The ocean plays a crucial role in the functioning of the Earth System and in the provision of vital goods and services. The United Nations (UN) declared 2021–2030 as the UN Decade of Ocean Science for Sustainable Development. The Roadmap for the Ocean Decade aims to achieve six critical societal outcomes (SOs) by 2030, through the pursuit of four objectives (Os). It specifically recognizes the scarcity of biological data for deep-sea biomes, and challenges the global scientific community to conduct research to advance understanding of deep-sea ecosystems to inform sustainable management. In this paper, we map four key scientific questions identified by the academic community to the Ocean Decade SOs: (i) What is the diversity of life in the deep ocean? (ii) How are populations and habitats connected? (iii) What is the role of living organisms in ecosystem function and service provision? and (iv) How do species, communities, and ecosystems respond to disturbance? We then consider the design of a global-scale program to address these questions by reviewing key drivers of ecological pattern and process. We recommend using the following criteria to stratify a global survey design: biogeographic region, depth, horizontal distance, substrate type, high and low climate hazard, fished/unfished, near/far from sources of pollution, licensed/protected from industry activities. We consider both spatial and temporal surveys, and emphasize new biological data collection that prioritizes southern and polar latitudes, deeper (> 2000 m) depths, and midwater environments. We provide guidance on observational, experimental, and monitoring needs for different benthic and pelagic ecosystems. We then review recent efforts to standardize biological data and specimen collection and archiving, making “sampling design to knowledge application” recommendations in the context of a new global program. We also review and comment on needs, and recommend actions, to develop capacity in deep-sea research; and the role of inclusivity - from accessing indigenous and local knowledge to the sharing of technologies - as part of such a global program. We discuss the concept of a new global deep-sea biological research program ‘Challenger 150,’ highlighting what it could deliver for the Ocean Decade and UN Sustainable Development Goal 14.

The UN Decade of Ocean Science for Sustainable Development represents a once in a generation opportunity to effect positive change in ocean use. We outline what is required of the deep-sea research community in order to achieve the ambitious objectives of the Ocean Decade and call for the development of a new ten-year research programme.The health of the global ocean, on which society is dependent, is in decline. The importance of sustainable use to ocean health has long been recognized 1 . The First World Ocean Assessment 2 highlighted increasing ocean pressures from accelerated expansion of human activities, including climate change, affecting all ocean regions, from the coast to the deep sea 3 . In response to this concern, and in keeping with several international policy commitments, the UN General Assembly proclaimed 2021-2030 the Decade of Ocean Science for Sustainable Development 4 . The Ocean Decade Roadmap recognizes the deep sea as a frontier of science and discovery, calling for research to advance understanding of deep-sea ecosystems, their functions, vulnerabilities, and services to society. Published in March 2020, the draft Implementation Plan for the Ocean Decade describes a framework to guide the design and implementation of 'Actions' throughout the Decade. These Actions underpin the move from the 'ocean we have' to the 'ocean we want'. Different levels of Actions are identified, and include programmes, projects, activities and contributions. The draft plan calls upon the scientific community to develop Actions to help deliver on four key objectives (see Fig. 1).The deep-sea biology community responded to this call through working groups of the Deep-Ocean Stewardship Initiative (DOSI) and the Scientific Committee on Oceanic Research. In keeping with the Ocean Decade's focus on fair and equitable partnerships, these groups gather experts from developed and developing nations, representing diverse ethnic backgrounds, different genders and career stages. Together, these groups considered each of the Ocean Decade objectives in a deep-sea biology context, and the associated research needs. Here we present a series of recommendations under each objective to inform the development of deep-sea focused Ocean Decade Actions. Figure 1: The Ocean Decade through a deep-sea biology lens, and our recommendations to support the development of Actions focused on achieving the Ocean Decade objectives.

No abstract

Despite a relatively long history of scientific interest fuelled by exploratory research cruises, the UK deep sea has only recently emerged as the subject of targeted and proactive conservation. Enabling legislation over the past 10 years has resulted in the designation of marine protected areas and the implementation of fisheries management areas as spatial conservation tools. This paper reflects on progress and lessons learned, recommending actions for the future. Increased investment has been made to improve the evidence base for deep‐sea conservation, including collaborative research surveys and use of emerging technologies. New open data portals and developments in marine habitat classification systems have been two notable steps to furthering understanding of deep‐sea biodiversity and ecosystem functioning in support of conservation action. There are still extensive gaps in fundamental knowledge of deep‐sea ecosystems and of cause and effect. Costs of new technologies and a limited ability to share data in a timely and efficient manner across sectors are barriers to furthering understanding. In addition, whilst the concepts of natural capital and ecosystem services are considered a useful tool to support the achievement of conservation goals, practical application is challenging. Continued collaborative research efforts and engagement with industry to share knowledge and resources could offer cost‐effective solutions to some of these barriers. Further elaboration of the concepts of natural capital and ecosystem services will aid understanding of the costs and benefits associated with human–environment interactions and support informed decision‐making in conserving the deep sea. Whilst multiple challenges arise for deep‐sea conservation, it is critical to continue ongoing conservation efforts, including exploration and collaboration, and to adopt new conservation strategies that are implemented in a systematic and holistic way and to ensure that these are adaptive to growing economic interest in this marine area.

Vulnerable marine ecosystems (VMEs) are particularly susceptible to bottom-fishing activity as they are easily disturbed and slow to recover. A data-driven approach was developed to provide management options for the protection of VMEs under the European Union “deep-sea access regulations.” A total of two options within two scenarios were developed. The first scenario defined VME closure areas without consideration of fishing activity. Option 1 proposed closures for the protection of VME habitats and likely habitat, while Option 2 also included areas where four types of VME geophysical elements were present. The second scenario additionally considered fishing. This scenario used VME biomass—fishing intensity relationships to identify a threshold where effort of mobile bottom-contact gears was low and unlikely to have caused significant adverse impacts. Achieving a high level of VME protection requires the creation of many closures (> 100), made up of many small (∼50 km2) and fewer larger closures (> 1000 km2). The greatest protection of VMEs will affect approximately 9% of the mobile fleet fishing effort, while closure scenarios that avoid highly fished areas reduce this to around 4–6%. The framework allows managers to choose the level of risk-aversion they wish to apply in protecting VMEs by comparing alternative strategies.