The sixth Alvin dive, No. 4866 / La sexta inmersión del Alvin, No. 4866

Friday night was spend waiting outside Guaymas Port for the pilot boat with emergency supplies. Finally, at 3:30 on Saturday morning, the pilot boat delivered the goods and RV Atlantis escapes in the last minute, or we would have to shorten Alvin’s window of precious dive time. As the sun rises, we have reached our next station, a presumable seep site halfway between the Ringvent and the northern Guaymas spreading center. La noche del viernes se fue esperando en las afueras del puerto de Guaymas a que llegue una lancha con suministros de emergencia. Finalmente, a las 3:30 de la mañana del sábado, el barco piloto entregó la mercancía y el R/V Atlantis zarpa a último minuto, o tendríamos que acortar el precioso tiempo del Alvin para su inmersión. A medida que el sol se eleva, hemos llegado a nuestra próxima estación, un posible yacimiento a medio camino entre el Ringvent y la zona de expansión en el norte de Guaymas.img_5748sm

This is a pit or training dive, with pilot-in-training Danik Forsman mentored by Jefferson Grau; Matt Saxton of UGA is the Science observer. Matt is working on anaerobic oxidation of methane, the microbial process of turning the greenhouse gas methane into the slightly less noxious greenhouse gas CO2,  and we hope that he will find a new methane-rich seep site with lots of bubbles and microbial mats. The seismic image – hydrothermal circulation burning a hole through an otherwise unbroken layer of methane hydrates – certainly suggests this possibility. Esta es una inmersión de entrenamiento, con el piloto en formación Danik Forsman dirigido por Jefferson Grau; Matt Saxton de la Universidad de Georgia es el observador científico. Matt está trabajando en la oxidación anaeróbica del metano, el proceso microbiano de transformar el gas de efecto invernadero en el CO2 de gases de efecto invernadero ligeramente menos nocivos, y esperamos que encuentre un nuevo sitio de filtración rico en metano con muchas burbujas y esteras microbianas. La imagen sísmica – la circulación hidrotermal abriendo un agujero a través de una capa intacta de hidratos de metano – sugiere ciertamente esta posibilidad.img_5750smSince we spent the night near Guaymas, this dive proceeds in the traditional mode, without the ultimate luxury of a freshly generated Sentry bathymetric map of the target waiting in the sub. On the other hand, the excitement and the glory of discovery await the dive team! What will they find? Puesto que pasamos la noche cerca de Guaymas, esta inmersión procede en el modo tradicional, sin el lujo de tener un mapa batimétrico recién generado con el Sentry. El blanco de exploración sería confirmado dentro del submarino. Por otro lado, la emoción y la gloria del descubrimiento que nos espera al equipo de exploración ¿Qué se encontrarán? 

It turns out, a carpet of worms in methane-saturated sediment. Near the summit of this seep mound, the ground has a peculiarly rough and silver-grey texture, which – on closer inspection – turns out to be little worm tubes in sponge-like sediment. In the following images, we zoom in from the macro to the microscale. First comes a landscape shot of the seep habitat with methane-dependent tubeworms and weathered carbonate outcrops, then a closer view of the ground with clam shell debris and tube worms, and finally the zoom of the sediment surface with worm burrows – visible as little lobes – embedded.screen-shot-2016-12-18-at-12-19-52-pmsm

screen-shot-2016-12-18-at-12-13-04-pmsm

screen-shot-2016-12-18-at-12-15-54-pmsmFrom other seep locations, similar colonies of amphitrid worms in methane-rich sediment are known; they inhabit a location that is so far the most sulfidic and methane-rich sediment seen on the entire cruise. Six cores were harvested quickly, not bad considering that the pilot-in-training had to rush as the weather decayed at the surface and Alvin had to return around 1:30 pm. During the science meeting in the evening, these sediments become fashionable, and tomorrow’s Alvin dive will go for more material. Also, Sentry is going in at night and is mapping the entire site; with a little luck, tomorrow’s dive team will start with a deluxe color bathymetric map of their dive target.

Now we need a name for this seep site. The old technical designation, Guaym-09A, is somehow not what we would like to see. Octopus Mound or Octopus Garden has been suggested, since these critters are all over the mound. Wormy Sponge is another possibility…

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