German research vessel Polarstern went to the Fram Strait on an expedition this year. On board were two scientists from CAGE, with a mission to install a methane sensor at the deep-sea observatory Hausgarten.
Text: Maja Sojtaric
Researcher Kasia Zamelczyk and PhD Candidate Pär Jansson from CAGE participated on the second leg of the RV Polarstern-expedition to the deep- sea observatory Hausgarten. The observatory is a network of 21 stations at water depths ranging between 250 m and 5500 m in the Fram Strait. RV Polarstern has revisited the observatory annually for the past 17 years, collecting long-term ecological data sampled by different instruments throughout the network.
“Our main purpose was to install a methane sensor and a CTD instrument (used to measure the conductivity, temperature, and physical properties of the ocean) on the deep lander platform in central Hausgarten says Zamelczyk.
Scientists expect to obtain a time series record of bottom water properties such as temperature, salinity and pressure as well as methane concentrations. The instruments were deployed at a water depth of 2500 meters, where no direct methane emission is expected. The data acquired at this location will mainly serve as a reference to compare with other sensors placed in active emission sites. Methane is a potent greenhouse gas that is naturally seeping from the ocean floor.
This work was conducted within the FixO3 project, which seeks to integrate European open ocean fixed-point observatories.
Additional sampling offshore Svalbard
In addition Zamelczyk and Jansson collected CTD profiles and water samples for methane concentration measurements at active methane seep locations close to Prins Karls Forland, Svalbard.
“Water sampling will result in methane concentration profiles for 12 different depths. These profiles will help us to estimate the magnitude of methane emissions and how high the methane can reach in the water column. In total 48 bottles were collected in an area where we have seen a lot of methane seeping from the seafloor” says Jansson.
Also, zooplankton net and surface sediment samples were collected at the same locations. These samples will be used to study the impact of methane release from the ocean floor on shells of planktonic (living in the water column) and benthic foraminifera (living at the ocean floor).