Science Update for Monday, August 23
Our mission is beginning to wind down; only one more full dive-day left. The Aquanauts have made significant progress on several fronts. Tiffany’s filtration rate experiment is underway; the first set of measurements have been downloaded from the instruments. It will be a couple of weeks before we can really analyze the data, but it is a good feeling to have the data in hand. We’ve also made good progress on the permanent transects. The three deep sites have all been visited, cleaned, and remarked. Some new sponges (both recruits of Xestospongia muta and newly monitored Geodia neptuni and Agelas conifera) have been tagged, as well. We should get back the these sites on Tuesday afternoon. Much of the past day has been spent setting out sponges for the caging experiment. We managed to set out all 160 sponges at our deep site (95 feet) and about half the sponges at the shallow site (45 feet). We’ll finish up that work tomorrow. The results of our experiments won’t be known for awhile (about a year in the case of the caging experiment), so we’ll keep you posted.
I didn’t write a summary yesterday because we were especially busy. Battery changing took a bit longer than expected, as data dumps from the instrument seemed to drag on and our four hour break wasn’t quite long enough. Actually, if I think about it our break is only about 2.5 hours. Once we stage in from a dive it takes about an hour to fill our tanks, strip out of our gear, and get showered and dry enough to enter the habitat. Then, we need to start gearing up about 30 minutes prior to the next dive. Also, the computer (yes, we’re sharing a single laptop) was occupied as Steve and Tse-Lynn weighed all 320 sponges we need for the caging experiment. Many thanks to them for staying up late to finish that work.
In addition to a busy day, yesterday was an especially tiring day. The current on the reef was howling…screaming…ripping; you choose the word and it applies. Our first indication of the strength of the current was the sound coming in over the communication system from the Pinnacle Gazebo (our remote fill station); you could hear the torrent running through the gazebo. When we arrived on site, the current was strong enough to sweep us out of the gazebo if we didn’t have a good hold. Luckily, the current was a bit better at our sites, which are just down slope from the gazebo. Because the gazebo is on top of a ridge, it tends to have stronger currents than some of the other reef areas. Still, it was an amazing site and experience to crawl from rock to rock against the current. This current lasted most of the dive. After about 4.5 hours, the current started to slack. Unfortunately, behind the current was more bitterly cold water. For this mission, I am diving in a full 5 mm wetsuit over a hooded vest; pretty severe gear for the tropics in August. However, I was still shivering from the cold water being upwelled onto the reef. It was an amazing day of extremes; first the current then the cold. No wonder we were tired.
As the mission winds down it is a good time for some accounting. All told, by the end of the mission, each Aquanaut will have spent about 55 hours of bottom time in the water in about 6.5 days. Not a bad work week. Many thanks to the Aquarius Reef Base staff, the crew of the MV Freedom Star, and (especially) to our Habitat Techs (Mark and Ryan) for making this possible.
One more full dive day, then a short dive on Wednesday. After that, decompression. We knew it couldn’t last forever. That’s probably a good thing; none of us could keep up this schedule for much longer.