematocarcinus sp.

07/16/16

07:53:14

28.15 N

88.48 W 1913 ShrimpUnidentified

07/16/16

08:04:16

28.15 N

88.48 W 1915 ShrimpCerataspis monstrosa
188

Date

Time Location Depth (m) Identity Image

07/16/16

08:21:20

28.15 N

88.48 W 1915 Squat lobster

Unidentified

07/16/16

08:36:22

28.15 N

88.48 W 1914 Coral

Unidentified
189

Date

Time Location Depth (m) Identity Image

07/16/16

08:46:46

28.15 N

88.48 W 1915

Glass sponge

Hexactinellidae

Unidentified

07/16/16

08:51:50

28.15 N

88.48 W 1915

Glass sponge

Hexactinellidae

Unidentified
190

Date

Time Location Depth (m) Identity Image

07/16/16

09:09:21

28.15 N

88.48 W 1914 Partial sea turtle carapace

07/16/16

09:37:48

28.15 N

88.48 W 1915 Holothurian

Unidentified
191

Date

Time Location Depth (m) Identity Image

07/16/16

09:59:00

28.15 N

88.48 W 1915

Cutthroat eel

Synaphobranchidae

Synaphobranchus sp.

07/16/16

10:17:12

28.15 N

88.48 W 1914

Fish

Halosauridae

Unidentified
192

Date

Time Location Depth (m) Identity Image

07/16/16

10:27:40

28.15 N

88.48 W 1914

Fish

Ipnopidae

Bathypterois quadrifilis

07/16/16

11:30:01

28.15 N

88.48 W 1914 Brittle starUnidentified

07/16/16

12:11:33

28.15 N

88.48 W 1915 Sea pen 

Umbellula sp.
193

Date

Time Location Depth (m) Identity Image

07/16/16

12:18:42

28.15 N

88.48 W 1915

Fish

Ophidiidae

Bassogigas gilli

07/16/16

12:21:15

28.15 N

88.48 W 1915

Fish

Halosauridae

Unidentified

07/16/16

12:25:31

28.15 N

88.48 W 1915 Brittle star

Unidentified
194

Date

Time Location Depth (m) Identity Image

07/16/16

12:29:42

28.15 N

88.48 W 1915 Lithodid crab

Neolithodes agassizii

07/16/16

12:37:57

28.15 N

88.48 W 1914 Swimming holothurian

Unidentified (Elpididae?)
195

Date

Time Location Depth (m) Identity Image

07/16/16

12:53:54

28.15 N

88.48 W 1914

Fish

Ophidiidae

Bassogigas gilli

07/16/16

13:01:22

28.15 N

88.48 W 1915 Coral

Unidentified
196

Date

Time Location Depth (m) Identity Image

07/16/16

13:07:06

28.15 N

88.48 W 1915 Holothurian

Unidentified

07/16/16

19:32:50

28.15 N

88.48 W 1914 Lithodid crabNeolithodes agassizii

07/16/16

20:10:18

28.15 N

88.48 W 1914

Fish

Ophidiidae

Bassogigas gilli 
197

Date

Time Location Depth (m) Identity Image

07/16/16

20:11:45

28.15 N

88.48 W 1912

Fish

Halosauridae

Unidentified

07/17/16

03:35:02

28.15 N

88.48 W 1676

Calycophoran 

siphonophore

Unidentified (Same 

individual as 09:54:14)

07/17/16

03:38:54

28.15 N

88.48 W 1676 Squid

Grimalditeuthis bonplandi 
198

Date

Time Location Depth (m) Identity Image

07/17/16

09:54:14

28.15 N

88.48 W 1237 Physonect siphonophore

Erenna sp.
199

3.7 Walker Ridge

3.7.1 WR467

Surveys at this site located far offshore were conducted in cooperation with Petrobras America. All surveys were conducted in the water column.

Table 20. Biological observations from WR467

Date

Time Location Depth (m) Identity Image

12/03/13

15:41:33

26.52 N

90.53 W 1796 LarvaceanUnidentified

12/03/13

15:46:15

26.52 N

90.53 W 1797 Lobate ctenophore 

Bathocyroe fosteri
200

Date

Time Location Depth (m) Identity Image

12/03/13

16:26:00

26.52 N

90.53 W 599 Trichiuridae

Unidentified

12/03/13

16:26:00

26.52 N

90.53 W 599 Physonect 

siphonophore
201

Date

Time Location Depth (m) Identity Image

12/06/13

20:27:17

26.52 N

90.53 W 1291 Piglet squid

Helicocranchia sp.
202

Date

Time Location Depth (m) Identity Image

01/30/15

15:06:25

26.52 N

90.53 W 459 Pyrosome

Pyrosoma atlanticum

03/31/15

10:27:14

26.52 N

90.53 W 2704

Ophidiidae 

Bony-eared assfish 

Acanthonus armatus
203

Date

Time Location Depth (m) Identity Image

03/31/15

10:27:14

26.52 N

90.53 W 5

Carangidae

Rainbow runner

Elagatis bipinnulata

03/31/15

10:27:22

26.52 N

90.53 W 3

Kyphosidae

Bermuda chub

Kyphosus sectator
204

Date

Time Location Depth (m) Identity Image

04/29/15

16:54:04

26.52 N

90.53 W 13

Balistidae

Gray triggerfish

Balistes capriscus

04/30/15

15:39:57

26.52 N

90.53 W 1218

Physonect 

siphonophore Apolemia

sp.
205

Date

Time Location Depth (m) Identity Image

04/30/15

15:26:07

26.52 N

90.53 W 1066 Trachymedusa

Halitrephes valdiviae

04/30/15

16:52:01

26.52 N

90.53 W 1061 Cranchid squid

Megalocranchia sp. 
206

Date

Time Location Depth (m) Identity Image

04/30/15

16:52:48

26.52 N

90.53 W 1057

Cranchid squid

Megalocranchia sp.

