CRINOIDS FROM THE CHARLIE GIBBS FRACTURE ZONE, NORTH ATLANTIC

Description

The CE18008 expedition (TOSCA: Tectonic Ocean Spreading at the Charlie Gibbs Fracture Zone, North Atlantic; Chief Scientist Dr Aggie Georgiopolou) took place in the summer of 2018 on board the RV Celtic Explorer. Its aims were to survey aspects of the geology and the benthic biology of the Charlie Gibbs Fracture Zone, a complex transform fault system which separates the Reykanes Ridge and the Mid Atlantic Ridge between approximately 50° and 52° North. Earlier hydrographic surveys had revealed a spectacular submarine landscape with vertical relief of over 4000m, rising to c. 600m depth.
The ROV Holland I was deployed during the expedition. The distribution of crinoids and the environments in which they occurred, from c. 3000 m to c. 600 m water depth, was ana- lysed using high definition video footage acquired during five transects totalling approxi- mately 30 km, together with ‘ground truthing’ of the identification of some taxa through limited biological sampling.
The environments encountered during the dives were very varied, ranging from pale coloured, soft sediment, commonly showing ripple marks, through admixtures of pebbles, cobbles and boulders of dark igneous rocks, in varying proportions, with pale sediment, to rock faces, many very steep, with only a patchy veneer of sediment.
The stalked crinoid fauna comprises at least three taxa, Anachalypsicrinus nefertitii, Democ- rinus parfaiti and a ten-armed, red form. Comatulids include Pentametrocrinus atlanticus and at least three, as yet unidentified taxa. The three stalked taxa have overlapping distributions but are each most common in certain parts of the transects. Both A. nefertitii and the ten-armed stalked form are attached by an attachment disc to hard substrates, ranging from cobbles
to large rock surfaces. D. parfaiti occurs both on rock surfaces and in pebbly sediment. Even though its holdfast is a radix, one of the specimens recovered shows the radicles cemented
to small pebbles. P. atlanticus occurs almost exclusively on soft substrates, but a few examples were attached by their cirri to isolated rocks in soft sediment. The other comatulids are asso- ciated with hard substrates and several utilize elevated positions on sponges and other erect benthos. With the exception of P. atlanticus, which typically extends its arms horizontally to form an upward facing feeding array, the other taxa form vertical filtration fans with the oral side of the arms down current.
The survey was carried out with the support of the Marine Institute, funded under the Ma- rine Research Programme 2014-2020 by the Irish Government to support and promote the At- lantic Ocean Research Alliance (2018-2021). Seabed mapping data and expertise, software and hardware were provided by INFOMAR, funded by the Department of Communications, Climate Action and Environment. Financial aid for the transportations and operation of the seismic equipment for this research survey was provided by the German Science Foundation (DFG)

Period	17 Sep 2019
Event title	10th EUROPEAN CONFERENCE ON ECHINODERMS<br/>
Event type	Conference
Location	Moscow, Russian Federation
Degree of Recognition	International