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The University of Southampton
Ocean and Earth Science, National Oceanography Centre Southampton

Chemical, biological and physical controls on primary production in the surface ocean


The Ocean is responsible for roughly half of global primary production and is a major absorber of the atmospheric carbon dioxide (CO2) released by human activities. In order for us to project how ocean productivity is going to fare in Future Earth scenarios and support ocean ecosystems, and thus the services they provide, we need to understand how primary production in the surface ocean is regulated.

Incubation experiments
Figure 1.

Key Questions:

1. What controls the flow of energy from the sun into ocean ecosystems? - How do phytoplankton use light? Are they all channelled to ‘fixing’ CO2?

2. What are the controls on phytoplankton distributions and productivity? – What is the relative importance of the various physical, chemical and biological factors in shelf seas and open ocean? What are the human impacts?

3. How do bioactive trace elements (Fe, Zn, Co) drive or limit primary production in the surface ocean? – How do they differ across large biogeochemical gradients and between oceanic regions?

4. How does availability of iron control nitrogen fixation? – and in turn impact primary production?

5. How does resource limitation (e.g. availability of light and nutrients) restrict the activity of marine phytoplankton and the biogeochemical processes they influence? – Which is the ultimate limiting resource, and/or if there is co-limitation of multiple resources?

Fluorometer on research ship
Figure 2.

Figure 1. At-sea, on-deck incubation experiments to capture natural light-dark cycles for phytoplankton.

Figure 2. Testing lab version of the new generation fluorometer on a research ship.

Figure 3. Setting up incubation experiments in a trace-metal clean lab onboard a research ship.

How do we do it?

We combine in situ observations and bioassay manipulation experiments, laboratory studies and at sea experimentation, as well as numerical models to develop mechanistic understanding of the interactions of phytoplankton growths and phytoplankton communities with their physical and chemical environments.  

We use state-of-the-art analytical techniques, at sea and in onshore facilities to determine among others trace element physico-chemical speciation in the water column in both dissolved and particulate forms, along with inorganic and organic macronutrients in seawater and carbonate chemistry.

We employ a range of omics technologies, including the use of our Environmental Sequencing Facility, to examine the underpinning molecular mechanisms that drive these phytoplanktonic communities, the up- and down-regulation of expressed genes and proteins of these communities along environmental gradients and in response to environmental stimuli, and the interactions among members within and between communities.

Onboard experiments
Figure 3.

We further use this mechanistic understanding to predict how system activity and biogeochemical cycles will alter under a range of different scenarios.

We further develop new technologies to more effectively estimate active phytoplankton primary production on autonomous platforms (STAFES-APP).

Who in the Marine Biogeochemistry Group is involved?

Prof Tom Bibby; Dr Anna Hickman; Prof Maeve Lohan; Prof Mark Moore; Prof Duncan Purdie; Prof Toby Tyrrell.

Links to other Research Themes

Vertical export of materials into the ocean's interior and processes in the 'twilight zone'

Biogeochemical cycles and their response to climate change

Dynamics of marine planktonic and microbial communities – from single cells to large scale processes and ecosystem functions

Development of photosynthetic microbes for algal biofuel and other biotechnologies

STAFES-APP - Single Turnover Active Fluorescence of Enclosed Samples for Aquatic Primary Productivity

Ocean currents and mixing

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