Tuesday, May 31, 2011

Glassy sponges in the Southern Ocean

May 28th

My name is Kate, and I’m a postdoctoral researcher at Woods Hole Oceanographic Institution. I was on the 2008 cruise with Laura and Rhian, which happened a mere month or so after I finished my PhD. Although it’s always difficult to be away from my family and friends (especially as I got married in January this year!), I’m really excited to have such a wonderful opportunity to return to the ARV N.B. Palmer with a few years more experience. In fact, when I walked on the ship on the first day, the smell of the labs and the decks brought it all back to me. I felt as if I had never left.

On the cruise, I’m here to collect deep-sea sponges, as well as help out the paleoceanography and biology teams with all the other science going on. My work involves using the chemistry of deep-sea sponge skeletons to tell us about past ocean chemistry. Sponges make their skeletons from glassy needles, called spicules. I collected sponges on the last cruise, in 2008, and found that the chemistry of these spicules relates to the amount of nutrients in the water in which they grew. This means that the fossil skeletons, picked out of deep-sea sediment cores, can be used to reconstruct past nutrient levels in deep waters. It’s these nutrients that upwell to the surface and are essential for the growth of algae, which take up carbon dioxide from the atmosphere. Understanding how their supply of food has changed in the past is really important for understanding the role that algae play in changes in greenhouse gases and climate. It’s really exciting to be carrying out such novel work, but a lot more studying needs to be done to understand thoroughly what is going on, and why spicule chemistry behaves this way. This trip I’ll be collecting more sponges, and sediments that contain fossil spicules, to start piecing together more about what controls sponge chemistry, and how seawater nutrients have changed in the past.

And I’m also helping to organize this blog every day! I helped with the website we ran on the last cruise, and enjoyed it so much I was really keen to get involved again. I hope you’re enjoying them!

At the moment, we’re transiting to Sars Seamount in the middle of the Drake Passage. It’s only about 100 nautical miles from Interim Seamount, but we’ve also been having some rather bad weather so we can only go very slowly. I’m particularly excited about getting to Sars, however, because last time we were there in 2008 it proved itself to be “sponge wonderland”. Not only did we collect some fantastic corals, but we also found the mother lode of sponges. Let’s see what we can find this time around…

By Kate

Weather: temperature 39°F, windchill 14°F, windspeed 50-60 knots decreasing to 20-30 knots; sunny!

The glassy spicules of a hexactinellid sponge taken under the microscope (100 times magnification). The chemistry of the spicules tells us something about the nutrients in the water when the sponge was growing (K. Hendry).
Sunrise after the storm last night, winding our way slowly to Sars Seamount (R. Waller).
Kais, David, Eric, Michelle and Suzy (with Kathy working in the background) trying to relax during the stormy transit by watching a film, complete with popcorn! (R. Waller).

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