Posted by graduate student Alison Sipe, University of Delaware College of Marine Studies.

Graduate students Brian Glazer and Liz McCliment assemble the last vent sampling instruments on Alvin’s Science Basket, a platform mounted in front of the submersible to stow tools, scientific equipment, and collected samples. The array of gear varies depending on the research questions and dive objectives. One major challenge in studying the hydrothermal vents is that the pressure in the deep sea (about 3,000 psi) is lethal and so all sampling must be done remotely by the people in the submarine. To do this, the submarine is fitted with two jettisonable, hydraulically powered manipulators. These “arms” have over six ranges of motion, making them quite manueverable. The pilot operates the arms using a joystick located within the submarine. This joystick is a long wand with joints corresponding to each of the six joints on the arms. Operating these manipulators requires great skill, and the Alvin pilots have practiced endless hours to perfect their abilities.

The basket measures 52x36 inches in size. There is barely an inch of unused space. Two Niskin bottles sit vertically in their holsters. When the pilot fires the triggers, the Niskin bottles clamp shut and trap 1.7 liters of seawater each. The water remains in the bottles until the scientists drain them when the sub is on the deck. Graduate student Alice Ortmann is filtering the water through fine mesh filters in search of microscopic marine viruses.

There are two boxes which hold the vent chimneys and animals that are collected. One of the boxes measures 12x12x12 inches, and the other is a bit longer (12x12x36 inches). In the past, the boxes have been called “coffins,” but chief scientist Craig Cary found the name to be too morbid and began calling his containers “bioboxes.” The boxes are equipped with lids that can be opened and closed using the manipulators when a specimen is retrieved from the sea.

One of the dive objectives is to collect some of the Vesicomyid clams (Calyptogena) for the deep-sea biologists who are studying the population genetics of these animals and their associated symbiotic bacteria. At the vents, the clams lay scattered in mounds of silty sediment. The pilot collects the clams using a 10-inch diameter net, which looks much like a butterfly net. This instrument, in addition to most other of the sampling equipment, is fitted with a standard “T” handle, allowing Alvin’s arms to grasp the instrument and maneuver it for sampling.

The Sipper is the name for the rosette of 12 glass syringes that are used to “sip,” or collect small water samples from specific areas of the vents. Connected to the Sipper by tubes and wires is a wand that houses a temperature probe, two electrochemical sensors that measure water chemistry, and two sipper tubes that suck the water samples up into the respective syringes on the rosette. Using the manipulator arm, the pilot positions the wand in a specific part of the vent . . . maybe under a flange or next to a clump of worms. This chemical sensor allows the scientists to measure the water chemistry in situ, or in its natural environment, and at the same time collect a discreet water sample that is chemically analyzed on the ship to make sure the in situ measurements are accurate.

Five sediment cores line the front of the basket. The pilot lifts the push cores from the basket with one of the manipulator arms and drives the core into the seafloor sediment layers using the hydraulics. The core is then lifted from the mud, and the bottom is capped to contain the sample. Although this sounds quite easy, collecting and preserving the cores during the dive has turned out to be one of the greatest challenges of this research expedition. Hopefully, they will collect good sediment cores tomorrow.

The scientists have checked and double-checked the Science Basket to make sure that all of the instruments are present and easily reachable for Alvin’s arms. If they forgot a piece of equipment, the sub would not be able to come back up to the surface in the middle of the day to pick up the forgotten pieces. All of these preparations are completed the night before the dive so that the pilot and observers can concentrate on the launch first thing in the morning.

Today’s dive was productive. Pilot Blee Williams and the science observers Melissa Kendall and Tim Rozan collected key samples for the rest of the group. They visited Robin’s Roost, K2, Kristin’s Summit, and Rebecca’s Roost during the dive. Chimneys and beehives (porous chimney structures that water diffuses through in many directions rather than through a single channel) were sampled for the microbiologists. Many chemical samples were collected with the sipper. They also collected five Calyptogena clams on the dive, which kept the vent biologists busy processing samples throughout the night. The dive objectives remain the same, but it will be interesting to see how they may change in the second half of the dive series.