Umitaka Maru — CEAMARC voyage25 January 2008Getting closer to the zonePhilippe Kobbi — correspondent aboard the Umitaka Maru
Here we are, two days at sea, the ship clipping along near 16 or 17 knots. We are now in international waters. Several albatrosses are following us and a sea lion was spotted this morning. Since this is a training ship, the automatic pilot is not in use and it is the cadets who steer under the benevolent eye of the officers and Captain Koike.
We are progressively learning the ship's rhythm, marked by its meals. Our Japanese colleagues are very attentive to our comfort and to the fact that we are adapting to their food and to the ship. For the moment, everything is going well; the food is very varied and each day brings a discovery. As we are close to the great frontal zones that mark the northern limit of the Southern Ocean, the first program is started. It is the Continuous Plankton Recorder (CPR), under the direction of Graham Hosie from the Australian Antarctic Division, who is also CEAMARC program leader. Kunio Takahashi is working with Graham; he is a post-doc in Australia, having done his studies in Japan.
This project is studying, year after year, the spatial distribution of plankton on the Southern-Ocean scale, its diversity and its responses to environmental changes. The data from the program are shared with the international scientific community via the SCAR-MarBIN program. Australia, Japan, Germany and New Zealand are part of this consortium and will be joined by the USA, Russia and the Census of Antarctic Marine Life program of South America. France could join the consortium by using the Astrolabe in its regular rotations between Hobart and Dumont d'Urville.
The CPR is an instrument that was conceived to be deployed from any ship, whether commercial or research, without hindering its navigability, speed or transit operations. It is a completely mechanical device that uses the speed of the vessel pulling it. It needs no other source of energy, like electricity, in order to function. Graham likes to say that it cannot break down because there are no electrons making it work. The CPR was developed in the 1930s by Sir Longhust Hardy and has been used regularly ever since, mainly in the North Atlantic. Thanks to the CPR, it has been possible to show the importance of climate fluctuations in the North Atlantic for planktonic swarms and for survival conditions of fish larvae.
Graham developed this program in the Southern Ocean with great conviction and inspired the polar institutes of several countries to join this wonderful project that will permit us to understand how the plankton of the Southern Ocean evolve. Find out more about the CPR on the Antarctic Division web site.
The CPR is pulled 100 m behind the vessel at a depth of about 10 meters. The plankton enters at the front of the device through an aperture that is 1.25 x 1.25 cm. Then it moves through a tunnel until it is trapped between two bands of 270-μm-mesh silk that unwind according to the distance traveled. These two bands and the plankton that is caught between them roll back up in a tank of diluted formol for conservation. The unwinding of the silk bands is constant, whatever the speed of the ship. Each cartridge, which holds the silk band and formol tank, gives us the surface plankton present over a maximum distance of 450 nautical miles. Given the speed of the ship, on the Umitaka Maru, we change the silks and formol tank every day at 9 h in the morning and take other samples.
At the laboratory in Tasmania, the bands are cut up into sub-samples corresponding to 5 miles. The plankton is then identified, counted and linked to environmental parameters that are measured continuously on the ship (temperatures and surface salinity, weather and navigation characteristics).
Every day, when the CPR cartridge is changed, we have planned to do a vertical track with a rosette of bottles and CTD (down to 200 m), a track with NORPAC nets (to 150 m) and a track with WP2 nets (to 200 m). Let us look at this assorted equipment that we are using all through the mission to familiarize you with the terms.
In order to sample sea water at different depths, we use oceanographic bottles that hold about twenty liters (rosette of bottles). These are closed with an electric signal. We close each bottle at a depth that is predefined by the mission leader. The water is then sampled and different measurements are taken on board or in the laboratory.
The CTD is a tool that lets us find out about the water column: the temperature, salinity and depth of the measurement. We can also mark the different water masses from the surface to the bottom. In the upcoming days, we will be able to show you the different hydrological zones that we cross. There are also other sensors that that let us measure the light, its spectral composition and plankton fluorescence.
Finally, two types of nets are used to collect plankton. NORPAC is a standard net used in the Pacific Ocean while WP2 is a standard defined by UNESCO. Both are conical nets for collecting zooplankton. On board the Astrolabe, we have been using WP2 nets for many years. Jean-Henri Hecq from the University of Liège is responsible for this net and for determining the plankton.
The other members of the team are not left with nothing to do. Everyone helps with these first maneuvers. Thanks to Jean-Henri's WP2, we have collected the first teleost fish of the campaign. Not a sea monster but a larva about 1-2 cm from the Myctophid family, also known as lanternfish. We hope to collect more of them during the mission.
The WP2 is not a net geared to collecting fish larvae, so this is something of a story, but we have taken it as an encouraging sign!
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