Monterey Bay Aquarium Research Institute

MBARI Ridges 2005 Expedition

Juan de Fuca Leg: August 7–18, 2005
Gorda Leg: August 22–September 2, 2005

August 31 update - Posted by Jenny Paduan and Dave Clague

Sleigh-riding south

The weather finally caught up with us today and we were unable to dive. Earlier this week, an area of gale-force winds was centered to the south of us while we enjoyed relatively calm, partly cloudy weather. But today the wind field slid north and we are getting beaten up. It is clear and sunny today, blowing over 30 knots, with 14-foot seas and big whitecaps rolling through.

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The normally placid moonpool on the Western Flyer became a seething cauldron after the wind picked up yesterday, making the recovery of ROV Tiburon a tricky process, to say the least.
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This photograph taken off the transom of the Western Flyer shows some of the wild sea conditions that we encountered during our sleigh ride south. No dives today....



Last night's ROV recovery was exciting: huge waves were washing through between the pontoons, hitting the deck of the moon pool, and splashing up toward the ceiling. The crew timed the raising of the ROV perfectly, however, and as it was lifted from the sea it never even tapped the edges of the moon pool.

We had planned to dive today in an area southwest of the Escanaba Trench, to look for evidence of the ground breakage on the seafloor from a magnitude 7.2 earthquake that occurred in this area last June. Unfortunately, this dive will have to wait until a later cruise, although the any cracks in the muddy bottom will heal with time, becoming less and less obvious. We stood on station this morning until about 10:30, waiting to see if the winds would drop. They increased. So the dive was called off and we turned south toward home. With the wind, swell, and current at our stern, even on just one engine, we were making about 12 knots. Our decision to leave was confirmed by worsening seas throughout the day.


Some of the seas were large enough to let the Western Flyer do a little surfing on her way down the coast. 

We spent the day sieving the last of the push cores collected yesterday and the day before, drying and chipping glass for analysis from lava samples, and cleaning up the lab. We still harbor hopes for one last dive on Pioneer Seamount (about 50 nautical miles off Half Moon Bay) on our way home, and the improving seas as we move south suggest we may get the chance to complete a dive we abandoned in 2003 due to rough seas. We should arrive at Pioneer Seamount at approximately noon tomorrow. We'll see whether we bring the winds with us.

   

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Jenny Paduan took a break from sieving core samples to show off some of the shrunken styrofoam cups that we decorated with colored marking pens, then sent down with ROV Tiburon during the last two dives. The immense pressure at 3,300 meters compressed these cups to about one third their original size.
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Despite the boisterous conditions, the crew of the Western Flyer continued their routine maintenance work on the boat.


Over the past month, we completed 18 out of 19 of our planned ROV dives, collected 166 rock samples, 183 push cores, 143 animals, and 151 glass suction samples. We also recovered 12 extensiometers from that had been deployed on the Juan de Fuca Ridge and 3 temperature recorders that were deployed on hydrothermal vents. One temperature recorder eluded us and remains hidden somewhere at the Axial Seamount hydrothermal vents. The samples and observations, as well as the data stored in the recovered instruments will keep our group of scientists busy for some time. If we succeed in completing a dive on Pioneer tomorrow, we will no doubt add to our sample collection, and may even make additional discoveries. That's what keeps us going. 

Jenny reflects: During our steam south, after we abandoned ideas of diving at the earthquake epicenters, and somewhere offshore of Cape Mendocino, the sky was clear (finally!) and we had gorgeous star-gazing. Mars was a bright orange beacon just south of Perseus, the Pleiades jumped out - the classic "seven sisters" and many more in the cloud, and the Milky Way was a brilliant arch overhead. It was almost hard to make out the constellations because the dimmer stars were so bright in the absence of the light pollution I'm used to on land, and the stars seemed close enough to touch. The velvety black water was punctuated by big flashes of bioluminescence, and the green, bioluminescent glow of our wake followed us for a long distance as we cruised south. Watching the bioluminescence in the water on a clear, starry night is one of my favorite things about being at sea.

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