Search

The last two decades have witnessed a complete shift in our perception of the deep sea, from a homogeneous, mostly muddy and unspoiled seafloor to a vast patchwork of diverse and fragile habitats as well as a reservoir of living resources, both energy and mineral. Growing and concomitant awareness of the potential for blue growth and vulnerability of deep-sea ecosystems triggered the implementation of management measures and Marine Spatial Planning (MSP) at national, regional and international levels, which are now cumulating in the UN Decade of Ocean Science for Sustainable Development and the International Conference on Marine Biodiversity of Areas Beyond National Jurisdiction (ABNJ). Based on the best available knowledge collated and produced in the framework of ATLAS, the objective of the present deliverable was to integrate all available data into a common analytical framework for systematic conservation planning at the scale of the North Atlantic. Regional-scale MSP in the deep sea unfortunately suffers from a lack of knowledge on the distribution of species and habitats. Such large-scale endeavours to date have thus been mainly relying on biogeochemical and physiographic proxies to design networks of marine protected areas. In just three years, ATLAS has taken an unprecedented step forward in synthesising the data available for the North Atlantic on the distribution of the most vulnerable deep-sea habitats where fragile and long-lived engineering species, such as corals and sponges, are aggregating. Such a synthesis has been enabled through trans-Atlantic collaboration. The 13 case studies (CS), evenly distributed from north to south and east to west of the northern Atlantic, provided new discoveries of deep-sea vulnerable habitats off Greenland, in the Alboran Sea and the Gulf of Cádiz, as well as on Formigas and Tropic seamounts. Beyond new discoveries, ATLAS CS confirmed and improved knowledge on the distribution, ecology and functionality of those vulnerable habitats in the North Atlantic. For Case Study 1 – LoVe Observatory, 1417 records of Lophelia pertusa coral reefs along the Norwegian coast are included. For Case Study 6 - Bay of Biscay, a total of 450 records of 12 different VME types, including coral reefs, coral rubbles, scleractinians, Antipatharians, gorgonians, seapens or pennatulids, mixed corals, aggregation of actiniarians, sponge community and Xenophyophores, are reported. For Case Study 7, VMEs are reported for two areas: 1) for Seco de los Olivos, in the Alboran Sea, 17 VMEs that include sea pen fields, deep-sea sponge aggregations and diverse coral gardens are reported, and 2) for the Volcano of Gazul, in the Gulf of Cádiz, 16 VMEs are reported, that include diverse coral gardens, mud and sand emergent fauna, cold-water coral reef of Lophelia pertusa / Madrepora oculata and deep-sea sponge aggregations. For Case Study 8, VMEs from different areas of the Azores are included: in the Formigas Seamount, 18 VMEs including diverse coral gardens and deep-sea sponge aggregations are reported. Cavalo Seamount, a ridge on the Mid-Atlantic Ridge, Gigante Seamount, Condor Seamount, Dom João de Castro Seamount, and Mar de Prata Seamount also host various coral gardens; the South of Pico Island hosts a deep-sea sponge aggregation of Pheronema carpenteri. The newly discovered Hydrothermal Vent Luso is also reported as a VME for the Azores. For Case Study 10 – Davis Strait, Eastern Arctic, 8 VME areas of deep-sea sponges, 5 VME areas of large gorgonian corals, 4 of small gorgonian corals and 13 of sea pens are reported. Under Case Study 10, the only known Lophelia pertusa reef in Greenland waters is also reported. For Case Study 11 – Flemish Cap, three VME types were identified by the Northwest Atlantic Fisheries Organization (NAFO) and for each, several VME areas are reported: 13 VME areas for sponges, 6 for sea pens and 7 for large gorgonians. For Case Study 12 - Mid-Atlantic Canyons and SE USA, four VMEs are included: 1) Cape Lookout Coral Banks, dominated by large bioherms built by Lophelia pertusa, 2) Hatteras Middle Slope, a physically and biologically unique area of rugged mini-canyons (composed of consolidated muds), 3) Norfolk Canyon, and 4) Baltimore Canyon and vicinities, two rugged submarine canyons that contain extensive cold-water corals. For Case Study 13 - Tropic Seamount is host to multiple VMEs, including dense patches of reef framework-forming scleractinian, dense aggregations of coral gardens, dense monospecific sponge ground of Poliopogon amadou, mixed deep-sea sponge aggregations, Xenophyophore field, and dense crinoid fields.Knowledge gained from ATLAS CS significantly increases the database of vulnerable marine ecosystem (VME) occurrences in the northern Atlantic but the species that define VMEs have been known about for over a century. In order to get an overview of the distribution of VMEs, data coming from sources as various as historical cruises, by-catch of fisheries surveys and Remotely Operated Vehicle (ROV) surveys must be compiled. The reliability of these data however varies and a confidence index has thus been developed in order