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Ship´s log POSEIDON 400

The research vessel POSEIDON will start its 400. cruise on June 29, to the Porcupine Seabight off Ireland. Together with colleagues from the Senckenberg Insitute by the Sea and from the University College Cork MARUM scientists will explore the cold-water corals in this area. Unlike their tropical fellows living in shallow and warm water, cold-water corals can be found in colder regions and in depths of 1.200 meter. Cold-water corals build up reefs with their carbonate skeletons, too, generating unique ecosystems, like the carbonate mounds off Ireland. Within the European research project HERMIONE (Hotspot Ecosystem Research and Man's Impact on European Seas) the scientists study the development of this ecosystem in the last 10.000 years. They want to find out, which changes in environmental conditions affected the vitality of cold-water coral ecosystems. With the remotely operated vehicle (ROV) MARUM-CHEROKEE the scientists can explore the sea bed, make measurements and take samples.

This Ship´s log report on the work and life on board the research vessel POSEIDON.

The current position of the POSEIDON and further information about the expedition can be found here.

Do you have questions to the scientists on board? Just send an e-mail to:

Research vessel POSEIDON

Wednesday, July 14, 08:40 p.m.

After the ending of the measurements yesterday evening, we left our study site in the Porcupine Seabight and set off towards Cork. This day we used to pack the rest of the equipment and to clean up the labs. We are all very pleased about the successful expedition.

Claudia and Marco look at the coast of Ireland (picture: MARUM).

We made 24 samplings with the gravity corer, 18 of them successful. If we add the cores up, we gained 78 metre of marine sediments. We took 31 samples with the grab sampler, 29 were successful. In addition we made three 12-hours-measurements with the CTD probe. Especially we were pleased about the short-term improvement of the weather conditions that allowed us to operate the CHEROKEE for all in all seven dives. The ROV was altogether 23, 5 hours underwater.
Position of the ship
51° 54’ North, 8° 27’ West
Harbour of Cork, Ireland
Weather
Rain
15, 3° C

Cook Horst prepares the lunch (picture: MARUM).

Claudia writes the cruise report (picture: MARUM).

The cruise members of the 400. cruise of the POSEIDON: André, Götz, Jana, Lydia, Claudia, Mark, Markus, Werner und Marco (picture: MARUM).

This evening we arrived at the harbour of Cork. Here our expedition with the POSEIDON ends. We want to thank our crew for the professional work at the bridge and on deck, for the great working atmosphere, for the very good food, for the kindness and the fun. Thank you very much!

For the last time greetings from the POSEIDON to all readers of our ship’s log, who came along with us on this cruise!

The POSEIDON in the harbour of Cork (picture: MARUM).

The POSEIDON in front of the coast of Ireland (picture: MARUM).

In Cork our container is lifted with a crane (picture: MARUM).

Tuesday, July 13, 09:11 p.m.

Today we started with station work at the Macnas Mounds at 06:00 a.m. with the deployment of the gravity corer. At the first station the pipe came up empty twice. Here the gravity corer could not be pushed into the sediment not even with high speed from the winch. After we gained a core at the second station, we took one more core at another place nearby instead for the first station.

Boatman Achim is helping the three Ms with packing the container (picture: MARUM).

During the deployment of the gravity corer, the CTD probe was prepared for another 12-hour-operation. Götz, Mark, Markus and Marco rotated by recording the results of the measurements.

Motorman Rüdiger in the machine room (picture: MARUM).

Position of the ship
51° 26’ North, 11° 33’ West
Porcupine Seabight, Macnas Mounds
Weather
Rain
15, 0° C, Wind: 4 Beaufort

Engineer Heiko at the work bench (picture: MARUM).

Jana labels the cores in the lab (picture: MARUM).

Because of a large area of low-pressure coming towards us with wind force of 10 Beauforts predicted, we finished our scientific program with today’s CTD measurements. We used the still calm sea to stow away the large part of the lab and sampling equipment in the container. Everybody helped packing so that the labs were emptied quickly.

