The scientists are digging into the data
- Now we have enough data to start drawing conclusions, says marine scientist Geir Huse.
A fine June day in 2022, halfway out in the One Ocean Expedition, Geir Huse and eleven other scientists board the ferry to Rosendal in the Hardangerfjord to review the data collected by Statsraad Lehnkuhl so far.
The results from the instruments doing automatic analysis on board is sent continuously to Norway via satellite. The samples filtered out of the seawater and picked up with the plankton net is stored on board, and transported to Bergen from the ports along the way.
This is the first time the research team meet to look into the data.
- Now we have enough data to start drawing conclusions, and write research articles, says Geir Huse.
Huse is research director at the Institute of Marine Research, and heads the research part of One Ocean Expedition.
A long line
The last ten months, Statsraad Lehmkuhl has drawn a 23,209 nautical mile long line on the world map. That is close to 43,000 kilometers, 3,000 kilometers more than the length of the equator.
First from Arendal to the Canary Islands, then across the Atlantic to the Caribbean, north to New York, across the Atlantic again to the Azores, and then across once more and to Brazil, down the coast of South America, around Cape Horn, north along the coast of Chile, out into the Pacific Ocean, first to Tahiti, the Cook Islands, and westward.
Before the expedition started, Statsraad Lehmkuhl was equipped with instruments for doing marine research, and during the entire voyage, the ship has collected data, around the clock.
One instrument has registered the content of oxygen, CO2 and chlorophyll in the seawater. The temperature of the water, and salinity are also measured.
Every day, the students on board take samples of the seawater, filter it to find out how much microplastic it contains, and to extract eDNA, where DNA is genetic material and "e" stands for "environmental". All the organisms that live in the sea give off some DNA, also we when we take a swim, and the water samples are therefore a kind of guest list, listing all species present, from huge whales, fish, jellyfish down to tiny plankton.
An advanced echo sounder that manages to penetrate 800 meters into the depths, constantly registers fish and plankton below the ship.
At regular intervals, the Statsraad Lehmkul is heaved to, and equipment lowered to take samples of the water deep under the ship. During these stops, the researchers also send down a long bag, a plankton net, to catch samples of the life that floats around in the water deep down there.
In the Caribbean, Statsraad Lehmkuhl was fitted with a hydrophone, a microphone that works underwater. The sound it picks up reveals how many, and which species of whales that are nearby, and what the whales are doing. The hydrophone also registers the noise we humans make.
The Council of State is not alone in collecting data on the sea. All coastal nations have their own research vessels out on cruises, high above us satellites collect data, and out in the sea buoys floats following the ocean currents and making registrations. Statsraad Lehmkuhl is not the most advanced research vessel out at sea, but the expedition is still completely unique
- It is rare that data is collected in such a long continuous strip, and this is the first time we use a hydrophone from a sailing ship, Huse says. This allows us to listen without the noise from the machine and propeller disturbing.
The first meeting
The researchers jump on the ferry to Rosendal. The boat navigates between small islands and narrow straits from Bergen and south to Os, over the Bjørnefjord and through the narrow Lukksundet to the Hardangerfjord and Rosendal. The view is magnificent, but the scientists are looking into their PCs, they are all busy. The first article will be published in the journal Frontiers in Marine Science, and needs to be submitted during the summer.
Arriving in Rosendal, the group sits around a large table at the top of the glacier museum Folgefonnsenteret. It was opened in 2017, and tells the story of the glacier Folgefonna and the Hardangerfjord. There is a steady stream of tourists going in and out of the door two floors below.
The meeting room is located in the old part of the center, next to the quay. Outside it is sunny and nice, and the large window at the end of the attic is open. The sparrows know that there are crumbs to pick up around the café tables outside the center, and chirps loud and happy.
The researchers come from different institutions, and are experts in their respective fields. But by looking at the various data together, they can find connections that they can not figure out on their own.