to objectively and quantitatively rank the reliability of VME records according to the source of records. The ranking ranges from low, for inferred records, to high, for visually assessed records. In addition, not all VMEs equally meet the criteria of rarity, functional significance, fragility and recovery, which vary according to taxa and the abundance of indicator taxa. A VME index has thus been developed to quantitatively and objectively score the vulnerability of VME records. The VME index and the confidence index have been applied to the records of the VME database created and curated by the joint ICES/NAFO Working Group on Deep-water Ecology (WGDEC). This spatial grid of VME likelihood was completed with the unequivocal VMEs mapped in the ATLAS CS. In general, the VME index provides a simplified, spatially aggregated and weighted estimate of the degree to which an area could be considered to contain VMEs under the Food and Agriculture Organisation of the UN (FAO) definition. The VME index clearly highlights areas where a VME is more likely to occur while the associated estimate of confidence gives an indication of how (un)certain that assessment is. The methodology is transparent, science based and data driven, and the aggregate cells can be explored in greater detail to reveal the individual data points that have contributed to the assessment. It integrates far more information than previous methods and as such, better captures the underlying reasoning for identifying VME areas or benthic deep-sea Ecologically or Biologically Significant Marine Areas (EBSAs). The VME index is expected to be updated each year as new data are submitted and will therefore provide an up to date, repeatable and defensible source upon which to base advice as new information is received. The VME index appears to capture most of the important elements of the VME database. This methodology may be considered as a first step towards a systematic approach for the identification and protection of VMEs and EBSAs in the North Atlantic. Our methodology clearly considered several of the steps proposed by Ardron et al. (2014), namely step 1 on assessing potential VME indicator taxa and habitats in a region, step 3 on considering areas already known for their ecological importance, step 4 on compiling information on the distributions of likely VME indicator species and habitats, step 6 on considering fishing impacts, and step 8 on identify ecologically important areas. However, at least one important aspect of the Ardron et al. (2014) framework is missing in the current VME index which refers to understanding the natural distribution of VMEs before significant impacts occurred. This aspect could be considered in future improvements of the VME index to encompass predicted distribution of VME as discussed in Vierod et al. (2014) and Anderson et al. (2016b). Systematic conservation planning is an explicit, objective-based and quantitative approach for allocating areas for biodiversity conservation, for instance used in Marine Protected Area (MPA) networks design process. It aims to identify priority areas answering specific conservation objectives for each considered species or habitat, whilst minimising the socioeconomic costs of conservation over the study area. For the purpose of systematic conservation planning, data on known or inferred VMEs are still too sparse at the scale of the northern Atlantic. The spatial prioritisation developed here aimed to identify zones of conservation importance for seabed species and habitats associated with VMEs in a comprehensive approach, by complementing the records of unequivocal VMEs and the VME likelihood over the basin resulting from the VME index with supplementary information targeting deep-sea species and habitats. ATLAS modelled the present and future distributions of six coral species indicators of VMEs as well as six exploited fish species (D3.3). Through a collaboration with the H2020 Blue Growth SponGES project, the present and future distribution of one sponge species have also been modelled to provide maps of the distribution of key VME indicator taxa with different environmental requirements, life-history strategies and functional significance. The overlap between the present and future distribution of these species under climate change scenarios furtherallowed the mapping of their future climate refugia, constituting resilient areas that were given a high conservation target in simulations. Although the primary focus of ATLAS is on cold-water corals, there is more at stake in terms of conversation in the northern Atlantic. In order to increase the scope of this systematic conservation planning exercise, chemosynthetic ecosystems that qualify as VMEs as well as large physiographic features known to be functional hotspots such as canyons, seamounts and fracture zones have also been considered. Conservation scenarios integrated current management and human activities aspects over the basin, to combine the conservation and socioeconomic stakes during the prioritisation process. While areas already profiting from conservation designations such as fishing