|Location:||Akpo field, Nigeria|
|Position:||West African coast|
1 – 6 May 2009
|Gas & Oil Company||Total|
|SERPENT Representative:||Dr Daniel Jones|
The deep-waters off Nigeria offer many interesting and valuable opportunities for novel science. SERPENT aims to carry out novel deep-water science in the area offshore Nigeria through collaboration with a variety of offshore oil and service companies. This visit to Jack Ryan was the first visit of its type in Nigeria and the most comprehensive visit undertaken by SERPENT in Africa. Our aim for the visit was to make initial assessment of Nigerian deep-water biodiversity. To achieve this we collected both images and physical samples of the benthic fauna. As there is limited knowledge of the Nigerian deep-water fauna, a taxonomic phase will be important to reinforce detailed future ecological research and to provide a strong baseline against which to assess changes in the deep-water environment.
The visit to the drill ship ‘Jack Ryan’ was carried out by SERPENT scientist Daniel Jones from the 1st to the 6th of May. The visit was very successful, the staff of the Jack Ryan were extremely helpful and accommodating. The Oceaneering ROV team (Phil Aylwin, Jackie Stewart, Maurice Onuoha, Brett Illich, Graeme Yates and Eric Monaigha) were instrumental in the success of the visit. A total of 7 dives were made with the ROV and ROV team involved in SERPENT activities for approximately 72 hours. We were fortunate that the visit coincided with a period where there was no operational work for the ROV.
A total of 36 taxa were observed either directly or in video obtained before the visit. A selection is shown in the table below and have representatives from 5 phyla. Several of these taxa are likely to be rarely studied and may represent new species.
Additional taxa found by the ROV team at Akpo are also included and marked with an asterix (*).
A swimming sea cucumber Peniagone sp.
A medusa jellyfish, Scyphomedusae.
A sea anemone, Edwardsia sp.
The sea cucumber Enypniastes sp. feeding on the sea floor.
A jelly fish of the Scyphomedusae species.*
A crab, Lithodes sp.*
A feeding holothurian or sea cucumber.*
A webbed seastar, Hymenaster sp.*
The long-nosed Chimaera, Rhinochimaera.*
A crab, Lithodes sp.*
Seabed temperature was 5.3°C (1366 m water depth). This is thought to be consistent with other areas in the region. The temperature profile obtained by SERPENT reveals a gradual transition between the warm surface waters of the Guinea Current to the colder Atlantic deep waters.
Oceanographically, this area is characterised principally by the wind-driven warm water Guinea Current flowing southward along the coast of the Gulf of Guinea almost to the equator (essentially a continuation of the Equatorial Counter-Current). A major influence on the region is the input of freshwater from the numerous rivers in this high-rainfall region, most notably the Niger (the second largest delta in the world). This results in large masses of warm (above 24°C) and low salinity (less than 35 ppt) water circulating in the Gulf of Guinea above colder water masses (as we see in this profile). These waters are permanent off Sierra Leone and Liberia and in the Gulf of Biafra (off Nigeria, Cameroon and Gabon) but seasonal along the central part of the north coast of the Gulf of Guinea (from Côte d'Ivoire to Benin). Here there are strong seasonal upwellings during the summer months. North of Sierra Leone, upwellings occur from October to April.