Wildlife of POS527

The Poseidon is heading back towards Kiel and we’re busy cleaning, writing, and processing data. And, of course, sharing photos. Besides our scientific work, we’ve been enjoying the local wildlife – here are few of the highlights!

Occasionally a larger animal gets caught up in our sediment samples. We found a sea star (Astropecten irregularis), mud shrimp (Callianassa), some hagfish, and a sea mouse (Aphrodita aculeate).

Sea star (left) and mud shrimp (right)

Hagfish (left) and sea mouse (right)

Lots of dolphins live in the area; they seem to enjoy swimming under the boat and surfacing just beside us as we work.

By Allison Schaap, NOC

Homeward bound

We are now sailing back over a friendly North Sea, as smooth as glass under a warm summer sun. Anna had her early morning coffee under a pink sunrise, with dolphins hopping around the ship.

The cruise work is mostly done. Deckhands are cleaning the ship from the last traces of North Sea mud. The scientists are now busy storing last samples, cleaning equipment, transferring data to hard-discs, packing and inventing cruise reports.

A beautiful creature from the bottom of the North Sea, found in a box-core

We aimed to determine the natural activity of the sea bottom. The seafloor here is flat and compacted mud with lots of pockmarks. These are 3-4 m deep valleys of about 100 m wide, formed by explosive methane release. It is possible that these pockmarks are more active ecosystems as they collect detritus and maybe are fuelled by ongoing methane release. We are curious if these pockmarks have a different faunal community, if they take up more oxygen and release more CO2, and if they expel compounds to the water column. Fauna is studied from box cores. Oxygen uptake rates are measured in situ by the so-called eddy covariance method. Sediment activity is measured by oxygen uptake using microsensors and sulphate reduction rates by radiotracer incubations. Possible effects on the water column chemistry are detected by CTD, a device for sampling and analysing the water column. First analyses indicate that the pockmarks are equally as active in oxygen uptake as the normal flat sediments. But sulfidic sediments and an area where drilling has occurred have a twice as active aerobic microbiology. Measurements on sulphate reduction will start next week in the home laboratory.

It was a good cruise. Yesterday the last box-core was taken (number 76!) and the last of the 8 gravity cores. Dirk Koopmans deployed the eddy covariance system 5 times. Satisfyingly, the instrument collected many hours of unique data on the biological activity of the seafloor, and how this depends on current and position. The data will keep him busy in the coming weeks.

Last recovery of the eddy co-variance lander

The lab-on-chips sensors from Allison and Martin worked like a charm, highly reliably. A battery of 4 is still working, continuously analysing seawater on transect from Goldeneye to Kiel. They will be the last ones to be packed, in the harbour.

Lab on chip sensors from Allison Schaap are measuring continuously the seawater composition

So, a fond farewell from the Poseidon as we make our way back to Kiel.

Dirk de Beer

Sampling gases from seawater

Poseidon cruise 527 is our second visit to Goldeneye to establish the environmental baseline conditions of the area. Contrary to last year’s visit, the weather this time has been on our side and we have managed to collect almost 3 times more samples as last year.
We used a standard 12 Niskin bottles CTD rosette to collect samples for dissolved gases (oxygen and CO2), nutrients and organic matter in the water column at 12 different depths. The CTD frame is deployed by a winch to the bottom of the water column (as close to the seafloor as possible (around 1 m above) and during the up-cast the bottles are closed at chosen depths.

With the CTD rosette we were also able to obtain full-depth profiles of water column parameters like salinity, temperature, oxygen and fluorescence (chlorophyll). Together the samples and CTD sensor measurements define some of the key parameters for the assessment of the major biogeochemical processes within the water column near Goldeneye.

CTD rosette ready for action

On the CTD casts we also deployed pH and pCO2 optode sensors, and on some of the CTD casts we deployed phosphate and pH lab on chip sensors. These deployments were successful and allowed us to gain insights into the sensor operations. The sensor data will be compared to the discretely sampled nutrient and carbonate chemistry data (following sample analysis back in the laboratory at GEOMAR).

Water samples for gases, nutrients and organic matter

In shelf seas such as the North Sea these parameters are strongly affected by natural daily/seasonal environmental variations, but also by anthropogenic disturbances. In the framework of the STEMM-CCS project, it is crucial to detect and discriminate variations caused by potential leakages at CCS sites from variations in natural background signals. Our goal is to determine an effective environmental baseline in order to provide the data needed to define measurement strategies for a controlled sub-seabed COrelease experiment, which is planned for May 2019.