(same individual as 

16:52:01)

04/30/15

17:16:53

26.52 N

90.53 W 3

Sphyraenidae

Great barracuda 

Sphyraena barracuda
207

Date

Time Location Depth (m) Identity Image

05/01/15

06:45:05

26.52 N

90.53 W 754

Phronimidae

Hyperiid amphipod

Phronima sp.

05/01/15

14:07:45

26.52 N

90.53 W 1525 Narcomedusa 

Solmissus sp.
208

Date

Time Location Depth (m) Identity Image

05/01/15

10:41:59

26.52 N

90.53 W 1066 Chaetognath

Undentified

05/01/15

11:25:11

26.52 N

90.53 W 1216 Shrimp

Unidentified
209

Date

Time Location Depth (m) Identity Image

05/01/15

13:02:20

26.52 N

90.53 W 1371 Shrimp 

Unidentified

05/01/15

17:14:31

26.52 N

90.53 W 455 Siphonophore

Unidentified
210

Date

Time Location Depth (m) Identity Image

05/25/15

13:57:16

26.52 N

90.53 W 70

Scombridae

Blackfin tuna 

Thunnus atlanticus

05/25/15

14:50:43

26.52 N

90.53 W 7

Sphyraenidae

Great barracuda 

Sphyraena barracuda
211

Date

Time Location Depth (m) Identity Image

05/26/15

08:00:52

26.52 N

90.53 W 14

Sphyraenidae

Great barracuda 

Sphyraena barracuda

05/26/15

08:22:27

26.52 N

90.53 W 313 Carangidae

Unidentified
212

Date

Time Location Depth (m) Identity Image

05/26/15

08:45:09

26.52 N

90.53 W 1033

Physonect 

siphonophore Apolemia

sp.

05/27/15

08:03:37

26.52 N

90.53 W 91

Scombridae

Blackfin tuna

Thunnus atlanticus
213

Date

Time Location Depth (m) Identity Image

05/28/15

08:01:41

26.52 N

90.53 W 34

Carangidae

Almaco jack

Seriola rivoliana
214

3.7.2 WR469

This site was operated by Petrobras-America and the surveys consisted of water column observations. Physonect siphonophores dominated with 

some ctenophores and medusae.

Table 21. Biological Observations from WR469

Date

Time Location Depth (m) Identity Image

03/02/15

14:30:27

26.52 N

90.53 W 608 Gonostomatidae

Cyclothone sp.

03/02/15

14:33:09

26.52 N

90.53 W 608 Narcomedusa

Solmissus sp.
215

Date

Time Location Depth (m) Identity Image

03/02/15

15:31:39

26.52 N

90.53 W 913 Lobate ctenophore

Bathocyroe fosteri

03/02/15

15:33:17

26.52 N

90.53 W 913 Lobate ctenophore

Possibly Ocyropsis sp.
216

Date

Time Location Depth (m) Identity Image

03/02/15

17:20:14

26.52 N

90.53 W 9

Ocean triggerfish 

Balistiidae

Canthidermis sufflamen?

Date

Time Location Depth (m) Identity Image

03/03/15

08:03:27

26.52 N

90.53 W 1521 Physonect siphonophore 

Unidentified
217

Date

Time Location Depth (m) Identity Image

03/03/15

08:45:04

26.52 N

90.53 W 1523 Physonect siphonophore Unidentified

03/03/15

08:57:12

26.52 N

90.53 W 1521 Physonect siphonophore

Apolemia sp.
218

Date

Time Location Depth (m) Identity Image

03/03/15

13:13:55

26.52 N

90.53 W 55 TunasThunnus sp.

03/03/15

14:35:56

26.52 N

90.53 W 2136 Holothurian

Enypniastes eximia
219

4. Vertical Distribution Patterns of Selected Organisms

4.1 Introduction

The oil and gas industry conducts regular inspections of subsea equipment using remotely-operated 

vehicles (ROVs). These inspection videos frequently image marine life in the vicinity of their target 

structures. Some of the primary targets for inspections are the risers that extend from the blow-out 

preventer (BOP) to near the surface production facilities. The upper limit for most riser inspection videos 

examined for this project was approximately 15–20 m (50–70 feet). These inspections are usually 

conducted annually. Extending through the entire water column for thousands of meters, these risers 

provide a hard surface upon which sessile organisms can attach (Fig. 3). The vertical distribution patterns 

of these organisms can potentially reveal their ideal depth and growth optima. Comparisons of the same 

sections of a structure from inspections spanning multiple years can provide estimates of growth rates. 

In addition to providing data on vertical distributions of sessile species, inspection videos contain 

information on the vertical distributions of mobile fishes and invertebrates. This provides biogeographical 

information on the presence of endemic as well as invasive species (e.g., lionfish). Many locations also 

have down-looking acoustic sensors (ADCPs) that provide the rig with data on current speed and 

direction through the water column. These sensors also record backscattering intensity data (receive 

signal strength intensity: RSSI) that is derived from echoes off biological targets. The inspection videos 

can provide data that assists in the interpretation of the sources of various acoustical scattering layers.

Figure 3. Part of the riser field below Shell’s Mars (MC807A) platform.
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Although BOEM sometimes mandates some biological ROV surveys before drilling, the majority of 

video collected by industrial ROVs does not target biota. Instead the focus is on the integrity and 

condition of subsea equipment. The information that these inspection videos contain represents a unique 

opportunity to extract biological time-series data. This section illustrates some of the potential data 

opportunities contained in inspection videos. A comprehensive examination of all the biological data 

contained in these videos would require hundreds of hours of effort. Although all companies collect 

inspection data, the following analyses were based on video provided to Gulf SERPENT by Shell through 

their online video archive maintained by Oceaneering.