closures, MPAs and EBSAs were favoured, areas situated in major bottom-fishing grounds or within deep-sea mining contracts were penalised. In order to suggest a geographically balanced protection network, conservation objectives were replicated within 13 provinces, which considered the main biogeographic and geographical boundaries over the basin as well as a dissociation between broad shallow (800m) habitats. This regionalisation approach ensured a regional replication and representativity of each conservation feature within the main deep-sea biotopes. Finally, this work addressed benthic connectivity aspects, by using the results of larvae drift models to favour connected networks of conservation as best as possible. Emerging from an incremental scenario complexification process, the final simulation (“all management”, Figure 1) resulted in an ecologically coherent conservation network that gave insight into spatial planning possibilities to better protect seabed vulnerable habitats and species. In particular, continental margin slopes, the Mid-Atlantic Ridge, and shelf areas comporting fishing grounds appeared as crucial zones for preserving deep-sea biodiversity (Figure 1). These identified areas comprised of specific habitats (e.g. canyons, ridges, seamounts), concentrating diverse substrates and representing key areas for nutrient circulation, that sustain VMEs and deep-water fish. Even if their depth range is larger, most of the VME indicator taxa used in this study largely occur between 500 and 2500m depths, which were prioritised here. For some species, including gorgonians (Acanella arbuscula, Acanthogorgia armata), scleratinian coral (Lophelia pertusa) and the sponge species (Geodia barretti), future climate refugia are almost exclusively predicted along margin slopes (ATLAS D3.3), that appeared as the most prioritised areas in conservation scenarios. In addition, the Mid-Atlantic Ridge concentrates sites of hydrothermal activity, giving rise to unique chemosynthetic ecosystems. As all known hydrothermal vents south of the Azores Exclusive Economic Zone (EEZ), but also several other VMEs, are located in areas already pre-empted for massive sulphide exploration, these latter contained substantial conservation potential. Identified conservation areas situated within the International Seabed Authority (ISA) contracts could inform the regional management plan to be implemented for preserving the Mid-Atlantic Ridge biodiversity from adverse mining impacts. Finally, the prioritisation results suggest that conservation objectives, especially for demersal fish species, could not be achieved without including large fished areas situated on shelves. This result may promote the development of conservation measures on fishing grounds, from full closures for the most efficient, to species-based catch limitation or minimum fish size. The implementation of such restrictions in EEZs or Regional Fisheries Management Organisations (RFMOs) regulatory areas in Areas Beyond National Jurisdictions (ABNJs) would also contribute to fisheries’ sustainability objectives.Selecting the most prioritised planning units allowed delineation of the main priority areas for deep-sea conservation (Figure 2). Covering approximatively 17% of the study area, these priority areas would answer a relatively high conservation goal for the deep sea, nonetheless they suffer from poor conservation at the moment (Figure 2). Less than 1% of the study area falls into fishing closures and marine reserves that already protect the priority areas for benthic deep-sea ecosystems. For instance, only a few unequivocal VMEs, species climate refugia or canyons currently benefit from some form of protection. In that respect, our systematic planning exercise has shown that, as important as they are, the sum of all Area-Based Management Tools (ABMTs) of the northern Atlantic still suffer from a lack of conservation efficiency, representativity and viability. Moreover, our results highlighted that a more continuous conservation network, displaying corridors or shorter distances between conservation areas, would lead to a more connected and thus more resilient benthic conservation framework. Ultimately, climate change pressures are likely to largely affect deep-sea oceanography and biodiversity, and the ability of current ABMTs to preserve them. Protecting the priority areas herein identified, which hold substantial resilience potential to future environmental changes through the central place of climate refugia in scenarios, could promote the long-term viability of the deep-sea conservation for the North Atlantic.To our knowledge, this study is the first in systematic conservation planning to address the conservation of deep-sea benthic and demersal biodiversity across a whole oceanic basin. These results contribute to the development of systematic approaches for large scale MSP, such as the conservation management of ABNJs currently the object of ongoing international discussions. Lacking of a coordinated framework as well as efficient, permanent and recognised protection measures, the North-Atlantic high seas conservation network could benefit from the suggestions provided by our scientific evaluation. Finally, this basin scale prioritisation will provide general material for local conservation, through a transfer to the MSP work implemented for ATLAS case studies in ATLAS Work Package 6.&nbsp

