The deep sea (>200 m depth) encompasses >95% of the world’s ocean volume and represents the largest and least explored biome on Earth (<0.0001% of ocean surface), yet is increasingly under threat from multiple direct and indirect anthropogenic pressures. Our ability to preserve both benthic and pelagic deep-sea ecosystems depends upon effective ecosystem-based management strategies and monitoring based on widely agreed deep-sea ecological variables. Here, we identify a set of deep-sea essential ecological variables among five scientific areas of the deep ocean: (1) biodiversity; (2) ecosystem functions; (3) impacts and risk assessment; (4) climate change, adaptation and evolution; and (5) ecosystem conservation. Conducting an expert elicitation (1,155 deep-sea scientists consulted and 112 respondents), our analysis indicates a wide consensus amongst deep-sea experts that monitoring should prioritize large organisms (that is, macro- and megafauna) living in deep waters and in benthic habitats, whereas monitoring of ecosystem functioning should focus on trophic structure and biomass production. Habitat degradation and recovery rates are identified as crucial features for monitoring deep-sea ecosystem health, while global climate change will likely shift bathymetric distributions and cause local extinction in deep-sea species. Finally, deep-sea conservation efforts should focus primarily on vulnerable marine ecosystems and habitat-forming species. Deep-sea observation efforts that prioritize these variables will help to support the implementation of effective management strategies on a global scale.
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The dataset generated and analysed during the current study is available from the corresponding author on reasonable request.
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We deeply thank M. Rex (University of Massachusetts) for valuable discussion and suggestions on an early draft of the manuscript. We are very grateful to M. Baker for supporting the authors in the distribution of the Qualtrics survey to the INDEEP and DOSI communities and to the deep-sea scientists that participated to the survey and J. Cerri for the analysis of Qualtrics results. This work was supported by the H2020 project MERCES (GA N. 689518) and IDEM (GA N. 11.0661/2017/750680/SUB/EN V.C2.). E.R.-L. was supported by the Norwegian project MarMine (247626), the Norwegian Institute for Water Research and the H2020 project MERCES (GA N. 689518). P.V.R.S. was supported by the NSERC Canadian Healthy Oceans Network and CFREF Ocean Frontier Institute. L.T. is supported by JPI Oceans2 and ONC. J.A. is supported by ARIM (Autonomous Robotic sea-floor Infrastructure for bentho-pelagic Monitoring; MartTERA ERA-Net Cofound). L.L. acknowledges NSF grant OCE 1634172 and the Deep-Ocean Observing Strategy subcontract from the Consortium for Ocean Leadership. H.R. was supported by the EMSO-Link project of the European Commission (Grant agreement ID: 731036).
The authors declare no competing interests.
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Ranking of the essential variables for biodiversity measures. Results of the Expert Elicitation obtained by using the Plackett–Luce model for the analysis about the prioritization of essential variables for biodiversity measures (y axis). The worth of each variable is reported on log scale (x axis). Average weighted Cohen’s κ is also reported on the upper part of the graph. ES, expected species number.
Ranking of the readiness of the available technologies for deep-sea ecological monitoring. Results of the Plackett–Luce model for the analysis of responses about the readiness of technology for deep-sea monitoring according to the essential variables identified for each scientific area. The Cohen’s κ value is reported on the upper part of each graph.
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Danovaro, R., Fanelli, E., Aguzzi, J. et al. Ecological variables for developing a global deep-ocean monitoring and conservation strategy. Nat Ecol Evol 4, 181–192 (2020). https://doi.org/10.1038/s41559-019-1091-z
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