September 19th: Last Day at French Frigate Shoals
Written By Dan Suthers September 19-20, 2004
Today is our last day at French Frigate Shoals. We will depart just after dinner this evening: see the Plan of the Day. In today's journal I continue to discover the variety of science being undertaken on this expedition.
Oceanography from a Small Boat
This morning I talked to Mooring Team members Kyle Hogrefe and Danny Merrit as their launch (HI-2) was prepared. They showed me the various devices that they would be using during the day's work. In my Sept. 16th journal, I briefly described the Mooring Team's job of replacing various kinds of sensors that are left in place for about a year. In yesterday's journal, I described Night Operations' testing of the CTD device from the Hi`ialakai to a depth of 500 meters. Today I learned that the mooring team is also doing CTD and related sampling, but they do it in shallower water than the Hi`ialakai can venture. Shallow water measurements are important for understanding reef health because water conditions may vary from shallow to deep water. Kyle and Danny showed me their small CTD device, which is lowered by hand. At each location they also take a water sample, using the device being shown by Kyle above. The water sampling tube has a spring loaded wire that holds the cap open; when a weight is slid down the line it trips the catch so the lid can close, capturing the water inside. The large CTD we saw last night also gathers water samples, so these two devices on the mooring boat are gathering data similar to that of the deeper water CTDs.
In addition to these measurements, radiation measurements are also taken by the mooring team at each site. According to June Firing ("Data Manager" on this trip but also an oceanographer), Photosynthetic Active Radiation (PAR) measures solar radiation at the wavelengths that can be used for photosynthesis. This source of energy is extremely important for life in the ocean because the majority of the food chain of the ocean is built on top of photosynthesis. (Recall that Randy Kosaki was collecting fish samples to determine the relative contributions of algaes to the food chain.) The device that the mooring team showed me (pictured here in two parts: the sensor and the control panel) measures radiation both looking up and looking down. The upwards-pointing sensor reads incoming solar radiation, while the downwards-pointing sensor reads reflected radiation. This latter measurement is important for another purpose: ground-truthing (validating) interpretations of remote sensing data gathered by satellite. Satellites measure radiation reflected from the ocean surface, and this data is interpreted to infer various characteristics of the water. By taking CTD, water sample, and radiometric readings all at the same locations (which have known characteristics) scientists can make sure that their interpretations of satellite data are correct.
Revisiting La Perouse
Right after breakfast, the bridge announced that a boat would be going to La Perouse Pinnacle for the convenience of any crew who would like to go snorkeling. Excursions are important to the mental health of crew whose duties don't take them off the ship. Of course I took the opportunity to visit the pinnacle again and test what I had learned about underwater camera operation.
We (Data Manager June Firing, shown to the left; GVA David Tipton, GVA Charles Sanford, Cheif Bos'n Mark O'Connor, and Electronics Technician Mike Crumley, shown to the right, and myself, cameraman in the return picture below) went out in a small boat, HI-4 known as the "rescue boat." The Commanding Officer (CO) wanted us within view, so we stayed on the sunny side of the pinnacle, opposite of where I had accompanied the REA team a few days ago. There were nice coral formations along the ridge between the pinnacle and the smaller rock, with a variety of fish, including one Ulua lording over its domain.
Back at the boat I did another satellite upload for the web site (unfortunately I am a few days behind: this was for the 9/16 stories). After lunch I had a conversation with the master of Night Operations, Scott Ferguson. Along with an interview of June Firing I'll conduct soon, this will form the basis for a feature story on physical oceanography. Before long, the various boat crews returned.
Planning for Gardner Pinnacle
Each evening after dinner the chief scientists Peter Vroom and Randy Kosaki and the other team leaders meet to plan the next day's activities. This plan is then brought up to the bridge for modification if necessary and approval. The Hi`ialakai had already began the transit to Gardner Pinnacles during the dinner hour, so planning focused on how to use our single day there. These two small rocks provide little protection from the open ocean, and some expeditions are forced to skip the location entirely during inclement weather.
After the meeting, I notice Molly Timmers of the Towboard Team working with a data sheet and a map of Gardner Pinnacles on a laptop. The map showed lines of little dots going around the pinnacles, some closer and some further away. Molly explained that the lines represented last year's towboard surveys, and the dots represent the points at which GPS coordinates were taken. The towboarding operation uses a telegraph system with which the diver uses prearranged acoustic signals to indicate when s/he is starting an observation, as well as to control other tow actions. When the boat gets these signals the boat records the GPS coordinates of the event. This year they want to follow the same lines. When the data is analyzed, they will use both GPS coordinates and depth information to determine which measurements are closest to a given measurement last year. Unlike laboratory science, in field work it is not always possible to replicate observation conditions exactly, so observations must be matched within an error tolerance level.
Science in the Wet Lab
After saying farewell to a receding La Perouse Pinnacle and viewing sunset on the upper deck, I went into the wet lab to see what was up. Danny Merritt of the Oceanography team was pouring water into a funnel with a filter connected to a large Erlenmeyer flask (pictured). A pump sped up the process. He said that these were the water samples they took today. They were to be tested for "Color Dissolved Organic Matter." The samples were being filtered before storage so that critters in the water would not eat the dissolved organic matter, thereby changing the sample.
Jean Kenyon was storing coral samples. She would take a piece of coral and snip off a piece small enough to fit in a vial (see pictures). These samples are being collected for a study in collaboration with Andrew Baker at Columbia University. Collaborative research is very important in many of these fields of study, because not everyone can come up here to gather samples. To minimize the impact of our visit, as many research missions as possible are scheduled into a single trip, and this involves collaboration between scientists on board and those who could not come. Many corals exist in a obligate symbiotic relationship with algae (more specifically, single celled algae called zooxanthellae), meaning that they are adapted to be entirely dependent on each other. The algae photosynthesize to produce a sugar that the coral uses for energy, while the coral gives the algae a home. Previously it was thought that all corals combined with a single kind of algae, but this has been brought into question. The researchers will be analyzing the DNA of these corals to determine what coral/algae relationships have formed. Pacific Ocean corals in particular have been insufficiently studied.
The photographers, David Liittschwager and Susan Middleton, were also in the lab, photographing some of the coral samples Jean had brought back.
At night we began the transit to Gardner Pinnacles, through a rainstorm and less than gentle seas. When I went to bed at 0130 the Hi`ialakai had stopped and the night operations team had just begun a CTD drop in the rain.