Dispatches from Sea >>
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| March 2007 |  Laura Preston, educator, UNH/Salem High School, Salem, NH. |
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| April 2007 | |||||||
April 20, 2007
Contributed by Liz Goehring, Ridge2000 Education Outreach Coordinator
What’s so special about 9˚50’N EPR?
Although we have explored only a few percent of our planet’s ocean floor, there are some spots on the seafloor that have been studied for years. 9˚50’N on the East Pacific Rise (EPR), our current location, is one such area. A few of the scientists aboard this research ship know this section of the ocean floor like the back of their hand. They are part of a community of deep-sea researchers who has worked here for almost 20 years.
A five-hour steam north from the overlapping spreading center we’ve been working at for most of this cruise, 9˚50’N is an area of on-going intense focus right now within the deep-sea research community. Volcanic eruptions that occurred in 2005-2006 have changed the seafloor topography, obliterated existing animal communities and provided fresh seafloor for new animals to colonize. The eruption provided a “reset” of the whole ridge ecosystem. What’s exciting is that the research community anticipated this would happen and, in fact, chose to focus their work here for this very reason.
The last major eruption at 9˚50’N occurred in 1991. At the time, scientists diving in Alvin realized they were catching an eruption just weeks after it occurred. Since 1991, scientists of all disciplines have returned again and again to understand the geology, hydrothermal geochemistry and biology of this site and how it changes with time. We’ve learned a great deal about the evolution of vent systems at fast-spreading centers. In general, we know processes in the deep ocean are very slow – where water is just above freezing and the sun’s energy does not reach. The studies at 9˚50’N however have revolutionized our ideas regarding how fast the changes on the ridge occur, both in the growth (and death) of animals as well as in the evolution of the waters and alteration of the rocks. The recent eruptions provide the opportunity to test hypotheses and expand the boundary of our understanding.
It takes a great deal of coordination (of people, deep-sea equipment and ships) to understand something as complicated and as remote as a mid-ocean ridge system. 9Ëš50’N is designated an “Integrated Study Site” (ISS) by the community of scientists in the Ridge 2000 research program. Several of the scientists on board have ongoing research programs at the 9° 50’N site including Karen Von Damm who studies hydrothermal fluid chemistry, and Adam Soule, Scott White, Ian Ridley and Dan Fornari who have been mapping the lava flows and analyzing the rocks.Â
is an NSF funded research initiative to understand Earth’s oceanic spreading centers as an integrated whole system, “from the mantle to the microbes,” including the animals living there. Since the discovery of hydrothermal vent systems in the late 1970’s, these spreading centers have been the focus of intense and coordinated research. A main theme of the current Ridge 2000 program involves studies at key locations, to develop focused, quantitative, whole-system models through coordinated, integrated, and interdisciplinary experiments. By focusing the research on specific areas, nicknamed “bull’s-eye” areas, researchers from diverse disciplines can bring their experiments and data together in space and time, to develop a fuller understanding of how the components of the system work together. They can explore, for example, how seismic activity changes hydrothermal circulation and fluid chemistry, and in turn see how changes in fluid chemistry affect the animal communities.
Which brings us back to our current work. Because of the recent volcanic eruptions at 9˚50’N, we need a new map of the area. Earlier in this cruise, we towed the DSL-120a sidescan sonar over the site to make a large-scale base map. For the next three days, Jason II will be traversing the seafloor and using its high-resolution sonar systems to make detailed bathymetric maps of the terrain. With these new detailed maps, we’ll be able to see the extent of the lava flows, and the fissures and features of the new landscape. We are also deploying new markers, to provide navigation benchmarks and help all researchers in the community co-locate their experiments. And as you’ve already read, thanks to the prowess of the Jason team, we’re recovering the OBSs that have been here since before the eruptions but became cemented in place as lava flowed around them. Bringing these instruments, and the data they recorded, back to the lab will help us better understand the nature of the eruption. The data will provide additional insight as to when exactly the EPR 9˚50’N vent system “clock“ was reset.
 Scientist, Paul Johnson shows me the area where the new eruption occurred over a year ago. |
 Dr. Karen Von Damm (UNH) is interested in the potential effect the eruption had on“Bio9” vent, such as the new glassy obsidian she noticed on the side of the chimney this afternoon. |
 Another “black smoker” in the well known ISS area. |
 A well packed elevator, including 4 benchmarks to be laid on fixed positions on the ocean floor, a camera with strobe for pictures, a battery to run the camera and strobe, and a rock crate. |
 WHOI scientists, Dan Fornari and Adam Soule the team leaders for this part of our cruise. |
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 The crew watches as the elevator is lifted above the ship’s bulwarks for deployment. |
 Down she goes! |
 And….Laura Preston enters the great sunset competition! |
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