By Kelly

I’m back at the airport, waiting for my flight back to the southern hemisphere, armed with christmas decorations painted with windmills, men’s slippers in the shape of clogs and a renewed enthusiasm for my project. On Friday last week I gave my first oral presentation at an international conference. As it was a smaller conference there was only one session running at a time so everyone was there. The technique I use is very different to most people at the Research School of Earth Sciences, my subject matter is also very different to even my supervisor’s area of expertise and as such I feel scientifically isolated at times (by ‘at times’ read a lot of the time). However the International Symposium on Deep Sea Coral was a wonderful opportunity to get in touch with like-minded folk, and to discover that some people are in fact interested in what I do! The presentation went off with out a hitch and it was well received. I think I have more questions about my research than before, and so much more reading to do on my return. However I listened to some really interesting talks and some fascinating discussions with people doing feeding studies on deep-sea corals. To use corals it is imperative that we understand what signal we are interpreting. The prevailing idea is that if we find ‘bomb’* radiocarbon in our sample then we know we are looking at an organism that derives its food from the surface. But as you can see from the figure at the bottom of the page, this signature is seriously dampened. This is in part to do with the fact that surface waters mix with deeper ‘older’ waters from below but what if…..what if these corals are metabolizing food that fixes carbon and or nitrogen at depth. I now have an admixture of a surface AND in situ signature. When analysing organic material we say that ‘you are what you eat’, which in my case would be a giant pancake, but in the case of my coral it allows me to reconstruct surface processes because that is where we believe the food source to have originated. I have long questioned how applicable this idea is when looking at exceptionally deep samples, and this weeks I learned from a number of laboratories that I may very well be on the right track. During times of resource limitation the corals readily take up free amino acids and dissolved organic matter, so what is the origin of the corals signature? I love being right, but I think I may have just made my project a little more complicated. Food for thought on my 24 hour flight home….

*from the pulse of radiocarbon injected into the atmosphere during nuclear weapons testing that subsequently labelled the surface ocean and all the autotrophic organisms within it.