Project Day 7: 5 March 2011
After no diving yesterday, the rebreather team was ready to get back in the water today. We were joined last night by the fith deep-diving member of our team, Ross Langston -- a researcher at Windward Community College and Bishop Museum. Ross works with Ken Longenecker on a technique called "Laser videogrammetry", which involves an underwtaer video housing equipped with a pair of green lasers, mounted in paralell. The lasers create a pair of dots in front of the camera a known distance apart, so that when the dots are shown on the side of a fish, the size of the fish can be estimated with a high degree of accuracy. Ken and Ross conduct surveys along a reef and capture video images of certain species of fishes, and thereby establish the size distribution of that species on the reef. Coupled with other experiments to study the age of fish at certain sizes, Ken and Ross can establish size-structure and mortality rates of fishes on deep and shallow reefs, to see if the deep-reef populations may be more protected from fishing pressure than the shallow-reef populations.
Because of the terrible weather yesterday, and the uncertainty of where the sub could be launched, we decided not to attempt a coordinated dive between rebreather divers and the submersible. While the sub conducted a series of fish surveys and collections, the rebreather team -- now five divers strong -- split the day into to separate shifts. The first shift included Dave Pence and CJ Bradley, and their mission was to return to the site where the "pulse-chase" experiment was established, so CJ could collect more samples for the "chase" part of the experiment. This was our first attempt to locate the site without the help of the submersible, so we came up with a plan to make it easy for them to find. We selected a spot mid-way between CJ's experiment site, and the nearby coral-stainging site, and dropped a weighted line with a bouy to serve as a marker. Dropping this marker between the two sites ensured that we didn't accidentally damage either of the two experiments, and also would make it easier for CJ and Dave to know which way to swim. Unfortunately, we didn't let out quite enough line, so when CJ and Dave got to the bottom, they discovered that the line had drifted down-slope of the drop-zone, and they were a barren sandy area in 315 feet (95 meters) of water. They swam up-slope and found the reef, then followd the reef and found the site, to make the collections. Meanwhile, on the surface we pulled in the marker like (Dave had sent the weight to the surface using a lift bag), and waited for them to complete their decompression. Because they were on the bottom for only a short time, their complete dive time was only about an hour and a half.
After CJ and Dave finished their decompression, Ken, Ross and I got ready to make the second deep dive of the day, at the place we are now calling "Heather's Reef" (where CJ and Ken dived on Day 4, with lots of coral and fish). Ken and Ross did their laser videogrammetry survey, and my job was to simply film the reef and them doing their survey. When Ken and Ross do these surveys, Ken tows a float at the surface that has a GPS tracker in a waterproof bag. Using that information, Ken can estimate the location of the survey. After a bit of a swim to get to the drop-line, we got to the bottom and conducted our dive. I have to say that this particular reef is even more amaxing than what I imagined from CJ's Video from Day 4. There were THOUSANDS of fishes, and the reef continued on in all directions, for as far as the eye could see. Although the reef was truly spectacular, the day was overcast, so it seemed unusually dark and gloomy on the bottom. I still managed to get some good vido of the reef, including some images of corals with, and without green pigmentation. We couldn't get very close to the large schools of fishes, because our lights seemed to startle them (Ken says this is typical on gloomy overcast days).
As I ascended from the bottom, I noticed a lot of tiny bubbles swirling around me. I asked Ken to see where the bubbles were coming from, and he indicated that it was the inflator for my Bouyancy Compensator. I thought he meand that the bubbles were coming from the inflator mechanism itself, but infact they were streaming directly through the rubber hose! In all my years of diving, I've never seen a failure quite like that before. The leak is relatively small, so I'm not concerned. But I will need to repair it after this expedition.
During the decompression, we had very special visitors: two large humpback whales swam directly underneath us, then hung out for about ten minutes nearby. I was able to swim completely around them, and Ken and I got some good video. They were absolutely amazing! At one point, then both glided down to a depth of about 30-40 feet, and hung nose-to-nose. Then they drifted a bit so they were basically cheek-to-cheek, and just floated motionless. I didn't want to get too close, but they seemed completely oblivious to my presenence, and I imagine they would have allowed me to swim right up to them (I was happy to keep my distance).
Although the water was gloomy, we all headed home in a good mood from the successful day. For the next four days, we will be conducting coordinated dives with the submersible, so we should have plenty of interesting images and stories to tell.
Click this link for the day's Video Highlights. Video by R.L. Pyle and K. Longenecker.
|Images:||Click on the small images below to see the the full-size image file.|
|Ken Longenecker (left) and Ross Langston (right) conduct a Laser Videogrammetry survey on "Heather's Reef". Photo: R.L. Pyle.|
|A Leptoseris coral head with extensive green pigmentation. This photo shows the coral under natural light conditions at a depth of 270 feet (82 meters). Photo: R.L. Pyle.|
|The same coral as the previous image, but with the video light turned on. Photo: R.L. Pyle.|
|A pair of Ornate Butterflyfishes (Chaetodon ornatissimus) among many hundreds of three-spot Chromis (Chromis verator) and Lemon Butterflyfish (Chaetodon miliaris), and other reef fishes. Note the two dots on the side of one of the ornate butterflyfish, from the lasers on Ross Langston's camera. Photo: R.L. Pyle.|
|Although the vast majority of corals on this reef appear to be extremely healthy, this patch of Leptoseris coral appears to have some bleaching. Photo: R.L. Pyle.|
|Ross Langston checks his VR3 decompression computer, as the two green parallel lasers on his camera pierce the water. Photo: R.L. Pyle.|
|Tiny bubbles stream from Richard Pyle's bouyancy compensator inflator hose. This is not a major problem, but it's certainly an annoyance. Photo: K. Longenecker.|
|An adult Humpback Whale comes in for a visit during the decompression. Photo: R.L. Pyle.|
|After catching a breath at the surface, the whale seems to dive towards the depths. Photo: R.L. Pyle.|
|Rather than descending, the whale glides towards what appears to be a giant mirror underwater, but is, in fact, another adult Humpback, approaching nose-to-nose. Photo: R.L. Pyle.|
|The two Humpback Whales hung motionless for nearly ten minutes, allowing us to take photos and videos before eventually moving on. Photo: R.L. Pyle.|
|On the decompression line, safety diver Holly Bolick reacts to the visit by the Humpbacks. Photo: R.L. Pyle.|
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