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Insights into the seabed in Byfjorden - Bergen

For two weeks at the end of summer 2011, two researchers from the Centre of Geobiology were involved in the testing of NIVA’s new lander system.

Laila Reigstad (left), Andrew Sweetman (right)
Laila Reigstad (left), Andrew Sweetman (right)
Photo:
NIVA

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The goal of the research cruise was to use NIVA’s new state-of-the-art lander (see photo) to investigate potential effects on seafloor life if CO2 should leak from the subseafloor storage site out in the North Sea.  

A traditional way of sampling is to bring seafloor animals and sediments to the surface for analysis, but through the use of a lander, researchers can now study seafloor life “in situ” as the lander is place directly on the seafloor. The lander is a new technology and is basically a metal skeleton that can be outfitted with different packages of sampling tools depending on the research questions being asked. 

The Norwegian Institute for water research (NIVA) in Bergen has a new lander that is equipped with two incubation chambers. Each chamber has sensors for oxygen, pH, and temperature, enabling continuous measurements of these parameters throughout the experimental period. In addition, it is possible to withdraw up to 8 water samples during each experiment. Analysis of these samples makes it possible to monitor changes and developments in the two chambers over the course of the experimental period. It is also possible to inject up to 100 ml of liquid into the chambers during the experiment in order to manipulate the conditions within one or both of the chambers.  In this NIVA state-of-the-art lander, all of these various functions are programmed in advance and are performed at set times during the experiment as the lander sits on the seafloor. 

When the chamber lander is dropped from the ship it sinks to the bottom due to heavy weights on each of its three feet. Once on the seafloor, the two chambers are pressed 10-15 cm into the seafloor sediments and then closed.  This summer the lander was left on the seafloor for 40-hour periods before it was programmed to return to the surface for recovery by the mother ship. 

Laila J. Reigstad, a researcher from the Centre for Geobiology (CGB), joined NIVA scientist Andrew K. Sweetman, who is also an Associate Professor II at CGB, and first-semester CGB masters student, Camilla Bøe, together with a NIVA team, were all on-board the MS Solvik  where they conducted the very first deployments of NIVA’s new chamber lander.

The lander was deployed 4 times. In all 4 deployments one of the 2 chambers was injected with CO2-acidified seawater in order to study the possible changes in the seafloor community compared to the parallel community captured in the second chamber where only normal seawater was injected. The communities contained in the water and sediments will be analysed to identify eventual differences in macrofauna, meiofauna, bacterial lipids, microorganism community structure and functions, nutrient fluxes, and microbial sulfate reduction rates. This follow-up work has already started both at CGB and NIVA. 

Both CGB and NIVA are partners in national (SUCCESS) and European (ECO2) projects evaluating the potential and actual impacts as well as risks involved in long-term subsurface CO2 storage. In addition, NIVA is a member of the European project RISCS, which is the major funding source for this lander project. For more information on the various projects, please follow the links below: 

Subsurface CO2 storage – Critical Elements and Superior Strategy SUCCESS
Sub‐seabed CO2 Storage: Impact on Marine Ecosystems ECO2
Research into Impacts and Safety in CO2 Storage RISCS