Ready to go to sea? Here is the background information you'll need about the oceanography research Dr. Ian MacDonald and Dr. Will Sager (Oceanography, Texas A&M University) will be conducting during the 17-day cruise aboard NR-1. The general outline of the entire background section is as follows: What the cruise is about. What we'll be doing from NR-1 Laser-line scan images of chemosynthetic communities Finding seeps with side-scan sonar Salt, the Jurassic gulf, and the formation of seeps Faults, gas hydrates and brine pools Getting ready to go to sea Planning the cruise Cruise Maps Looking at some sonar images   Note: Some graphics in this section may be better viewed as PDF files with Acrobat Reader. You can download the latest version free. Every time you see , click on it and view a higher-resolution graphic. This cruise is all about hydrocarbon seeps. Natural hydrocarbon seeps on the seafloor of the Gulf of Mexico are special environments that oceanographers discovered only recently. At the seeps, oil and gas from far below the sea bottom bubble and stream out of cracks and fissures in the gulf floor. Seeps chemically enrich the nearby water and sediments, supporting lush chemosynthetic communities of tube worms, mussels, and other animals. These organisms live in total darkness, surviving off a food chain based on bacterial degradation of the seeping hydrocarbons rather than photosynthesis.   The "ice worm" is a member of the chemosynthetic communities that Texas A&M scientists will study. Mussels and starfish also live in the gulf's natural hydrocarbon seeps.   Tubeworms and a crab dwell in the seafloor ecosystem of the seeps.  On this cruise we are doing two things: 1. Creating huge images of the seep zones, including all their special features and the organisms living around them 2. Experimenting with a new method of locating yet unknown seep communities At three seeps where we know there are chemosynthetic communities, Dr. MacDonald will use a specialized survey tool called the laser line scanner to create the underwater equivalent of an aerial photograph of the entire seep zone. The resulting image should be so detailed that we'll be able to identify individual organisms. This is remarkable because normally you can't take an "aerial photo" through water. Most underwater photos can only show subjects a few meters away. The laser scanner can penetrate water much better, and by making several parallel passes over each site Dr. MacDonald will be able to piece together a huge image, covering an area of thousands of square meters. Images made with the laser line scanner will be much more informative than the bits and pieces of information we can gather by observing the seep communities from a submersible. Who knows what we'll discover?!  Next page

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Page updated 5/7/98
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