We will investigate how sediment dynamics affects and is affected by sediment organisms such as worms, shellfish, and how this interaction is impacted by human intervention. The cruise is a cooperation of three research projects: PULS, SANDBOX and DISCLOSE, each focusing on slightly different aspects of the animal-sediment interaction, and bringing on board their own expertise. The people involved are from NIOZ, from TU Delft, from the University of Twente, and from the University of Groningen.
Karline Soetaert, expedition leader
Blog 8 by Karline Soetaert, expedition leader, 13th of June - One for all, all for one.
We are close to the end of two weeks working on the North Sea, and it has been an amazing experience. The scientific crew had the one-for-all, all-for-one mentality where everyone worked together and for each other; the Pelagia crew was impressive by their professionalism and flexibility.
For me it was almost 20 years ago that I participated in a scientific cruise that long, and there were so many things that I had forgotten. How beautiful and diverse the water surface can be: the first week we saw the North Sea change from an amazingly calm, slowly rippling, and beautifully blue-greyish sea into a violently whirling mass of foamy waves with crests of 5 meters during the storm.
Almost every evening our hard work was rewarded with the most beautiful sunset, turning the sky from yellow into red and violet and eventually black. I also forgot what an emotional roller coaster a scientific cruise can be: our doubts whether to put out the landers and moorings as we knew a storm was getting closer; our anxiety as we saw the storm becoming much more violent than we had thought and our expensive equipment was at risk; the relieve we felt when, after the storm somewhat slackened, we could see the buoys marking the presence of the landers; the horror when the cable broke as we tried to retrieve one of the landers; the joy when, after several hours of work, the lander eventually surfaced, and –finally- the excitement when we saw the first data that were recorded during the Beaufort 9-10 storm!
We worked very hard, stood up around 7 to commence working at 8, lunch at 12.30 (delicious food!) and dinner at 6 and then working till around 10 o’clock in the evening or even well into the next day if necessary, and all that 7 days in a week for two full weeks. During work we would take time to improvise, brainstorm, discuss, share knowledge (i.e. explaining the Coriolis force to the biologists and the digestive system to the engineers), and simply enjoy each other’s presence.
Within a few days we will all continue with our regular lives and these two weeks will become distant memories. All in all we had a very productive and memorable time on the North Sea with the Pelagia!
Blog 7 by Leo Koop, Delft University of Technology, 11th of June – Productive days at Egmond aan Zee
Much has happened since our last blog. After over a week in the Frisian Front we sailed a hundred kilometers south to Egmond aan Zee. While here, we deployed two landers, and a mooring. And we took thirty box cores, ten multi cores, a hundred and twenty sediment profile images, mapped 10km2 of sea floor with both a multibeam echosounder and side scan sonar, and recovered the landers and mooring. All of this work was done in a 10km long transect, with one end of it being almost on the beach and the other on the door step of the Egmond aan Zee wind farm. Needless to say, these have been a productive three days.
While most of these tasks start early in the day and make the crew and most of the researchers long for their bed by night fall, a team of three researchers and the officer of the watch gear up for their work which will go until the early morning hours of the following day. While the officer of the watch sails survey lines at a constant speed, Johan, Karin, and I (Leo) work on the aft deck carefully feeding out or reeling in towline to keep the side scan sonar at a steady height between five and ten meters above the seafloor. The survey data collected with the multibeam echosounder and the side scan sonar will be used to create a detailed map of the seafloor around which all the experiments on this cruise have taken place. Tonight, on one of the few nights that we are not performing surveys, I have the time to write this blog as the beach of Egmond becomes distant and the Pelagia sails to our new and final research site off the coast of Texel.
Blog 6 by Sarah O'Flynn, NIOZ researcher, 9th of June - The struggle to get the landers back on board
After almost a day and half of waiting for workable weather, we were all very happy to resume our work this morning. Today was our last day on the PULS project, so we hoped that everything would go according to plan. Unfortunately, we had some difficulty in retrieving the moorings as well as the Albex and Trol landers. This was partly due to the swell in the morning, but primarily owing to the stormy conditions of previous couple of days.
One of the issues was that the turbulence of the stormy weather and 5!!-meter-high waves had caused the feet of the landers to partially sink into the soft sediment. The first lander that was recovered was missing a foot, but suffered only minor damage to the sensors. While attempting to retrieve the second lander the cable broke so we were all feeling extremely anxious to say the least, particularly Rob and Magda. It was unwillingly dredged from the seabed and when its flag eventually emerged from beneath the waves there were a real sense of elation and relief with ‘high fives’ all round, both on the bridge and out on deck too.
The second lander was successfully recovered by our super technical crew; excellent work by whole team, under very difficult circumstances. No one was more relieved than Rob and Magda, to have their second lander back on board. It suffered a badly bent leg, but more importantly: the sensors appeared to be intact and functioning. In the afternoon our galley crew provided a nice cake for Leo’s birthday, which we enjoyed before our boxcoring work. After another beautiful sunset at the Frisian Front, we began our transit to a nearshore site, off Egmond aan Zee. All things considered, we are very satisfied with what we have achieved for the PULS and DISCLOSE projects this week, and look forward to what tomorrow will bring on the first day of the SANDBOX project.