Greetings from all cruise members on board the POSEIDON!

Markus and Marco packing the lab equipment together (picture: MARUM).

Electrician Dietmar at the working bench (picture: MARUM).

Monday, July 12, 07:15 p.m.

Today we steamed to another study site at the Porcupine Seabight to explore the Macnas Mounds. They lie to the east of the coral mounds Poseidon, Pollux and Lions Head from which we already took samples. In contrast to the roughly 100 metre high coral mounds there, the Macnas Mounds are only little rises of maximum 10 metre height. According to a theory these little mounds maybe form the basis for big coral mounds. To find out more, the ROV pilots flew the CHEROKEE over the Macnas Mounds. Beside coral rubble we saw again many crabs, starfish, anemones and sea urchins, but we could not spot any living corals.

Electrician Dietmar and engineer Kurre repair the cable of the winch (picture: MARUM).

To get further information about the nature of the Macnas Mounds, we took two cores with the gravity corer after the dive. On the first sight the sediment looked sandy and contained no corals. This led to the suggestion that the Macnas Mounds are just sand dunes at the sea floor. But this will only be confirmed when the cores are analysed in the lab.

Greetings from all cruise members on board the POSEIDON!
Position of the ship
51° 33’ North, 11° 35’ West
Porcupine Seabight, Macnas Mounds
Weather
Overcast
14, 4° C, Wind: 1 Beaufort

Werner navigates the CHEROKEE over the Macnas Mounds (picture: MARUM).

After the dive Götz rinses off mud and saltwater from the CHEROKEE (picture: MARUM).

Second officer Alexander Hänsel holds the ship on its position during the dive (picture: MARUM).

Mark and Captain Oliver Secchi at the bridge (picture: MARUM).

Sunday, July 11, 08:09 p.m.

Like the two previous days we started today with a ROV dive. This time the CHEROKEE dived along the long crest of the Poseidon Mound, which ranges about 900 metres from the northeast to the southwest. We discovered areas with pronounced current ripple marks and many dropstones.

A very big dropstone (diameter about 1.5 metre) colonised by barnacles. In the foreground a deep sea swimming crab and more dropstones (picture: MARUM).

These stones were transported to the area of the Porcupine Seabight by icebergs during the last glacial. Then, during the so called Heinrich events, increased numbers of icebergs broke from the glaciers and drifted southwards in the North-Atlantic. The last one of these events occurred about 14,000 years before today. While they were melting, the icebergs lost the enclosed stones on their way. The stones sank to the sea floor where they still can be found in some areas today. These dropstones are an indicator for very strong currents near the sea floor. These currents prevented the dropstones from being covered by sinking material. The currents are important for the animals living on the seafloor because they deliver food for the organisms who filter the water and feed on the particles.
Position of the ship
51° 20’ North, 11° 49’ West
Porcupine Seabight, Poseidon Mound
Weather
Overcast
15, 1° C, Wind: 4 Beaufort

We as observers are also observed: a curious octopus eyes the CHEROKEE (picture: MARUM).

Steward Uli is setting the tables in the mess for lunch (picture: MARUM).

Captain Oliver Secchi holding the ship at the position during the ROV deployment (picture: MARUM).

At another place on the Poseidon Mound we found large-scaled, ragged carbonate structures, which the scientists could not define. Therefore, samples were collected with the CHEROKEE for further analyses in the lab. After the ROV deployment at the study site on the Poseidon coral mound, cores were taken with the gravity corer. On the first try the gravity corer hit hard substrate. It could only penetrate into the sediment less than one metre before it bent. The pipe came back on deck buckled, for a marine researcher a so-called “banana”. After the steel pipe was changed, we could gain three cores without any further incidents. On the working deck Marco, Markus and Mark divided the cores into sections, which were closed, cleaned and labelled by Claudia and Jana in the Geo-lab.

Greetings from all cruise members on board the POSEIDON!

