You are here: Home › Ecosystems › National Marine Sanctuaries › Tortugas Cruise 2007 › Day 4
Dry Tortugas Cruise Day 4 - August 28, 2007
Greg Piniak (foreground) and Brett
Harrison, conducting a transect survey.
Photo credit: Kim Foley
Today began with a lunar eclipse just before sunrise—a treat for those willing to wake up early enough to see it. Many of the scientists and crew were awake to see the eclipse, due to our early dive operations. We have been concentrating operations on West Tortugas Bank, which contains many of our sites within the Reserve. Today we are moving operations east to Dry Tortugas National Park. We will be working a long day by running three dive cycles rather than the usual two. We can increase our workload now that everyone is up to speed, comfortable and working well together. It is a good opportunity to make up for time lost in port due to mechanical issues with the ship.
Photo credit: Amy Uhrin
"the eye".
Photo credit: Shay Viehman
Morning dives took place on the southwest corner of the east bank at three unprotected sites. While not as picturesque as some of the sites in the Reserve, this morning’s sites had moderate relief and plenty of fish. One of the ship’s officers, ENS Lecia Salerno, helped out as an extra safety diver on one of our deeper dives. The morning work went smoothly, the weather cooperated, and there was little current. One team had trouble retrieving its anchor at the end of the dive, but that only served as a welcome excuse for two more of the ship’s divers—Lt Sarah Mrozek and Lt (jg) Mike Davidson—to get in the water and give a hand. It is worth mentioning how well the ship’s crew works together to make everything happen for us. They are an integral part of all operations and are to be equally credited for our successes.
Our team (Kelty, Foley, Harrison and Piniak) was out of the rotation for the afternoon dives. We were looking forward to some rest before taking our turn on night operations. The Park contains some amazing dives, but this afternoon’s sites are not among them. We are always very careful with our buoyancy to avoid damaging the reef, but this afternoon’s dive requires care for a different reason. Some of the sites along the northern edge of the Park contain very soft muds, and the slightest disturbance of the bottom causes the sediment to swirl up into the water, reducing visibility in the blink of an eye. The three teams that did dive these sites kept out of the mud. They found low–relief rubble on the bottom, but the coral cover, though low, was higher than expected. Several teams saw black coral and some interesting zoanthids. One of the dive teams had a loggerhead turtle swim overhead.
data collection during drop
camera operations.
Photo credit: Amy Uhrin
Evening operations of drop camera work and beam trawl are headed up by scientists John Burke and Amit Malhotra. Drop camera deployment consists of lowering a camera to within a foot or two of the bottom and observing and recording 200 meter transect sections. This is a delicate operation that requires our 170 foot ship to maintain steerage along a distinct line at a snail’s pace of less than 1 knot. Thanks to a skilled and well–coordinated captain and crew, we have again captured quality data.
Last night’s beam trawl was highly successful as well, capturing many species of flounder, crab, small fishes, shrimp, and more. We even captured a mantis shrimp—named for its similarities to the praying mantis in speed and hunting prowess. Mantis shrimp employ their front claws in lightning–quick attacks which have earned them the nickname "thumb splitters."
We continue to make adjustments, learning from the previous nights’ trawling to increase our effectiveness. The pressure is on our team tonight to keep up the good work.