What is really down there?

After the last few posts, I wanted focus this one on what we see at 2500 meters under water.

First, a little science lesson on plate tectonics:

We have studied plate tectonics in school in marine science. I am now studying hyrdothermal vents at the East Pacific Rise. The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from (north to south) the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate.

Along the East Pacific Rise, you can find basalt pillows that demonstrate sea floor spreading, literally new rock formed from volcanic eruptions on the sea floor. To live here, you must be able to live in total darkness, be able to live in an environment that is so hot in places that it would cook other living things, and make your food from chemosynthesis - where the center of this food chain, the plants, so to speak are tube worms. These tube worms have a symbiotic relationship with bacteria who produce sugars in a chemical reaction where they oxidize and reduce ions of manganese, iron, and sulfur.

These reactions form "chimneys" of minerals that either are very hard or can be so fragile that they break when you touch them. Vent water pours out of these into the cold, dark water.

Black smoker vents are central to the life that exists here. The surrounding water is only about 2-4 degrees celsius, but the vent water can be as high as 375 degrees celsius or higher - well above the boiling point at normal atmospheric pressure.

There are several of these active vents in the location where we are. The water coming out of these vents is extremely valuable to the research being conducted by the scientists on this ship.

Once the ALVIN gets to an active vent site, one of the first things to do is to take a temperature reading. When the temperature is deemed adequate, the port (left) arm of the ALVIN takes a major sampler (hey, those look familiar) and collects water from the vent.

Samples of rock are collected with bacterial mat samples and small tubeworms called alvinella, some of the first colonizers to an area around a hydrothermal vent.

Of course, the real stars of the show are the Riftia pachyptila or "giant tube worm." These are the animals that I showed dissecting in yesterday's blog. Riftia feed only on internal symbiotic sulfide oxidizing bacteria. Actually, the bacteria make sugars that feed the worm. Their tubes are made of a chitin-protein system. In the picture, you can see mussels clinging to the Riftia as well as a zoarcid fish.

They are truly beautiful animals. They have blood with a pH similar to our own. Here are a few more pictures of these amazing animals. They can grow to lengths of 1.5 meters.

Our researchers are interested in the chemistry surrounding the riftia. Temperature is again taken at different spots along the riftia.

Once we take the initial temperature readings, we again sample the water around the riftia. They like water just a little cooler than the hyrdothermal vent, but can only live near it due the "food" they obtain from it in the form of chemicals.

Using a chemical "wand" we can determine the amount of materials present in the water around the sample.

This sample is taken in relatively cool water - 60 degrees celsius!

I took these images from the 6+ hours of video we collect per day. I will be making a highlight video that I will be showing in class when I get back. Making the video is another one of my responsibilities while at sea. Stay tuned!

After dinner this evening, I also worked with the crew of the Atlantis to run another CTD cast. The device is lowered over the side and water samples are taken to determine pH and salinity at various depths.

This takes a few hours to complete. Makes me feel like I am part of the crew!

Here's a little video clip of us putting it over the side.

It has been an amazing day. I can't wait for tomorrow!

Images courtesy of Woods Hole Oceanographic Institution and Dr. George Luther, University of Delaware.