Blog 5 by Justin Tiano, NIOZ researcher, 8th of June - A race against time for the PULS project
On Tuesday, we conducted a field experiment to measure effects from an electric pulse trawler. We already finished the first half of this study using a conventional beam trawl vessel. This day, however, held the most critical part for our mission: to immediately collect samples from a pulse-trawled area. The forecast provided more drama as the afternoon predicted stormy weather coming our way. This meant that we had to quickly coordinate the experiment with the fishing vessel, deploy our benthic landers and collect samples before the waves picked up!
The pulse trawler arrived on time and was able to conduct his job successfully for us. We then hurried to get our landers out and collected benthic samples until the whether made it too dangerous to work outside. Overall, we accomplished our main goal and the rest of the day was spent admiring Mother Nature’s fury from the deck or from the inside of a bucket.
Blog 4 by Chiu Cheng, NIOZ researcher, 6th June - A tale of two kitchens
Here we are, already on the 5th day aboard the RV Pelagia of the Royal Netherlands Institute for Sea Research! Each morning for breakfast, everyone can enjoy some slices of bread with a smidgen of a variety of jams, butters or pastas followed by, of course, the choice of a generous sprinkle of hagelslag.
All this available from the fully-equipped, aromatic galley of the vessel. But just right next door is another special laboratory “kitchen” for researchers to process samples. Among the many things you will find here include slices of sediment! And while these are not recommended for human consumption during mealtime, some of the marine benthic animals do in fact ingest this sediment to digest the organic matter and other nutrient-rich particles that may be embedded within the fine grains of the muddy samples. Sometimes, there will even be a thin layer of silt on the surface-like Nutella on bread. So whether one prefers a slice of bread or slice of mud, both are readily available to serve on board!
And thankfully, these orange slicing plates aren’t radioactive like the certain dinnerware from the decades past!
Blog 3 by Johan Damveld, University of Twente, 5th June.
Today we got to test Sarah’s newly purchased auto-sieve (0.5 mm). It can automatically sieve large samples of various cores taken out of the substrate. Due to the very fine and cohesive sediments we encountered (clay, silt and even peat), this took up a large part of the day. In total, we processed 8 boxcores and 6 cores taken with the Albex landers. As a result, we found some nice benthic animals in the cores; hard urchins, burrowed shrimps, crabs, brittle stars and various types of worms, such as Nephtys.
In the late evening, the DISCLOSE project had time to carry out the first part of a two-night multibeam and side scan sonar survey. A large area was monitored and again we found some nice trawling marks. The image of the side scan sonar was even so detailed, that we could trace back the location of the TU Delft lander (which was successfully retrieved earlier that day) by the marks it left on the seabed.
Blog 2 by Karin van der Reijden, Rijksuniversiteit Groningen (RUG), 2th June.
Although everyone thought it was hardly possible, we woke up with even better weather than the day before; an almost flat sea and during most of the day, a clear blue sky. Definitely a good day to perform fieldwork on the North Sea!
The day started with a CTD. This device is lowered from the ship to the bottom, and it measures the conductivity, temperature and depth as it is lowered. This data was then used in the acoustic survey that we performed next. Using the multibeam echosounder of the vessel, we surveyed the sea floor in the area that had been (beam) trawled the day before in order to look for beam-trawl marks.
In addition, we performed transects with a sidescan-sonar, which is another acoustic surveying device that is towed behind the vessel. Both resulted in good images of the seafloor and as hoped the beam-trawl marks were clearly visible. Remarkably, we also found (less clear) beam-trawl marks outside our study site. These probably have been there quite a while, but are still visible in the survey data!
After a delicious lunch, we continued with retrieving a lander and then performed video observations of the seafloor. Gathering good-quality footage of the seafloor in this part of the North Sea can be very difficult as fine sediments easily form low-visibility clouds when disturbed. However, due to the great weather we were able to shoot some nice footage of the sediment. We ended the day by taking boxcores; which are samples of the substrate up to a depth of 20cm. The content of these samples are sieved over a 1mm-sieve, collecting all organisms living in the substrate. One of the species encountered was the mud shrimp (Callianassa sp); this shrimp (up to 10cm) lives within self-established burrows, some of them visible in the sediment samples.
Looking forward to see what we encounter in the coming days!
Blog 1 by Erik Hendriks, 1th June
The first day of the two-week North Sea cruise is spent on the PULS project. In this project, the environmental effects of conventional beam trawling are studied and compared with puls trawling. Today in the early morning, a fishing vessel trawled an area, using thick tickler chains.
Because of the trawling, the upper part of the seabed is brought into suspension. This is a part of the environmental impact of fishing, as this sediment plume causes turbidity. To measure that, we are using the TUDelft lander. Luckily, we deployed it just before the fishing vessel trawled the last stretch!
The fishing vessel passed by the TUD lander closely, which should give us a nice insight in how much sediment is suspended, and for how long the sediment plume is present. Hopefully everything went well: we’ll find out in several days when we pick up the lander with the Pelagia. Fingers crossed!