Designing conservation networks requires a well-structured framework for achieving essential objectives such as connectivity, replication or viability, and for considering local management and socioeconomic stakes. Although systematic conservation planning (SCP) approaches are increasingly used to inform such networks, their application remains challenging in large and poorly researched areas. This is especially the case in the deep sea, where SCP has rarely been applied, although growing awareness of the vulnerability of deep-sea ecosystems urges the implementation of conservation measures from local to international levels. This study aims to structure and evaluate a framework for SCP applicable to the deep sea, focusing on the identification of conservation priority networks for vulnerable marine ecosystems (VMEs), such as cold-water coral reefs, sponge grounds, or hydrothermal vents, and for key demersal fish species. Based on multi-objective prioritization, different conservation scenarios were investigated, allowing the impact of key elements such as connectivity and conservation cost to be evaluated. Our results show that continental margin slopes, the Mid-Atlantic Ridge, and deeper areas of large and productive shelves housing fishing grounds appeared as crucial zones for preserving the deep-sea biodiversity of the North Atlantic, and within the limitations imposed by the data available, of the Mediterranean. Using biologically-informed connectivity led to a more continuous and denser conservation network, without increasing the network size. Even when minimizing the overlap with socioeconomic activities, the inclusion of exploited areas was necessary to fulfil conservation objectives. Such areas included continental shelf fishing grounds for demersal fish species, and areas covered by deep-sea mining exploration contracts for hydrothermal vent communities. Covering 17% of the study area and protecting 55% of each feature on average, the identified priority network held a high conservation potential. However, these areas still suffer from poor protection, with 30% of them benefiting from some form of recognition and 11% only from protection against trawling. Integrating them into current marine spatial planning (MSP) discussions could foster the implementation of a basin-scale conservation network for the deep sea. Overall, this work established a framework for developing large-scale systematic planning, useful for managing Areas Beyond National Jurisdiction (ABNJ).

The abyssal seafloor covers more than 50% of planet Earth and is a large reservoir of still mostly undescribed biodiversity. It is increasingly targeted by resource-extraction industries and yet is drastically understudied. In such remote and hard-to-access ecosystems, environmental DNA (eDNA) metabarcoding is a useful and efficient tool for studying biodiversity and implementing environmental impact assessments. Yet, eDNA analysis outcomes may be biased toward describing past rather than present communities as sediments contain both contemporary and ancient DNA. Using commercially available kits, we investigated the impacts of five molecular processing methods on eDNA metabarcoding biodiversity inventories targeting prokaryotes (16S), unicellular eukaryotes (18S-V4), and metazoans (18S-V1, COI). As the size distribution of ancient DNA is skewed toward small fragments, we evaluated the effect of removing short DNA fragments via size selection and ethanol reconcentration using eDNA extracted from 10 g of sediment at five deep-sea sites. We also compare communities revealed by eDNA and environmental RNA (eRNA) co-extracted from 2 g of sediment at the same sites. Results show that removing short DNA fragments does not affect alpha and beta diversity estimates in any of the biological compartments investigated. Results also confirm doubts regarding the possibility to better describe live communities using eRNA. With ribosomal loci, eRNA, while resolving similar spatial patterns than co-extracted eDNA, resulted in significantly higher richness estimates, supporting hypotheses of increased persistence of ribosomal RNA (rRNA) in the environment and unmeasured bias due to overabundance of rRNA and RNA release. With the mitochondrial locus, eRNA detected lower metazoan richness and resolved fewer spatial patterns than co-extracted eDNA, reflecting high messenger RNA lability. Results also highlight the importance of using large amounts of sediment (10 g) for accurately surveying eukaryotic diversity. We conclude that eDNA should be favored over eRNAfor logistically realistic, repeatable, and reliable surveys and confirm that large sediment samples (10 g) deliver more complete and accurate assessments of benthic eukaryotic biodiversity and that increasing the number of biological rather than technical replicates is important to infer robust ecological patterns.

