February 26, 2009 | 2
Editor’s Note: University of Southern California geobiologist Katrina Edwards is taking part in a three-week drilling project at the Atlantic’s North Pond—a sediment-filled valley on the ocean floor—designed to locate and study what she calls the “intraterrestrials”: the myriad microbial life-forms living inside Earth’s crust. This is her third blog post. To track her research ship’s current position, click here. To see all her posts, see "60 Seconds in North Pond."
EN ROUTE TO THE NORTH POND FROM MARTINIQUE (February 18, 2009)—As predicted, we launched promptly at 11:00 A.M. local time yesterday. As usual, most of the science party was on deck for our last glimpse of shore for a few weeks.
The boat and safety drills came first. These are always done shortly after launch, often after lunch in the heat of the day, and often right after we’ve started to see some serious swell. As you can probably imagine, many folks are usually feeling not-so-hot, and for me it is usually a real struggle to pay attention to what the safety officer is saying. Not yesterday; I was fine and reasonably alert, although I couldn’t understand a word of what he was saying, because it was all in German. Oh well. I’m hoping the minor haze hanging over me will dissipate and I’ll be able to focus again on science.
There are some definite differences between German and American vessels and procedures. On American ships, for example, they love to have you try on the "Gumby suits," made to protect you from hypothermia if you have to abandon ship. They are made of thick rubber, and are very awkward. And big. About two of me could fit in one, and I’ve always worried that in a real emergency I would slip out through the head hole.
Here on the Merian, there were no Gumby suit try-outs. Instead, we got on the emergency evacuation boat that sits on the yellow deck. The boat is at a 30 degree angle or more, and you tuck yourself into a little tiny chair—imagine the smallest airline seat you’ve stuffed yourself into and there you have it. I won’t complain—we have some bigger people than me on this ship.
The creature comforts on this ship also contrast starkly with American ships. American ships have sheets so thin they are transparent, while we have real sheets and comforters for the beds. Bath towels are like you would buy for yourself here, unlike on American ships, where they are scratchy like sandpaper.
Those creature comforts were nice, but they didn’t make up for a tumultuous first night on the high seas. In my room on the high third level, I was convinced sometime in the middle of the night that I was going to roll right out of my (top bunk) bed. Today, I dig the straps out that are available to prevent this from happening.
So why is all of this worth it? I mentioned in an earlier post that back in the mid ’70s marine geologists were trolling for places they could learn about the ocean crust, and selected North Pond to do what is called a "site survey". In a nutshell, a site survey is a characterization of the site by geophysical and other means to figure out as best you can what the sediments look like, what the crust looks like, so that you can pick the best site for drilling.
At North Pond, we want a really good set of 3-D maps of the pond, so we can really have a good look at how the sediments are layered, where exactly the crust is, and figure out accurately where we want to drill deep holes. Why do this again, since people did this 30 years ago? That’s simple—as you might guess, technology has changed since the mid 1970s, and to use what we did then today … just doesn’t make much sense.
The other thing the geophysicists in our group will do is make heat maps for the pond. I will be honest: I really don’t understand how they do this. I hope to learn, and then I’ll let you know. I do know what the heat maps tell you, which is how the fluids flow under the sediment pond. Cool spots tell us that seawater is going in, warm spots tell where the heated fluids are coming back out. And this is absolutely critical for understanding the stars of our show—the intraterrestrials.
We study the intraterrestrials using microbiology and chemistry to study cores of sediment from all over the pond. We use genetic tools. We measure what kind of chemistry the microbes are living in—how salty, how much oxygen, etc., and then try to make sense of it by asking, for example, if we always see the same type of microbes in the same kind of chemistry. Those are the details, but the really big picture has to do with something we have little understanding of in the microbial world anywhere: biogeography.
Biogeography has to do with the distribution of life on Earth. It has its roots in the macroscopic world—and this being the year of Darwin’s 200th birthday, I’ll use the finches of Galapagos as my example. Add physical separation of finches on the different islands, plus time plus natural selection, and you end up with biogeography—the influence of geography on biological species distributions.
We’ve known about biogeography in the plant and animal worlds for a long time, but it is a frontier in microbiology, owing in part to the fact that we have only recently had tools available to give microbial species meaningful "name tags" and also, because microbes are so small and easy to transport, some skeptics have wondered whether we will see any differences in biogeography at this scale.
Biogeographers in the macroscopic world go to islands or continents on land, we do the same analogy in the ocean—go to a very isolated little pond of sediments in the middle of the Atlantic. We proposed to do this to a large degree because there is another deep biosphere sedimentary program, led by Steve D’Hondt of the University of Rhode Island, located in the very middle of the Pacific. A perfect comparison.
Bottom photo: Jim McManus (Oregon State University) and Frieder Klein (University of Bremen) working on the multi-corer. Top: The "fast escape rescue boat" cocked at about 45 degrees. Both courtesy USC/Katrina Edwards