ATLAS Deliverable 3.2 Water masses controls on biodiversity and biogeography Project ATLAS acronym: Grant 678760 Agreement: Deliverable Deliverable 3.2 number: Work Package: WP3 Date of 28.02.2019 completion: Author: Lea‐Anne Henry (lead for D3.2), Patricia Puerta (alphabetical, all contributors are also authors) Sophie Arnaud‐Haond, Barbara Berx, Jordi Blasco, Marina Carreiro‐Silva, Laurence de Clippele, Carlos Domínguez‐Carrió, Alan Fox, Albert Fuster, José Manuel Gonzalez‐ Irusta, Konstantinos Georgoulas, Anthony Grehan, Cristina Gutiérrez‐ Zárate, Clare Johnson, Georgios Kazanidis, Francis Neat, Ellen Contributors Kenchington, Pablo Lozano, Guillem Mateu, Lenaick Menot, Christian Mohn, Telmo Morato, Ángela Mosquera, Francis Neat, Covadonga Orejas, Olga Reñones, Jesús Rivera, Murray Roberts, Alex Rogers, Steve Ross, José Luis Rueda, David Stirling, Karline Soetaert, Javier Urra, Johanne Vad, Dick van Oevelen, Pedro Vélez‐Belchí, Igor Yashayaev This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 678760 (ATLAS). This output reflects only the author's view and the European Union cannot be held responsible for any use that may be made of the information contained therein. 1 Contents 1. Executive Summary ..................................................................................................................................... 3 2. Review: Influence of water masses on deep‐sea biodiversity and biogeography of the North Atlantic ........ 5 3. Case Studies on Effects of Hydrography and Oceanography on North Atlantic VME Biodiversity and Biogeography ................................................................................................................................................... 114 3.1 Faroe‐Shetland Channel (northeast Atlantic, UK): Biodiversity of deep‐sea sponge grounds in relation to oceanographic and anthropogenic activities .................................................................................................. 116 3.2 Mingulay Reef Complex (northeast Atlantic, UK): Impacts of the North Atlantic Oscillation and gyre dynamics on cold‐water coral reef biodiversity and biogeography ................................................................ 135 3.3 Flemish Cap and continental slope (northwest Atlantic, High Seas): Effects of sea temperature, food availability, and currents on macrofaunal species and phylogenetic diversity relative to fishing pressure ... 162 3.4 Alborán Sea to the Azores: influence of water mass properties on VME biodiversity and geography .... 179 3.5 Davis Strait, Rockall Bank, Azores: effects of organic matter supply on VME biodiversity ....................... 256 Appendix: Document Information .................................................................................................................. 278 2 1. Executive Summary The oceanographic and hydrographic conditions of the North Atlantic are predicted to dramatically change by this century’s end. The Atlantic Meridional Overturning Circulation (AMOC) is anticipated to slow, and many of the waters that currently bathe vulnerable marine ecosystems (VMEs) are predicted to be warmer, have reduced oxygen and food supply, and be more acidic. Among the many ways in which impacts of climate change on VMEs are being studied in ATLAS is the empirical approach, whereby effects of present day oceanographic variables are directly related to VME biodiversity through systematic review or statistical analyses. Deliverable 3.2 adopts this empirical approach: first, D3.2 reviews what is known about effects of oceanographic variables on VME biodiversity across the North Atlantic to derive a basin‐scale synoptic view of key ocean controls on system biodiversity; second, D3.2 examines the statistical significance of these variables in selected regional ATLAS Case Studies covering several Exclusive Economic Zones (EEZs) and Areas Beyond National Jurisdiction (ABNJ). Our review concluded that VMEs in several ATLAS Case Study areas will likely be impacted by critical changes and multiple stressors, even without additional human activities from the Blue Economy. VMEs in the western North Atlantic that are predicted to experience critical changes in sea temperatures and food supply (Flemish Cap and Davis Strait) are also the Case Studies that the review and empirical analyses identified as having temperature and food supply playing significant roles in the occurrence of VMEs and biodiversity of their associated communities, which seem to depend on relatively cooler water at least on the Flemish Cap. Projected critical declines in oxygen, pH, and a shoaling of the aragonite saturation horizon for the Davis Strait however need further in‐depth investigations to ascertain