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Logbook
July 9, 1999

Contents:

• News from Thompson
• Participant Perspective
• Logbook from Teacher at Sea
• Question/Answer from shore to sea

Science Report - Friday, July 9
Ships Location: 45 56.1/129 58.9

Deployment of the osmosampler at Magnesia Vent.

The objectives of ROPOS dive 499 were to collect additional fluid samples at several vent sites, deploy the OSMO sampler at Magnesia vent (photo right), and collect biological samples at some of the vent sites that exist in older lavas around the 1998 lava flow. These older sites are of interest to see if they are providing larvae for vent animals that are colonizing the new lava flow. Last year, different assemblages of species had colonized different vents on the new flow, even if they were nearby each other, which was a surprise. This year, the dominant species have spread over larger areas and there are more similarities between the new vents, but there are still some vents that have much different animals than others. This story of how vent animals colonize a patch of brand new seafloor will be an interesting puzzle to sort out in the years to come. Dive 499 had to be suspended when a hydraulic end cap burst, but it was quickly resumed after repairs (as dive 500, a milestone for ROPOS!) and will continue into the night.

Listing of all Science News postings

Kim Wallace
Canadian Scientific Submersible Facility

Its three in the morning. I could see my breath if it wasn't raining so hard and the wind makes a misery of working under a tarp stretched over the cage. Fluid-4 and salt spray is keeping my hair in place. Im wet, tired and I'm grinning; our ride is ready . However it may look from behind the yellow line, this is the fun part.

For the ROPOS guys taking this puppy to sea is the tangible expression of our ever-expanding technical aspirations. Here at Axial we have the opportunity to test our mettle, and that of the machine we have put together, against some of the most intense environmental stresses imaginable: on the hearth of a blast furnace at the bottom of the ocean. Most of the time we win.

Notice I can't say much without saying we. That's another reality out here. We are a team as close as any family. We are here to operate and service the vehicle, twenty four hours a day, for a month. Can you name six people that you could live and work with for that long without going crazy?

On the beach were dealing with budgets, schedules, suppliers, customs and, on a good day, design problems. At sea we leave a lot of that behind. This is where it all comes together. Its a little intense and a lot rewarding.

This is the fun part.

Listing of all Perspectives postings

Thompson Teacher at Sea Log

Teacher Log #19 7/9/99

Animal seen at CASM vent; most likely a sponge.

The most important thing to remember about hydrothermal vent ecosystems is that we are still in the research and discovery stage. Researchers interested in the biology of the vents are still busy counting and identifying organisms (photo right). A more complete understanding of this unusual ecosystem requires an in-depth analysis of all the intra- and inter-species relationships.

The organisms that are most common to all vent sites are the various forms of microbes, bacteria and archaea. Fluid samples of the vents and suction samples of the surface show an abundance of these microorganisms. The macrofauna (larger animals) are the most visible of the hydrothermal vent ecosystems. Each vent with its own peculiar chemical signature and temperature, creates an environment for specific creatures. Any vent site may have any number of smaller communities each with its own diversity of organisms.

Palm worms overlaying tube worms; palm worms behave agressively towards each other.

Common animals observed at many sites include snails and limpets. These are hearty individuals that graze on the microbial mats, which grow most everywhere. Limpets, snail-like creatures with a single domed shell on their back are sometimes found in the thousands on rocks. Other grazers include sulfide worms. These worms are known for their uniquely aggressive behavior towards each other. Whether its has a territorial or reproductive connection is not known yet. These worms use both tentacles and gills for feeding. One question that researchers are trying to answer is what exactly they are feeding on. Aside from the grazing animals, you will also find filter feeders in the vent environment. Particles suspended in the sea water and vent fluids supports the numerous suspension feeders that exist here. Palm worms, named due to their palm tree like looks, can be found wherever drift or suspended particles can be seen. They can often be found on the tubes of the tubeworms (photo left). Their palm like tentacles can be also seen undulating within a stream of vent fluid, as they go about collecting possible food particles. Clams found in these areas often have symbiotic bacteria within them. The mechanism for this is not well known. Do they take just fluid or is the particulate matter also important for them. Sea anemones can also be found at some vent sites, but they are mostly located along the periphery of a site, rather than near the vent fluid.

Carnivorous species also exist here but are found in smaller numbers. Within the tube worm bushes, crawling about on open surfaces and even swimming, scale worms, centipede like creature with scales on their backs can be found in large numbers (some species are grazers as well). Nereid worms are not as commonly seen, but make up an important link in the transference of nutrient energy. Crabs and octopi can also be seen here searching for a meal, as can vent fish and the ever common rattail fish.

The most unique of the organisms at hydrothermal vents are the tube worms. These creatures, which have no mouth or anus, are known to have large numbers of bacteria within their tissues. This unique relationship (symbiosis) is believed to benefit both organisms - bacteria get a suitable environment to live and the worm takes advantage of the chemosynthetic properties of the bacteria for it nutrients. The most noticeable part of the tube worms are the bright red gill plumes that extend from the tops of their tubes. This gill plume is believed to absorb the vent fluid, which is then spread throughout the body of the organism, thereby feeding the bacteria.

The end of our cruise is quickly approaching. ROPOS is on the way to the bottom for its 500th dive! Will update you on its results tomorrow.

Bye for now.

Logbook of all Teacher At Sea postings

Questions from HMSC auditorium audience:

1) Have any dna studies been done on the sea floor critters to see how much their dna has diverged from sea surface critters? That is, do we have any idea where they fit into the ancestry chain?

Comparison studies looking at the ancestry chain have not necessarily been done using DNA but rather from fossils. It appears that most seafloor critters are newer than sea surface critters - that is that the modern sea fauna came from above.

2) Are any precious metals turning up in the rocks?

(Also see information in the 7/5/99 Perspective)
The 1998 lava flow is made of a volcanic rock called basalt. Generally, there are no precious metals in basalt, although one of the minerals in basalt is olivine, which is called peridot when it is gem-quality. This is rare however (there is no peridot at Axial volcano). On the other hand, there are precious metals in the sulfide chimneys that form at hydrothermal vents. When seawater circulates down into the ocean crust and gets heated up in volcanic areas, the heated water leaches out many elements from the rocks and these get concentrated in the vent fluids. Where the hot water exits the seafloor and mixes with the cold bottom water, it immediately cools and precipitates minerals which build a sulfide chimney around the vent orifice. Elements such as zinc, copper, platinum, silver, and gold can be concentrated in hydrothermal sulfide deposits. It is unlikely that it will ever be economical to mine hydrothermal deposits on the seafloor, but there are many mineral deposits presently mined on land that were formed long ago on the seafloor. In fact, the study of the active ore-forming processes at hydrothermal vents has helped geologist better understand how these ancient deposits originally formed.

All Questions/Answers from sea
Send Your Question to NeMO
(oar.pmel.vents.webmaster@noaa.gov)

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