Before my shift in the lab begins I went for a walk around the ship.
In the first laboratory I find Tanja and Dick (NIOZ) testing whether the algae injector of their deep-sea incubator works properly and does not release the algae before the instrument reaches the seafloor. For the test they use tea because it took more than half a year to grow the algae. When the incubator is deployed at the seafloor the algae will be injected into the chamber, sink to the seafloor and will be eaten by the microorganisms and animals of different size classes. After 4 or 5 days the ROV takes push core samples of the sediment and then Tanja, Dick, Lisa and Andrew will follow the carbon and nitrogen flow through the food web. In other words, they want to find out which food web compartments (macro-, mega-, meiofauna) ate which parts of the algae. This information will help to identify different food webs in disturbed and less disturbed areas, and they gain information about the changes that occur after the sediment disturbance.
Tanja and Dick seem pleased with the result of their test. Nevertheless, they plan to repeat it to be sure that the instrument will work properly on the seafloor.
Next door Frank Wenzhoefer (MPI/AWI) has some time to show me the instrument he is currently working on. This is how it works: The ROV will take up a nodule with the scoop-like instrument to put it into the green plastic sieve. A little motor underneath stirs the water inside to mix the oxygen in the bottom water. Then a sensor measures the oxygen flow inside. This is done with a nodule and without one to compare the differences. It is the first experiment of its kind to measure the respiration of everything alive on and inside a manganese nodule.
Inside the hangar I see Johannes (AWI) conducting some last preparation work on the so called Tramper (or Crawler) which will be tested at the deep-seafloor for the first time. On the seafloor it moves autonomously based on a path Johannes and Frank determine before. Therefore the advantage is that it has a longer range for measurements than a benthic chamber or a lander.
When I leave the hangar I meet Andrew (IRIS). He is installing a benthic respirometer on a Lander. This respirometer measures the seafloor respiration and traces the carbon and nitrogen flow through the food web. The experiment is conducted in disturbed and undisturbed areas to see how the food web recovered after 26 years after disturbance.
Right behind Andrew I find the GEOMAR elevators which are used as “carriers” for the ROV. They bring down the tools (as for example the incubator or the nodule…). The ROV can than approach the elevator to take off the instruments which should be used during the dive. Of course, this is very time efficient as the ROV can use several instruments in one dive.
Tanja and Johannes promised to contribute to the blog about their results when the incubator or the Tramper have been deployed on the seafloor.