First visual occurrence data for deep-sea cnidarians in the South-western Colombian Caribbean

Study Extent

Anadarko Colombia Company’s hydrocarbon exploratory activities in the Southwestern Colombian Caribbean, include four wells (i.e. Gorgon A-1, Calasu 1, Kronos 1, and Purple Angel C-1), and five other areas of interest (i.e. Chamana, Chamai, Yaduli, Cana Norte, and Cawa). The exploratory wells and areas of interest are localized in the South-western Colombian Caribbean, at depths between 375 m and 2500 m. In general, wells and areas of interest are approximately 54 to 74 off shore from the nearest point in the Caribbean coast of Colombia.

Sampling

Occurrences of cnidarians were registered from ROV surveys and towed camera surveys using videos and still images. Sampling included soft bottoms in the Colombian Caribbean from 375 m to 2500 m.

Quality Control

Videos were analyzed twice for the presence of cnidarians, by two different experts in different times. This methodology allowed us to ensure all cnidarians were registered. Still images were also analyzed twice by the same expert, who did a preliminary identification to Phylum and Class. All cnidarian images were then identified to the lowest possible taxonomic level, and when in doubt of an identification, we sent the images to additional experts. Photographs were cropped to include only the organism, and we performed image correction to reduce the blueish colour cast with the Auto Tone function in Adobe Photoshop CC 2018.

Method steps

1. ROV surveys ROV video surveys consisted of 80 meter-long transects in cross fashion, north, south, east, and west, from a central point that could be a transponder (tool for positioning of the drilling vessel) or the exact drilling location. Video-transects mainly included soft bottom images and few of them recorded pelagic megafauna. Videos were taken before and after drilling for the wells Kronos 1, Calasu 1, Gorgon A-1, and Purple Angel C-1. Additionally, for Kronos 1 and Calasu 1 there was a video survey during drilling. We analysed 48 video transects (duration: 9h 9min 26sec), looking for benthic and pelagic fauna. We took snapshots of each organism (cnidarian and non-cnidarian), registered coordinates and depth, and identified to the lowest possible taxonomic level. Towed camera surveys Areas of interest (i.e. Chamana, Chamai, Yaduli, Cana Norte, and Cawa) were assessed using twenty-five (25) towed camera transects. These transects registered seafloor features, during a 3-hour survey and taking still images every 20 seconds. Benthic and pelagic megafauna were recorded in the images. We analysed a total of 5066 photographs, looking for benthic and pelagic fauna. For each organism (cnidarian and non-cnidarian) coordinates and depth were registered, and identified to the lowest possible taxonomic level. We cropped the photographs to include only the organism, and performed image correction to reduce the blueish colour cast with the Auto Tone function in Adobe Photoshop CC 2018. Taxonomic identifications
   Using photographs and video footage, all the organisms were grouped to Phylum and Class. In this paper, we only highlight the occurrences for the Phylum Cnidaria. Cnidarians were further identified to the lowest possible taxonomic level, based on comparison with literature, databases and with the help of taxonomic experts from each group. The taxonomy here presented is in accordance to the World Register of Marine Species – WORMS (http://www.marinespecies.org/).

The data presented here corresponds to occurrences of deep-sea Cnidarians and one Ctenophore from the South-western Colombian Caribbean, spotted over soft bottoms at depths between 375 to 2565 m.

1. Poralia rufescens
   rank: species
2. Hydrozoa
   rank: class
3. Semaeostomeae
   rank: family
4. Rhopalonematidae
   rank: family
5. Narcomedusae
   rank: order
6. Actiniaria
   rank: order
7. Ceriantharia
   rank: order
8. Corallimorphus
   rank: genus
9. Hormathiidae
   rank: family
10. Kadosactinidae
    rank: family
11. Bathypathes patula
    rank: species
12. Virgulariidae
    rank: family
13. Trichogorgia lyra
    rank: species
14. Umbellula
    rank: genus
15. Chrysogorgiidae
    rank: family
16. Epizoanthus stellaris
    rank: species
17. Adamsia
    rank: genus
18. Phelliactis
    rank: genus

Anadarko Colombia Company’s hydrocarbon exploratory activities in the Southwestern Colombian Caribbean, include four wells (i.e. Gorgon A-1, Calasu 1, Kronos 1, and Purple Angel C-1), and five other areas of interest (i.e. Chamana, Chamai, Yaduli, Cana Norte, and Cawa). The exploratory wells and areas of interest are localized in the South-western Colombian Caribbean, at depths between 375 m and 2500 m. In general, wells and areas of interest are approximately 54 to 74 off shore from the nearest point in the Caribbean coast of Colombia.