impacts on future VMEs. Many VMEs in the mid‐ to eastern North Atlantic are also projected to experience multiple critical changes (Reykjanes Ridge, Norway, Faroe Shetland Channel, Rockall, Porcupine Seabight, Mingulay Reef Complex, and the Azores), which our review and empirical analyses strongly suggest will impact VMEs. Targeted studies at our eastern Atlantic Case Studies showed warmer oceans are likely to alter the biogeographic affinities of cold‐water coral communities at Mingulay, the biodiversity and density of sponge grounds in the Faroe Shetland Channel, while reductions in food supply could significantly reduce the density of octocorals and black corals at Rockall, and result in species loss of sponge grounds and coral gardens in the Azores. Deliverable 3.2 shows that a backdrop of climate change will narrow the margins for safe ecological and thus operational limits of existing and emerging ocean industries. It is understood that biodiversity enhances ecosystem resilience by contributing to both climate change mitigation and adaptation. Thus, we make the policy recommendation under the Convention on Biological Diversity Aichi Target 15 that regulatory frameworks for licensing and planning such as Environmental Impact Assessments and Strategic 3 Environmental Assessments explicitly incorporate climate change impacts to assist blue economy sectors to avoid, minimise, restore or offset biodiversity loss resulting from resource exploration or exploitation. 4 2. Review: Influence of water masses on deep‐sea biodiversity and biogeography of the North Atlantic Authors: Patricia Puerta, Covadonga Orejas, Marina Carreiro‐Silva, Clare Johnson Contributors: Lea‐Anne Henry, Telmo Morato, Georgios Kazanidis, José Luis Rueda, Javier Urra, Pablo Lozano, Ellen Kenchington, Igor Yashayaev, Dick van Oevelen, Lenaick Menot, David Stirling, José Manuel Gonzalez‐Irusta, Steve Ross, Christian Mohn, Alan Fox, Sophie Arnaud‐Haond, Anthony Grehan and J. Murray Roberts Acknowledgements: Luis Rodrigues, Carlos Domínguez‐Carrió 5 Summary Different water masses and their characteristic properties are major drivers of biodiversity and biogeography patterns in the deep sea. Circulation patterns and water mass characteristics along the North Atlantic have changed and re‐organized multiple times since the genesis of this ocean, affecting the composition and functioning of deep‐sea ecosystems. We reviewed the evolution of the North Atlantic circulation and water mass properties, such as temperature, salinity, oxygen or organic matter content, and their impacts on VMEs occurring from the continental shelves to the bathyal regions of the deep sea. Eleven case studies, spanning different features and habitats across the North Atlantic, have been included as examples to illustrate how different water masses shape VME biodiversity and biogeography. Finally, we forecasted conditions in several water mass properties to explore how these changes might affect VMEs and their associated deep‐sea benthic communities, with a particular focus on critical cumulative changes in the case study areas. This review and the assessment of future conditions might help identify areas likely to experience the biggest changes in oceanic properties to help us learn how to better manage the deep North Atlantic as deepwater industries develop. Setting the context: the North Atlantic Ocean In the North Atlantic Ocean, the Atlantic Meridional Overturning Circulation (AMOC) re‐ distributes warm saline water masses northwards. These water masses are compensated by a deeper southerly circulation of cooler fresher waters, accounting for 25 % of global heat transport. Climate models forecast a slowing or even disappearing of the AMOC by the end of the century, which will modify water masses characteristics and circulation patterns. Thus, warmer temperatures of 1 or 2 °C, reduced organic carbon fluxes (up to 50 %), ocean acidification, shoaling of the aragonite saturation horizon (above 1000 m) and deoxygenation are expected to significantly impact the deep‐ sea benthic communities and VMEs, and even compromise their survival. This review will show that most, if not all, of the areas encompassed by Case Studies in ATLAS will experience a critical change in at least one of the variables but since the potential impacts on their VMEs has remained poorly investigated, this part of the Deliverable 3.2 begins by reviewing how VMEs might be impacted by looking at contemporary controls on VME biodiversity and biogeography. 6 Oceanic Drivers of Deep‐sea Biodiversity and Biogeography Patterns Deep‐sea ecosystems have been traditionally considered vast habitats in the ocean characterised by stable and homogeneous environment (darkness and constant