High-rise condos in 10 days!... Mariner revisited

Yesterday, scientists again sent Jason II down to the Mariner vent site.  One goal of the dive was to collect additional sulfide samples, but more importantly we were very excited to revisit the two thermocouple arrays that were deployed 10 days ago (See previous blog post:  South to the Valu Fa Ridge).  These titanium cages are set over actively venting black smokers to monitor the temperature and microbial colonization as the minerals precipitate and form a new chimney around the array. Each dive to check on these arrays, or recover them, is exciting and met with heightened anticipation as we are never quite sure what will have formed...  

The array shown in the photo above was visited first and we were very happy to see a brand new "chimlet" growing out of the array cage.  The white microbial biofilm can already be seen on the chimlet!  We decided to keep this array down a little longer, so stay tuned for details on what we recover in the coming days.  Nothing, however, could prepare us for what we were about to see as we approached the second array... If you remember one of our earlier blog posts, "A microbial home in 72 hours!", what formed on this array after 10 days can be more aptly described as a microbial apartment complex!  It even has vacancies for fellow organisms like shrimp and crabs!! 
We were able to recover the majority of the chimney structure and can't wait to "see" what our analyses tell us about the microbial inhabitants and geochemical formation.  A new array was placed in the same location that will be recovered after three days (see photo below).  Who knows what type of structure we can expect to recover?!? 

High Temperature Vent Fluid and Seawater Don't Mix

At least, they don’t mix without something remarkable happening – the near instantaneous formation of microscopic mineral particles. This is the “black smoke” you may have heard about and seen in pictures. A lot of people on this cruise are interested in what happens at the seafloor: what types of microbes are there and how they make their living, as well as how the mineral chimneys form. But some of us are interested in the “smoke,” which forms a “plume” as it rises 100’s of feet above the ocean floor. People have been looking at deep sea “smoke plumes” for years; but, because of some unresolved questions a few us* recently decided to take a second closer look at these “smoke” particles. So we sharpened our pencils and we lined up the best new laboratory methods for looking at such things and we even invented our own tool for getting samples from the parts of the “plume” that were hard to get to before. And we began the process of collecting and analyzing new samples. 

Now up until this cruise we had collected about sixty samples and completed a full analysis of just a hand full; but the really interesting thing has been that when we* looked at those samples with our newest tools (X-Ray Synchrotron Spectroscopy at the Univ. of California Berkeley’s Advanced Light Source) we found that they didn’t look anything like what we expected (Breier et al. 2009; Toner et al. 2009). The mineral particles were covered in “goo” – which is short hand for the more scientific sounding phrase transparent exopolymer – which is scientific jargon for organic carbon of an unknown origin. Basically these particles, which so far have all come from the high dispersing part of the “plume”, are what we call micro-aggregates of the mineral particles we knew about and the organic carbon that we didn’t know about. We don’t know where this organic carbon is coming from – it could be from microbial activity, or some mixing of mineral particles and the organic residues (body parts and excretions) common in seawater, or it could in some way be coming out of the vents.

If you want to know why we care, we’ll give you two reasons. First, if the formation of this micro-aggregate structure turns out to be common then it means the currently excepted conceptual model of “plume” formation (the two processes just described) is incomplete. It doesn’t explain the complete formation process and it doesn’t account for the different characteristics of a micro-aggregate versus a bare mineral particle. That’s important because a mineral particle covered in ‘goo’ doesn’t react with seawater the same way a bare mineral particle would; and, a micro-aggregate sinks much more slowly than an individual mineral particle – and can be transported much further away from a vent than they otherwise would. Second, particle formation in vent plumes is an extreme example of a more general process that happens in many other parts of the environment: rivers, estuaries, the surface ocean, and the middle ocean depths – a more general process that is a very important factor determining how chemicals move through the hydrosphere (scientific jargon for all the water on the planet). Plume particles are quite distinct from the particles that form in these other cases. But scientifically that makes them very useful because they may highlight parts of the particle formation process (microbial action for instance) that are less prominent in the other cases. Thus by studying these ‘plume’ particles we have the chance to learn something new and true for particle formation in all these other places.

*We are Chip Breier, Brandy Toner, Greg Dick, Karthik Anantharaman, Jason Sylvan, Sarine Fakra, Matthew Marcus, Katrina Edwards, Sheri White, and Chris German.

