Same procedure as every year: „Gardening“ in the deep Arctic Ocean

Today, HAUSGARTEN resembles a large network of 21 stations at water depths ranging between 250 m 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 investigates variations at the deep seafloor.

The expedition will also be used to implement installations for the HGF infrastructure project FRAM (Frontiers in Arctic marine Monitoring). The FRAM Ocean Observing System aims at permanent presence at sea, from surface to depth, for the provision of near real-time data on Earth system dynamics, climate variability and ecosystem change. It serves national and international tasks towards a better understanding of the effects of change in ocean circulation, water mass properties and sea-ice retreat on Arctic marine ecosystems and their main functions and services. Within the framework of a ‘Trans-National Access’ (TNA) initiative of the European project FixO3 (Fixed-point Open Ocean Observatories), the expedition will also provide access to the FRAM Ocean Observing System thereby supporting external and joint scientific projects logistically.

Right after leaving port we started to set up our laboratories and prepared all the different scientific instruments, gears and sampling devices. After a short but rather stormy transit (and the well-known side effects…) we reached the first HAUSGARTEN station in the early morning of July 24^th, where we deployed a so-called CTD/Rosette. This device combines a sensor array for various physical and chemical parameters with a carousel of water samplers, which collects discrete samples for biochemical and biological studies at defined water depths. CTD/Rosette sampling was followed by optical measurements in the water column and a number of plankton hauls. A so-called multiple corer was used to take surface sediments from the deep seafloor and a towed camera system provided images to assess distribution patterns of larger organisms living at the deep seafloor. All these instruments (and other gears which I will describe in the following weekly reports) will routinely be deployed at each HAUSGARTEN site to assess the ecological status quo of the marine system in Fram Strait in summer 2015.

A highlight of the first week was a dive with an underwater robot, a so-called Remotely Operated Vehicle (ROV), made available by the Center for marine Environmental Sciences MARUM in Bremen. The ROV “Quest 4000” was used to sample an experiment at the deep seafloor (2300 m water depth), which was installed already two years ago during an expedition of RV “Maria S. Merian”. This experiment was conducted to assess and quantify the perturbation of larger organisms inhabiting the upper sediment layers of the seafloor, the so-called benthos. The “bioturbation” of crawling and digging benthic organisms has important effects on the biogeochemical processes taken place at the sediment-water interface.

The next weekly reports will describe our ecological time-series work and the broad range of scientific equipment we use for our long-term studies in much more detail.

With the warmest regards from all cruise participants,

Thomas Soltwedel