Azores Deep-sea Research — Cruise MedWaves 2016

Summary

MEDiterranean out flow WAter and Vulnerable EcosystemS

The primary objective of the MEDWAVES cruise at Formigas Bank was to characterize the physical and biogeochemical properties of the water masses interacting with the seamount and to document the associated benthic communities, particularly vulnerable marine ecosystems (VMEs) like cold-water coral habitats. The work aimed to determine if Formigas acts as an ecological "stepping stone" influenced by the Mediterranean Outflow Water, connecting fauna between the Mediterranean and the Mid-Atlantic. The methodology included high-resolution multibeam mapping, detailed CTD/LADCP profiling to trace the MOW signal, and intensive ROV operations for visual surveys and biological sampling. The results contribute to ATLAS goals of improving understanding of deep Atlantic biodiversity, quantifying ocean transport pathways, and assessing the vulnerability of benthic ecosystems to environmental change.

The MEDWAVES (MEDiterranean out flow WAter and Vulnerable EcosystemS) survey was an EU Horizon 2020 ATLAS project cruise aboard the R/V Sarmiento de Gamboa. Led by Cova Oreja (IEO) it targeted seamounts under the influence of the Mediterranean Outflow Water (MOW). The Formigas Bank in the Azores was one of the study sites. The expedition aimed to characterize the interaction between oceanographic conditions and deep-sea ecosystems, collecting multidisciplinary data through ROV dives (500-1575 m depth), CTD casts, and seabed sampling to understand biodiversity patterns and connectivity.

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Statistics

Transits

km

Multibeam Bathymetry

2255 km²

Filmed Seabed

11 km

Visited Areas

1

Stations

Dives

10

Video Footage Recorded

37 hours

Used Storage

Tb

Samples

49

— We acquired 18 specimens of the bamboo coral *Acanella* sp., plus several samples of *Acanthogorgia* sp., Alcyonacea (small), Antipatharian, *Candidella* sp., *Crypthelia* sp., *Leiopathes* sp., *Swiftia* sp., Plexauridae, *Narella* sp., among other taxa.

Highlights

(Focusing in the Formigas seamount only)

Discovery of highly diverse coral gardens: The expedition documented extensive and dense coral gardens on Formigas Bank, dominated by octocorals like Acanella arbuscula, primnoids (Narella spp., Candidella imbricata), and plexaurids. A key highlight was the first in-situ observation of the bamboo coral Chelidonisis aurantiaca in the Azores, a species previously linked to MOW pathways.
First in-depth characterization of Formigas benthic habitats: Ten ROV dives provided the first comprehensive video survey of the seamount's slopes, revealing distinct megafaunal communities stratified by depth and substrate, from soft-sediment areas with cerianthids and sponges Stylocordyla pellita to steep basaltic walls covered by black corals, scleractinians, and diverse sponge assemblages.
Mapping the influence of Mediterranean Outflow Water: Physical oceanography data confirmed the presence of diluted MOW at Formigas (salinity max ~35.82 at ~1000m), demonstrating its westward transport over 900 nautical miles from the Strait of Gibraltar. Yo-yo CTD casts suggested internal wave activity, a potential mechanism for vertical nutrient supply.
Collection of unique biological samples: The cruise collected 49 benthic samples with the ROV, including numerous octocorals, black corals, and sponges for taxonomic, genetic (connectivity), and ecophysiological studies, building an invaluable reference for North Atlantic deep-sea biodiversity.
Identification of Vulnerable Marine Ecosystem (VME) Indicators: ROV transects identified several potential VMEs, including large aggregations of habitat-forming corals and sponges.
High-resolution bathymetric mapping: New multibeath bathymetry covered approximately 2,256 km² around Formigas, revealing a complex geomorphology of ridges, fractures, and volcanic knolls that directly influences local current regimes and habitat distribution.

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Location of operation

Formigas

AZORES DEEP-SEA RESEARCH © CRUISES

Stations

MedWaves 2016

Activities

Video survey (ROV Liropus) Multibeam

Funding

Regional Government of the Azores, PO Açores 2020, European Regional Development Fund (ERDF / FEDER) ACORES-01-0145-FEDER-00056

European Union’s Horizon 2020 678760 (ATLAS)

