Pelagic Social-Ecological Systems Under a Changing Climate

ORCID

Abstract

Pelagic habitats make valuable contributions to human quality of life, yet climate change and human activities are suspected of putting these benefits at risk. Here, plankton indicators were explored as a lens to track and project the potential societal impacts resulting from climate-driven changes in pelagic habitats. First, trends from the Continuous Plankton Recorder Survey were assessed and signalled decreasing fish larvae abundances, widespread declines in the biomass of zooplankton, and increases in the abundance of some hazardous plankton taxa in some regions. These changes in plankton ecology highlight long-term declines in pelagic habitats’ potential to support fisheries over the past 60 years of warming, alongside changing risks of human health and economic hazards. Plankton size spectrum slopes were then used to project global changes to the supportable biomass of fish and the efficiency of biological carbon export to depth from Earth System Model outputs. Both supportable fish biomass and carbon export efficiency were projected to decline globally with continued ocean warming, highlighting threats to capture fisheries and pelagic habitats’ contributions to global climate regulation. The hazard-exposure-vulnerability framework was then used to identify where projected fish biomass declines have the greatest potential to adversely impact human quality of life. Risk hotspots were identified across Southeast Asia and the western seaboards of Africa, where addressing illegal fishing activities and restoring essential fish habitats could provide an opportunity to offset societal harms. Finally, climate risk frameworks were also explored as a tool for assessing the societal risks from ecosystem hazards that are not comprehensively addressed in current climate and ecosystem governance frameworks – including pelagic hazards that may be influenced by climate change.

Awarding Institution(s)

University of Plymouth

Award Sponsors

DEFRA, University of Plymouth

Supervisor

Abigail McQuatters-Gollop, Sian Rees, Angus Atkinson, Clare Ostle

Document Type

Thesis

Publication Date

2026

Embargo Period

2027-08-01

Deposit Date

August 2026

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

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This item is under embargo until 01 August 2027

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