A fly-trap anemone and barnacles on a drop stone, in front two sea urchins. Around the stones there lays coral rubble (picture: MARUM).

The gravity corer hit hard substrate and came back as a “banana” on board (picture: MARUM).

Saturday, July 10, 10:15 p.m.

At 07:00 a.m. the preparations for another dive with the CHEROKEE began. When we arrived at the station, a sample with the grab sampler was taken to get a first impression of the sea floor beneath us. Then the CHEROKEE dived to a small mound south of the Poseidon Mound, named Little Poseidon. The two ROV pilots flew the underwater vehicle just above the sea floor, whilst they landed it on the sea floor again and again to take pictures or collect samples with the manipulator. Today again we encountered some of the carrier crabs that often carry different corals on their backs. A murmur went trough the control stand when one of these crabs pushed off the ground and swam away in front of the CHEROKEE. So far no one had seen this species swimming.

Bathymetrical chart of the coral mounds Poseidon and Little Poseidon (copyright: Andreas Beyer).

The ROV pilots can read all the information they need for controlling the device on several screens. One screen shows a chart with the topography of the sea floor and the positions of CHEROKEE and POSEIDON, another screen displays the pictures of the sonar. On additional screens the signals of the photo and video cameras come in. At lunch time the CHEROKEE reached the top of Little Poseidon and then dived the slope down again towards the tall Poseidon Mound. As soon as the CHEROKEE was standing on deck again, the gravity corer was dropped down into the deep. Today’s station work was finished with two cores from the top of the Poseidon Mound.

Greetings from all cruise members on board the POSEIDON!
Position of the ship
51° 37’ North, 11° 55’ West
Porcupine Seabight, Poseidon Mound
Weather
Sunny
14, 4° C, Wind: 5 Beaufort

The CHEROKEE is launched (picture: MARUM).

Jana is filming the work on deck (picture: MARUM).

Whales came very closely to the POSEIDON (picture: MARUM).

All cruise members watching the dive of the CHEROKEE on screens of the control station (picture: MARUM).

Friday, July 09, 06:08 p.m.

During the night the swell decreased so now we could execute the planned dives with the CHEROKEE at the Lions Head coral mound. The ROV (remotely operated vehicle) is operated by remote control over a cable and can dive to a water depth of 1000 meter. Just before breakfast, the two ROV pilots Götz and Werner started to get the device ready. Prior to every dive all the systems and instruments, such as manipulator, drive mechanisms and lights, are checked. Then the 450 kilogramme vehicle was launched. These first few minutes are critical, because it is possible that waves might push it into the vessel’s side. Therefore Werner immediately brought the diving robot to a secure distance from the ship. As long as the vehicle is visible at the surface, he can navigate the CHEROKEE with a portable control panel from the deck. As soon as it is under the sea surface, it is operated from the control station in one of the labs. All other cruise members joined the ROV pilots to observe the dive on the screens.

Stone coral thicket with various species of corals, such as Lophelia pertusa and Madrepora oculata (picture: MARUM)

The CHEROKEE dived down to a water depth of 850 meter to the southwest margin of the Lions Head Mound. Meanwhile Marco operated the winch and continuously paid out more cable overboard. Götz and Werner flew the underwater vehicle along the sea floor over the slope of the mound up to his top at a water depth of 720 meter. With this dive the Lions Head Mound was explored with an underwater vehicle for the first time. Everybody was enthusiastic about this lively underwater world, which was brought to us with the help of the video camera on the CHEROKEE.
Position of the ship
51° 20’ North, 11° 41’ West
Porcupine Seabight, Lions Head Mound
Weather
Rain
14, 7° C, Wind: 5 Beaufort

As long as the CHEROKEE is visible at the surface, Werner can navigate it with a portable control panel (picture: MARUM).

A cylinder rose (Cerianthus) (picture: MARUM)

There at the bottom, where cold temperatures reign and no sunlight comes through, we recovered different species of cold-water corals, crabs, sea urchins, starfish, various fish, tube worms, snails, anemones and much more. Surprising to the researchers was the huge amount of living corals even in the lower areas of the mound. The higher the ROV got, the more densely populated the mound became with increased numbers of corals living there.