Scientific crew

Manuela Ramos

PhD Student

Gerald Hechter Taranto

Early-career Researcher

Collaborators

Meri Bilan

Maria Rakka

Íris Sampaio

Covadonga Orejas

Anna Addamo

Marta Álvarez

Alberto Aparicio

Daniel Alcoverro

Sophie Arnaud-Haond

Joana Boavida

Verónica Caínzos

Rubén Calderón

Peregrino Cambeiro

Mónica Castaño

Alan Fox

Marina Gallardo

Andrea Gori

Cristina Gutiérrez

Lea-Anne Henry

Miriam Hermida

Juan Antonio Jiménez

José Luis López-Jurado

Pablo Lozano

Ángel Mateo-Ramírez

Guillem Mateu

José Luis Matoso

Carlos Méndez

Ana Morillas

Juancho Movilla

Alejandro Olariaga

Manuel Paredes

Víctor Pelayo

Safo Piñeiro

Teodoro Ramírez

Jesus Reis

Jesús Rivera

Alberto Romero

José Luis Rueda

Toni Salvador

Héctor Sánchez

Rocío Santiago

Alberto Serrano

Javier Urra

Pedro Vélez-Belchí

Nuria Viladrich

Martha Zein

Cruise Summary Report - Medwaves Survey (Mediterranean Out Flow Water And Vulnerable Ecosystems)

Zenodo

|

Apr, 2017

2 team members are authors

OA Citations 11 DOI 10.5281/zenodo.556516

Authors 10.5281/zenodo.556516

Covadonga Orejas Anna Maria Addamo Marta Álvarez Alberto Martín Aparicio Daniel Alcoverro Sophie Arnaud‐Haond Meri Bilan Joana Boavida Verónica Caínzos Ruben Calderon Peregrino Cambeiro Mónica Duque-Castaño Alan Fox Marina Gallardo Andrea Gori Christina Guitierrez Lea‐Anne Henry Miriam Hermida Juan Antonio Jimenez José Luís López‐Jurado Pablo Lozano Ángel Mateo‐Ramírez Guillem Mateu Mateu Jose Luis Matoso Carlos Mendez A. Morillas-Kieffer Juancho Movilla Alejandro Olariaga Manuel Paredes Victor Pelayo Safo Piñeiro Maria Rakka Teodoro Ramı́rez

Manuela Ramos Jesus Reis J. Rivera Alberto Romero José L. Rueda Toni Salvador Íris Sampaio Héctor Sánchez Rocío Santiago Alberto Serrano

Gerald H. Taranto Javier Urra P. Vélez‐Belchí Núria Viladrich Martha Zein

Abstract

The MEDWAVES (MEDiterranean out flow WAter and Vulnerable EcosystemS) cruise targeted areas under the potential influence of the MOW within the Mediterranean and Atlantic realms. These include seamounts where Cold-water corals (CWCs) have been reported but that are still poorly known, and which may act as essential “stepping stones” connecting fauna of seamounts in the Mediterranean with those of the continental shelf of Portugal, the Azores and the Mid-Atlantic Ridge. During MEDWAVES sampling has been conducted in two of the case studies of ATLAS: Case study 7 (Gulf of Cádiz-Strait of Gibraltar-Alboran Sea) and Case
study 8 (Azores). The initially targeted areas in the Atlantic were: the Gazul Mud volcano, in the Gulf of Cádiz (GoC) area, included in the case study 7, and the Atlantic seamounts Ormonde (Portuguese shelf) and Formigas (by Azores), both part of the case study 8. In the Mediterranean the targeted areas were The Guadiaro submarine canyon and the Seco de los Olivos (also known as Chella Bank) seamount. Unfortunately it was not possible to sample in Guadiaro due to time constraints originated by adverse meteorological conditions which obligate us to reduce the time at sea focusing only in 4 of the 5 initially planned areas. MEDWAVES was structured in two legs; the first leg took place from the 21st September (departure from Cádiz harbour in Spain) to the 13th October 2016 (arrival in Ponta Delgada, São Miguel, Azores, Portugal took place the 8th of October due to the meteorological conditions that obligated to conclude the first leg earlier as planned). during the Leg 1 sampling was carried out in Gazul, Ormonde and Formigas. The second leg started the 14th October (departure from Ponta Delgada) and finished the 26th October (arrival in Málaga harbour, Spain). MEDWAVES had a total of 30 effective sampling days, being 6 days not operative due to the adverse meteorological conditions experienced during the first leg which forced us to stay in Ponta Delgada from the 08th to the 13th October. During MEDWAVES the daily routine followed a similar scheme, depending of course on the weather and sea conditions. The main activity during the day, starting early in the morning (around 08:00 AM, once the night activities were finished), was the ROV deployment. Generally a single ROV dive of around 8 hours was performed, however in several occasions two dives were carried out in the same day (see General station list, Appendix II). After the ROV (and sometimes between two dives) the Box Corer and/or Van Veen Grab and/or Multicore was deployed. After these activities, during the night CTD-Rosette deployments and MB was conducted. Accordingly to this schema the scientific personnel worked in the day or in the night watch. A total of 215 sampling stations have been covered in MEDWAVES, using the following sampling gears: Multibeam echosounder, CTD-Rosette, LADCP, Box Corer, Van Veen Grab, Multicorer and a Remotely Operated Vehicle (ROV). Table 1 sumamrised the number of sampling stations conducted with each gear in each sampling zone. Additionally MB surveys have been conducted during the transits between areas.

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Images

Dives images