PhD: Robotic observations of marine snow storms

Project Description

What is the topic and why is it important?

Every year snow falls within the ocean. “Marine snow” forms when particles sink from the surface to the deep ocean, transporting with them the carbon they are composed of.  This process is also known as the Biological Carbon Pump and is critical because it contributes to controlling the Earth’s climate.

As this organic carbon settles, it is consumed and respired to CO2 by bacteria and zooplankton in the deep sea. Surprisingly however, current estimates suggest that significantly more carbon is consumed by deep organisms than is supplied.  How could that be?

A recent study has provided a potential answer to this question (Giering et al., 2014), but the expensive expeditions needed to complete this study limited it to a specific location.  As a consequence, it is extremely difficult to verify these findings at the global scale.

Fortunately, novel autonomous robotic floats (Bio-Argo, see www.oao.obs-vlfr.fr/web/index.php) are becoming globally available and can be exploited to estimate carbon fluxes (Dall’Olmo and Mork, 2014) and respiration rates (Martz et al., 2008).  These floats, therefore, have a tremendous potential for shedding new light on fundamental carbon cycle questions.

 

What you will do

Using data from floats and satellites you will:

  • Determine photosynthetic rates, carbon fluxes, and oxygen in the surface and deep ocean.

  • Determine the characteristics of the biological carbon pump and its relationships with environmental factors.

  • Quantify the deep budget of carbon supply and oxygen consumption.

What you will learn

You will learn about the ocean carbon cycle, to analyse large datasets, to code in a programming language (e.g., Python), to run an ecosystem model, and to calibrate scientific instruments. You may take part in oceanographic expeditions and be trained in sea survival techniques, instrumentation and analytical techniques. You will also acquire additional transferable skills including oral and written communication, and outreach. You will present your work at international conferences, and attend an international summer school on earth system science.

 

Should you apply?

Yes, if you are enthusiastic, love the ocean, and have a degree in oceanography, environmental sciences, chemistry, biology, mathematics or physics.

 

References

Dall'Olmo, G. and Mork, K. A. “Carbon export by small particles in the Norwegian Sea”, Geophysical Research Letters, 2014, 41, 2921–2927, doi:10.1002/2014GL059244 (freely available).

Burd, A. B. et al.  “Assessing the apparent imbalance between geochemical and biochemical indicators of meso- and bathypelagic biological activity: What the @$! is wrong with present calculations of carbon budgets?” Deep Sea Research Part II: Topical Studies in Oceanography, 2010, 57, 1557-1571. (abstract freely available)

Giering, SLC., Sanders, R., Lampitt, RS., Anderson, TR., Tamburini, C., Boutrif, M., Zubkov, MV., Marsay, CM., Henson, SA., Saw, K., Cook, K. & Mayor, DJ. “Reconciliation of the carbon budget in the ocean’s twilight zone”. Nature, 2014, 507, 480-483, doi:10.1038/nature13123. (abstract freely available)

Martz T., Johnson, K, Riser, S. “Ocean metabolism observed with oxygen sensors on profiling floats in the South Pacific”, Limnology and Oceanography, 2008, 53, 2094-2111. (freely available)

 

Start date: October 2015

Programme: PhD

Mode of Study: Full Time

 

Read more and apply online.