Tokt2 Kvitøyrenna NGU teamet — The geology team: From left to right: Lilja Rún Bjarnadóttir, Valérie Bellec, Christine Tømmervik Kollsgård and Margaret Dolan. Photo: Margaret Dolan

A geologist’s life onboard R/V «Kronprins Haakon»

Cruise diary: What’s a typical day onboard like for the geology team on a MAREANO cruise? Alongside the biologists we watch video footage of the seafloor streamed live from the Remotely Operated Vehicle (ROV) and log changes in the seabed substrate, from mud to boulders and bedrock.

Published: 26.04.2024 Author: Valérie Bellec, Christine Tømmervik Kollsgård, Margaret Dolan and Lilja R. Bjarnadóttir, Geological Survey of Norway

After the video surveys we process a sediment sample obtained with the ROV. At a few stations, additional sampling gear is deployed to get additional information on the sediment composition, genesis and chemical properties.

MAREANO seabed mapping is based on video surveys, supplemented by biological, geological and chemical sampling. Video surveys are systematically planned to document the different seabed environments within the survey area on any given cruise.

Video logging

Each video survey runs in a straight line for around 200 m, and several are taken each day, so video logging is a large part of our working day. Geologists and biologists sit together in the video room and interpret the live-stream video coming from the seafloor. We document the seabed sediment type and note any visible geological processes, while the biologists log the fauna. Very often changes in the geology are reflected in the biology.

In the video room — Geologist Christine Tømmervik Kollsgård (to the left) and biologists Yngve Klungseth Johansen, Felicia Keulder-Stenevik and Pål Buhl-Mortensen (to the right) getting ready to log in the video room.

From the video log — Here we see an extract from our video log, together with images of some of the substrate types encountered. We also have a comments field where we may note other relevant geological observations such as the presence of cobbles (cc) and boulders (b) where finer substrate types dominate, or current induced features e.g. ripples. Video data from MAREANO/IMR.

Since distinguishing substrate type from video is not always straight forward, we obtain samples from the seabed to help verify our observations. During this cruise, we are using the Remotely Operated Vehicle (ROV) Ægir 6000 for the video surveys. We also use the ROVs’ manipulator arm to push 40 cm long tubes into the seabed to retrieve short sediment cores at soft-bottom locations. Where the seabed is too hard for a core, we use a metal scoop to take a sample. These samples help verify our video observations and their geological properties are logged in detail. A small sub-sample is taken back to NGU to aid post-cruise interpretation.

Ægir 6000 (ROV) — Push core (left) is mostly used in soft sediment. When the sediment is too coarse for the push core, we use the scoop to take a sample. Video data from MAREANO/IMR

Cure tube — Core being pushed out of the core tube.

From a shallow video line — Here is an example of a shallow video line (about 40 m deep). The substrate here consists of gravel with a few cobbles. At 40 m depth some light from the surface still reaches the seafloor, allowing red encrusting algae to live here. At these depths bottom currents are often very strong, washing away sand and mud, and this erosion can be compounded by storm waves. Video data from MAREANO/IMR

Mixture on the seafloor — The substrate type in this image is a mixture of mud, sand, gravel, cobbles and boulders, which are colonised by a range of animals. Video data from MAREANO/IMR

Bedrock — In some places the bedrock sticks up from the sediments. Video data from MAREANO/IMR

At some stations, we use a wider range of sampling gear: grabs, boxcores and multicores and occasionally gravity cores, many of which are shared between the geologists, biologists and chemists on board. Further biological sampling using additional gear can also give useful information for geologists, like the presence of gravel and cobbles, and perhaps the rock types.

The grain size

Geologists describe the geological properties of samples taken with the grabs and boxcores. These give similar information to the push cores and the scoop but are less deformed as we do not need to push the sediment out of the core to examine them. The most important information we get is the grain size. Other useful characteristics such as the colour, density, the water content or the presence of shells are also recorded for each distinct layer in the sample.

Work on deck — On left geologist Lilja Rún Bjarnadóttir and biologist Andrey Voronkov check the grab to decide if it is approved. Om the right Lilja Rún Bjarnadóttir digs into the approved grab to take a sediment sample and describe the different layers.

The multicorer is used for chemistry. Onboard we measure, photograph, and describe the sediment characteristics of the multicore samples. Once this is done, we slice the two longest cores and freeze the slices. Then we seal three cores: one will be X-rayed to study its internal structures, while the two others will be analysed for microplastics.

Multicorer on deck after a sample has been taken. Each of the six tubes contains a sample of the sediment: 4 plastic tubes used for chemistry analysis and 2 metallic tubes for microplastics. Here we see geologist Christine Tømmervik Kollsgård measuring the cores (lower left). The longest cores are then sliced. Here the geologist Valérie Bellec and chemist Stepan Boitsov (IMR) work together slicing the core.

A typical day onboard

Scientific operations run 24/7 with all personnel onboard working shifts. Here is an example of a typical day for the geology team.

Time	Activity	Geologist Shift
00:00 - 01:30	ROV video line	B – continued from 20:00
01:30 - 02:30	Process push core/scoop during transit to next station	B
02:30 - 04:00	ROV video line	B
04:00	Change of shift.	A
04:00 – 05:00	Process push core/scoop during transit to next station	A
05:00 – 06:30	ROV video line	A
06:30 – 07:30	Process push core/scoop during transit to next station	A
07:30 – 09:00	ROV video line Rolling breakfast 07:30-08:00 for shift A	A
09:00 – 10:00	Process push core/scoop during transit to next station	A
10:00 – 10:30	CTD deployment. This oceanographic instrument tells us the temperature and salinity at the seabed, and also how these properties vary throughout the water column	A
10:30 – 12:00	ROV video line	A
11:30 – 12:30	Lunch before (shift A) or after the shift (shift B)	A/B
12:00	Change of shift	B
12:00 – 15:00	5 Grabs, one is described in detail and sampled by the geologists, additional grabs are acquired for biologists but also logged by geologists	B
15:00 – 16:00	Multicore. This is done when the beamtrawl and the RP-sledge are in the water	B
16:00	Change of shift	A
16:00 – 19:00	Multicore. This is done when the beamtrawl and the RP-sledge are in the water, and during the transit to the next video line	A
17:30 – 18:15	Dinner when possible between 17:30 – 18:15 for shift A, dinner off shift for shift B	A / B
19:00 – 20:30	ROV video line, and finishing the work on the multicore if necessary	A
20:00	Change of shift	B
20:30 – 21:30	Process push core/scoop during transit to next station	B
21:30 – 22:00	ROV video line	B
22:00 – 23:00	Process push core/scoop during transit to next station	B
23:00– 00:30⁺¹	ROV video line	B

While on board we also do some initial data processing, go through all the videos to grab pictures from the seabed and interesting geological features, and write cruise diaries for the MAREANO website.

Along with the other scientists we are also responsible for keeping our labs, conference room and the look-out deck clean. This makes for a busy schedule but in the few hours we have off each day we can work out in the gym, take a stroll on the helideck or be on the look-out for marine mammals.

Nature — Some of the icy landscapes and wildlife we met during this cruise. Photo: Valérie Bellec.