4.2 Target Organisms

4.2.1 Tuna Vertical Migration Patterns

Three species of tunas belonging to the genus Thunnus are common in the oceanic waters of the Northern 

Gulf of Mexico. These include bluefin tuna T. thynnus, yellowfin tuna T. albacares, and blackfin tuna T. 

atlanticus. These fishes undertake extensive vertical migrations in order to forage on small fishes, 

cephalopods, crustaceans, and other zooplankton. 

Tunas are frequently observed during riser inspections. A series of riser inspection videos collected 

during June 2017 below Shells MC807A Mars Platform provided an opportunity map the vertical 

movements of tunas in relation to acoustic scattering features in the water column. Videos were 

downloaded from the Shell’s video archive1 in Motion Picture Expert Group 4 (MPEG4) format. These 

had a resolution of 1080i (1920 x 1080 pixels). Videos from twenty (1–11, 13–20) of the 23 production 

risers that were inspected were examined for tuna observations. Individual videos were inspected using 

Quicktime software. Tunas were observed below nine of the risers (A2, A3, A4, A5, A7, A8, A9, A17, 

and A19). Frames containing regions of interest (tunas) were copied and saved in Portable Network 

Graphics (PNG) format using the MacOS Preview Application. The filename of each frame used the 

convention of yyyy_mm_dd_hh_mn_ss_zzzzxnn.png, where: yyyy=year; mm=month; dd=day; hh=hour; 

mn=minute; ss=second; zzzz=depth in feet; xnn=number of individuals in the frame. All times were taken 

from the video overlay and were in local time. Filenames were read into Matlab and the structure of the 

filename was converted to numeric values using the str2num function. Each observation was then 

converted to a local time in year-day format (x value) and a corresponding depth converted to meters (y 

value). This general approach was used to analyze the depth distributions of other taxa discussed later in 

this chapter. The trajectories of each inspection were estimated as straight lines between the start point 

(time, depth) and end point (time, depth). This is a simplification since the ROV frequently paused at 

anodes and areas that needed additional observation; however, given the time for each inspection (>1 h) 

this linear approximation provided a reasonable picture of the position of the ROV in time and space. 

ADCP backscatter intensity data were obtained for the Mars Platform (NDBC Station 42363) from the 

National Data Buoy Center2

. Data were imported into Matlab and times were converted to year-day 

format and then corrected to local times from GMT. Backscatter intensity pseudocolor plots were 

visualized in Matlab using the pcolor function after averaging echo intensity (receive signal strength 

intensity) values among beams 1 and 2. The data from beams 3 and 4 could not be used because beam 4 

contained only zero values for the time period of interest and beam 3 appeared to be impacted by an 

obstruction. Bad data that produced strong vertical banding was identified and masked out in Matlab.

Video frames containing a total of 327 tunas were isolated. In most frames the tunas were recognizable 

due to their size and shape; however, since the risers were to intended video targets, focus was usually not 

sharp because the tunas were generally behind the focal point of the camera. In addition, the tunas were 

1 See https://omvshell.oiigds.com/ 2 See www.ndbc.noaa.gov
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fast-moving targets and seldom slowed sufficiently to reduce the substantial motion blur associated with 

most images. This motion blur combined with poor focus (e.g., Fig. 4) made it difficult to identify the 

species of tuna though the morphology appeared consistent with the genus Thunnus. Based on the relative 

geometry of the pectoral fins in relation to the posterior dorsal fin, position of the anal fin, and colors of 

finlets, yellowfin tuna are the most probable species.

Tuna were primarily encountered within the midwater scattering layer centered near 500 m (Fig. 5). Some 

individuals were also observed deeper between 600m and the seabed (895 m). It was evident from the 

videos that the tunas were foraging. Swimming speed was rapid and the fish often undertook rapid 

changes in direction. The gaps in the ADCP record meant that it was not possible to associate all 

observations to the acoustic scattering record. In order to overcome this issue, daily acoustic patterns from 

June 5–June 9, 2017 were combined and averaged to produce a mean acoustic day below the Mars 

platform (Fig. 6). 

When tuna observations color-coded by numbers per frame are superimposed on the mean acoustic day a 

clearer pattern of the foraging behavior of these yellowfin tuna emerges. Feeding was only documented at 

depth during the morning. From approximately 03:00–04:00, foraging occurs in the midwater scattering 

layer (400–600 m) and just above the seabed. From ~03:30 until 07:00 tunas feed on the descending 

scattering layer as it returns from the surface to mid-depth. Some feeding occurs in, and just below the 

midwater scattering layer until approximately 11 am. No tuna were observed in the afternoon or evening.

Just what the tuna were feeding on was not clear. In many cases there were not obvious prey organisms 

collocated with the foraging tuna. In some cases, small fishes, squids, and unidentified zooplankton were 

observed near or in the same section of the water as the tunas. The small fishes (Fig. 7) appear to be 

deepwater cardinalfishes (family Epigonidae). They did not actively school in a coordinated manner but 

occurred in aggregations of individuals that swam sluggishly in different directions.

The observations of tuna foraging underscore the value of ROV inspection video. Most tuna vertical 

migration behavior is obtained from tagging studies using acoustic or archival tags (e.g., Schaefer et al. 

2007; Weng et al. 2009). This example came from a relatively small quantity of video collected over a 

few days at a single site. With time a more comprehensive picture of the daily and annual changes in 

movements of tunas could be assembled from additional data at this, and other sites.
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Figure 4. Example frames showing tunas imaged during riser inspections below Shell’s Mars 

platform.
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Figure 5. Observations of yellowfin tuna () superimposed on acoustic backscatter from the Mars 

ADCP from June 5–10, 2017.

Black lines indicate the average trajectory of the ROV. Tuna observations may contain more than one individual.

Figure 6. An average acoustic day below the Mars platform for the period June 5–10, 2017.

Tuna observations are overlaid on the acoustic backscattering pattern and are color-coded by abundance (white=1, 

yellow=2-3, red=>3).
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Figure 7. Small fish observed in aggregations near, and coincident with foraging yellowfin tuna.