 Breier, J. A., et al., A suspended-particle rosette multi-sampler for discrete biogeochemical sampling in low-particle-density waters. Deep-Sea Research I (2009), doi:10.1016/j.dsr.2009.04.005

 Toner, B. M., et al., Preservation of iron(II) by carbon-rich matrices in a hydrothermal plume. Nature Geoscience 2 (2009), 197–201.

Green Thumbs on the High Seas

The bottom of the ocean here at the ELSC is a feast for the eyes.  The smokers look like beehives and wasps nests; there are low, wide flanges and tall spires that look like California redwoods.  And then there are the animals: snails, mussels, crabs, shrimp, sponges and a myriad of other fascinating creatures. But it's the diversity of what we can't see that brings many of us out here - we're here to study the microorganisms that live in the vent system. The Eastern Lau Spreading Center provides an ideal opportunity for microbiologists to explore whether the observed geological and geochemical differences along the Center influence the distribution of microorganisms.  One way we have been investigating the diversity of the microbes from this area is by trying to grow them in the lab. This is like trying to figure out if somebody you have never met before is allergic to peanuts. How would you know if they didn’t tell you?!  So, when trying to grow novel microorganisms in the lab, one has to be rather clever in trying to figure just what conditions they would like to grow under in the environment and then mimic that somehow in the lab. Conditions in the natural microbial world are much more favorable that in your sterile lab and in the glass tubes and incubators!

The very basics for growth are an energy source and a carbon source.  That’s how we start our detective work.  Then we decide what physical conditions might be conducive to grow (like acidity and temperature).  With a combination of conditions and many tubes of media (see photo above), we use the sulfide chimney samples as the inoculums.  In the photo below, you can see a sulfide chimney (in two pieces) with a white crust material.  This crust material is actually teeming with microorganisms!  We then incubate, and wait…

Once we have a microbe in culture in the lab, we can test it for all sorts of things.  For example, we can test the extremes of temperature and acidity that it can withstand.  We can also figure out how diverse it's diet is, and how it might be contributing to chemistry of the vent environment.  All of these things help us to understand why different microorganisms live in different places in vent environments.  And just like the animals that live in vent environments, there are many different kinds of microorganisms.  On this cruise we've got a large team of microbiologists, all looking for different kinds of organisms.  We each are targeting different energy and carbon sources, and different geochemical conditions using various kinds of media.  We’ll try to summarize our efforts…

Of course much of the vent fluid here is quite acidic, around pH 3.5-4, so many of the organisms people are looking for are acidophiles ("acid lovers"), but even these come in various shapes and sizes.  The Reysenbach group is looking for two different kinds of organisms.  One group is the Aquificales, organisms that actually gain energy by combining oxygen and hydrogen to make water!   Another group they're looking for are the DHVE (see previous blog post).  Karyn is looking for organisms that use organic sulfur compounds to gain energy.  Not much is known about these compounds in vent systems yet, but recent geochemical modeling suggests that they should exist in vent systems and that they could be a potential energy source for organisms in these environments.  Tatyana, Alex and Anna are targeting other interesting metabolisms, including methane oxidation, oxidation of simple organic compounds with sulfur and sulfate, and manganese and iron reduction.  In addition, Lise is even working on the microorganisms that feed on the colder rocks away from the venting structures.  We’ve had some positive and encouraging results, but growing microbes is a slow business, so hopefully we'll have an update for you later! 

One of our most successful culturing efforts has used the same approach, but with slightly different motivations.... Jon and Chris (from the Girguis group) have been using the same strategy for making yoghurt!  Their initial inoculum: some yoghurt bought by the ship for breakfasts; the energy and carbon sources: milk; the physical conditions: 37 C (~100F) and a few hours….

And we have “Boaghurt”!! Boat Yoghurt. It is quite yummy!

Thermoacidophilic Microorganisms of Deep-Sea Hydrothermal Systems

One of the main focuses of this cruise has been to continue studying the ecology of thermoacidophilic (heat and acid loving) microorganisms at deep-sea hydrothermal vents. This unusual physiology was first discovered in these environments following our last trip to the Eastern Lau Spreading Center (ELSC) in 2005. Specifically, Aciduliprofundum boonei was isolated and characterized from a sulfide sample collected from the “bench top” area of the Mariner vent field.  Photo 1 (above)- Electron photomicrograph of Aciduliprofundum boonei, from Reysenbach et al., 2006. 