A carrier crab (Paromola cuvieri) with a gorgonian coral in its hind legs (picture: MARUM)

Marco operates the winch while CHEROKEE is diving (picture: MARUM).

A flytrap anemone (Actinoscyphia) (picture: MARUM)

In addition to the video documentation Götz took lots of beautiful underwater pictures. With its manipulator the CHEROKEE collected various cold-water corals and stored them in its drawer. Back on the deck Lydia and André analysed the samples, Götz and Werner uploaded the pictures and prepared the ROV for a second dive. This time it was to dive up the slope of the mound in a west-east-direction. In the beginning the ROV drifted due to a strong current but it was brought back to its planned track again. Today the vehicle completed two dives, all in all seven and a half hours underwater.

Greetings from all cruise members on board the POSEIDON!

A colony of octocorals of the species Anthomastus grandiflorus (picture: MARUM)

In a drawer CHEROKEE brings the collected samples from the sea floor on board (picture: MARUM).

Thursday, July 08, 08:52 p.m.

Today we regard the summery temperatures in Germany with envy. We only reached 15°C. As well, it was raining with waves swashing over the deck and our feet. The wet coldness was creeping into our bones and warm pullovers and woolly socks could not drive the clammy feeling away.

Lydia and Mark waiting on the afterdeck for the next grab sample (picture: MARUM).

We continued our sampling from yesterday at the Poseidon Mound and took five samples with the grab sampler until lunch. Here again the scientists found living Lophelia-corals. But the bulk of the samples consisted of dead cold-water corals from the species Madrepora oculata.
Position of the ship
51° 28’ North, 12° 07’ West
Porcupine Seabight, Poseidon Mound
Weather
Overcast
14, 8° C, Wind: 3 Beaufort

Lydia checks fine-grained material she caught with a sieve (picture: MARUM).

A sea urchin from the grab sample (picture: MARUM).

The wind direction turned again and again causing a turbulent cross-sea. Thus we could not operate the gravity corer as was planned for the afternoon. Claudia decided to take some more samples with the grab sampler, which can be handled easier because it is not so heavy. After lunch we could take one more grab sample on deck. Afterwards we could not continue with the sampling due to disadvantageous current and weather conditions. But the forecast for tomorrow predicts a considerable enhancement of the weather conditions, so that we want to start tomorrow with a dive of CHEROKEE.

Greetings from all cruise members on board the POSEIDON!

Marco and Lydia rinsing a subsample out of the sieve into an aluminium tray (picture: MARUM).

André taking pictures of the sample (picture: MARUM).

Lydia and Marco pouring the sample over the sieves (picture: MARUM).

Wednesday, July 07, 10:52 p.m.

Right after breakfast the preparations for more sampling with the gravity corer began. In the container on the afterdeck we store the five meter long plastic pipes, which are pushed into the steel pipe of the gravity corer. To be able to arrange the one meter long sections of one core in the right alignment afterwards in the lab, we draw a line along on every pipe for the orientation.

Mark and Marco draw the line onto the plastic pipe (picture: MARUM).

Marco and Mark prepared the gravity corer and finally put the core catcher on the lower end of the pipe. While Claudia worked on the retrieved cores in the Geo-lab, the two are already preparing for the next sampling.
Position of the ship
51° 20’ North, 12° 18’ West
Porcupine Seabight, Pollux Mound and Poseidon Mound
Weather
Overcast
15, 3° C, Wind: 5 Beaufort

The core catcher will be fixed on the lower end of the gravity corer and prevent the sample from getting lost on the way up (picture: MARUM).

Mark and Marco pushing the plastic pipe into the steel pipe of the gravity corer (picture: MARUM).