These are likely a species of deepwater cardinalfishes (Family Epigonidae Epigonidae). The sizes of these fish could 

not be estimated accurately but they appeared to be 3–5 centimeters in length.

4.2.2 Great Barracuda Sphyraena barracuda

Great barracuda Sphyraena barracuda are commonly observed in the near surface waters around oil and 

gas structures in the Northern Gulf of Mexico (Fig. 8). The vertical distributions of these large predators 

have usually been determined using tags (e.g., O’Toole et al. 2010; Hansen and Kerstetter 2015). Great 

barracuda appear unafraid of ROVs and will often approach the vehicles very closely while the systems 

are conducting inspections. This provided a means of estimating their vertical distributions based on the 

relative numbers of observations at different depths. 
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Individual frames containing great barracudas were extracted from inspection videos recorded below 

Shell’s MC809A Ursa and GB426 Auger platforms in 2018. Frame grabs were saved with a filename 

structure that was the same one used for tunas (yyyy_mm_dd_hh_mn_ss_zzzzxnn.png). Depth was 

estimated as the ROV depth even when barracudas were imaged slightly above or below the vehicle 

because there was no way to estimate the vertical offset. Given that target fish were generally close to the 

ROV suggesting an error of less than a few feet, this error would not be important since our depth bin 

intervals (2 m) were likely larger than the positioning error. 

At Ursa, observations were collected between August 9–16, and October 16, 2018. The Auger 

observations spanned March 31–April 16, 2018. In both locations, although ROV operations occurred on 

a 24 h basis, most observations of barracudas were confined to daylight periods because the ROV lights 

were normally directed at a riser or other structure and were generally inadequate to illuminate a 

sufficient amount of the water in front of the vehicle to detect barracudas and other targets at night.

Figure 8. Examples of great barracuda Sphyraena barracuda below Shell’s Ursa platform in 2018.

Below Ursa, the vertical distribution of great barracuda was confined to a narrow zone within the upper 

42 m of the water column (Fig. 9) with a mean vertical depth of 22.2 m. The ROVs did not operate above 

approximately 15 m, which constrains estimation of their complete distribution in the upper water 

column. When the ROV panned the camera upwards it was common to see multiple barracuda just below 

the surface (Fig. 9 inset). Below Auger the distribution pattern was quite different (Fig. 10). The mean 

vertical depth was deeper (38.7 m) and the distribution extended deeper down to 85.3 m. The sample size 

at Auger (n=110) was double that of Ursa (n=55), though the patterns were so different that sample size 

was not likely a contributing factor. In both sites the fish were constrained to the same depths. Both 

distributions were obtained from daytime data, therefore, vertical migration differences can be ruled out.
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Figure 9. Vertical distribution of great barracuda Sphyraena barracuda beneath Shell’s Ursa 

platform.

The inset image shows barracudas just below the surface. Fish located shallower than 14 m could not be enumerated 

by the ROV because it did not operate in that region.
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Figure 10. Vertical distribution of great barracuda Sphyraena barracuda beneath Shell’s Auger 

platform.

4.2.1 Juvenile Caribbean Moonfish Selene brownii

One of the benefits of access to large amounts of inspection video is the opportunity that it affords for 

unexpected discoveries. The presence of juvenile moonfish Selene setapinnis (Carangidae) is one such 

example. During examinations of riser inspection videos below the Ursa platform, numerous small, silver, 

laterally-compressed fish were observed near the riser in the 300–688 ft (102.2–203.7 m) depth range 

(Fig. 11). These were identified as juvenile Caribbean moonfish, a species that is normally an upper 

epipelagic inhabitant with juveniles occurring in estuaries and off river mouths (Cervigón 1993). The 

presence of these fish down into the base of the epipelagic zone was an unusual observation and a series 

of riser inspections from August 2018 were used to evaluate its vertical distribution pattern.

Caribbean moonfish were initially observed in inspection videos from Shell’s Ursa platform of the 18 

Inch Oil Export riser. Only two individuals were seen on that riser and the video quality was poor. 

Additional videos were examined to construct a clearer picture of this species’ vertical distribution pattern 

at that site. Caribbean moonfish were documented on the following risers: Crosby West Import, Princess 

Gas Lift SCR, Princess Water Flood Umbilical, Production A2, A3, and A4. Criteria for riser selection 

were video quality, lack of missing video segments, and water clarity. 
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Figure 11. Example frame grabs of Caribbean moonfish Selene brownii on risers below Shell’s 

Ursa platform.

Depths (m): A: 121.9; B: 136.2; C: 146.6; D: 156.5; E: 160.9; F: 173.0; G: 180.7; H: 190.4; I: 198.7; J: 203.7.
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The vertical distribution patterns on six risers below Ursa indicate that juvenile S. brownii use sections of 

riser in the lower half of the mesopelagic zone and extend in some cases, into the upper mesopelagic zone 

(Fig. 12). Abundances were quite variable, perhaps indicating local patchiness in settlement. This is the 

first time that this species has been documented in association with oil and gas structures. Whether this is 

a regular pattern and what the seasonality of riser use will require examination of additional inspection 

videos at Ursa and other sites. The implications of this habitat for the population of S. brownii is an 

interesting question. There are a lot of risers and similar artificial habitat on rigs and platforms in the Gulf 

of Mexico. This additional juvenile habitat could provide an important supplemental nursery area. In 

many videos, individuals appeared to be grazing on epibionts attached to the riser. In the event of a spill, 

this is another species that may be at risk to hydrocarbons in the epipelagic zone. 

Figure 12. Vertical distribution patterns of juvenile Caribbean moonfish on six risers below Shell’s 

Ursa platform in August 2018.

