Monday, May 16, 2011

Over to Laura…

May 15th 2011

Here we are in the middle of the Drake Passage, half way between the southern most tip of South America and Antarctica. Even though we are far from land, we are safely in the hands of our wonderful ship’s crew - so much so it easy to forget how far away we are as we make the ship our home for the next month. Three years ago we were here on the same boat on an exploratory expedition to collect deep-sea corals in the Drake Passage. Since then we have been looking forward to coming back to answer all the questions we came up with as we looked at the samples we collected. Why do corals live in the Southern Ocean? Where are they located? Why are some only found in their fossil forms, whilst some are only found live? We put together a plan, describing why we wanted to come back, and the National Science Foundation gave us a month long cruise to complete our project.

We have lots of projects going on, so today I will tell you why we are collecting fossil corals. The Southern Ocean is a really important part of the climate system, so we want to know how it has behaved in the past, when the Earth’s climate was very different. Of course it is very difficult to work out what the ocean was doing before people started to measure things like the temperature of the water. The skeletons of the fossil corals that we are collecting can help us with this problem. We can work out the age of each fossil coral using radioactive decay, and then we use other chemicals in the skeletons to find out what the ocean was doing when the coral was alive. In a way we can think of the coral skeleton as a recording device: when they grow they capture information about the water they are living in, when they die they lie on the seafloor waiting for us to come along, pick them up and play the record. We think that the corals we have collected so far will cover an age range all the way from today back to more than sixty thousand years age. What we would really like to do is find corals from different locations and with different ages and use them to build up a picture of what the Southern Ocean has been doing over tens of thousands of years. This analysis will take us a long time after the cruise, so for now we are sorting and packing them carefully so that when we get back we can get to work quickly.

So far we have been out for less than a week, but we have already made some really great progress – we spent the first few days on the shelf and slope area off South America. We have already collected hundreds of fossil corals all the way from 300m to 2000m below the surface of the sea. One of the reasons we are doing so well out here is because of the passion with which everyone is working towards making the cruise a success. It is truly thrilling to be out here with such a great group of people – despite working 24 hours a day everyone keeps smiling as the samples come on deck.

By: Laura

Weather: Temperature 36°F. windchill 5°F, wind speed 30 knots, cloudy

A tray full of fossil Balanophyllia corals collected as part of a fantastic dredge at Burdwood Bank from about 750m water depth (A. Margolin).

Three examples of fossil Flabellum corals, from pristine (left), through normal preservation, to really old and corroded (right). We collect fossils from all ages possible, so we can understand changes in the Southern Ocean over a wide time range (A. Margolin).

Kais and Michelle collecting fossil (and live) corals from a dredge a couple of days ago (R. Waller).

Laura giving a talk this morning about her work on deep-sea corals (A. Margolin).

Ben driving the Towcam this evening (A. Margolin).

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