We gained three cores at the Pollux Mound from water depths of 910 to 945 meter. The launching and hauling onboard, as well as the further work on the cores, were filmed with the video camera. After lunch we steamed to the Poseidon Mound. It was sampled for the first time in 2002 on a cruise with the research vessel POSEIDON. Then, André was on board and gave the mound its name. We took four samples at different stations with the grab sampler.

Greetings from all cruise members on board the POSEIDON!

The core catcher is fixed with nails on the pipe (picture: MARUM).

Marco and Mark pushing the plastic pipe into the steel pipe of the gravity corer (picture: MARUM).

The end of the gravity corer is greased before putting on the core catcher (picture: MARUM).

One box is already filled with cores (picture: MARUM).

Tuesday, July 06, 08:31 p.m.

This morning we did not have any of yesterday´s good weather. Without looking out the bull’s-eye you already notice from the ship’s movement that a deployment of the underwater vehicle would not be possible today. So, we steamed to another coral mound named Pollux to get some grab samples. From the top and the western slope of the Pollux mound living Lophelia corals were brought on deck for the first time on this cruise. We gained all in all nine grab samples from different water depths of 900 to 980 meter.

Glass sponges from the grab sample (picture: MARUM).

As soon as the grab sampler was heaved on board, the big tub was already standing by. In single file the scientists follow the sample from the working deck to the afterdeck where it was analysed. The wind increased during the day and waves swashed over the deck giving some of us wet feet. The samples – divided into subsamples of different particle sizes – were filled in aluminium trays and are stored for several hours in drying cupboards. One of these cupboards did not function and the other one could not contain the huge amount of sampled material, so the lab was quickly covered with aluminium trays.
Position of the ship
51° 22’ North, 12° 06’ West
Porcupine Seabight, Pollux Mound
Weather
Overcast
16, 3° C, Wind: 6 Beaufort

The grab sampler is fixed before it is dropped down to the sea floor (picture: MARUM).

The cold-water coral Lophelia pertusa occurs in colonies (picture: MARUM).

After dinner it was decided to store the samples in the warmest place on board, the machine room. To the delight of the other cruise members – some of these samples gave off a strange stink. With the help of today’s grab samples Claudia chose the stations at the Pollux mound at which we will take cores with the gravity corer tomorrow. For now we packed up work for today to spend the evening altogether in the mess watching the first semi finals of the football World Cup.

Greetings from all cruise members on board the POSEIDON!

The calcified hydrozoa Pliobothrus belongs to the Stylasteridae (picture: MARUM).

With the winch over the working deck the grab sampler is dropped down to the sea floor. The gravity corer stays lashed on the deck today (picture: MARUM).

The subsamples divided into different size groups are dried in aluminium trays (picture: MARUM).

Monday, July 05, 09:37 p.m.

Today we had the best weather conditions since our arrival at the study site, and of course we used this to our advantage all day long to get samples. At eight stations samples were taken at a so far unnamed carbonate mound. We gave the 100 meter high mound the name “Lions Head” after the famous mountain in Cape Town, where the German soccer team made it into the semi finals.
First we took eight samples with the grab sampler in different water depths of 730 to 800 meters. Its two buckets have to be fixed before dropping the device down to the sea floor. When it touches the ground both buckets snap automatically and bring the sample securely on board. Here the samples are received starry-eyed by our colleagues from the Senckenberg Institute (SaM). First they took some pictures of the samples and made a review of the material by noting what the grabber brought up to the day light. Besides different species of cold-water corals they found worms, snails, crabs, sponges, sea urchins and much more. For further analyses in the lab, subsamples were removed before rinsing the remains with water over different sized sieves. The samples, then grouped to fractions with different particle sizes, were stored for several hours in the drying cupboard.

Everybody wants to have a look at the sample (picture: MARUM).

