December 3, 2011 Slideshow

Visibility was much better and the zones on the seafloor were clearer in Discovery Basin than in Urania Basin. In this screen grab from the Jason video camera, you can see injection cores that Jason placed in a pale strip about 40 cm wide that researchers think is the bathtub ring where the upper part of the halocline meets the seafloor, and a darker zone that researchers think is where the lower part of the halocline meets the seafloor. The reddish-beige area at the top is normal seafloor.

Jason team member Hugh Popenoe and ship’s crew members Patrick Hennessy and Richie Barnes watch and wait as Medea, the companion vehicle for Jason, nears the surface. Weather has been great during the whole cruise, but on Saturday the sea was almost completely smooth.

After Jason returned to the ship, Dr. Kostas Kormas from the University of Thessaly and Dr. Hera Karayanni of the University of Ioaninna processed the samples that were in the chamberpots. Here, Hera draws water off the sample so the sediment can be removed from the pot.

Material from every pushcore will be tested for concentrations of oxygen and sulfide. To prevent contamination by the oxygen in air, the sample is kept inside a plastic tent (the “glove bag”) filled with nitrogen. The person doing the test, however, must stay outside the tent. Here, Hans-Werner Breiner of the Technical University of Kaiserslautern measures the oxygen level in a sediment sample from Urania Basin.

Dr. Joan Bernhard advises Colin Morrison as he draws the water off a pushcore. It is important to do this very carefully, so the sediments are not stirred up. Joan and Colin are bundled up in coats because the work is done in a cold room to help keep the samples from degenerating.

Eureka! The bacterial mat on the top of this pushcore was about 1 cm thick. It came from high up in the halocline. The other pushcore with a bacterial mat came from lower in the halocline, where salinity is higher and oxygen levels are lower. That mat was much thinner, like a gooey film. Photo by Joan Bernhard.

Each pushcore was mounted in a holder so 1-cm-thick slices could be cut from it, starting from the top and going to 3 cm deep in the core. Here, Joan uses a piece of stainless steel to slice through the core.

The precious bacterial mat is deposited in a sample bottle. Joan and her colleagues will examine it with light and microscopes to look for protists, some of which may be species that are new to science.

Let the celebration begin! Dr. Joan Bernhard reacts to seeing the bacterial mat on the pushcore from Discovery Basin’s halocline.

On the starboard deck behind the Main Lab, Dr. Craig Taylor and chief scientist Dr. Ginny Edgcomb work to figure out how to get SID-ISMS back in the water and sampling again.

One of the problems SID-ISMS had involved the poppet, a small white cylinder made of hard polyethylene. The end of the poppet was machined to be very flat, so that it would form a good seal with the bottom of the chamber. But under the intense pressure at 3,500 meters depth, the end of the poppet bent just enough to allow the part to leak. The researchers discovered a quick and easy fix: They simply turned the poppet around. The other end has a narrow rim—and under high pressure, that rim forms a good seal.

All the filter chambers have had their poppets turned upside down and are now ready to go back on SID-ISMS and get to work sampling the water inside the Mediterranean DHABs.

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