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“Hey, you guys….”*

September 24, 2012

September 22, 2012:

The danger of nets

A picture of wreck diving: the danger of abandoned trawl nets, a historically significant vessel, and unique biological communities.

We visited two submarines from the Billy Mitchell fleet today! Yesterday’s tedious work on the cable paid off and the ROV crew was able to launch on time this morning. Dropping steadily through the increasingly dark blue waters, I am quickly confronted with the realities of wreck diving. Materializing out of the darkness so slightly at first that you think your eyes are playing tricks on you, and then suddenly blindingly clear as the lights of the ROV strike something other than water, walls of thick netting and tangles of longlines appear. Unfortunately for fishermen and archaeologists alike, fishing vessels have found these sites long ago with their gear and were forced to cut their lines and nets free. The heavy bottom weights of trawls in particular, have led to significant degradation of the historical sites. Now the spider web of nets and drifting line presents a dangerous and tormenting situation for the ROV crew and archaeologists alike…they are constantly left wondering what additional details they might be able to see if they could only fit through “there” or “around that corner” or “under that layer” without getting the ROV entangled. Everyone dreams of miniature cameras.

It has been a humorous learning experience working with two groups of researchers with different objectives. Dr. Rod Mather describes the work of the archaeologists as similar to that of a doctor. When you go in for a visit feeling ill, the doctor takes your blood pressure, listens to your heart, and looks in your eyes and ears, taking a series of diagnostics that provide clues as to what might going on with your overall health.  Archaeologists do essentially the same thing when exploring shipwrecks (or historical buildings). They look for and hope to find particular structural features of the U-boat (or ship) in question so they can positively identify the site, unique features (e.g. the absence of deck guns), and artifacts of historical significance, with the overall goal of documenting and preserving. Watching the live video feed from the ROV, you can tell if an archaeologist is “driving” if they hover on bolts and cylinders and portholes. On the other hand, the natural scientists approach the ocean floor and wrecks like the first explorers of a new world. They hope to document the unique diversity of plant and animal life, the behaviors of the inhabitants, the vast array of natural resources, and environmental conditions that characterize these rarely seen locations. They appreciate wrecks for the exceptional “structure” they provide to the biological community beneath the surface. Watching the live video feed from the ROV, you can tell if an ecologist is “driving” if they hover on hermit crabs, polychaete worms, and anemones waving their tentacles in the currents, or move the camera to follow a conger eel swimming away from the lights of the ROV. Thus, each day, each dive is a balancing act. Everyone jokes around, but in all seriousness, understands the holistic nature of this multidisciplinary work and the importance of working together as a team to ensure that as many learning objectives are met as possible.

Collecting a hydrozoan colony from the wreck

The ROV arm collects a voucher specimen, a hydrozoan colony, from the wreck.

At each dive site, the scientists try to use the ROV to collect a few “voucher” specimens of common species that are seen on the ocean floor or the wrecks themselves. These live specimens are collected so that the scientists can definitely classify organisms seen in the video footage. Today we were able to use the claw to collect a hydrozoan colony growing on the wreck. Similarly, we also attempted to take a core sample of sediments from near the wreck. The geological components of the sample (rocks, sediments, etc.) will be analyzed separately from the faunal components (shells, polychaete worms, anemones, corals, etc.) to look for any similarities or differences between locations around the canyon as well as both on and off wreck sites.

*Quote from the movie “The Goonies”.

Taking a core sample

Taking a core sample under the watchful eye of a black sea bass on the lookout for dinner.

Esprit (left) and Kirstin (right) show off the voucher specimens from the dive

Esprit (left) and Kirstin (right) show off the voucher specimens from the dive

One Comment leave one →
  1. lizbaird permalink
    September 25, 2012 9:05 pm

    How cool to find part of the Billy Mitchell Fleet! I love the analogy of looking at shipwrecks is like looking at human health. Never thought about it that way. I can only imagine what it was like for Bob Ballard to find the Titanic. We are excited about the opening of that exhibit in a few days!

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