Because we gained a sample at every station by the first attempt, we had finished this part of the working plan quickly. Next we took cores with the gravity corer at three of the eight stations sampled before. With a yield of all in all 14 meters these were the first coral cores we took on our cruise. After ending the successful sampling with grab sampler and gravity corer the captain suggested to use the ongoing good weather conditions for a dive with the CHEROKEE. Actually the dives were planned for tomorrow, but as the forecast predicted worse weather coming during the night, the pilot team did not hesitate and the CHEROKEE was launched after a check of all the instruments.
Position of the ship
51° 20’ North, 11° 41’ West
Porcupine Seabight, Lions Head
Weather
Sunny
15, 4° C, Wind: 3 Beaufort

The grab sampler is heaved on board again (picture: MARUM).

With the help of a colour chart for sediments Claudia defines the colour of our sample (picture: MARUM).

All cruise members were present in the control stand of the pilot team and could observe on the screens the vehicle as it dived into the deep. At the eastern foot of the Lions Head mound we could see the sea floor appear on the screens at about 810 meters. Here we could spot special stones lying on the ground, called “drop stones”. They are an indicator for very strong bottom currents. Unfortunately this current was so strong that the CHEROKEE could not follow the scheduled track westwards over the slope of the coral mound and drifted away. But although the dive had to be interrupted, due to the profitable sampling this day was a great success for all of us!

Greetings from all cruise members on board the POSEIDON!

André and Lydia above the grab sample (picture: MARUM).

Claudia notes the first review of the grab sample (picture: MARUM).

André examining a coral with a hand-lens (picture: MARUM).

Lydia is taking subsamples for further analyses in the lab (picture: MARUM).

Sunday, July 04, 11:11 p.m.

The morning had welcomed us with rough sea once more. After a short briefing at the bridge it was decided to only operate the CTD probe today. The waves were too high to deploy any of the other devices. The probe was launched at 8:45 a.m. and dropped down to 15 meter above the sea floor corresponding to almost 1000 meter water depth at this station. Then a measurement program was started like the day before yesterday; that is the probe was heaved and veered over 12 hours at the same position. The recorded parameters, like salinity and temperature, give information about the different water bodies moving under the ship over a tide cycle.

View to the bow (picture: MARUM).

Several cruise members managed the data processing by taking shifts in rotation. In coordination with the bridge, chief scientist Claudia wrote the working plan for tomorrow, as the forecast says we can finally expect better weather. But, although the wind is already decreasing, the waves probably will be still too high for the deployment of the underwater vehicle, so we are planning grab sampling tomorrow. All in all the device shall grab samples at eight stations from the surface of a carbonate mound. With great expectations we all look forward to the sampling tomorrow!

Greetings from all cruise members on board the POSEIDON!
Position of the ship
51° 19’ North, 11° 38’ West
Porcupine Seabight
Weather
Overcast
14, 8° C, Wind: 4 Beaufort

View out of the bull’s-eye (normally above sea surface) (picture: MARUM).

The POSEIDON seen from the foredeck (picture: MARUM).

One of the many northern gannets come along with the ship (picture: MARUM).

Saturday, July 03, 9:28 p.m.

This morning the state of the sea abated so that we could finally sample with the gravity corer. Here cores are punched out of the sea floor with a pipe. We used a six meter long steel pipe that carried an additional weight of 1.2 tons. With a winch, the pipe was dropped down to the sea floor. Due to the weight at the upper end of the pipe it was pushed into the sediment. The core catcher, a sleeve at the lower end of the pipe, locks automatically when the pipe is heaved again. So it prevents the sample to get lost on its way up to the ship.

The gravity corer filled with sediment back on the deck (picture: MARUM).

Position of the ship
51° 32’ North, 11° 36’ West
Porcupine Seabight
Weather
Overcast
15, 8° C, Wind: 6 Beaufort

The gravity corer is launched (picture: MARUM).

Back on the deck the gravity corer was lashed to the deck and sediment remnants were rinsed off the outside. A plastic pipe within the steel pipe contained the sediment core. With a pipe cutter the core was cut up into one meter long sections. These sections were locked with caps and labelled. The cores will be opened and analysed in the lab in Bremen.

Götz and Marco cutting up the core into one meter sections. Markus has already the caps ready to close the sections (picture: MARUM).