4.2.2 Coldwater Coral Lophelia pertusa

Lophelia pertusa is a coldwater coral that occurs throughout the North Atlantic (Davies et al. 2008) and 

extends into the Gulf of Mexico where conditions are favorable (Schroeder 2007). Within the Gulf of 

Mexico it is found on hard structures including hydrocarbon extraction structures (Larcom et al. 2014). 

Routine ROV inspection videos archived by Shell Oil were used to document the distribution of L. 

pertusa colonies on various risers connecting subsea wells or pipelines with surface facilities at Shell 

production facilities (Mars MC807A, Ursa MC809A) in the Northern Gulf of Mexico. The risers are 

conduits for hydrocarbons that run vertically between the seabed and the surface. ROVs collect video of 

the risers by ascending or descending in close proximity to the riser while facing them and recording 

video. The external diameters of the production risers extending from the wells are 24.4 cm.
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At MC807A, we used all available well riser surveys from October 2013 that contained abundant L. 

pertusa growth, were complete, and were free from playback problems. A series of videos from 2013 

collected at 14 wells (Table 37) met these criteria. Videos were downloaded from an archival site in 

MPEG-4 format. Although the original videos were recorded at (1980 x 1080 pixels) resolution using 

Oceaneering’s OceanPro system, the archived videos from 2013 were stored at reduced resolution (320 x 

240 pixels). Each video is identified by the date it was recorded and is associated with a specific facility 

and riser. We used the most recent inspection video available, unless there was evidence that the riser had 

been cleaned, in which case, we used the most recent video containing undisturbed coral growth. The 

local time (hh:mm:ss), depth (feet), and location (easting and northing when available) were obtained 

from the video overlay. Downloaded videos were visually processed using MPEG Streamclip software on 

a Mac computer. 

Table 22. Locations, Depths, Survey Dates And Construction Dates of 14 Well Risers

These risers, which extend 897 m below Mars (MC807A), were examined for Lophelia pertusa vertical distributions. 

Riser Easting (m) Northing (m) Survey Date 

(mm/dd/yy)

Riser 

Installed

Number of 

Colonies

Well A1 281756.53 3117786.80 10/02/13 2005 461

Well A2 281739.48 3117812.95 10/01/13 2004 424

Well A4 281754.41 3117802.99 10/08/13 2004 419

Well A5 281747.16 3117809.76 10/01/13 2004 341

Well A6 281752.86 3117807.41 10/01/13 2004 391

Well A7 281760.20 3117805.05 10/01/13 2004 110

Well A10 281761.36 3117800.46 10/08/13 2005 329

Well A12 281744.32 3117802.67 10/01/13 2005 366

Well A15 281739.12 3117801.02 10/01/13 2005 324

Well A17 281751.86 3117796.26 10/02/13 2005 309

Well A18 281759.13 3117793.71 10/02/13 2005 120

Well A21 281747.76 3117793.76 10/02/13 2005 338

Well A22 281754.89 3117791.16 10/02/13 2005 326

Well A24 281749.84 3117789.50 10/02/13 2005 171

In 2013, two metrics of L. pertusa abundance were estimated: number of colonies and percent cover. In 

the case of the former, when L. pertusa colonies were observed, a frame grab (PNG format) was saved for 

each colony (Fig. 13) using a filename that identified the location, date, time, and depth of the 

observation. For each riser inspection (Table 37) the resultant filenames were read into Matlab and the 

depths were parsed out. The water column was then separated into 10 m vertical bins and the frequency of 

colonies was estimated for each bin using the interp1 function in Matlab. The mean distribution pattern at 

each site was estimated by averaging the colony abundances in each 10 m vertical bin across all risers at 

each site. For percent cover, the amount of coral covering the riser was estimated from frame grabs 

collected at 10 m depth intervals. First area of the riser (sum of pixels) was estimated from a 

parallelogram bounding the top, bottom, and edges of the riser using Adobe Photoshop®. Then the area 

of L. pertusa colonies covering the riser within its boundary (sum of pixels) was divided by the riser area.
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Lophelia pertusa distributions were also evaluated below Shell’s Ursa platform based on inspections 

conducted in 2018. The risers and tendons selected for examination were: Crosby West Import; 

Production Riser A6; and tendons T1, T5, and T10. Only colony abundance was estimated from these 

videos, which were obtained in full HD (1080i) resolution. Because of the very different abundances of 

colonies on these structures, each histogram was converted to percentages of the total before averaging to 

estimate the mean distribution pattern.

In 2013 at Mars, Lophelia pertusa colonies were observed within a 443.5 m vertical zone extending 

between 280.1–723.6 m (Fig. 14). The maximum colony abundance of 48 10m-1 was observed on well A2 

at 490m. The mean colony abundance estimated over all 14 wells was approximately normally distributed 

with a maximum of 27.4 10m-1 (95% confidences on the mean = 22.0–32.9), which also co-occurred with 

the modal colony density at a depth of 490 m (Fig. 14). Most wells had similar colony abundances 

although three wells: A7, A18, and A24, had lower colony abundances albeit with similar vertical 

distribution patterns (Fig. 14).

The pattern of percentage coverage by L. pertusa (Fig. 15) in 2013 below Mars was generally similar to 

the colony abundance (Fig. 14). The percentage of the visible half of the riser that was covered by L. 

pertusa ranged from 0–87.6% (Well A4) with an overall mean coverage (between 250–650 m) of 6.4%. 

The mean coverage distribution was approximately Gaussian reaching a maximum of 30.2% (95% C.I. = 

17.2–43.2%; Fig. 15). 

The 2018 videos below Ursa indicated a generally similar vertical distribution pattern to those observed 

below Mars in 2013. The exception was the Crosby West Import riser which had an irregular pattern (Fig. 

16). The remaining riser and tendons indicated a Gaussian distribution that was generally confined to the 

zone between 300–750 m. Abundances were generally higher on the tendons (possibly due to their larger 

diameter and therefore greater surface area) than on the risers. The maximum colony abundance (116 

colonies 10m-1

) was observed on tendon T1 at 530 m. The overall maximum abundance based on the 

average distribution (Fig. 16) occurred at 520 m depth (Fig. 16).
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Figure 13. Example frame grabs of Lophelia pertusa colonies on risers below the Mars platform.

