NeMO September 2, 2003

Logbook: September 2, 2003

45° 55.6' N, 129° 58.8' W
Air temperature 62°F, 1700 PST

Dive R738 was another successful dive. Four transponders were cut loose by ROPOS. Three were bundled together and released to the surface. The Thompson and ROPOS crew used a grappling hook to grab them from the water and haul them on board. The forth transponder came up with the vehicle. The transponders are used to navigate the remotely operated vehicle. A CTD was performed after the dive. At 0420 this morning ROPOS went back in the water for its first hot fluid sampling dive (R739). Most vents at the ASHES vent field were sampled, as well as two hot vents on the east side of the caldera. In addition to fluid sampling, two temperature probes were deployed and two suction samples for biota were collected. The dive has just finished. The next task will be to deploy three refurbished transponders on the north edge of the caldera in preparation for a dive there in a few days. The refurbished transponders will replace those that were recovered yesterday.

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Aug/Sep 2003

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Nick Delich, PMEL engineer, and a transponder. The transponders are used to navigate the remotely operated vehicle over the seafloor.

Teacher's Report
Bill Hanshumaker, Educator at Sea

Researcher Interview:
Amanda Bates
Graduate Student in Biology at the University of Victoria

Amanda Bates, graduate student in the biology department at University of Victoria, stands beside the gastropod pressure chamber (lower right.

Bill:
What is the focus of your research on this cruise to Axial Volcano?

Amanda:
I am interested in the distribution of three different gastropod (snail and limpet) species found in the vent systems. These three species are found in different vent habitats and I want to discover if they have different temperature preferences. I chose temperature because it is correlated to oxygen, pH, sulfide, and vent flow rate and these are factors that define habitats at the vents.

Bill:
How do you study these animals?

Amanda:
Initially I used a vertical pressure chamber, but these snails are geotactic (orient to gravity) and when you bring them up to one atmosphere their impulse was to climb up. I needed to set up a horizontal pressure chamber with a temperature gradient that has a high to low range. I also designed similar chambers to use underwater at the vents.

The ROPOS claw holds the hot fluid sampler probe in a "bee hive" at the top of Inferno vent.

Bill:
Where do you go from there?

Amanda:
It's intriguing because a really hard thing to know is when to stop an experiment. When is there an endpoint? In my first experiment on the Thompson, I used three species of gastropods and let them acclimate at 4 degrees in our walk-in cooler. Then I increased the temperature up to 12 degrees and they scattered. Next I heated up one side to 35 and cooled the other to 2 degrees by continuously adding ice to the other side for 5 hours. What I found was neat! For the first hour the animals moved down the chamber remaining in the 20-degree range, but they didn't move into water that was warmer than 20 degrees. But after three hours they all moved to the area in the chamber where the water was 14 degrees. What I'm doing now is replication over a smaller temperature range of 20 to 2 degrees and see where they go after 5 hours. I hope to use this information to determine why these animals are found in different vent habitats. My current hypothesis is that temperature can define the habitat where each species is found.

Bill:
What are the names of the species that you're studying?

Amanda:
Aside from the Provanna snail (Provanna variabilis), there's the glob snail, Depressigyra globulus and Lepetodrilus fucensis, which can reach incredible population densities. It's called a limpet because of its shape, but isn't related to the limpets that are common in the intertidal zone.

Bill:
Well, you've been up all night and only had three hours of sleep before then. It must be as stressful on you as on the limpets.

Amanda:
Well, you might get that idea, but this is really exciting. Doing experiments at hot vents and on ships at sea is very challenging. Designing an apparatus that can be handled with an ROV, and yield clear results is difficult. Plus ship time is limited to once a year. I've been really busy this year and have spent the last three months training in molecular work. I'm really interested in the bacterial symbiants that are found in the gills of gastropods. I think that some species are "farming" these bacteria and moving them into their gut. I spent four months planning experiments for this summer, which are probably the most complicated thing that I've ever executed. But if the results are clear, then the reward is sweet!