Circulation patterns in the North Atlantic Ocean have changed and re-organized multiple times over millions of years, influencing the biodiversity, distribution, and connectivity patterns of deep-sea species and ecosystems. In this study, we review the effects of the water mass properties (temperature, salinity, food supply, carbonate chemistry, and oxygen) on deep-sea benthic megafauna (from species to community level) and discussed in future scenarios of climate change. We focus on the key oceanic controls on deep-sea megafauna biodiversity and biogeography patterns. We place particular attention on cold-water corals and sponges, as these are ecosystem-engineering organisms that constitute vulnerable marine ecosystems (VME) with high associated biodiversity. Besides documenting the current state of the knowledge on this topic, a future scenario for water mass properties in the deep North Atlantic basin was predicted. The pace and severity of climate change in the deep-sea will vary across regions. However, predicted water mass properties showed that all regions in the North Atlantic will be exposed to multiple stressors by 2100, experiencing at least one critical change in water temperature (C2C), organic carbon fluxes (reduced up to 50%), ocean acidification (pH reduced up to 0.3), aragonite saturation horizon (shoaling above 1000 m) and/or reduction in dissolved oxygen (>5%). The northernmost regions of the North Atlantic will suffer the greatest impacts. Warmer and more acidic oceans will drastically reduce the suitable habitat for ecosystem-engineers, with severe consequences such as declines in population densities, even compromising their long-term survival, loss of biodiversity and reduced biogeographic distribution that might compromise connectivity at large scales. These effects can be aggravated by reductions in carbon fluxes, particularly in areas where food availability is already limited. Declines in benthic biomass and biodiversity will diminish ecosystem services such as habitat provision, nutrientcycling, etc. This study shows that the deep-sea VME affected by contemporary anthropogenic impacts and with the ongoing climate change impacts are unlikely to withstand additional pressures from more intrusive human activities. This study serves also as a warning to protect these ecosystems through regulations and by tempering the ongoing socio-political drivers for increasing exploitation of marine resources.&nbsp

Environmental metabarcoding is an increasingly popular tool for studying biodiversity in marine and terrestrial biomes. With sequencing costs decreasing, multiple-marker metabarcoding, spanning several branches of the tree of life, is becoming more accessible. However, bioinformatic approaches need to adjust to the diversity of taxonomic compartments targeted as well as to each barcode gene specificities. We built and tested a pipeline based on Illumina read correction with DADA2 allowing analyzing metabarcoding data from prokaryotic (16S) and eukaryotic (18S, COI) life compartments. We implemented the option to cluster Amplicon Sequence Variants (ASVs) into Operational Taxonomic Units (OTUs) with swarm v2, a network-based clustering algorithm, and to further curate the ASVs/OTUs based on sequence similarity and co-occurrence rates using a recently developed algorithm, LULU. Finally, flexible taxonomic assignment was implemented via Ribosomal Database Project (RDP) Bayesian classifier and BLAST. We validate this pipeline with ribosomal and mitochondrial markers using eukaryotic mock communities and 42 deep-sea sediment samples. The results show that ASVs, reflecting genetic diversity, may not be appropriate for alpha diversity estimation of organisms fitting the biological species concept. The results underline the advantages of clustering and LULU-curation for producing more reliable metazoan biodiversity inventories, and show that LULU is an effective tool for filtering metazoan molecular clusters, although the minimum identity threshold applied to co-occurring OTUs has to be increased for 18S. The comparison of BLAST and the RDP Classifier underlined the potential of the latter to deliver very good assignments, but highlighted the need for a concerted effort to build comprehensive, ecosystem-specific, databases adapted to the studied communities.

