I’m Brian Glazer, an associate professor of oceanography at the University of Hawaii. My lab group specializes in understanding how chemical cycles influence and are influenced by microbes. I’m currently on sabbatical this year, on fellowship with the Hanse-Wissenschaftskolleg Institute in Germany, but I’m participating on this expedition because of the exciting opportunity to work with friends and colleagues at an amazing site, and use some cutting edge tools like ROV Jason II and AUV Sentry. This is my 19th oceanographic expedition, 7 of them with Jason II. It’s also my 5th expedition to Loihi.
The hydrothermal environments at Loihi Seamount serve as an ideal natural laboratory for studying aspects of geology, chemistry, and biology. Heat energy from Earth’s interior warms basalt rock that interacts with deep subseafloor circulating seawater, altering its chemistry. That altered fluid rises back to the seafloor, and microbial communities take advantage of the chemical energy in the fluids, and in the case of iron-oxidizing bacteria, they leave ferric oxyhydroxides behind (bacteria growing & producing rust in the process!). The synergetic relationship between fluids, rock, and microbes that results in such visually striking vents and microbial mats at the seafloor is an expression of subseafloor processes occurring within the rock; the rock is alive!
Ultimately, the rust that the bacteria leave behind may even be preserved in the rock record, helping us learn something about the biology & geology of earlier times on Earth…and it’s really tantalizing to speculate about potential for such geological-chemical-biological relationships on other planets like Mars & Europa. The active volcanic pit crater at the summit is at about 1100m below the sea surface, which intersects the oxygen minimum zone in this region of the Pacific, and provides optimal conditions for iron-oxidizing bacteria to thrive. We’ve estimated that between ten million and four hundred million cells per square centimeter per year could be supported by the iron-oxygen energy flux commonly found in the pit crater area. This could equate to about 20 kilograms of biological carbon per day. Hydrothermal microbe math, yay!
In contrast to the warm, actively venting habitats at the summit (shown above), we’ve also located a new ultradiffuse hydrothermal field at the base of the volcano in 5000m water depth. During a combination of this expedition on board R/V Thompson, and a planned expedition on board R/V Falkor in 2014, we will compare and contrast the geochemistry, microbiology, and geologic settings between summit and deep sites. We hypothesize that the cold, deep mats found at FeMO Deep are a microbially-controlled genesis of geologic-scale iron deposits similar to umbers found in the rock record. Over the course of several dives, we’ll use a variety of high-tech and low-tech in situ analyzers, samplers, and data recorders to collect as much physical, chemical, and biological information about our sites as possible. Days are long, and the schedule is busy, but very rewarding. Here’s what a typical day at sea is like for me early on in the expedition:
06:00 – wake up, shower, make a double cappuccino
06:30 – check the computer lab whiteboard & the Jason Virtual Van for a quick check of where we are on the current dive plan. My group has the lead for characterizing the geochemistry of fluids and particles collected from various Loihi sites, so we divide our time between our scheduled shifts in the ROV control van running in situ electrochemical analyses, and preparing for or analyzing discrete samples that are brought up by Jason or elevators. There’s always lots to do, and it can sometimes be a little confusing to try to get up to speed after catching a few hours of sleep.
06:50 – a quick lesson on the new navigation system from the AUV Sentry team. While the ship is very maneuverable and can be positioned precisely by using GPS, GPS doesn’t work underwater. Jason and Sentry have to rely on acoustic signals from the ship in order to precisely navigate their positions on the seafloor. The first task when we arrived on station was to calibrate the ship’s GPS navigation system with the ultra-short baseline navigation system (USBL) underwater acoustic navigation system by dropping a nav beacon overboard and having the ship do figure 8’s back and forth to coordinate the two systems.
07:25 – breakfast of fruit, cottage cheese, pancakes, bacon, and, of course, more coffee.
07:45 – fluid sampling team meeting to review objectives, and finalize protocols & subsampling methods. For this expedition, our fluid sampling and analysis team consists of me and my two postdocs, Angelos Hannides and Arne Sturm, and collaborating scientists, Karyn Rogers (Carnegie Institute of Washington), and Jason Sylvan (University of Southern California). In addition to the in situ analyses explained below, we have a suite of fluid and particle analyses that we’re targeting in order to better understand the synergy between the Loihi heat source, rocks, hydrothermal fluids, and the microbes that colonize the vents, walls, and chimneys.
09:00 – adapting inline filters for the in situ mat sampler syringes with Dave Emerson and Jared Scott. In addition to collecting whole samples of a mix of particles and fluid, we’re really interested in sampling just the pore fluids, independently of the particulates. This will allow us to be sure that the chemistry that we measure on the samples isn’t compromised or contaminated by fluid-particle interactions within the syringe after collection. This is the first Loihi expedition for the new mat sampler (developed by Chip Breier, WHOI), so we met to work out some possible ways to try it.
09:25 – checking the in situ electrochemical analyzer (ISEA) on the ROV Jason science basket and finalizing cabling with Jason pilot and science basket management guru, Jimmy Varnum. Any instruments that go on the ROV have to be secured, checked, double-checked, and safely and neatly arranged on Jason’s science basket for optimal utilization on the seafloor. It’s a refined, somewhat miserable, but rewarding art, and Jimmy is the best in the universe at it. The ISEA is a custom e-chem analyzer designed by Don Nuzzio of AIS, Inc. and optimized for deep-sea operations through years of close communication and collaboration. We deploy custom, hand-made sensors on every dive that allow us to measure a suite of redox reactive chemicals in real time. At Loihi, measuring iron concentrations in situ gives us the capability to guide discrete sample collection and decide how/where to make collections or deploy incubation experiments.
