Azores Deep-sea Research — Cruise iMAR 2021

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ADSR-CRUISE-2

iMAR 2021

Integrated assessment of the distribution of Vulnerable Marine Ecosystem along the Mid-Atlantic Ridge in the Azores region

The MAR is the most prominent ocean seafloor feature in the Atlantic Ocean, dividing it into eastern and western deep basins. The unique setting of the Azores in close proximity to the ridge, offers an exceptional opportunity to survey the role of the MAR in shaping the distribution of deep-sea megabenthic communities, mostly those considered Vulnerable Marine Ecosystem (VME). The diverse geomorphology and complex oceanography patterns surrounding the Azores has generated an extraordinary diversity of benthic organisms, making this area a hotspot for cold-water corals in the North Atlantic. Latitudinal gradients and dissimilarities between the deep-water coral fauna on both sides of the MAR were noted at local and wider scale studies, raising the question on whether the MAR can represent a boundary for the biological dispersion between the East and West Atlantic. However, there has been considerably few explorations on seamounts, ridges and other topographic features along the MAR.

The RV Pelagia Cruise No. 64PE487 / Eurofleets+ iMAR aimed to evaluate the role of the Mid-Atlantic Ridge (MAR) in shaping the latitudinal and trans-Atlantic patterns in deep-sea biogeography, connectivity and spatial distribution patterns of deep-sea megafauna. Additionally, the cruise aimed to (i) map and characterize deep-sea coral and sponge communities inhabiting unexplored seamounts and ridges in the MAR around the Azores; (ii) identify new areas that fit the FAO’s Vulnerable Marine Ecosystem definition; (iii) add to the existing knowledge on the environmental drivers that determine the spatial distribution of deep-sea benthic biodiversity in the MAR; and finally (iv) determine the condition of benthic communities by looking at evidence of fishing damage to fauna, presence of lost fishing gear and marine litter.

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Statistics

Transits

2390 km

Multibeam Bathymetry

5500 km²

Filmed Seabed

48 km

Visited Areas

Stations

Dives

Video Footage Recorded

54 hours

Used Storage

13 Tb

Samples

731

— 380 samples for environmental DNA, 280 samples for nutrient analyses, 27 sediment samples for geological analyses, 24 for microplastic analyses, 10 samples for bacteriological, and 10 samples meiofauna analyses.

Highlights

Although the data has yet to be analyzed in detail, this expedition revealed some surprising discoveries.

The iMAR expedition identified new areas that fit the definition of Vulnerable Marine Ecosystems, and compiled valuable scientific information to inform the development of policies that promote the preservation of the natural heritage, ensuring the sustainable use of the deep sea, minimizing negative impacts on these vulnerable ecosystems.
The video work that aimed to characterize the benthic communities revealed the largest aggregation of black corals ever seen in the Azores and perhaps across the Atlantic. These corals grow very slowly and can live for several thousands of years and, therefore, black coral gardens can be considered the equivalent of the redwood forests (oldest trees on the planet) that still persist, for example, in the United States of America.
We discovered several areas with formations of deep-sea coral thickets that have an important role as carbon reservoirs and in mitigating climate change. Some of these corals, but also sponges, are habitat structuring species, functioning as refuge areas for several other species including commercially important deep-sea fish, and thus enhancing the total biodiversity associated with these habitats.
We found aggregations of orange roughy and cardinalfish, which in a way confirm that the trawl ban within the Azores EEZ, declared in 2005, has had positive effects for these species and the habitats they are associated with.
The multibeam bathymetric surveys revealed several locations in the northern part of the Azores EEZ that are much shallower than previously thought. One of these areas reaches depths susceptible to be fished (less than 600 meters), but since it has remained unknown it can be considered intact. These areas are fundamental for understanding what ecosystems looked like before they were impacted by fishing activities and may be considered as reference sites and priority areas for conservation.
These new discoveries will contribute with scientific information to the development of policies that promote the preservation of the natural heritage, ensuring the sustainable use of the deep sea, minimizing the negative impacts on these very vulnerable ecosystems. The expedition contributed significantly to the Instituto Hidrográfico (IH) program Mapping the Portuguese Sea, and to the international initiative United Nations Decade of Ocean Science for Sustainable Development (2021-2030).