Feb 3rd Science - Part I The Southern Ocean

And back to some science. I've got a short break from interview travel, so I can finally sit down for another science post.

The February 3rd issue of Science provides me two special opportunities to highlight exciting science: how the release of carbon dioxide from the Southern Ocean contributed to deglaciation and how signaling pathways and gene regulatory networks interact to specify endoderm and mesoderm in the sea urchin. They are special because they represent the well-deserved culmination of efforts by some of my friends. The two articles also demonstrate how very separate development and oceanography can be. Its no wonder why its can be a challenge and so exciting to bring them together.

Andrea Burke and Laura Robinson use the chemistry incorporated into now fossilized coral skeletons to understand deglaciation events in their article The Southern Ocean's role in carbon exchange during the last deglaciation. (Admittedly, Laura is really a friend of a friend. However, my dear friend Rhian Waller was instrumental in obtaining the samples... so I still count it. For the adventures of Laura and Rhian on their latest cruise adventures in the Southern Ocean check out their blog.)


The Southern Ocean surrounding Antarctica is often thought of as a carbon sink because upper waters are chilled and sink to the ocean bottom. All of the dissolved carbon dioxide in the sinking waters is thus removed from the atmosphere and stored (temporarily) near the ocean bottom. Temporarily is key. The entire ocean circulates which means that these waters will eventually reach the surface again. It is hypothesized that just after the last glacial maximum old carbon-dioxide rich waters were brought to the surface in the Southern Ocean - changing the area from a sink to a source of CO2 to the atmosphere.

Reconstructing the past can be considered a murder mystery - consulting clues left behind by the murderer and victim to solve the puzzle. Luckily, marine organisms can respond to and record clues to their environmental conditions. When the corals lay down their skeletons (during development, may I point out), they incorporate chemical signatures of the water in which they live. These signatures are preserved in their skeletons and can be used to reconstruct past conditions.

My collecting fossilized corals at different depths in the Southern Ocean, Andrea and Laura were not only able to show that old deep water rose towards the surface just after the last glacial maximum, but were also able to provide a mechanism through the break down of the stratification (segregation) between the deepest two layers. There is still a mystery though - how did an hypothesized shift in winds cause such an effect on the deepest layers? Of course it is completely possible. I, afterall, showed that wind-generated eddies at the surface could impact the deep-ocean. Though, I would be intrigued to know how such widespread changes could be accomplished. 

Still a beautiful example of integrative science - using biology to get at chemistry to understand physical oceanography and climate.