Project Day 3: 1 March 2011

Today's coordinated dive with HURL's Pisces V submersible and the team of rebreather divers proceeded flawlessly! Our new communications protocol was successful both from the perspective of the team aboard KoK, and from the dive boat. The purpose of today's dive was to establish an experiment to study the growth rates of Leptoseris corals in these mesophotic reefs off Maui. Terry Kerby once again piloted the Pisces V to the same site as the previous two days, and he and science observer John Rooney located a coral head to serve as the study subject about 20 meters (65 feet) from the previous study site. After they sent the marker buoy to the surface, the rebreather team splashed into the water to see a large Humpback whale hanging lazily beneath the boat, about 40 feet down. As much as we all wanted to watch the whale, we had a scientific mission to perform, so the four-person dive team (Ken, CJ, Dave, and myself) descended along the marker buoy line towards the sub. When we got to within about 100 feet (30 meters) of the 89-meter (290-foot) bottom, we could see the sub below. Dave and CJ continued down the maker buoy line to its anchor, which Terry had deployed next to CJ's "pulse-chase" experiment from the previous two days. While Dave sent the marker-buoy anchor back to the surface, CJ collected her samples from two days after the beginning of the experiment. Meanwhile, Ken and I descended directly to the Pisces V sub, where John Rooney was pointing a bright green laser through his observation port at the Leptoseris coral head that he selected to serve as the subject of the growth-rate experiment. While I began photo-documenting the coral, Ken tested the functionality of the water pump on the dome that the sub had brought down. Ken then held a ruler near the coral at various angles, while I took many close-up photographs. Once we felt that we had adequately documented the size of the coral, Ken took a syringe of special non-toxic dye that the sub had brought down and injected it around the outer edges of the coral. We then carefully placed the dome over the coral, and injected another syringe of the same dye inside the dome. Ken then switched the pump on to circulate the dye inside the dome, to keep it suspended in the water. The sub would return several hours later to inject a third syringe of dye into the dome, before finally removing the dome at the end of the submersible dive. The purpose of this experiment was to carefully document the coral, and then expose it to the stain, which will be incorporated into the skeleton of the coral as it grows, leaving a visible band of where the outer edge of the coral was on this day. Several months from now, we'll return to this site to measure how much the coral has grown. Understanding the rate at which these corals grow at these depths is critical for understanding how best to protect them.

We managed to complete the entire task in only 15 minutes, which means that we had less than two hours of decompression. During the decompression, we were visted by several more humpback whales, two of which I managed to capture on Video (though at a distance). We ended the day happy that we had now completed three successful dives!

Click this link for the day's Video Highlights. Video by R.L. Pyle.

Images:Click on the small images below to see the the full-size image file.
The Leptoseris coral selected by John Rooney for the staining experiment. It lies near the base of a coral slope, at a depth of 88 meters (290 feet). Photo: R.L. Pyle.
The Leptoseris coral selected by John Rooney for the staining esperiment. Next to it is a small marker float with an electronic pinger attached, to make it easier to find again. Photo: R.L. Pyle.
One of several close-up images taken to document the size of the coral colony. We will return to this colony later to see how much it has grown. Photo: R.L. Pyle.
Ken Longenecker injects a nontoxic dye into the acrylic dome that surrounds the selected coral colony. This dye will be incorporated into the coral skeleton, so that in the future the amount of growth can be measured. Photo: R.L. Pyle.
The Pisces V submersible on the bottom, as the divers head for the surface. Photo: R.L. Pyle.
Dave Pence signals that he's "OK" on a decompression stop. Photo: R.L. Pyle.

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