Lophelia pertusa has been reported in many locations in the Northern Gulf of Mexico. Its presence was 

first reported by Moore and Bullis (1960) who identified a large reef at a depth of 420.6–512.1 m, that 

was approximately 1219 m in length with variable, but undefined width. Schroeder (2002) reported a L. 

pertusa reef in the Viosca Knoll lease block on an authigenic carbonate mound at a depth of 

approximately 434 m. Reed et al. (2006) noted that high relief L. pertusa reefs occurred within the 490–

550 m zone of the Blake Plateau off the Georgia coast and at 500 m off the West Florida escarpment. 

Cordes et al. (2008) reported L. pertusa at 4 sites in the Northern Gulf of Mexico where the species 

occurred at depths ranging from 313–525 m. Larcom et al. (2014) examined L. pertusa distributions on 

oil and gas structures and three shipwrecks in the Northern Gulf. Their study included only one structure 

(a riser) that extended throughout the water column. They found L. pertusa distributed between 201–801 

m, a similar but slightly broader distribution than what we observed below the Mars platform. The depth 

zone 503–518 m contained the highest density of L. pertusa, which is slightly deeper than our observed 
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maximum below Mars located at 490 m but generally consistent with the depth zone where we found 

abundant coral. The factors that appear to be responsible for L. pertusa include: suitable substrate; 

topography; hydrographic conditions; and food availability (Mortensen et al. 2001). Two or more of these 

factors may be correlated.

Figure 14. Lophelia pertusa colony abundance on risers below Shell’s Mars platform in October 

2013.

Though we did not attempt to measure the sizes of all individual colonies, it was notable that the size of 

colonies did not appear to increase from the edges of the vertical distribution towards the depth of 

maximum abundance. In many cases, the sizes of individual colonies near the edges of its vertical range 

were frequently quite large (Fig. 17).

One of the primary values of using these inspection surveys is that they provide a picture of the ideal 

settlement pattern of L. pertusa and other sessile organisms given uniform hard structure that extends 

throughout the water column. NOAA has produced habitat suitability index models that predict where 

cold water corals may occur in the Gulf of Mexico. These models appear to be driven primarily by 

temperature and depth. The recent release by BOEM of 3-D seismic amplitude data3 and high-resolution 

bathymetry4 collected by the oil and gas industry has the potential to allow identification of areas that fall 

within the depth zone favorable for L. pertusa. If combined with side-scan sonar to identify hard surfaces, 

3 See https://www.boem.gov/oil-gas-energy/mapping-and-data/map-gallery/seismic-water-bottom-anomalies-mapgallery

4 See https://www.boem.gov/Gulf-of-Mexico-Deepwater -Bathymetry/
234

then the habitat suitability model could be updated. Combining the presence of hard surfaces with the 

habitat suitability index model and the L. pertusa settlement patterns would enable a much better 

predictive capability for where this species will likely occur.

Figure 15. Percent coverage of risers below Shell’s Mars platform by Lophelia pertusa in October 

2013.

There are challenges associated with the surveys that will require coordination with the operator of the 

structure to reduce them. Risers are cleaned from time to time using an ROV-mounted high-pressure 

water jet. The frequency varies among locations and depends upon the amount of growth and the 

frequency of ROV surveys. Unfortunately there is no ready mechanism to determine when areas will be 

cleaned in advance. This may have been why the distribution on Ursa’s Crosby West Import riser in 2018 

was so patchy and irregular. Other factors such as strong currents could also dislodge larger Lophelia 

colonies, though this is unlikely to explain the pattern on Crosby West since other structures retained 

what appeared to be normal distributions.

The abundance estimates are certainly underestimates. The ROV can only observe one side of the circular 

riser at any time. When colonies growing on the other side protruded beyond the edge of the riser and 

were visible, they were counted. Colonies usually assumed a spherical geometry which made them easy 

to delineate and count when they were sparse. Once they grew closer together and the colonies merged, 

distinguishing one from another was challenging. This also contributed to an underestimate of their 

numbers. 

The definition of a coral reef varies. It may refer to a submerged structure that rises from the seafloor 

(Wood 1999). Davies et al. (2008) defined L. pertusa reefs as biogenic structures that alter sediment 
235

deposition, provide habitat structure, and are subject to both growth and bioerosion. The L. pertusa stands 

growing on petroleum risers are a unique example of a kind of midwater reef, isolated from the seabed, 

with limited relief extending away from the riser, and possessing few of the megafauna associated with 

traditional reefs. The only obvious inhabitants of the colonies that were observed with any regularity were 

squat lobsters likely belonging to the genus Umunida sp.

Figure 16. Vertical distribution of Lophelia pertusa colonies below Shell’s Ursa platform in 

December 2018.

Error bars in the lower right panel are 1 standard error on the mean.
236

Figure 17. Examples of Lophelia pertusa colonies on risers and tendons below Shell’s Ursa 

platform in 2018.

A: Production Riser A6; B: Tendon T5; C: Tendon T10. 
237

4.2.1 Deepwater Soft Coral Anthomastus sp.

The mushroom coral Anthomastus sp. is a member of the family Alcyoniidae (true soft corals) that occurs 

on hard surfaces in the Gulf of Mexico and elsewhere. Frequent observations (Fig. 18) of this species on 

the deepest sections of risers during inspections suggested it was sufficiently common on some systems to 

be suitable for an estimation of its vertical distribution pattern. Risers from Ursa (MC809A) were selected 

for analysis because the depth of this site was sufficient to encompass the vertical distribution of 

Anthomastus sp. Risers used for the analysis were: Crosby West Import and Production Risers A3, A4, 

A5, A6, and A7. These inspections were conducted on August 13–14, 2018 by an iTech7 ROV.

