Nov. 24: Alvin dive 4999

Starting with this third-last dive, we are beginning to wrap up the deployments of deep-sea gear, and to recover the osmosamplers, T-loggers, and indispensable samples to round out the haul of sediment cores. The seas have calmed down, and Alvin emerges into a sunrise of Wagnerian grandeur.


Today, Alvin is piloted by Jefferson; in his capable hands are the science observers, Dirk deBeer, leader of the Microsensor Dept. of the Max-Planck-Institute for Marine Microbiology in Bremen with an unruly mop of grey hair that results from his previous participation in Guaymas cruises, and Roland Hatzenpichler, originally from Austria but now on the faculty at Montana State University. Roland usually works on hot spring microbial ecosystems in Yellowstone National Park, over 2000 meters above sea level, where he studies the physiological and biogeochemical activities of uncultured extreme microbes. Now he descends to 2000 meters below to finally experience the Guaymas hydrothermal springs that will keep him busy for quite a while.


This dive is extremely successful; all four osmosamplers plus their attendant T-loggers and satellite cores are recovered, a large number of background cores and several hot sediment cores from the M14 area are collected, not to forget a biological specimen that looks like a tangled piece of black wire but turns out to be a deep-water coral.

Nov24BackgroundcoresSmallHere stands the small army of background cores, taken in cold sediment where Alvin has landed; these are needed as a reference of comparison for the numerous hydrothermal vent cores that were collected during this cruise. In the lab, it turns out that even some of these cores contain a whiff of hydrocarbons; obviously it is not easy to escape the fumes of Guaymas Basin entirely.

Nov24OSMORecovery2SmallHere, Alvin is picking up one of the osmo samplers, pre-packaged in a milk crate, an essential device in oceanographic research. Osmo samplers have collected long-term porewater records at various places, including the brines and cold seeps of Mississippi Canyon 118 in the Gulf of Mexico; but this is their first deployment in Guaymas Basin. It will be exciting to see the porewater chemistry data that the samplers have collected during the last 24 hours.

Nov24ElevatorFogSmallAt some safe distance, the elevator is waiting to be fully loaded, and released for the return to the surface. This ungainly-looking structure is indispensable for moving large pieces of equipment to the seafloor and back. Properly calibrated for minimal weight in water, it sheds weights when triggered and becomes buoyant, even with a full payload of equipment. However, releasing the elevator involves pulling particular strings, which is hard to do once sediments are resuspended. A 45-minute waiting game to let the dust settle is part of the day.


Finding all the osmosamplers, T-loggers and sediment cores gives the dive team plenty of opportunity to experience the strange scenery of the Marker 14 area, with its huge yellow-lime sulfur-stained mats. The weird black tangle in the center of this view is not a piece of barbed wire from a cattle ranch in Sonora; Javier identifies it as a deep-water coral, growing as a wiry bush with very thin and tangled black branches; it is frankly the strangest coral that this blogger has ever seen. The dive team sees a lot more unusual deep-sea fauna, even an anglerfish; we will look for the photo and have it posted asap.



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