BlueAzores 2019

Dives with LULA1000 in Baixo de São Mateus

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BlueAzores 2019

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Dives with LULA1000 in Baixo de São Mateus

Location: Baixo de São Mateus

Year: 2019

2 stations

2 dives

20 km transits

1 areas visited

AZORES DEEP-SEA RESEARCH

Summary

Dives with LULA1000 in Baixo de São Mateus

The primary objective of this survey was to evaluate if the Baixo de São Mateus seamount ridge fits the FAO criteria that define what constitutes a Vulnerable Marine Ecosystem (VME). Namely, the IMAR/Okeanos team from the University of the Azores aimed to: characterize the diversity and spatial distribution patterns of benthic communities and commercial fishes in this important historical fishing ground, and document potential fishing impacts on the main structuring species that form the different benthic communities. By utilizing the unique capabilities of the LULA1000 manned submersible, which allowed for close-up observation of steep slopes and vertical walls, the team conducted two exploratory dives covering 3.7 linear kilometers. The data collected on benthic community zonation and anthropogenic pressure was used to perform a formal expert assessment against the five FAO VME criteria, informing management recommendations for the region.

By taking advantage of the collaboration with the Rebikoff-Niggeler Foundation and the use their submersible LULA1000, based in the harbour of Horta (Faial), we aimed to explore the never surveyed seamount ridge Baixo de São Mateus. The primary goal was to explore the never-before-surveyed seamount ridge south of Pico Island to evaluate its potential as a Vulnerable Marine Ecosystem (VME). These dives were conducted under the protocol between IMAR University of the Azores and the Blue Ocean Foundation.

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Statistics

Transits
20 km
Multibeam Bathymetry
km²
Filmed Seabed
3.7 km
Visited Areas
1
Stations
2
Dives
2
Video Footage Recorded
7 hours
Used Storage
Tb
Samples

Highlights

  1. First visual survey of a key fishing ground: The expedition provided the first-ever in-situ video survey of the Baixo de São Mateus seamount, a historically important fishing area whose benthic communities were previously known only from fisheries bycatch.
  2. The dives identified seven distinct benthic communities with clear depth zonation, ranging from soft-sediment foraminifera fields at 970m to a unique 'living fossil community' of oysters (Neopycnodonte zibrowii) and crinoids (Cyathidium foresti) on vertical walls between 580-715m.
  3. A formal assessment against FAO criteria concluded that, despite the presence of long-lived species like the black coral Leiopathes expansa, the area's overall low species diversity and density do not support its classification as a high-priority VME for conservation in the Azores.
  4. The survey documented evidence of fishing pressure, observing 13 lost fishing lines and some damaged corals, though the overall visible damage to benthic communities was assessed as low.
  5. The LULA1000 submersible captured approximately 7 hours of high-definition 4K video footage, providing a valuable baseline dataset for studying species distribution, behavior, and human impacts on this seamount.
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Location of operation

Baixo de São Mateus

AZORES DEEP-SEA RESEARCH © CRUISES

Stations

BlueAzores 2019

Activities

Video survey (LULA 1000)

Scientific crew

Collaborators

Telmo Morato
Carlos Dominguez-Carrió
Kirsten Jakobsen
Joachim Jakobsen
Jordi Blasco-Ferre
Luís Rodrigues
Cruise report - Dives with LULA1000 in Baixo de São Mateus, Azores
Zenodo
|
Aug, 2019
4 team members are authors
OA DOI 10.5281/zenodo.6593184
Authors 10.5281/zenodo.6593184
Abstract
Background: Baixo de São Mateus is known for its historical importance as a fishing ground south of Pico Island. Fisheries bycatch information suggests that this seamount may host important deep-sea benthic communities. However, Baixo São Mateus has never been explored with video surveying techniques. By taking advantage of the collaboration with the Fundação Rebikoff-Niggeler (FRN) and the use of their submersible LULA1000, based in the harbour of Horta (Faial), we aimed to explore the never surveyed seamount ridge Baixo de São Mateus. The main objective of this survey was to evaluate if this area may fit the FAO criteria that define what constitutes a Vulnerable Marine Ecosystem. Namely, we aimed to: characterize the diversity and spatial distribution patterns of benthic communities and commercial fishes in this important fishing ground; document potential fishing impacts on the main structuring species that conform to the different benthic communities. Deep-sea benthic communities in Baixo de São Mateus: Overall, approximately 3.7 linear kilometers of seafloor were covered during the two exploratory dives carried out on the southern flank of Baixo de São Mateus. A total of seven benthic communities were identified, showing a clear bathymetric zonation. Remnants of longline fishing gears (e.g. ropes and monofilament lines) were recorded during the two dives, with several broken or damaged colonies of corals and sponges observed. Management recommendations: Based on the assessment described in the report, the seamount ridge Baixo de São Mateus does not fit the FAO criteria to be considered a VME and thus there is no sufficient scientific information to support this area as high priority for conservation in the Azores. Despite the presence of some long-lived species, there was an overall low number of species and communities and in low densities, when compared to other geomorphological features of the Azores region. Baixo São Mateus is an important fishing ground in the Azores. The low natural diversity of the benthic communities observed may suggest that existing fishing pressures in Baixo São Mateus will likely not have produced significant adverse impacts in the existing benthic living communities. However, it should be noticed that the present assessment is based only on two video transects, which covered a limited area of the seamount ridge. It is thus possible that we may have missed some important communities or areas with higher species diversity or other large structuring species. Therefore, continued scientific research is necessary to better understand the distribution of species, as well as the structural and functional role of such deep-sea benthic communities to better define adaptive management and conservation strategies.
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Location

Institute of Marine Sciences — Okeanos, University of the Azores

Departamento de Oceanografia e Pescas — Universidade dos Açores

Rua Prof. Doutor Frederico Machado, No. 4
9901-862 Horta, Portugal

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