Extraction of images and filename conventions followed the same approach as described for the previous 

taxa. Coral colonies were binned into 5 m depth bins in an attempt to better resolve their vertical 

distribution because they had a narrower distributional range than a species such as Lophelia pertusa.

Figure 18. Images of the deepwater soft coral Anthomastus sp. imaged during an inspection of the 

Crosby West Import riser at MC809A.

The abundances of Anthomastus sp. varied among the surveyed risers from 14 (A4) to 135 (Crosby West 

Import) with a mean of 62.8 colonies per riser. Colonies occurred between 781.8 m and 1111.6 m. The 

bottom depth at Ursa was 1159 m indicating that Anthomastus sp. has a distribution that extends to within 

~50 m above the seabed. The distribution patterns (Fig. 19) among risers generally indicated a Gaussian 

distribution skewed towards the seafloor with mean depths of 1061 m (Crosby West Import), 983 m (A3), 

1013 (A4), 975 m (A5), 1054 (A6), and 1026 m (A7). The overall mean colony depth was 1035 m; 

however, the mean distribution pattern (Fig. 20) suggested the peak density could be slightly deeper,

based on a mode at 1086 m.
238

Anthomastus sp. was not observed at Auger (GB426A) or Mars (MC807A). The depths of these sites 

were 868.1 m and 715.7 m, respectively. The absence of Anthomastus sp. from Mars is not unexpected, 

given that the shallowest colony observed below Ursa was deeper than the maximum depth at this site. 

Auger was deeper than the shallowest observations at Ursa; however, the degree of sedimentation or 

possibly the absence of a sufficiently large population in the vicinity reduces the likelihood of recruitment 

to that site. Olympus (MC807B) with a bottom depth of 925 m was within the expected zone where 

Anthomastus sp. colonies could be expected. No colonies were observed between 715 m and the bottom. 

The relative youth of the risers in that location may explain this species’ absence. Olympus produced first 

oil in 2014 and the risers show little evidence of colonization and growth by any species except small 

hydroids.

Figure 19. Distributions of Anthomastus sp. colonies on six risers below Shell’s Ursa platform in 

2018. 

The absence of Anthomastus sp. from the zone within ~50 m of the seabed may reflect temperature or 

currents that are unfavorable. Another possibility is that there is too much sedimentation within that zone 

to allow the survival of new recruits. Some of the risers at Mars slant away from vertical and approach the 

seabed at a shallow angle. Heavy accumulations of sediment were evident on the tops of the risers near 

the seabed indicating heavy sedimentation rates.
239

Figure 20. Average vertical distribution pattern of Anthomastus colonies for the six Ursa risers.

4.2.2 Other Potential Candidate Organisms for Assessment

The risers, subsea equipment, and surface structures of deepwater production facilities are colonized and 

used as habitat by in incredibly diverse group of organisms. There is a need for an inventory of 

biodiversity on these structures. Understanding the depth ranges of as many of these taxa as possible has 

several values. First, a clear picture of their depth distributions will inform models that predict where 

species occur. Second, many of these sessile organisms have the potential to serve as sentinels in the 

event of another oil spill. The sensitivity of corals to oil from the Deepwater Horizon spill (White et al. 

2012) supports the use of corals as indicators of adverse impacts. Creation of a database showing where 

different coral species occur would enable these sites to be monitored in the event of a spill. Because of 

the density of oil and gas facilities in the deepwater region of the Northern Gulf of Mexico, such a 
240

network might allow a clearer picture of the spatial extent of injury to be obtained in a more efficient 

manner than simply searching the seafloor for signs of damaged coral. Third, understanding where 

different organisms occur on artificial structures will assist in the siting of deepwater artificial reefs. By 

ensuring that new reefs are created down-current from existing populations on both natural and artificial 

substrates, the likelihood of successful recruitment can be increased.

4.2.2.1 Coldwater Corals

A variety of coldwater corals grow on deepwater risers (Fig. 21). Diversity generally increases with depth 

below the Lophelia pertusa zone although densities may be sparse. The latter factor will likely require 

surveys of multiple risers to assemble a composite picture of their distributions. The taxonomy of these 

cnidarians can often require a sample; however, collection of reference material by ROVs would be a 

simple value-added task for vehicles that already have manipulator arms and could be equipped with 

collection chambers.

Figure 21. Examples of coldwater corals on risers below Shell’s Auger (GB426A) platform. 

These all appear to be octocorals that are members of the family Plexauridae; however, identifications to species are 

challenging given the limited resolution of the images. Depths are A: (759 m); B: (826 m); C: (828 m); D: (850 m); E: 

(747 m); F: (806 m); G: (863 m); H: (858 m).

4.2.2.2 Brisingid Sea Stars

Brisingid sea stars (family Brisingidae) are suspension feeders that attach to hard surfaces. They are 

generally present on risers (Fig. 22) though they are not highly abundant. Relatively little is known about 

their spatial distribution in the Gulf of Mexico. Like coldwater corals, they may have the potential to 

serve as indicators of environmental stress. ROVs have been used elsewhere to document their presence 

(Campos et al. 2010) and are the only feasible means of documenting these sea stars given their depth 

range. 
241

Figure 22. Examples of brisingid sea stars on risers and tendons below Shell’s Ursa platform.

A–D appear to belong to the genus Novodinia. Depths: A: 497 m; B: 385 m; C: 387 m; D: 411 m; E: 544 m.

4.2.2.3 Lionfish

Lionfish (Pterois sp.) are invasive members of the family Scorpaenidae that are endemic to the tropical 

Indo-Pacific. Since their release into the South Atlantic, they have spread through the Caribbean and Gulf 

of Mexico. Two species are present: Pterois volitans and P. miles; however, they are morphologically 

similar and difficult to distinguish based on images. Lionfish are highly effective predators and pose a 

potentially serious threat to native fishes. Their depth distribution extends from the surface to at least 112 

m (Nuttall et al. 2014). ROVs have reported the presence of lionfish during routine operations (Fig. 23) 

and the network of ROVs operating in deepwater provides a useful monitoring capability to document 

any changes in abundance or range extensions. The USGS maintains a sighting submission page for 

lionfish5

. 

