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March 8, 2003: Leg 2, Day #7

“One merges into another, groups melt into ecological groups until the time when what we know as life meets and enters what we think as non-life: barnacle and rock, rock and earth…” -The Log from the Sea of Cortez, John Steinbeck

This is my third visit to the seafloor of the Sea of Cortez. Every time I return, I leave in awe—in awe of one of the most beautiful deep-sea vent sites in the world, in awe of the spectacular diversity of colors of animals, rocks, and microbes that reside in this murky sedimented seafloor. Two thousand meters below the surface, we drop down onto brown sediments, pock-marked with activity of benthic organisms, anemones, large spider crabs, and brilliant white starfish. 

Suddenly, in this dark world, large patches of white appear, like a localized snowfield. Closer inspection with illumination from the ROV, reveals gentle orange, yellow, and white hues. As we get closer, the patches are clearly a biological mat made up of filamentous microbes, fluffy masses, providing a habitat for millions of other microbes and small invertebrates. Occasional red, feather-like creatures poke out from under this mat of microbes, and then suddenly you see more color, more animals. Huge clumps of tubeworms, white, so white, with fleshy plumes lazily moving in the current. Zoarcid fish and crabs cruise by the view, opportunistically looking for scraps of potential food. 

Look up and the mat extends up a rocky mound, with tubeworms between crevasses, large shelf-like structures covered in animals and microbes— delicately balanced like caps of toadstools— strange rocks that look like spires… Zoom in and the water emanating from areas in the mat appears viscous and shimmering. Fluid under the rocky shelves is mirror-like, and tips of the spires seem to be smoking like chimneys. And here, associated with all these structures, is the answer to this unusual ecosystem. 

The water is hot, hydrothermal fluid, rich in metals and gases. It's fueling the ecosystem with energy for microbes—microbes that live at high temperatures in the chimneys, in the porous rock of the shelves (“flanges”), microbes that make up the mats, and microbes that live inside the tubeworms. The diversity of microbes in these ecosystems far exceeds that of the animals, and we have only started exploring the vastness of this microbial world.  

These microbes can precipitate minerals, contributing to minerals and colors in the mats we see. Some live off a little hydrogen and carbon dioxide and make much of the methane we measure in the fluids, and some probably can utilize the hydrocarbons—that oily mess we collected a few days ago. The microbes that live in the tubeworms are called endosymbionts, and enable these animals to thrive on hydrogen sulfide, carbon dioxide and oxygen.  Most animals cannot live in the hydrogen sulfide concentrations that the tubeworms can! So here, the microbes play a critical role in the life of these animals. “Microbe, tubeworm, hot water and rock, rock and earth…”

Again, I am left in wonderment about the diversity of life on earth, how geology, geochemistry, biology, are all so interlinked, and how little we understand our oceans and our planet. I am then reminded of the trip the Western Flyer took into the Sea of Cortez with Steinbeck and Doc Ricketts, and how much of the excitement of discovery that we are experiencing on today's Western Flyer, is much of the same they experienced on their little Western Flyer more than half a century ago.  I look out to the setting sun on the mountains in Baja and on the golden reflections on the Sea of Cortez, and I am reminded again of a passage from their research expedition:

“Then one can come back to the microscope and the tide pool and the aquarium… And it is a strange thing that most of the feeling we call religious, most of the mystical out crying which is the most prized and used and desired reactions of our species, is really the understanding and the attempt to say man is related to the whole thing, related inextricably to all reality, known and unknowable… The knowledge that all things are one and that one thing is all things—plankton, a shimmering phosphorescence on the sea and the spinning planets and an expanding universe, all bound together by the elastic string of time. It is advisable to look from the tide pool to the stars and then back to the tide pool again.”

-Anna-Louise Reysenbach

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