PS99 - Weekly Report No. 2| 20 June - 26 June 2016
A short stopover?
[27. June 2016]
On 23rd June, we reached Longyearbyen and the expedition PS99.1 came to an end. The hydrographical, biological and geological studies of the two EUROFLEETS2 projects, explained in detail in our first weekly report, could successfully be completed. Within only 2½ days available ship-time we managed to sample the water column and the seafloor, to map the seafloor with a towed camera system, and to exchange moorings with current-meters and sediment traps at a total of 40 stations at water depths between 150 and 1800 m. Exhausted but as happy as could be for the huge data-set and the multitude of samples, the EUROFLEETS2 working group left the ship in the early morning of the very same day.
To safe as much as possible of the valuable ship-time on our cruises, we planned to embark the following group of participants for the subsequent Polarstern expedition PS99.2 already in the afternoon of June 23rd. However, what was planned as a “short stopover” failed due to irregularities in the flight schedule. Because of a cancelled flight, the majority of incoming participants had to be transferred to other flight connections. The last group finally arrived on June 24th at 1 p.m. – in the end, we lost an entire day before we could even start for the expedition.
At 4 p.m. on June 24th we finally set sail for Polarstern cruise PS99.2 which will take us to the LTER (Long-Term Ecological Research) observatory HAUSGARTEN in Fram Strait. This area is re-visited by us annually in the summer months already since more than 17 years. The multidisciplinary work at HAUSGARTEN observatory is carried out to investigate the impact of Climate Change and the continuously retreating sea-ice on the Arctic marine ecosystem.
Today, HAUSGARTEN resembles a network of 21 stations at water depths ranging between 300 and 5.500 m, which were sampled by us in the water column as well as at the seafloor. Climate-induced changes of plankton communities in Fram Strait are investigated by the AWI research group PEBCAO (“Phytoplankton Ecology and Biogeochemistry in the Changing Arctic Ocean”). The HGF Young Investigators Group SEAPUMP (“Seasonal and regional food web interactions with the biological pump”) studies the particle flux to the deep sea, while the HGF-MPG Joint Research Group for Deep-Sea Ecology and Technology mainly investigates variations at the deep seafloor. Long-term studies at HAUSGARTEN contribute to various large national and international research and infrastructure projects (e.g. ABYSS, TRANSDRIFT, FRAM, ROBEX, FixO3, ICOS and SIOS) as well as to the research programme PACES-II (“Polar Regions and Coasts in the changing Earth System”) of the Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (AWI).
Shortly after leaving Longyearbyen we started to install the labs and to prepare all the scientific equipment. On June 25th at 6 a.m. we reached the southernmost HAUSGARTEN site and started with this year’s “gardening”.
To determine various physical, chemical and biological properties of the seawater we take water samples at all permanent HAUSGARTEN sampling sites using a CTD/Rosette. This gear combines a number of physico-chemical sensors and a carousel of Niskin water sampler. The CTD/Rosette is lowered close to the seafloor and collects discrete water samples for various parameters on its upcast.
Plankton is sampled using different kinds of nets. In addition we deploy a special camera system to optically detect zooplankton in the uppermost water column.
The sampling of sediments from the deep seafloor is conducted using different kinds of grabs, the so-called multiple corer and the box corer, which were lowered by a cable to the seabed. A steel-armoured fibre optic cable on Polarstern allows following the seafloor sampling online on TV screens. A towed photo/video system is used to assess large-scale distribution patterns of larger organisms (megafauna) on the seabed. The comparison with images retrieved during the preceding years will allow the evaluation of temporal variations in megafauna densities and composition.
To assess the proportion of organic matter from primary production finally reaching the seabed as food for benthic organisms, we collect sinking particles in funnel-shaped sediment traps attached to moorings. These moorings consist of an anchor weight, a Kevlar line of several kilometres (depending of the water depth) and buoyancy bodies keeping the mooring line in an upright position in the water column. Alongside with the sediment traps, our moorings are equipped with several sensors registering current velocities and directions, water temperature, salinity and oxygen concentrations.
Beside these more “classical” sensing and sampling devices, there is also a number of technically highly complex systems we use at HAUSGARTEN observatory. These include autonomous underwater vehicles operating in the upper water layers (Autonomous Underwater Vehicle, AUV) and at the deep seafloor (Benthic Crawler), a free-falling system (Bottom-Lander), and also remotely operated multicopter (Unmanned Aerial Vehicles, UAV), which truly provide new insights (see figures). The next weekly report will provide detailed information on these devices and illustrate their great potential.
With the warmest regards from all scientists,
Thomas Soltwedel
Contact
Scientific Coordination
Rainer Knust
+49(471)4831-1709
Rainer Knust
Assistant
Sanne Bochert
+49(471)4831-1859
Sanne Bochert
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