During examination of ROV inspection videos from all sites, care was taken to locate and document 

lionfish. Lionfish are very cryptic and many were missed during initial video inspections. Though they 

may not be abundant, they are certainly present in the oceanic region of the Northern Gulf of Mexico. 

One potential observation of a lionfish occurred at the Ursa platform. Only one set of pectoral fin rays 

was visible in the image. A reexamination of videos documented 13 individuals (Table 23), primarily at 

Ursa but also at other facilities. The average observation depth was 29.3 m. Monitoring of inspection 

videos for lionfish is one of the few time-series available to detect their presence and potential spread into 

the deepwater region.

5 See https://nas.er/usgs.gov/sightingreport.aspx
242

Table 23. Locations of Lionfish Pterois sp. Observed by ROVs

Date Depth (m) Facility Easting Northing Image

08/09/16 49.4 Unknown 783853.2 Bad value

09/29/17 81.7 GB172 599650.1 3079737.9
243

Date Depth (m) Facility Easting Northing Image

05/27/18 23.7 SS241A 638883.4 Bad value

07/26/18 20.7 MC807B 280161.9 3116797.1
244

Date Depth (m) Facility Easting Northing Image

07/28/18 24.1 MC807B 282609.6 3113102.1

Date Depth 

(m) Facility Easting Northing Image

07/28/18 23.4 MC807B 299441.1 3141834.0
245

Date Depth 

(m) Facility Easting Northing Image

07/28/18 23.3 MC807B 299441.2 3141834.0

07/28/18 20.8 MC807B 280105.1 3116808.9
246

Date Depth 

(m) Facility Easting Northing Image

08/06/18 18.8 MC807B 280094.4 3116782.1

08/06/18 19.2 MC807B 280103.2 3116797.1

08/06/18 26.2 MC807B 280098.6 3116804.3
247

Date Depth 

(m) Facility Easting Northing Image

04/12/18 22.5 GB426 554943.0 3046938.4
248

Figure 23. A lionfish observed by an industrial ROV operating in Walker Ridge 29 during May 2019.

4.2.2.4 Orange Cup Coral Tubastrea coccinia

The orange cup coral Tubastrea coccinia is an invasive anthozoan that colonizes hard structure (Fig. 24). 

The orange cup coral has spread throughout the Northern Gulf of Mexico and is particularly prevalent on 

hydrocarbon extraction structures (Fenner 2001; Sammarco et al. 2004). During decommissioning, one 

option is to convert structures into artificial reefs. The depths at which reefing is conducted will have an 

impact on the survival and growth of both existing and newly recruited T. coccinia. Information on the 

vertical distribution patterns of this species gained from ROV inspection videos can inform site selection 

for decommissioning to ensure that subsequent survival and growth of this invasive species is reduced.
249

Figure 24. Orange cup coral Tubastrea coccinia at different depths on various Auger platform 

(GB426) structures during a 2018 survey. 

A: 19.6 m; B: 24.2 m; C: 47.2 m; D: 66.4 m; E: 86.0 m; and F: 108.1 m.

Estimation of the vertical distribution of T. coccinia is challenging because of its density and the fact that 

it is frequently interspersed among other organisms that are of similar color or shape. Moreover, since it 

often forms a dense covering over risers, it becomes difficult to determine the actual boundary of the riser 

beneath the cup coral. This makes it difficult to estimate the area underneath the coral that is being 

covered by the coral.

Orange cup coral was observed on every deepwater structure for which inspection videos were obtained. 

In general it is abundant down to approximately 91 m (300 feet) and then its abundance diminishes 

rapidly until it disappears between 91–122 m. A simple approach to determine the lower boundary of the 

zone in which it is abundant is to measure the greatest depth at which it occurs as dense aggregations of 

polyps (rather than as isolated polyps). Results for this method are shown for the Mars platform based on 

October 2018 surveys (Fig. 25). The maximum depths that small aggregations of polyps were observed 

on 18 different risers were very consistent with a mean depth of 118 m (standard error = 1.8 m, range of 

97–123 m). Measurements of orange cup coral maximum depths need to be undertaken at other locations 

to confirm the generality of the findings from Mars; however, when combined with data from other sites, 

appropriate reefing depths can be established to reduce the probability that orange cup coral will continue 

to grow on the reefed structure.
250

Figure 25. Deepest observations of aggregations of Tubastrea coccinia polyps on 18 production 

risers below Shell’s Mars platform.

Numbers indicate the depth of each observation in meters.

4.2.2.5 Flytrap-like Anemones

The flytrap anemone Actinoscyphia sp. is a large anthozoan predator that occurs on hard substrates as 

well as on soft sediments (Aldred et al. 1979). In the Gulf of Mexico, it is frequently found on hard 

substrates. Most bilobed anemones growing on hard surfaces are referred to as flytrap anemones and are 

mistakenly identified as Actinoscyphia. Anemones are one of the most abundant organisms on deepwater 

risers (Fig. 26). The challenge is determining their taxonomy from images. After determining that the 

anemones in our images likely represented several different genera and were not actually Actinoscyphia

sp. but more likely members of the family Hormathiidae, determining the vertical distributions was 

halted. Nonetheless, these predators are conspicuous and represent another potential candidate group for 

use as sentinel organisms.
251

Figure 26. Flytrap-like anemones at different depths on an Ursa platform (MC809) riser during a 

2018 survey. 

A: 823.4 m; B: 867.2 m; C: 907.4 m; D: 1020.2 m; E: 1100.8 m; and F: 1150.3 m.
252

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