April 12th, 2003; Leg 4, Day #9

Alarcon Rise—Part II

The follow-up sequel to the Alarcon Rise survey began at 8:05 a.m. local time when the ROV Tiburon touched the bottom at 2413 meters.  The dive got off to a fast start when we had a push core and a rock sample under our belt in the first 15 minutes of the dive.  As we cruised around on the bottom, we noticed many of the pink cucumbers from the previous dive yesterday.  One of the problems in sampling is the inherent fact that our observation and collection alters our perception of our study organism(s).  Take, for example, the pink cucumber. In yesterday's logbook, the pink cucumber was described as a frilly, pastel pink cucumber few could imagine living in the dark, murky depths of the Sea of Cortez.  Wispy, pink tentacles trailing gently in the current at 2400 meters below the ocean's surface could never be visible to human eyes without the development of vehicles such as Tiburon. When we collected one of the pink cucumbers to bring it up for closer inspection, we realized that the massive pressure change (about 240 atmospheres) resulted in the pink cucumber losing all of its tentacles (see above).

However, we were not disheartened by our echinoderm in Emperor's Clothes. Quite the contrary—we were enthralled to be able to hold and photograph a creature that may be new to science.  DNA analysis of our denuded pink cucumber will reveal its relationship to other sea cucumbers in the Pacific Ocean.

Having the technology and experience onboard the R/V Western Flyer that we are fortunate to have, one develops a great respect for the marine biologists who pioneered the field.  As recently as the early 1970s, basic concepts of marine science such as plate tectonics (the idea that the crust of the Earth's surface is composed of a series of interconnected plates that meet at junctions where the fate of the crust may be birth, such as the spreading center at the Mid-Atlantic Ridge, or death as at the Mariana Trough in the Western Pacific Ocean) and the presence of hydrothermal vent communities were mere fantasies to much of the field.  Today, sitting in the control room of the Western Flyer as the Tiburon flew over pillow basalts and elaborate lava sculptures 2400 meters below us, I realized the profound amount of work and knowledge that has been done in the marine science field.  Today, plate tectonics and vent systems are firmly established in the marine science literature and textbooks.  It is indeed exciting to extrapolate to the next 30 years. It is truly an exciting time to experience the exploration and discoveries of the ocean.

Today was a truly unusual day.  Other than being a much shorter dive (only 6 hours on the bottom), we collected no animals.  We had continued our search for the elusive Alarcon hydrothermal vents, but in the end, we found no vents or bivalves.  This doesn't mean we didn't see any exciting animals today—we saw pink sea cucumbers, a few octopuses, starfish, and tunicates among others.  Also during dinner this evening, we were greeted by a pod of hundreds of  Pacific white-sided dolphins swimming on the bow wave of the boat while schooling with yellowfin tuna.

Tonight, we begin our 17 hour transit to 21º North on the East Pacific Rise (EPR).  Here, we will continue our exploration of hydrothermal vents.  This will be the farthest point that the Western Flyer will be from Moss Landing during this 103-day oceanographic expedition.

Joe Jones