What made this discovery so exciting was that thermoacidophiles had been predicted to exist in these environments based on geochemical models of sulfide chimneys but had never been identified prior to the characterization of A. boonei. Additionally, A. boonei belonged to a lineage of the Archaea (the deep-sea hydrothermal vent Euryarchaeota 2, DHVE2) that has only been found in deep-sea hydrothermal systems suggesting that some microbial species may be endemic to these environments as has been observed with several vent animals.  Photo 2 (below)- Phylogenetic relationship of the DHVE2 within the Euryarchaeota based on 16S rRNA gene sequences, from Reysenbach et al., 2006.

Since those initial discoveries, we have sequenced and analyzed the genome of A. boonei, revealing a strictly fermentative metabolism based on amino acids (proteins) as carbon and energy sources. We have also isolated several new species of the DHVE2 from the Mid-Atlantic Ridge (MAR) and the East Pacific Rise (EPR). Molecular techniques such as quantitative polymerase-chain reaction (QPCR) and high throughput pyrosequencing have revealed interesting insights into the relative abundance of the DHVE2 and community composition of individual sulfide structures along the MAR.  Photo 3 (below)- Example of a flange structure collected from the Lucky Strike vent field along the MAR in 2008 where the DHVE2 were found. 

Our goal for this current expedition is to continue building upon our data set on the occurrence and distribution of thermoacidophiles and how the geology of specific vent types help to shape distribution patterns. In this regard, the ELSC provides a unique opportunity because the underlying host rock varies from north to south and is different from both the MAR and EPR.

More about Jason II

Jason II

• Jason II is rated to 6500 m
• Longest Jason II dive on record - 96 hours
• Biggest limiting factor to the length of a dive:  oil.  (There are approx. 38 gallons of oil in Jason II at a time)
• Annual hours on the seabed:  ~2000
• Jason and accompanying equipment take up 5 shipping containers

Motors used to drive Jason II: 

• 6 thruster motors
• 1 hydraulic
• the motors are 5hp each; they are made by Kongsberg Simrad.  They have proven to be very reliable, and the electrical parts are cast in epoxy.

 Jason weighs 9800 lbs in air, but -50 lbs in water due to positive buoyancy.  The buoyancy is achieved by a 50 cubic foot foam block.  The foam is made of glass epoxy spheres.  Because of the positive buoyancy, Jason is actually driven to the seafloor at a rate of 30 meters per minute, rather than sinking.

Medea

Medea acts as a cushion so that Jason can move around freely and maintain a constant depth, without being affected by the ship's movement.  Medea is typically about 30 meters above Jason in the water column and contains two additional motors.

In the Jason Van:

• 51 monitors
• 15 cameras (10 on Jason, 3 on Medea, 2 on deck)
• 14 computers
• 2 A/C units
• 12 DVD recorders

 

6 people occupy the van when the vehicle is in the water:  3 members of the Jason team- a navigator, pilot and engineer; 3 members of the science party- a watch leader, data recorder and DVD recorder.

Elevators to the Deep

Jason II is able to stay down on the sea-floor for many hours exploring and sampling.  The average dive length is 21 hours, but we have had Jason down for as many as 30 hours in one dive.  As we collect samples during a dive, the sample baskets and bio-boxes (we affectionately call them "chamber pots") begin to fill with sulfide chimneys, flanges, and water samples.  In order to lengthen the time Jason can stay down, samples need to be swapped out so collection can continue.  Autonomous Vertical Transporters (AVT's), or "Elevators," are loaded at the bottom and used to send samples to the surface (see photo below).

The weighted elevator is dropped over the side of the ship and travels to the bottom.  Sample boxes and instruments are then carefully switched out by the Jason pilot.  When the ship is ready to retrieve the elevator, an acoustic signal is sent to it that triggers the release of the attached weights.  The elevator is then recovered by the crew and brought on deck using the ship's crane (see photo below).
Once the elevator is secured on deck, scientists are able to retrieve their samples.  In the photo below, Chief Scientist, Anna-Louise Reysenbach is removing sulfide samples from the elevator and Lucia Upchurch, Kristen Myers and Tatyana Sokolova are waiting to take them into the lab for analysis.