The echo sounder
The data from the echo sounder is a good example, it shows how the organisms are distributed downwards into the depths. In the upper meters there are few organisms. During the day, the zooplankton, small crustaceans, stay from about 20 meters deep and downwards.
In the depths, what researchers call the mesopelagic zone between 200 and 1000 meters down, there is less light and easier to hide, and the risk of being eaten is less. But at night, these organisms swim up to the surface, where they find the phytoplankton from which they live. Fish and other animals that hunt the small crustaceans follow, and that is why the pattern on the plot taken between the Azores and Brazil is undulating.
But which species are swimming up and down? The sounder does not reveal this, but the eDNA samples can provide answers.
Some of the eDNA samples are analyzed on board the ship. Then the researchers look for eleven different groups of organisms, from fish to phytoplankton. Are they present at this location, or not?
But most eDNA samples taken on board are frozen and have to be analyzed in Norway.
Still not sent
The plan is to send the freezing samples home at regular intervals, but this sounded easier when the cruise was planned, than it turns out to be in practice. The samples must be kept at minus 20 degrees during the entire journey, from the ship to the warehouse, to the airport, and during the flight, and not all shipping companies can guarantee that.
So far, the researchers have not received a single sample. The next option is to have them sent from Japan in September.
If you look closely at the echo sounder plot, there are several waves present in addition to those that undulates through the day. A long one, which shows that the organisms stay closer to the surface at the equator than further north and south. And then some waves that might be noise in the measurements?
- Or maybe internal waves down in the depths, which move the plankton up and down, says Johnny Johannessen from the Nansen Center.
He works with satellite data, which may provide answers. Johannessen takes on the task of checking.
The amount of fish in the mesopelagic layer is also interesting. The species that live down in the depths are small, but there are many of them, and they can become an important food resource.
An earlier research expedition suggests that the amount may be ten times greater than previously estimated. The echo sounder installed in Statsraad Lehmkuhl constantly measures the amount of organisms in the mesopelagic layer, and can confirm or deny this.
- Statsraad Lehmkuhl sails in waters where there are few research cruises, which makes our observations extra valuable, says Huse.
During the conversation about plankton, a question arises.
- Can we trust the measurements, asks Berengere Husson, who works with ecosystem processes at the Institute of Marine Research.
All water tests are done with an instrument called a Ferrybox, which takes in seawater through a pipe to the side of the ship. Sensors in the box detect the color of the water, and use this as a measure of the amount of plankton present. There is a big difference in how much plankton there is in the water around the globe, and it is not certain that the sensor is calibrated so that the values it gives off can be trusted everywhere.
- And is the instrument cleaned properly, do organisms live inside the pipes? Husson wonders.
The researchers agree that regular water tests are needed to calibrate the measuring instruments to the various environmental conditions encountered along the way.
The rest of the day is spent writing articles. The researchers work on the same documents, everything happens online. Some work on the introductions, some take care of the analyzes, others write conclusions. When needed, they talk softly around the table.
The conversations are mostly in Norwegian, but some of the researchers come from England, Germany, and France, and occasionally switch to English when things get difficult.
One of the researchers, Nils Olav Handegard from the Institute of Marine Research, grew up in Rosendal. In his spare time, he is part of the team that takes care of the old Hardangerjakt Gurine. The tallship was built in Rosendal in 1875, and transported stockfish from northern Norway to Bergen. For many years it was in disrepair in Bergen, but in 2011 a group of enthusiasts brought it home and restored the ship. Now it is a gem, which adorns the harbor.
After the laptops are clapped shut for the day, Handegard invites us aboard the Gurine and serves local cider under deck. Gurine is much smaller than Statsraad Lehmkuhl and Rosendal is not Tahiti, but the visit brings us a little closer to the life on board the Statsraaden for a few hours.
Thursday starts with a short status report. There are several things that need to be checked up. Huse makes a list, and the researchers divide the tasks among themselves. And continues to write, concentrating on their respective laptops.
Deadline is only a few weeks away.