On Location Aboard Alvin: Fifth Dispatch

Wednesday, May 19

(Click on the image to see it full size)

This is a picture of some of the crab traps that are being deployed at different sites within the 9 North vent field. photo of crab traps on the bottom of the sea

The news of the day (aka more detail on the crab traps):

A group of researchers from the University of Delaware is collecting crabs and growing them on the surface in high pressure aquaria. Their goals is to gather information about the life history of vent crabs (Bythograea thermydron) to begin to answer questions about the dispersal of crab larvae to newly formed vent communities.

In practice this means setting traps using canned sardines or ordinary cat food as bait. The traps are attached to the basket that is used to hold science gear on Alvin and then are set at different locations on the bottom. Some of the traps are set in the middle of a patch of Riftia (see photo) while others are set away from the areas that contain active hydrothermal venting.

After the traps have been sitting on the bottom a few hours or up to a few days, they are brought back to the surface when crabs have been trapped inside the cage. After Alvin has been brought to the surface, the crabs are rushed into a cold room and put into specially designed aquaria. These aquaria are not open at the top like the type that you see in pet stores. Instead they are designed to be pressurized to 1500 psi so as to mimic the conditions seen by the vent crabs on the bottom.

On today's dive Ana Dittel is diving and is going to several different areas looking for adult crabs and young crabs. She is hoping to find young crabs for experiments here on the ship and to bring back to the University of Delaware. At the moment, the sub is on its way to the surface. I hope that the time that she and her graduate student, Gina Perovich, spent baiting traps this morning will pay off because it looks like a messy, smelly job.




Other dispatches:

First dispatches from May 8th, 10th, and 12th
Introduction to Alvin, and the first launch!

Second Dispatch - May 14th
Tubeworms:the poster child of deep-sea hydrothermal vents

Third Dispatch - May 15th and 16th
Gathering samples from the bottom of the sea...

Fourth Dispatch - May 18th
Incubators...and the Rusty Riftia Story...

Fifth Dispatch - May 19th
Crab traps...

Sixth Dispatch - May 24th
The Pompei worm (Alvinella pompejana)

Seventh Dispatch - May 26th
Several pictures were received today showing how scientists are examining changes in the temperature of a vent over time.

Eighth Dispatch - Second from May 26th
Some excitement today! A dive is aborted!

Ninth Dispatch - May 27th
Update on the aborted dive, and a Researcher's typcial day aboard ship....

Tenth Dispatch - May 28th
Krista's research about beehives! (Undersea ones....)

Eleventh Dispatch - May 29th
Throwing a DOG overboard...

Twelfth Dispatch - May 30th
Setting up the equipment basket before a dive...

Thirteenth Dispatch - May 31st
Life at sea: leisure time...

Final Dispatch - June 3rd
Heading home...




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