From the pictures it can be seen that we had not optimum conditions for sampling with the gravity corer. But thanks to the professional navigation and the perfect teamwork between the bridge and the crew on deck this sampling was such a great success! Chief scientist Claudia is happy about the productive sampling: All in all we gained five cores from different water depths between 530 and 950 meter. Altogether they come to 24 meters of ocean deposition. Due to the efforts of everybody today’s station work could be completed in time. At 04:00 p.m. we all met in the mess to view the World Cup game between Germany and Argentina. The cheers about the progression of the German team into the semi finals resounded far onto the Atlantic.

Greetings from all cruise members on board the POSEIDON!

View over the bow at rough sea (picture: MARUM).

Marco rinsing the sediment remnants off the pipe (picture: MARUM).

Claudia taping the caps onto the pipe ...

... and labelling the cores (pictures: MARUM).

Friday, July 02, 10:15 p.m.

During the night we finally arrived at our study site at the Porcupine Seabight. The station work should have began in the morning at 6:00 a.m. with the deployment of the CTD probe. Due to bad weather conditions the start had to be put off until 10:00 a.m. Most of the cruise members used the time to make up for lost sleep, as the night before we were jerked from our sleep again and again by the heavy movements of the ship and the squealing and rattling noise around.

Seaman Gent and Marco launching the rack with the CTD probe (picture: MARUM).

Position of the ship
51° 21’ North, 11° 42’ West
Porcupine Seabight
Weather
Overcast
15, 2° C, Wind: 6 Beaufort

In the morning at 6:00 a.m. the sea was too rough to operate the CTD probe (picture: MARUM).

A little bit fresher than before we met at 10:00 a.m. for the second try of CTD measurements. Since we did not want to take water samples, the bottles were removed and only the empty rack with the probe was launched. With a winch the probe was dropped (veer) to a water depth of 850 meters and then drawn up (heave) again until ten meters beneath the ocean surface. Like a yoyo the probe is heaved and veered over a complete tide cycle while the ship holds its position. The CTD probe measures continuously the conductivity and temperature of the water as well as the depth. From these parameters the salinity and the density can be calculated.

Seaman Ralf operating the winch that heave and veer the probe (picture: MARUM).

In rotation Marco, Markus and Mark work with the programme that record this data. They check the depth and give the commands for heaving and veering to the seaman working at the winch. The station work will probably end at 11:00 p.m. Tomorrow morning we will then explore the first carbonate mounds.

Greetings from all cruise members on board the POSEIDON!

A short shower gave us this beautiful sight at the evening sky (picture: Lydia Beuck, SaM).

Markus and Mark checking the measurements of the CTD probe (picture: MARUM).

The data measured with the CTD probe is recorded and processed with this programme (picture: MARUM).

Thursday, July 01, 9:35 p.m.

During the night the weather got worse and the wind increased. Waves with heights up to three or four meters made the ship rock and kept several cruise members awake. Towards the morning the sea calmed down a little bit and even the sun came out again. Over the day the waves still reached heights of two to three meters and often swashed over the working deck.

A wave swashing over the working deck (picture: MARUM).

Position of the ship
50° 46’ North, 11° 35’ West
On the way to the study site
Weather
Overcast
16,5° C, Wind: 6 Beaufort

Some waves mount up so high, that the horizon disappears behind them (picture: MARUM).

We hope the swell will furthermore decrease, so that the deployment of the sampling and measurement devices in the study site can be carried out as planned. Due to the weather conditions our arrival in the Porcupine Seabight will be delayed. We will arrive there during the night. Chief scientist Claudia already wrote the working plan for the next few days. The station work shall begin tomorrow morning at 6 a.m.. First the CTD probe will be deployed. While it is dropped down with a winch to 800 meters water depth, the probe continuously measures the temperature and the conductivity of the ocean water. With the conductivity the scientists can calculate the salinity of the water. Mark and Markus will operate the probe over 12 hours and were therefore instructed in the operation software by Götz.

