Iron and manganese impacts on the future of Southern Ocean ecosystems (Iron-Man)

Developing a paradigm that integrates the processes regulating Southern Ocean productivity to improve climate model projections
Mountains and sea ice in the Southern Ocean

Iron and manganese impacts on the future of Southern Ocean ecosystems (Iron-Man)

Developing a paradigm that integrates the processes regulating Southern Ocean productivity to improve climate model projections
Title: Iron and Manganese Impacts on the Future of Southern Ocean Ecosystems (Iron-Man)
Funding amount: £4 million
Location: UK, Southern Ocean, Antarctica
Dates: June 2025 – July 2029
Project partners: University of Liverpool (Lead PI Tagliabue), University of Exeter, University of Southampton, University of East Anglia
University of Plymouth PI/Co-I: Professor Simon Ussher and Dr Angela Milne
 

Overview

The Southern Ocean plays a critical role in the Earth system. It hosts emblematic components of global biodiversity that motivate international conservation efforts. It is also the flywheel of the ocean circulation and climate system, where it plays a critical role in the carbon sequestration and supplies nutrients to lower latitudes where they support global productivity. These key ecosystem services are supported by the activity of photosynthetic phytoplankton and zooplankton that underpin food-webs and biogeochemical cycling. 
We need accurate climate model projections to assess the response of Southern Ocean ecosystems and biogeochemical cycles to climate change. But our best models cannot even correctly reproduce the direction of ongoing change. 
This suggests fundamental problems with projections, undermining efforts to protect and conserve ecosystems and lowering confidence in our understanding of how carbon and nutrient cycling will respond, both in the future and in the geological past. 
Iron-Man will develop a new paradigm that integrates the processes regulating Southern Ocean productivity by addressing critical knowledge gaps. This is urgent given the rapid ongoing changes to the region and the timescales of policy action that require robust science.
Seaweed and rock pools in the Southern Ocean

Aims

We have assembled a team of world leading scientists, operating across multiple disciplines, using state-of-the-art observational, experimental and modelling tools in an integrated and co-designed manner. Iron-Man must address three questions: 
  1. How does the relative supply of iron (Fe) and manganese (Mn) vary to set the resource limitation regime? 
  2. How do phyto- and zoo-plankton in different regions respond to changes in Fe and Mn? 
  3. Does integrating Mn and regional ecology alter future projections? 

Objectives

  1. Quantify the relative supply and abiotic recycling and removal of Fe and Mn to the upper ocean varies in different regimes, using ship-based and autonomous platforms. 
  2. Assess biological cycling of Fe and Mn, alongside the adaptive and acclimatory responses via integrated measurements across natural gradients and manipulative experiments. 
  3. Produce improved model projections of NPP and ecological change in the Southern Ocean and test the importance of newly identified knowledge gaps.
Simon Ussher and Angela Milne on the Iron-Man project in Antarctica
Iron-Man project team on deck in Antarctica

Context of the issue

Over past decades, extensive research has focused on the role of the micronutrient Fe in the Southern Ocean. However, recent work, spanning observations, experiments and models (mostly led by our team), now shows that accounting for Mn as a limiting nutrient and the associated unique ecophysiology of the resident phytoplankton community is also critical to the ecological-biogeochemical function of the Southern Ocean. Importantly, these issues are neglected by current models. 
Iron-Man is focused on unravelling how the supply and cycling of Fe and Mn affects the net primary productivity (NPP) and biomass of Southern Ocean ecosystems. In doing so, we will deliver 'fit for purpose' assessments of how future change will affect this critical system. 

Potential applications and benefits 

International experts acting as partners will maximise our ability to upscale and engage stakeholders with our results. We focus specifically on key international initiatives (e.g. CCAMLR, CMIP7, etc.) and science-to-society challenges, including co-financing of stakeholder facing events and outputs throughout the project duration. 
In this way, Iron-Man will make critical contributions to the scientific knowledge base around the response of the Southern Ocean in a changing climate, but also make a difference by translating science for the policy makers grappling with a rapidly changing system.

Centre for Coastal and Ocean Processes and Engineering (C-COPE)

C-COPE brings together strength areas from across the University's Faculty of Science and Engineering with a research focus on the physical and chemical processes in coastal, ocean and marine environments, and their human impacts.
The Centre's sphere of interest stretches from the head of tidal estuaries to the bottom of the ocean, and includes the disciplines of physical oceanography, marine biogeochemistry, coastal engineering and marine geology.
Tuvalu Tepuka atoll