7: 9N Area

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East Pacific Rise

Our last five Alvin dive days have been spent doing research conducted by Karen Von Damm of the University of New Hampshire and Breea Govenar of Penn State University. Their long-term studies, funded by National Science Foundation's Ocean Sciences Division, focus on the biology and chemistry of vents at the 9N area. Most dives this week have been dedicated to their work, for Karen that means water collections from black smokers as hot as 386 degrees C and for Breea, recovery of experimental deployments.

Karen's studies of the chemistry of hydrothermal vent fluids document changes over the last dozen years, following a volcanic eruption. Because the temperature and chemistry of vent fluids relate to activity deep within the earth, changes in these fluids may be the first indication that molten rock is moving again below the surface. Breea studies ecology of vent animals. Last December she had Alvin place experiments near vents at 9N that we recovered this week. Because the recovery operation is fairly complex, using an "elevator" that is released from the bottom to float free to the surface, we've sent a video to share for the Expeditions web page that details the whole operation.

Other members of the science party have not been idle. We've been towing the plankton net built by Peter at increasing depths with the same great success as in its original deployment. I refer you again to our web page and the video of Peter, which is the current favorite of the science party. In addition to seeing what comes up in the net after it's been towed for 30-40 minutes each night, photographing the animals and preserving them, the biologists have examined and photographed animals recovered from Breea's deployments and very much appreciate her generosity in allowing them to do so.

Our geology-types have been using the ship's sonar system, SeaBeam, to map the terrain of the seafloor whenever Alvin op's and plankton net tows allow. SeaBeam is the preferred means to map large areas of the seafloor, and the desire to SeaBeam seems to be insatiable. Without these maps we would have no idea of what might face us on the seafloor before the sub reaches the bottom. Those of you with access to the web can call up maps of just about any country, city or village that comes to mind. However, in no way have all the interesting areas of the planet have been mapped; we know more about the backside of the Earth's moon than we do about the Earth's seafloor, less than 10% of which has been mapped.

To use sonar to map a given area of the seafloor, the ship has to sail directly over that area at a speed of 10 knots or less. This would not appear to be a huge onus, but the big problem is getting one of what we estimate to be the 12 ships in the world that are equipped with SeaBeam technology to sail over that part of the seafloor you want to map. Jim and Beth are out on this cruise largely because my having the ATLANTIS here gives them this very opportunity. When Alvin ops don't require the ship to hold station for a few hours, Jim has been giving the bridge crew a very specific course to follow. If you were watching us, you'd see the ship stay pretty much in one place during daylight (Alvin operations occur from 6 AM to 6 PM). Once the sub is secure in its hangar, we take off. Jim's course sends the ship to an imaginary point in the middle of nowhere where it turns back (after an hour or two spent with the plankton tow in the water), following a parallel, but non-overlapping course to near the point from which we started. An alien biologist watching this series of events repeated over days would likely conclude that we function as a nocturnal predator, feeding through a plankton tow lowered at that imaginary point. I bet they would wonder how we subsist on transparent animals that live between us and the bottom of the deep blue sea.

I've taken to saying "we" a lot, because doing so emphasizes the collaborative nature of at-sea research. Discovering the Stauromedusae vent field at the first are was a result of: having picked the general dive area based on earthquake acoustic records from 2001 and a remote survey our Marine Techs did during my December 2002 cruise; maps made by Jim and Z; discussions during a science meeting; adjusting the launch target as suggested by Karen; keen observations by Jim, Todd, Stephane and Beth during our two dives there; images from the towed camera, which was operated by a team overnight while I slept; and let's face it, plain good luck. The plankton collections resulted from a net Peter built and operated with the help and guidance of the deck crew of the ATLANTIS, and the scientists who helped pull it in and identified and photographed those tiny animals. Although use of "we" emphasizes the collaborative nature of our work, in the last week I've spent more time standing around with a clipboard than actually doing the science I've looked forward to since I wrote the proposal. When I talk about accomplishments, and blurt out "we", I try to correct myself to credit the people who really did the work. You know what members of my science party say? Those smiling people with whom I am sharing this cruise (who right now, seven minutes after midnight are pulling in the plankton net) tell me that I should just keep saying "we".

During the expedition you may email us questions about our research cruise (expeditions@fieldmuseum.org). Selected emails will be answered on video and the video answers to these questions will be posted periodically on the expeditions@fieldmuseum website.

© Stefani Smith
Giant Tube Worms