Albacore tuna (Thunnus alalunga) is an important target of tuna fisheries in the Atlantic and Indian Oceans. The commercial catch of albacore is the highest globally among all temperate tuna species, contributing around 6% in weight to global tuna catches over the last decade. The accurate assessment and management of this heavily exploited resource requires a robust understanding of the species' biology and of the pattern of connectivity among oceanic regions, yet Indian Ocean albacore population dynamics remain poorly understood and its level of connectivity with the Atlantic Ocean population is uncertain. We analysed morphometrics and genetics of albacore (n = 1,874) in the southwest Indian (SWIO) and southeast Atlantic (SEAO) Oceans to investigate the connectivity and population structure. Furthermore, we examined the species' dispersal potential by modelling particle drift through major oceanographic features. Males appear larger than females, except in South African waters, yet the length-weight relationship only showed significant male-female difference in one region (east of Madagascar and Reunion waters). The present study produced a genetic differentiation between the southeast Atlantic and southwest Indian Oceans, supporting their demographic independence. The particle drift models suggested dispersal potential of early life stages from SWIO to SEAO and adult or sub-adult migration from SEAO to SWIO. This work was conducted in the framework of the GERMON project “N°759/DMSOI/2013” funded by the European Fisheries Funds EU FEP 2013-2015, IFREMER, and IRD

Summary Evolutionary theory predicts that clonal organisms are more susceptible to extinction than sexually reproducing organisms, due to low genetic variation and slow rates of genetic evolution. However, plants that reproduce clonally are among the oldest living organisms on our planet. Here, we test the hypothesis that clonal seagrass meadows display epigenetic diversity that compensates for the lack of .genetic diversity. In a clonal meadow of the seagrass Zostera marina we characterized DNA methylation among 42 shoots. We correlated methylation patterns with photosynthetic performance under exposure to, and recovery from 27°C. Here we show for the first time that methylation variation in clonal seagrass promotes variation in fitness-related traits of ecological relevance: photosynthetic performance and heat stress resilience. The recovered shoots memorized heat responsive methylation changes for >five weeks. While genotypic diversity has been shown to enhance stress resilience and invertebrate diversity in seagrass meadows composed of several genotypes, we suggest that epigenetic variation plays a similar role in clonal meadows with the potential to secure function and resilience not only of Z. marina plants, but of the entire associated ecosystem. Consequently, conservation management of clonal plants must include epigenetic variation as indicator of resilience and stability.

Versión del editor

This synthesis, outlined during the course of the workshop was developed and consolidated in the following months on the basis of further inputs provided by the participants under the coordination of Salud Deudero.

International audience; * Connectivity is a crucial process underpinning the persistence, recovery, and productivity of marine ecosystems. The Convention on Biological Diversity, through the Aichi Target 11, has set the ambitious objective of implementing a ‘well connected system of protected areas’ by 2020. * This paper identifies eight challenges toward the integration of connectivity into MPA network management and planning. A summary table lists the main recommendations in terms of method, tool, advice, or action to address each of these challenges. Authors belong to a science–management continuum including researchers, international NGO officers, and national MPA agency members. * Three knowledge challenges are addressed: selecting and integrating connectivity measurement metrics; assessing the accuracy and uncertainty of connectivity measurements; and communicating and visualizing connectivity measurements. * Three management challenges are described: integrating connectivity into the planning and management of MPA networks; setting quantitative connectivity targets; and implementing connectivity-based management across scales and marine jurisdictions. * Finally, two paths toward a better integration of connectivity science with MPA management are proposed: setting management-driven priorities for connectivity research, bridging connectivity science, and MPA network management. * There is no single method to integrate connectivity into marine spatial planning. Rather, an array of methods can be assembled according to the MPA network objectives, budget, available skills, data, and timeframe. * Overall, setting up ‘boundary organizations’ should be promoted to organize complex cross-disciplinary, cross-sectoral and cross-jurisdiction interactions that are needed between scientists, managers, stakeholders and decision-makers to make informed decision regarding connectivity-based MPA planning and management. Copyright © 2014 John Wiley & Sons, Ltd.