The collection of samples could not have been possible without the great support from our Captain and crew on board of the Poseidon 527. After 16 days of a pleasant weather conditions we are now leaving Goldeneye area and sailing back to Kiel on a beautiful calm sea.

Greetings from all aboard the Poseidon!
Mario Esposito and Dominik Jasinski

Measuring pH changes in seawater

We are on day 11 of our research cruise to the North Sea to investigate water column chemistry, and biogeochemistry and ecology of the seafloor at a site where we will experimentally release carbon dioxide below the seafloor next year. That sounds like an odd scientific objective, experimentally releasing carbon dioxide, but the justification is a good one. Former oil and natural gas bearing formations hundreds or thousands of meters below the seafloor are among the sources of carbon that now accumulates in our atmosphere as carbon dioxide. Carbon dioxide emissions can be reduced with improved technology, improved efficiency, and increasing uses of renewable energy, but additional progress could also be made by taking an active role in capturing carbon dioxide at point sources, such as industrial power plants, and sequestering it in geologic formations that are the least likely to leak. Candidate formations include former oil and natural gas bearing reservoirs deep beneath the seafloor. If natural gas could be held naturally there for millions of years, it is likely a good location for sequestering carbon dioxide. An additional advantage of these formations is that the infrastructure that was developed to extract oil and natural gas from them could be used to inject carbon dioxide back into them.

The benthic lander developed by the Max Planck Institute for Marine Microbiology (MPI) on the back deck of the GEOMAR Research Vessel Poseidon

Our objectives in releasing carbon dioxide from the seafloor next year is to investigate the potential damage to local ecosystems that could be caused by a leak, and to develop technology to quantify carbon dioxide emission from the seafloor should a leak occur. To accomplish this, engineers at the Max Planck Institute for Marine Microbiology have adapted ion sensitive field effect transistors to be used for rapidly detecting pH fluctuations in seawater. We are using these sensors in a novel application. Marine sediments naturally take up oxygen and produce carbon dioxide as they respire organic matter, like we do. As carbon dioxide is produced in seawater, pH is reduced. We can use the change in pH to calculate the carbon dioxide production.

pH, dissolved oxygen, and water velocity (all lower left) are measured at 16 Hz to capture their turbulent fluctuations in water

To do this, we have adapted a technique from atmospheric research based on turbulence. The pH sensors are positioned 25 cm above the seafloor and measure at 16 Hz as turbulence transports eddies of low pH water upwards from the sediment surface. Eddies are monitored at the tip of the sensor with an acoustic velocity instrument. Combined, pH and vertical velocity can be used to calculate the vertical transport of hydrogen ions. In measuring from second-to-second, minute-to-minute, and hour-to-hour, we can use this technology to examine changes in the metabolism of benthic ecosystems over time. Improvements in this technology would allow us to watch changes in the metabolism of marine ecosystems from season-to-season, and year-to-year, helping us to do a better job of protecting them.

Deployment of the MPI benthic lander.

An array of fast sensors for turbulence measurements by the MPI lander at the seafloor (120 m depth).

Greetings from all on the ship

Dirk Koopmans

Sampling seafloor sediment

Box corer coming onto deck (Photo: A. Schaap)

Macrofauna sampling and particle size analysis (PSA) are being used to create a baseline study of the macrofauna found around the Goldeneye site. We want to document the community structure and will do the sampling again following next year’s CO2 release experiment in 2019, in order to understand how the introduction of CO2 may affect it. Over 200 sites around the Goldeneye platform have been earmarked for sampling, 60 of which are of top priority. The sites have been carefully selected to represent different variables and factors including sites inside pockmarks, outside pockmarks, sandy mud sediment, muddy sand sediment, and whether or not a well head is nearby. Our approach will allow for comprehensive macro fauna sampling data of the area.

The sampling process of a site begins with collecting 0-2 cm, 2-5 cm, and 5-10 cm depth samples of the surface sediment using a syringe corer for PSA. 30 cm round sub-cores, with a depth of 30 cm, are then taken from 50×50 cm sediment box cores. These sub-cores are then portioned out into buckets, topped up with seawater, elutriated by hand to suspend the macrofauna within the buckets into the water, and poured over a large 1 mm pore size sieve inside a larger tub. Each bucket requires 3-5 elutriations to ensure that all the macrofauna, including heavy bivalves, in the portion of sub-sample in each bucket are suspended and poured into the sieve. The macrofauna that are retained by the 1 mm sieve once all elutriations have been completed, become the corresponding samples for the site where the box cores have been taken.