Götz explains the operation programmes for the CTD probe to Marco, Markus, Mark (yes, we are already thinking of some nicknames) and Claudia (picture: MARUM).

We all can hardly wait to arrive in the Porcupine Seabight and start with the scientific programme.

Greetings from all cruise members on board the POSEIDON!

On the bridge of the POSEIDON (picture: MARUM).

Course and investigation area are plotted into the sea charts (picture: MARUM).

Wednesday, June 30, 9 p.m.

Under best weather conditions the POSEIDON continued her cruise to Porcupine Bight off the coast of Ireland. Together with her colleagues from the Senckenberg Institute chief scientist Claudia Wienberg located the tracks for the dives of the CHEROKEE. With the help of bathymetric maps showing the altitude difference of the sea floor the scientist can locate single carbonate mounds which shall be explored by the diving robot. The defined tracks are plotted into the maps and together with the coordinates passed on to the pilots of the CHEROKEE.

Claudia and Lydia locating the tracks for the dives of the CHEROKEE (picture: MARUM).

In the morning we came to an unexpected stop in the Biscaya when buoyancy material with a kind of mounting or anchorage appeared in front of the POSEIDON. The ship was stopped to retrieve the material. It was the remnants of a fishing net. The retrieved rope was colonised with hydrozoa and goose barnacles. So some parts of the rope were sampled to study the animals under the microscope.

André and Markus cut some parts of the retrieved rope to study the organism that colonised the rope (picture: MARUM).

Position of the ship
47° 16’ North, 10° 51’ West
On the way to the study site
Weather
Overcast
19,4° C, Wind: 6 Beaufort

These buoys drifting towards the POSEIDON were probably cut loose (picture: MARUM).

Seaman Pedro and boatsman Joachim retrieve the buoyancy material which turned out to be remains of a fishing net (picture: MARUM).

Goose barnacles and hydrozoa stick to the rope (picture: MARUM).

Because of the bad weather forecast for tomorrow, the pilot team used today’s good weather conditions and the unexpected stop to run a first diving test with the CHEROKEE. After a check of all instruments the underwater vehicle was launched and then operated by the pilot in the control station. The vehicle ran smoothly during the dive and was lifted on board again and lashed for the transit. Afterwards the POSEIDON continued its way to the study site which we probably will arrive at tomorrow evening.

Greetings from all cruise members on board the POSEIDON!

Pedro and Joachim launching the CHEROKEE (picture: MARUM).

At the control station Götz operates the CHEROKEE (picture: MARUM).

Tuesday, June 29, 11:45 p.m.

The 400th cruise of the research vessel POSEIDON started in Vigo on the Spanish Atlantic coast. Seven of the nine cruise members arrived already at the weekend and took the equipment out of the container in which it was sent to Vigo in advance. The labs on board were set up and the sampling devices constructed on the working deck. The pilot team of the underwater vehicle CHEROKEE made ready the instrument and its control station for takeoff.

Dolphins are joining us on our way to the study site (picture: MARUM).

This morning at sunrise the POSEIDON left the harbour of Vigo and started its way to the investigation area off the coast of Ireland. Under good weather conditions we will arrive at the study site on Thursday and start directly with a CHEROKEE test dive.
Position of the ship
44° 16’ North, 09° 51’ West
On the way to the study site
Weather
cloudless sky
18, 6 ° C, Wind: 2 Beaufort

The POSEIDON steams out of the harbour of Vigo at sunrise (picture: MARUM).

Götz, Claudia and André with their life jackets at the security training (picture: MARUM).

At the security training the chief officer explained the security rules on board and the behaviour in a case of emergency to all cruise members. At the alarm practice everybody had to put on their life jacket and go to the Muster station on the working deck. After these instructions the cruise members used the transit time to install devices and make last preparations for sampling.

Greetings from all cruise members on board the POSEIDON!

Lydia and Götz install the microscopy camera in the lab (picture: MARUM).

The research vessel POSEIDON in the harbour of Vigo (picture: MARUM).