Remipedes and cave diving: Field notes from Joey Pakes
By UCMP grad student Joey Pakes, July 1719, 2008
A satellite view, courtesy of Google Maps, of the unspoiled Walsingham Nature Preserve, Hamilton Parish, Bermuda. Beneath this tract is a network of mostly submerged limestone caves where Joey did some cave diving as a warmup for her trip to the Yucatan.
|Joey is a graduate student at UCMP currently doing research on remipedes, crustaceans that live in underwater caves and look a bit like centipedes. Her research requires SCUBA diving in these caves. Check out an introduction to Joey's research.|
June 17, 2008
I am in Bermuda this week and am lucky to have been invited along on a few cave dives with Terrence Tysall, a masters student at Texas A&M and a highly regarded diver with over 25 years of cave diving experience. He's studying Bermuda cave formations and the water masses within them and is a great person to practice my skills with before I head to Mexico.
Bermuda's caves are really fascinating. They began forming between one and two million years ago during the Pleistocene when periodic glaciation resulted in large fluctuations in sea level. Since the last Ice Age, sea level has risen again and submerged many of the caves. It's obvious that sea level changes have been substantial, since stalactites and stalagmites which don't form underwater can be found as deep as 20 meters below today's sea level!
Last week, I spent hours assembling my diving harness after some slight frustration concerning the location of various rings, straps, and clips, I was feeling pretty confident. So, after attaching the harness to a backplate, I began to lay out the rest of the gear that I'd need to pack: a wing which, when inflated, allows divers to stay neutrally buoyant, a knife, my new dive computer, and fins. I also packed two regulators, the devices that control your airflow. One will serve as a back up. The other has hoses for breathing, for checking how much breathing gas is left in my tanks, and for inflating my wing. To keep myself warm, I packed my dive booties, a five-mm thick wetsuit, and a hood. To provide some light in the dark cave environments, I brought a High Intensity Canister dive light (HID) and two backup lights. Finally, I packed a cave reel and a shorter safety reel with guidelines a guideline is used in caves so that divers can find their way back to the cave entrance in an emergency. Each person in a team should carry both reels, even though one guideline is laid out per team. All of this gear, much of it specially designed for cave diving, isn't cheap, but it is necessary and worth the expense.
I will meet Terrence tomorrow for a couple of dives in the caves of Tom Moore's Jungle (an unspoiled woodland area also known as Walsingham Nature Reserve), located in Hamilton Parish, Bermuda. I am quite excited, but also a bit nervous. During past trips to Bermuda as a coral reef ecologist, I supplemented my income by leading snorkel tours in cavern zones areas of caves where light penetrates but I have never before entered these caves using SCUBA. I am about to get a new perspective of the island.
June 19, 2008
Yesterday, I met Terrence and his research assistant, Marshall, at their gear shed in Tom Moore's Jungle and ran into an immediate problem. Terrence assumed that I would be using a single tank since I am not yet fully cave certified. I thought that I'd be diving with two tanks, since Terrence is an instructor and is authorized to lead intro cave students like me. Double tanks provide another level of safety in cave diving they are connected by a valve, normally open, that can be shut should there be a problem with one tank or regulator and you need to isolate the working one.
In itself, this misunderstanding about the tanks was not an issue my lack of an adaptor for the single tank that Terrence provided was. Fortunately, Terrence had access to a set of double tanks and went off to get them. Not so fortunate was the weight of this set of steel doubles: 140 pounds! Aluminum tanks would have been more manageable. After re-rigging some of my gear and attaching the tanks to my backplate/harness and wing, I shouldered the whole assembly like a backpack, and we set off on our hike to Walsingham Cave, the main entrance to a whole network of caves. Earlier, while Terrence was off getting my tanks, I had taken the opportunity to carry much of my gear to the cave entrance, but now, just lugging the doubles the short hike up to the cave, through gates, trees and shrubs, was quite challenging. I managed to knock open one of my tank valves on a tree and had to stop to turn it off. When we got to the cave entrance, a pool at the base of a small cliff, we put on the rest of our gear and I hobbled into the cavern zone with some help from my dive buddies. After checking out our equipment we headed in … with Terrence taking the lead.
Once in the water, I realized that getting the heavy tanks to the cave may have been the easy part. I had to limit any side-to-side motions and keep myself from looking back, otherwise, the weight of the tanks would roll me over. In cave diving, you want to minimize movement which can stir up sediment. It's important to maintain visibility, especially if a quick escape should become necessary.
Walsingham Cave was filled with small passageways and big rooms. We surfaced in a room with an air pocket where Terrence took some measurements. Then it was back underwater and into another big room which was entirely submerged. While Terrence collected more data on the water, I got to look around at the limestone walls and admired the now-submerged stalactites and stalagmites. We then entered into a very small spot where it became clear that I would need more practice before I felt comfortable in this heavy setup. After a bit of sediment disturbance on my part, we turned around and followed the guidelines back to the cavern entrance. On the way, my HID battery ran low and I was forced to use a weaker backup light. Popping up at the surface we found a group of screaming snorklers who must have thought we were cave monsters. Hilarious!
Once the screams had subsided, Terrence headed back into the cave, and Marshall and I carried our gear to Deep Blue Cave, the point where Terrence planned to exit the cave system. Since I was now carrying all my gear, and wet gear at that (maybe 160 pounds?), the hike was slow. My legs shaking, I was grateful to enter the water where my wing could do all the carrying for me. We stayed in Deep Blue Cave's cavern zone due to my lack of HID light. The view of the entrance, toothed with stalactites and stalagmites, was stunning we turned our lights off to appreciate the sunlight streaming in. We stayed long enough to check out some coral and another room before heading back to the shed, this time made easier by using mopeds.
What a great experience! I can't wait to do this again in Mexico. I am crossing my fingers for some aluminum tanks though …. Perhaps by then, I will be less sore.
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Satellite photo of Bermuda courtesy of Google Maps.