by members of the Microbe Team
One of the main tasks for the Microbe Team is the harvesting of water from different sites along the reefs at each atoll visited. These water samples are our mainstay, the first step required for virtually all our work. When we later process and analyze the samples, we can get:
- The numbers of microbes and viruses per unit volume.
- Sufficient collected microbes and viruses for DNA analysis to characterize both communities.
- The concentrations of nutrients and dissolved organic carbon (DOC).
- Isotope data to determine if there is human-derived fertilizer (a pollution indicator).
Collecting water from specific locations underwater is not simple. We use special collectors devised by wizard and “toy” builder Mark Hatay who works with the Rohwer Lab at SDSU. We call these collectors Niskins because they are modifications of the Niskin bottle invented by Shale Niskin in 1966 (which in turn was a modification of the Nansen bottle invented by Fridtjof Nansen in 1910). They really should be known as Hatays, or maybe H-Niskins, but the Niskin name has stuck. The original Niskins were designed for remote use at great depths, provide only approximate control over location and position, and, worse yet, are made of materials that leech chemicals that are toxic to microbes. Mark’s devices are designed to be used by SCUBA divers to collect clean water samples from precisely 1 meter above the coral surface. Each is a polycarbonate tube with caps at each end, materials that are compatible with the chemistry and the biology of seawater. When capped each holds 2 liters of seawater.
Back on board the ship, the contents are typically filtered to collect the viruses and microbes for study. For this step, the Niskins are mounted in a custom Mark-designed filtering platform that uses air pressure from a SCUBA tank (the one constant form of power that we have in the field). The innovative Niskins and the filtering apparatus built by Mark have been deployed literally around the world.
For this trip, Mark redesigned our Niskins so that they can be used as ultra-big syringes to sample the water inside the benthic tents dubbed cBATs by microbe Tracey McDole: collapsible benthic analysis tents. (For cBAT pictures and info, click here, here, or here.) Oh, Mark also had to design and build the tents. This was a major endeavor that took several months, but well worth the effort because the tents are the main experimental tool for all the measurements being made by the Benthic Team on this cruise. So both the Benthic and Microbe Teams owe Mark for the equipment that is making this cruise work.
Editor’s Note: I thought it might be interesting to see how all this looks from Mark’s point of view, so I e-mailed him, asking a few questions. He replied in fine style, excerpted below.
Another Point of View
by Mark Hatay, “toy” builder par excellence for the Rohwer Lab, SDSU
Working with people like Jen and Forest is very interesting, fun and rewarding, but not for the squeamish! It starts out with “we are going to answer this question that has no answer, using equipment that doesn’t exist.” This is delivered accompanied by a bunch chicken scratches on napkins, much hand waving, and a whole bunch of stuff I don’t really understand. But no matter what they say, I respond, “No Problem! We can do it!”
This is not a flip response. I have learnt that there will be hundreds of hours spent detailing the project, but first and foremost it needs to take on a life of its own, and that doesn’t happen by shooting it down before it ever has a chance. It is the commitment of a group that will succeed. All great ideas sound unreasonable when first asked. Engineers like to stay within the clearly defined realm of reality. Scientists need to think way beyond the comfort zone. So my job—to have a foot in both worlds. The project will take a long and winding path, and the end product never looks like what we originally envisioned.
So you asked me what was involved to make the cBats. Let me see….I remember being overwhelmed. Yes, then I got a few ideas and it was better for a while. Talked to Jen and got overwhelmed again. Ran out of time. Panic! Do whatever is necessary, so much is riding on this! Life becomes a blur……then IT’S DONE!!!…followed by…well, now what?
Ya, something like that. Funny, I really can’t remember what happened, I bet its some self-protective brain thing. But, you know, I’m kind of pleased with the tents and how they turned out, can’t wait to see how well they work and how the divers like (or don’t like) working with them.