10:00 – electrode polishing. My lab specializes in applying voltammetry to aquatic environmental biogeochemistry. We make custom solid-state voltammetric microelectrodes for deployment on the ISEA for every ROV lowering. They consist of a 100-um diameter gold wire, sealed in epoxy, carefully hand polished, and coated in a thin film of mercury. By applying a voltage to the mercury film, we can measure a current response peak for any detectable chemical species, and the current peak height is proportional to its concentration in the fluid. Voltammetry is a technique that has been used in a lab environment for many years, but only optimized for in situ applications over the past 10 years or so. More coffee and good music is critical to the electrode polishing process.
10:30 – temperature logger assembly. Many important biological and chemical processes are influenced by temperature in hydrothermal environments. At Loihi, we typically encounter temperatures as high as 40-50oC in the more vigorous flowing vents, while the more diffuse flow areas are in the range of ~25 oC. During this expedition, we’re deploying a combination of temperature data loggers from RBR and Antares.
11:15 – fluid sampling team recap of titanium major samplers (or majors for short). Titanium syringe samplers were designed especially for collecting hot fluids, up to 400oC, from hydrothermal environments for measuring most major ions. They are robust and reliable samplers that work well with the ROV manipulator arms, and their somewhat complex cleaning, assembly, and disassembly procedures have been a bit of a right of passage for sea-going hydrothermal scientists for decades.
11:30 – lunch
12:00 – prepare & mount helium sampler. Collecting samples from deep hydrothermal fluids for gas analyses is challenging: PV=nRT! In some cases fluids at deep hydrothermal sites could contain 1000-fold gas concentration, compared with surface waters. At Loihi, we’re especially interested in measuring helium isotope ratios, and are collaborating with colleagues at the University of Bremen (Dr. Jurgen Sultenfuss) who has developed a prototype gas sampler for in situ collection using the ROV.
12:30 – more coffee, more voltammetric electrode polishing.
13:00 – science meeting. The whole science party tries to meet every few days or dives to allow for coordination of individual groups’ science plans, go over any concerns or new requests, and plan the upcoming few dives.
14:00 – mount helium sampler on Jason basket. Again, Jim Varnum is the man with the plan, and fashions a sturdy mount to allow for the gas sampler to be launched, recovered, or carried on the ROV.
15:00 – mat sampler fluid & particle subsampling discussion. Many different kinds of in situ & lab measurements, and discrete samples are being collected. Typically, one person is placed in charge of coordinating distribution of fluid & particulate subsamples to each group from each kind of sampler (e.g., mat sampler syringes, scoops, slurps, titanium majors, etc.).
15:15 – elevator & ROV configuration planning. Both scientists and ROV engineers alike prefer for the ROV to stay on the bottom doing work for as long as possible. In order to enable cycling certain samplers and samples between the seafloor and the ship, we use an independent elevator like a shuttle between the ship and seafloor. Various samplers will be mounted on to the elevator on deck, the elevator is dropped over the side, freefalls (after careful weight vs. buoyancy calculations), and lands on the bottom in the general working vicinity. Jason flies in to the elevator, swaps out samples for empty samplers, releases the elevator to the surface, and then continues working, while the elevator is recovered to the ship and samples are processed in the lab. For this to work most efficiently, careful diagrams of what samplers are in what containers on which vehicle and at which site have to be coordinated.
15:45 – Jason pre-dive check and science instrumentation check. Just like a team of engineers and pilots run through a series of equipment and instrumentation checklists before a place takes off, the Jason team tests all vehicle systems before launching in the water. Likewise, any scientific instruments that communicate through the Jason (like the ISEA) are tested one last time before launch.
16:15 – yes, more coffee
16:25 – resume preparing more voltammetric electrodes with Arne.
17:15 – dinner
17:30 – resume preparing voltammetric electrodes with Arne.
18:30 – prepare two more temperature data loggers for deployment on Jason.
18:45 – final check of elevator configuration before elevator launch.
19:30 – mount electrochemistry wand to ROV. The ISEA runs the voltammetry, but the voltammetric (and temperature) sensors have to reach out away from the vehicle basket to the sites of interest. The ROV manipulators are very strong, and anything that gets held, moved, or operated by the ROV needs to be robust and anything cabled to the vehicle needs to also have a well-designed cable management strategy. We typically mount 4 replicate voltammetric electrodes along with a high-resolution temperature sensor on an electrochemistry wand with a T-handle that the Jason pilots can then position using the manipulators. But, the voltammetric sensors are vulnerable to dirty on-deck conditions, as well as air, so we make every effort to keep them clean & enclosed in deionized water until right before vehicle launch.
20:00 – ROV Jason launch, descent, finding the elevator, and finally, conducting super cool science at 1300m (or more) below the sea surface!
02:00 – off to bed for a few hours, …then repeat various tasks, …for a couple weeks…
Photo credits: subsurface photos from the Jason control van; other photos Brian Glazer unless otherwise specified