Easter Microplate Expedition
April 3, 2005 Day 23
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-Jenny Paduan
Right image: Dave, Kazumi and Jenny winching in the magnetometer we towed during the transit.
Left image: The nearly empty rock dredge. Right image: Nicole holding the one, lonely rock collected in the dredge: a small, glassy piece of a sheet flow.
Image on right: Greg photographing Ana removing eggs from the
Riftia tubeworm collected yesterday.
This animal is very important in that it was the first demonstration of this type of bacteria-marine invertebrate partnership. Since it's discovery, a number of other similar arrangements between bacteria and invertebrates have been discovered in a variety of habitats including vents, cold seeps, sewage outfalls, eelgrass beds, and anoxic basins. In fact, they may be more the norm, than the exception, in sulfide-rich environments. Many important studies have been conducted on the metabolic needs of both partners as well as the nutritional dialogue between them. For example, it is now known that the worm host has evolved many biochemical adaptations for symbiont accommodation, including effective mechanisms to concentrate inorganic carbon internally, sulfide acquisition from the environment using specialized hemoglobin molecules, as well as unprecedented pH and ion regulation. The symbiont, in turn, provides the host with organic carbon, which enables the worm to grow rapidly, quickly dominating communities around newly established hydrothermal vents. Although much progress has been made toward understanding basic biological processes enabling these organisms to tolerate sulfide-rich, oxygen-poor environments, many questions concerning the ecological physiology, diversity, biogeography, and community dynamics still remain. For these reasons we continue to study these fascinating animals.
-Shana Goffredi
Left image: Michel examining a Nematocarcinus shrimp through his
magnifying loupe. Right image: Victor and Victoria, our microbiologists, in their new
matching Atlantis
t-shirts.
The ship's track since the beginning of the expedition. We are
at the red star (26o 12' S latitude, 112o 36' W =
247o 24' E longitude). Tahiti is in the upper left and
Easter Island, where we will arrive April 6, is at the extreme right.
All underwater photos were taken with the submersible Alvin, and are courtesy of Woods Hole Oceanographic Institution.