ADSR - Azores Deep-Sea Research

CRUISES / Rainbow 2019

RV Pelagia cruise 64PE454: Rainbow hydrothermal vent and southern MAR 2019

Summary Show more ↓

In a long-lasting collaboration with scientists from the Royal Netherlands Institute for Sea Research (NIOZ), deep-sea scientists from IMAR Instituto do Mar and Okeanos University of the Azores joined the RV Pelagia cruise 64PE454 to improve the understanding on the sphere of influence of hydrothermal vents on the distribution of deep-sea megafauna around vent sites and to explore the Sarda seamount to improve our knowledge on the distribution and abundance of large Vulnerable Marine Ecosystem indicator species and deep-sea commercial fishes in the large Azores region. This was the first time we visited seamounts on the western side of the Mid-Atlantic Ridge.

Statistics

Transits

1370 km

Multibeam Bathymetry

0 km²

Filmed Seabed

18 km

Visited Areas

Stations

Dives

Video Footage Recorded

18 hours

Used Storage

0.98 Tb

Samples

No information available at this moment

Highlights

Two Hopper dives were carried out at the Rainbow hydrothermal vent site, at depths between 2100 and 2450 m. Both dives were performed following a similar path aimed to cross the western group of vents to identify changes in species composition and seabed features on both sides of the chimneys.
In terms of the geological composition of the seafloor, the Hopper images showed the existence of clear changes in the aspect, colour and texture of the substrate while approaching the vents.
Very few organisms were spotted on very soft sediments, with a dominance of a purple holothurian still to be identified to species level and several Lebensspuren, sedimentary structures produced on the upper layers of the sediment by surficial bioturbation of benthic megafauna. Once the Hopper frame started to approach the vent area, the number of stones and outcropping rocks started to increase, providing substrate for other sessile megafauna species.
Four Hopper dives were carried out at Sarda seamount aimed to obtain video footage from a wide bathymetric range, starting down to 1000 m depth all the way up to the summit. The 4 dives covered 14.8 km of seabed, generating over 15 hours of bottom time.
Only one dive revealed coral-dominated communities, with an aggregation of large colonies of the coral Paragorgia johnsoni, which were surrounded by a large number of the small scleractinian Leptopsammia formosa.