South to the Valu Fa Ridge

Scientists and crew have been working the past several days at vent sites along the Valu Fa Ridge (VFR), south of the Eastern Lau Spreading Center (ELSC).  The VFR is closer to the subduction zone, where the Pacific plate is subducting beneath the Australian plate in the Tonga Trench (east of the VFR).  As mentioned in a previous blog post, the composition of the substrate reflects this closer proximity as it is more felsic, indicating the partial melting of oceanic crust in the mantle below the VFR.

Most of our time has been spent at the Mariner site which is approx. 1910 m deep.  Hydrothermal chimneys here are much taller than at other sites, e.g. 27 meters, which makes exploring this site much more treacherous (see top photo).  Vent fluids at Mariner are hotter and more acidic (pH 2.6-2.8) than those at the vent fields to the north.  The hottest temperature recorded so far on the cruise (369˚C) was measured here at a vigorously venting black smoker (see photo above).  The increased acidity at Mariner makes it ideal for culturing thermoacidophiles (heat and acid loving microbes).  Mariner is also home to many fewer animals than other vent sites we've visited.  We observed mainly shrimp (see photo below) but did not see any snails.

In addition to collecting many samples of sulfide chimneys, two arrays have been successfully deployed here.
We also visited the Vai Lili vent site, where scientists sampled microbial mats rather than sulfide chimneys.  Microbial mats are dense accumulations of microbes, so thick that they resemble a mat.  In the photo below, we were measuring the temperature at the bottom of the yellow mat, which was 48˚C.

It's all in a name...

Deep-sea hydrothermal vents are structurally diverse systems.  Two kilometers below sea surface, Jason comes across 20m tall spires, puffy pillow lava, and projecting flanges - and everything in between, including some more creative formations.  Scientists onboard the R/V Thompson have taken to giving these structures "working names."

Back in 2005, when last exploring the Lau Basin, a structure was nicknamed "Bench Top" (photo above).  This structure proved not only to have an interesting formation, but was also microbially fascinating.  The first thermoacidophile (heat loving, acid loving) ever to be isolated from a deep-sea hydrothermal vent was from "Bench Top" samples.  It is in part due to those scientific findings around "Bench Top" that Dr. Reysenbach has brought the expedition back to Lau.  Yesterday, however, when the Thompson arrived at "Bench Top," its formation seems to have changed over the past 3 years.  We came across something that can only be described as "The Toilet," complete with water tank and seat cover (see photo below).  It will be interesting to determine the geochemical and microbial reasons behind such a modification.

Other nicknames include a beehive structure that looks like a "Christmas Tree,"

A cluster of spires called "Hogwarts,"
And a "Cappuccino" spire!

A microbial home in 72 hours!.. Kilo Moana revisited

The ship departed ABE after a very successful ~30 hour Jason lowering and steamed north, back to Kilo Moana.  Our primary objective was to recover the array that had been deployed to study microbial colonization of sulfides.  The array was in position over an actively venting sulfide chimney and we were very excited to revisit the site and observe the newly precipitated mineral material.  In the three photos below, you can see the array at 2620m and the array in the lab after being brought back on board.

In addition to recovering the array, we sampled more sulfide chimneys, flanges and a "beehive".  "Beehives", or "diffusers," are highly porous, protuberant structures where vent fluid seeps through and flows out as cooler (less than 350˚ C) clear fluid.  Due to the fragile nature of these structures, "beehives" are very difficult to collect and present one of the numerous challenges in recovering deep-sea samples.  On this dive, Jason pilot and expedition leader, Phil Forte, skillfully used the arm of Jason to nudge the "beehive" into the scoop!

ABE Vent Field

After leaving Kilo Moana, we headed south to the ABE vent field.  The ABE vent field is in a transition zone of the ELSC.  One question scientists on board are interested in answering is whether this is reflected by the composition of the microbial communities.  ABE is approx. ~180 meters shallower than at Kilo Moana, and has a more felsic substrate and slightly less acidic vent fluid (pH 4.3-4.9).  The Jason team was very successful in obtaining samples and scientists had a very busy night processing those brought on board.  Pictured below is sample of a sulfide chimney top being placed in one of the sample cylinders that sits on the front of Jason. 

The igneous rock, andesite (pictured below), is more felsic and silicious than basalt, and forms as the subducting oceanic crust (rich in minerals) mixes with magma.  We see an increase in the abundance of felsic vs basaltic substrate material as we get closer to the subducting zone.  