Sampling with syringe (Photo: A. Schaap)


Hi-tech bucket technology used in preparing the samples (Photo: A. Schaap)

The final sample, ready for analysis back in the lab at PML. (Photo: A. Schaap)

These samples will be analysed at a later date at Plymouth Marine Laboratory to provide important species abundance, biomass and diversity data that will help us understand the benthic ecology and macro fauna community found at each of the sampling sites. This baseline study will also allow us to make a direct comparison as to how the benthic macro fauna communities found at these sites have been affected when sampled again after the controlled CO2 release experiment in spring 2019.

Greetings from all on the ship!

Thomas Mesher


A swarm of sensors!

One of the goals of this expedition is to test some new sensor technology from the National Oceanography Centre (NOC) in Southampton. We’ve brought along thirteen autonomous chemical sensors – the largest deployment we’ve done to date! – and are putting them on a variety of platforms.

The sensors work by taking a chemical analysis usually done in a chemistry lab and performing them autonomously with a device called a “lab on a chip”, which has small channels, pumps, valves, mixers, and optical readouts to measure the result of a chemical reaction.

On this expedition we have sensors for measuring nitrate + nitrite, phosphate, and pH which have been developed and deployed before in the context of other projects. We’ve also brought along some new technology: sensors for measuring total alkalinity (TA) and dissolved inorganic carbon (DIC). This is the first time these two have been deployed outside of the NOC. While on Poseidon we’re trying to prove that they work in a realistic environment both on the ship and in the water and to collect some initial data. To that end, we’re running them in the lab with surface water samples while the ship moves around. We’ve also put the TA sensor on its first deep cast down to about 120 m here and measured along the water column. Later in the cruise we’ll also put both on the lander brought by our colleagues from the Max-Planck-Institute for Marine Microbiology to do a longer-term test on the sea floor.

Two of the sensors mounted on the MPI lander

Left: the TA sensor mounted on the CTD device for measuring along the water column (on the left side). Right: the CTD device just under the surface during a deployment


Greetings from all on board!

Allison Schaap and the POS527 team

Expedition POS527 gets underway

The Poseidon 527 cruise to the Goldeneye region in the North Sea forms an important component of the STEMM-CCS project.

Mobilisation and departure
Cruise POS 527 mobilised in Kiel on August 14, 2018. The participants travelled from Plymouth Marine Laboratory (UK), National Oceanography Centre Southampton (UK), MPI Marine Microbiology (Bremen Germany), Develogic GmbH (Hamburg, Germany) and GEOMAR (Kiel, Germany). We have a total of 11 participants and all were looking forward to a couple of weeks at sea on the RV Poseidon.

We sailed in the morning of August 15 with very calm weather in the Baltic Sea. We passed Danish islands and sailed under high bridges whilst the sun was setting and the moon rising. In the Skagerrak and the North Sea the wind and waves were a little more demanding for some of the cruise participants. Not all were able to eat their dinners and had to retreat to their bunks. Getting sea legs always takes a couple of days.

Arrival and start of work
We arrived at the Goldeneye site at 0730 h on August 18 and commenced with locating the NOC Develogic lander. The wind was ca. 6 Bf, with significant wave action, which made it challenging to operate.
The poor weather conditions only allowed us to undertake a CTD cast (station 1) and no Box corer work or lander deployment could be undertaken. We had to wait for better weather.

In the period between dinner and breakfast the next day, we undertook multi-beam surveys to improve our bathymetry maps. Our multi-beam operator (Catherine Wardell) has been doing an excellent job at enhancing the quality and coverage of the multibeam data around Goldeneye.

Good weather arrives
August 19 and 20 are providing us with excellent weather and calm seas. We are making great progress and have sofar conducted 4 CTD casts, deployed the MPI lander that measures sediment-water fluxes of oxygen and inorganic carbon. In addition, the benthic biologists (Saskia Ruhl and Thomas Mesher) have been handling a dozen box cores sofar. The speed of their operations is impressive. The crew of the Poseidon has been facilitating all this with excellent support.

Above, left: Work on the MPI lander for benthic flux measurements. Above right: deployment of MPI lander. Photos by Allison Schaap.

Above left: The sensors suite on MPI lander, ready to make benthic flux measurements. Above right: deployment of box corer for collection of sediment samples and benthic ecology samples. Photos by Allison Schaap.
Next on the list of things to do is the retrieval of the MPI lander. In our next blog we will report on this!

Eric Achterberg, Chief Scientist