Integrating Drivers of Atlantic Productivity (IDAPro)

The open ocean ecosystems which dominate the surface of our planet are all dependent on the generation of new organic matter by single celled organisms which are collectively termed phytoplankton. These organisms use light, nutrients and carbon dioxide to grow through a process termed primary production. In addition to forming the base of the marine food web, the collective primary production by these organisms is ultimately responsible for ocean biology keeping atmospheric carbon dioxide levels around 30-40% lower than they would otherwise be, thus exerting a significant impact on global climate. Understanding how primary production may vary in the future is thus important for predicting the ongoing response of both ocean ecosystems and carbon cycling to climate change.

The abundance and activity of phytoplankton in the upper ocean is always a balance between growth rates (determined by the availability of resources) and loss rates including through grazing by organisms collectively termed zooplankton and mortality due to viruses and direct sinking. However, the factors determining both growth and loss dynamically vary both across the different regions of the ocean and throughout the annual cycle in complex and interacting ways.

We currently try and capture the knowledge necessary to predict future changes in primary production using numerical models of these interacting processes. However, our current state-of-the-art models differ substantially in their predictions of future change due to the differing ways they represent a variety of these key processes.

Focusing on an important region of the ocean for biological carbon storage, the mid-high latitude North Atlantic, our proposal aims to make exciting new year-round observations of primary production and the controlling factors using a combination of satellite, ship-based and novel robotic platforms. We will augment these observations with detailed experimental work undertaken at sea, alongside targeted numerical modelling, in order to generate an improved understanding of the balance between controls on growth and loss and, crucially, establish how this varies over the dynamic seasonal cycle.

Data from our observations and experiments will allow us to establish key drivers of the magnitude and seasonal changes in primary production and link these to the overall controls on the efficiency of ocean carbon storage across a broad region of the North Atlantic Ocean. In addition to providing new understanding, our research will generate improved data sets of rates of growth and loss, providing more rigorous constraints for numerical models and hence pointing the way towards more confident predictions of future primary production and carbon cycle responses to climate change.