Posted by graduate student Alison Sipe, University of Delaware College of Marine Studies.

Marine geologist Dr. Dan Fornari has completed his contour bathymetry maps of the Guaymas Basin. This is the first time that the basin depth has been mapped using a multi-beam system. The SeaBeam multi-beam sonar system detects features on the seafloor that are greater than the size of a football field and are taller than about 10 –15 meters. This means that a small vent chimney would go undetected, but more expansive seamounts would be detected. Dan has been running the SeaBeam at night because during the day when Alvin is diving, the ship must remain stationary at the dive site. Each night, the ship makes 40-mile-long transects across the Sea of Cortés, each track 2 1/2 miles from the next. The total area covered is 60-by-40 miles, or 2,400 square miles.

The two most prominent features of the Guaymas Basin are the northern and southern troughs, which are the seafloor spreading axes of the Sea of Cortés. Dan and his group will analyze the data further when he returns to Woods Hole Oceanographic Institution. He will create two-dimensional contour maps as well as three-dimensional perspectives of the basin. Dan Fornari has constructed bathymetric maps of many other ocean basins as well, but this map will be a wonderful contribution to hydrothermal vent researchers.

As I walked down the hall past the darkroom where the microscope is located, I could hear squeals coming from inside. I found Anna-Louise Reysenbach and her graduate student Krista Longnecker taking turns peering through the microscope. Drs. Reysenbach and Cary have been trying to learn what types of hyperthermophilic (hyper=super, thermo=hot, philic=loving) bacteria live in the vent chimneys. Their culturing, or growing, experiments have led to unique findings. I gazed through the microscope lenses to see a continuous line of filamentous bacterial cells connected like a freight train. What is unique about this bacterium is that it is sheathed — it’s like the microbes are wearing a little coat. Although Anna-Louise is an expert researcher of hyperthermophilic bacteria, this is the first time she has seen sheathed bacteria growing at 70° C (that’s pretty toasty!).

Barbara Campbell, Jane Boone, and Krista Longnecker have all been growing methanogens (methane-producing bacteria) that they have collected from the vent chimney and sediment cores. In addition to methanogens, graduate student Melissa Kendall has succeeded in her attempts to culture iron-reducing bacteria. These bugs produce magnetite, or iron filings, as they grow. The scientists hold a magnet up to the test tube culture of the bacteria and the iron filings drift to the side of the tube touching the magnet. The microbiologists on board are undoubtedly growing bacteria that no one else has ever seen. The microbial world is not well investigated — only 1% of the Earth’s bacteria have been described. The microbiologists have a lot of work ahead of them.

Tonight, we witnessed a remarkable celestial event. I feel honored to have seen not only a spectacular sunset over the Baja peninsula and a gray whale spy-hopping in the distance, but at the same time a full moon rise over the flat ocean. I couldn’t decide where I should stand on the ship to see both, but found that the ship’s bow provided a prime view. Even more, a full eclipse of the moon occurred. We watched the sky grow darker as the Earth’s shadow slowly crept across the moon; the moon turned into a mustard-yellow glowing ball. With the sky so dark, the stars appeared in the trillions. What better place to witness such an event.

At one point, someone heard a flap in the water. Thirty feet below us at the tip of the bow where the ship’s hull cuts through the sea were six dolphins playfully racing the boat. They swam at incredible speeds, weaving in and out of each other. Some took a break for a few minutes and then returned to play with the group. We heard their grunts as they blew air threw their blowholes. With our hands curled around the ship’s hull, we gazed until the last two turned away from their fun, either through exhaustion, boredom, or who knows what. It was a breath-taking show.

If we stared at the sky long enough, each of us began to spot shooting stars. It was then interesting to watch the Earth’s shadow creep away from the moon following the 1 1/2-hour total eclipse. The sky brightened, and the trillions of stars we were privileged enough to see slowly disappeared against the lightened sky. A frigate bird perched on the antenna above seemed to enjoy the display equally as well.