Mission Blue: Medusa Drops to the Bottom of the Gulf
January 6, 2011
At Roughtongue Reef in the Gulf of Mexico, some 80 miles east of the BP Deepwater Horizon spill site, Dr. Edie Widder of the Ocean Research and Conservation Association (ORCA) deploys the Medusa–a sophisticated deep sea observatory that can film and test seawater conditions–for the first time in the open ocean.
At dock in Pensacola, Florida, a crane hoists ORCA’s Medusa deep sea observatory onto the research vessel Brooks McCall.By Edith “Edie” Widder
I’ve brought the Medusa deep sea observatory. It’s a lander system that you can just throw off the back of the ship. It floats down to the bottom and settles there, and then it can record for two to three days. It uses the same principle as the Eye in the Sea camera system that I developed.
It uses far red light that’s invisible to the animals. The idea is to be able to see without being seen. In this particular instance, one of the things we’re hoping to see is six-gill sharks, because we’ve seen a lot of six-gills in the past using this kind of unobtrusive recording.
I’m very curious to see how they’re doing, given the impacts of the oil spill. One of the things that we discovered using the Eye in the Sea is that they feed by slurping sand up from the bottom sometimes. That sand would likely have a lot of oil in it now.
The ship’s GPS-assisted navigation system displays the expedition team’s location above Roughtongue Reef.To be able to record for hours and hours may seem long-term: With submersibles, we have incredibly brief visits that are fairly disruptive to the animals, because the white lights and noisy thrusters scare them away. This is better, but it’s still not nearly long enough. That’s the hardest thing to make people understand: With these very brief visits it’s hard to get any kind of a sampling of what it was like before and what it’s like now.
The system is stationary while it’s on the bottom: It better not move, at least, unless there’s a six-gill pulling on it–which actually has happened. That was with the old Eye in the Sea. We had a number of instances where we found that it tipped over, and we thought it was some kind of current. But no, now we realize that it was probably six-gills, because they can be fairly tenacious once they find the bait. Wanting to yank it, they yank the camera over with it sometimes.
Edie Widder and the Medusa on the aft deck of the Brooks McCall.Here’s the great thing: The Medusa can go down to 2,000 meters. So we can go down to the depth of the spill site. The question is whether we will or not, because we have a lot of concerns about the currents and how bad they’re going to be. It takes a long time for theMedusa to get down–it can take almost two hours. It could drift along the way, so we have some concerns. There’s a certain amount of trepidation associated with throwing $70,000 worth of gear off of a perfectly good ship and just hoping you’re going to see it again.
The way we retrieve it is we send an acoustic signal, and there’s a transponder on theMedusa that responds by dropping a weight. We have 75 pounds of steel that will turn to rust and basically disappear eventually. We leave that on the bottom, and then it pops to the surface with its own floatation. We have a satellite beacon on it, so if we don’t happen to be in quite the right place we can still find it.
Brandy Nelson adjusts a soil sampler on ORCA’s Medusa immediately before it goes into the Gulf of Mexico at Roughtongue Reef.The Medusa takes video, and it also has a CDT–so it’s measuring conductivity, temperature, and depth. And it’s got a light meter on it so it’s measuring a profile of light penetration as it goes down.
This is the first time I’ve worked with this unit in the field, so there’s more than a little trepidation. We deployed it once in a lagoon at very shallow depths just to work the kinks out. But this is its first open ocean deployment. We are going to put it in at a depth where, if it didn’t come back, the Deepworker could reach it and hopefully help retrieve it. That gives us a sense of reassurance for this first deployment.
The Medusa underwater observatory is lowered into the Gulf of Mexico at Roughtongue Reef for its first-ever drop to the open-ocean seafloor.Support for the Mission Blue Gulf of Mexico expedition is provided by the National Geographic Society, Google Inc., the Waitt Institute, and Hope Spots LLC. Follow along in context by clicking on the ship icon near Pensacola, Florida using Google Earth.
Read all Mission Blue expedition coverage here.
Photos by Ford Cochran