In addition to collecting sulfide chimneys, flanges, and water samples, an objective of the dive was to collect animals for the Girguis lab members on board.  Pictured below are deep-sea mussels, snails, crabs, shrimp and anemones.  

First Jason II Dive

After steaming 8 hours, the ship arrived at the Kilo Moana vent field, characterized by a basalt substrate, acidic pH (3.2-4), and a maximum temperature of 332 degrees Celsius.  Jason II headed down to an approximate depth of 2620 meters carrying empty sample boxes, multiple sensors and one of the thermocouple arrays, and was brought back on board 12 hours later with sulfide chimney samples and water samples.  Many large branching chimney structures were observed (photo below) along with many ledges, or flanges (see future blog post on the formation of flanges).

Scientists observe and document the events during a dive from the "Jason Van."  In the photo below, the watch leader, Meg Tivey (center), is looking on with the Jason II pilot, Will Sellers (left) and navigator, Bob Waters (right) as Jason II just reaches the Kilo Moana vent field.  

One of the objectives of this dive was to deploy a thermocouple array over the top of an actively venting chimney to investigate the colonization of microbes on newly precipitated chimney material.  Mineral precipitation occurs as the hot, acidic, mineral-rich vent fluids mix with the cold surrounding ocean water.  Thus, we can study the newly formed material on the thermocouple array (after recovery) and characterize the associated microbial community.

  

One of the big surprises when visiting Kilo Moana this time was the abundance of flanges.  In 2005, we did not observe any flanges.  This suggests that the geochemistry may have changed between 2005 and 2009.  

Setting Sail

The R/V Thompson set sail at 1:30 pm local time on June 12th.  Most people in the science party were able to take a short break and watch the ship leave the wharf in Nuku'alofa and admire the smaller islands on the way out to sea.

Why is Lau such an interesting place to study?

The spreading ridge (ELSC in the north, and the Valu Fa Ridge in the south), is farther from the subducting plate in the north, and gradually gets closer to the subducting plate to the south.  See image below.

Several other geological feature covary with this trend: the depth of the seafloor shoals from ~3000 m to ~1700 m, spreading rate decreases, lavas become more felsic, and there is a magma chamber reflector present only south of 20deg 30'S.

Thus, in the Lau Basin we can study how geophysical, petrologic, hydrothermal and biological factors along the ELSC and VFR differ as a function of distance from the subducting plate and as functions of all of the other differences that covary with distance from the subducting plate (including depth and lava chemistry).

Summarized in the Lau ISS Workshop Report, July 2006

ROV Jason II

The ROV Jason II will be used by scientists on this cruise to reach the deep sea hydrothermal vents.  The scientists will work alongside the Jason pilots to deploy seafloor instrumentation and take rock, water and biological samples.

Click here to learn more about the ROV Jason II. 

R/V Thomas G. Thompson

On June 12, 2009, the R/V Thompson will depart the Kingdom of Tonga and head to the Eastern Lau Spreading Center (ELSC).  The ship is owned by the U.S. Navy and operated by the University of Washington.  It will be home to 21 scientists, the team supporting the remotely operated vehicle (ROV) Jason, and ships crew for the next month as they sail along the ELSC, NNE towards Western Samoa.

Click here to learn more about the R/V Thompson.

ELSC Location and Regional Bathymetry

The Eastern Lau Spreading Center is noted by the red star on the map and the main island of the Kingdom of Tonga is represented by the red dot.  This image has been adapted from an original image credited to Fernando Martinez and Brian Taylor of the University of Hawaii.

Research Objectives

The two primary objectives of this research cruise are:

1.  To study the microbial ecology of actively venting sulfide deposits along the Eastern Lau Spreading Center.  This will include exploring the patterns of functional and phylogenetic diversity associated with sulfides, and culturing a range of different thermophiles, including thermoacidophiles.

2.  Investigate the temporal and spatial microbial colonization of sulfides.  This will involve deploying thermocouple arrays on hydrothermal vents, and collecting the fresh deposits at different periods of time for microbial characterization.

Invited ancillary project goals:

1.  Analysis of rising hydrothermal vent plumes, focusing on the process of particle formation, it's affect on seawater chemistry, and it's relationship to water-column microbial activity.

2.  A study of the physiology of vent organisms and their symbioses.  This will include measuring metabolic rates and conducting high pressure respirometry studies, thermal tolerance studies and chemical tolerance studies at in situ conditions.