Bridging International Activity and Related Research Into the Twilight Zone (BIARRITZ)

The Twilight Zone spans from 100m to 1000m depth in the ocean. It is a region where very little light penetrates and where little is known about the processes that take place within it. Each year, nearly as much plant material is produced by microscopic plankton in the surface ocean as by all the land's forests and plains. Although created in the sunlit top 100m, this organic material eventually sinks, potentially taking a huge amount of carbon with it deep into the ocean interior where it could be trapped, away from the atmosphere, for up to hundreds of years. All but a few percent of this material is converted back into carbon dioxide within the Twilight Zone. To understand the role that marine life plays in regulating carbon dioxide in the atmosphere it is thus crucial to understand what controls this enormous recycling activity in the Twilight Zone.
The UK is world-leading in this area, recently providing the first "budget" for how the Twilight Zone processes carbon. UK projects currently extend from the North Atlantic to the Southern Ocean and represent an investment of over £9M. Simultaneously there are similar current projects in the US and Spain totalling £19M, with major projects being developed in France and Germany. A new US project alone has received £26M from the Audacious Project (previously TED) fund to explore the Twilight Zone. Although each project tackles different aspects of the functioning of the Twilight Zone, by bringing them together a much more profound analysis is possible than by one alone. Working together there is a once-in-a-generation opportunity to revolutionise how we understand the functioning of the Twilight Zone.
Therefore BIARRITZ will seek to create something even greater than the sum of these already significant parts by using two linked approaches. It will provide fora for the projects to meet, to share data, best practice and novel approaches, to pool data from the huge span of environments they encompass and to initiate collaborations to address gaps identified by this interaction. It will also lead by example, to stimulate the necessary four types of collaboration, by initiating four small scale collaborations representing something old, something new, something borrowed and something out-of-the-blue. These seedcorn collaborations will have the primary purpose of providing incentive to the BIARRITZ community to develop a larger network of collaborations, but they will also significantly enhance the scientific insights from an ongoing research programme:
- 'Something old' is to reinforce existing collaborations. In BIARRITZ we re-establish a collaboration with a French expert in measuring how much carbon enters the top of the Twilight Zone.
- 'Something new' is to build new collaborations. In BIARRITZ we begin a collaboration with an American world-leading expert on dissolved organic carbon, to quantify the importance of this little studied pathway into the interior.
- 'Something borrowed' is to bring in new skills and equipment. In BIARRITZ we will be trained by a French researcher whose equipment allows us to quantify the 'dragon kings' of the ocean, the large particles that may dominate the downward rain of material deep in the ocean.
- 'Something out-of-the-blue' is to provide opportunities for young scientists outside the established projects. In BIARRITZ we will provide a young US researcher with his first opportunity to deploy a new high-tech approach to measuring organic carbon in the open ocean.
These small scale collaborations will exploit the NERC CUSTARD project which, as part of the Role of the Southern Ocean in the Earth System programme (RoSES), is investigating how marine life, in the remote part of the S. Ocean southeast of the Tierra del Fuego, influences the global carbon budget. This both provides BIARRITZ with a unique platform for these collaborations and in turn significantly enhances the understanding that will be gained from CUSTARD and RoSES.

The greatest impact of BIARRITZ will be on the understanding of how marine life helps the ocean store carbon dioxide, by bringing together multi-million pound projects on the Twilight Zone in an international endeavour on a scale that no single project could achieve.

To make use of this enhanced understanding to assist in policy decisions, related to potential exploitation of the Twilight Zone or predictions for carbon mitigation, it is necessary to capture the new understanding in earth system models, such as those used to provide predictions for the IPCC. The lead people for marine biogeochemistry in 6 IPCC models have agreed to take part in a workshop run by BIARRITZ. In addition to the wide-ranging benefit of providing a forum for observationalists and IPCC modellers to interact, discuss and build collaborations informally during the workshop, there will be a dedicated session on how IPCC models can best capture Twilight Zone function. This will involve IPCC modellers giving a short overview of how Twilight Zone function is represented in their models and how this controls the distribution and quantity of carbon stored in the ocean. Discussion groups will then contrast this model view with data from the different projects, in order to identify dominant influences and potential gaps in models. In this way, it is anticipated that BIARRITZ will ultimately result in improved predictions of future ocean carbon storage, hence contributing essential knowledge for evidence-based policy-making.

BIARRITZ will also use the workshop to showcase autonomous technology, a government industrial priority. The proposed collaboration with Rutgers will be highlighted as a stimulus to other projects which are keen to exploit autonomous vehicles. Beyond BIARRITZ, those involved will be invited to the community workshop being organised by CUSTARD in 2021 to focus on best practice in using autonomous vehicles to quantify carbon fluxes. Based on previous successful, similar events, it will draw in AUV manufacturers and stakeholders responsible for ocean monitoring such as CEFAS and Defra.

The workshop will also be used to showcase the silicate sensor, developed at NOC and due to be deployed by CUSTARD for a year in the Southern Ocean. This is the only such sensor on the market and the exposure will both increase marketability in a range of countries and provide an opening for NOC to discuss other sensors and collaborations with external partners. As part of the workshop, the Marine Robotics Innovation Centre (MARSIC), which houses SMEs engaged in collaborative development of sensors and autonomous platform technologies, will host an evening event, offering opportunities for researchers to engage with relevant industries.

BIARRITZ will achieve further impact at no extra cost by engaging in the existing outreach and impact programmes of the large COMICS project and the RoSES programme, in both of which the BIARRITZ PI is involved.