17 Jan ’25

PolarQuest 2021

interview with elias meier on e-dna publication

Four years and one publication later …

Elias Meier, who holds a Master in Environmental Science at ETH Zurich, reminisces about the 2021 PolarQuest Arctic expedition. He tells us about the eDNA sample collection in the fjords, and how the data was later analysed and published by Loïc Pellissier’s group in 2023 [1].

It has been a while since you came back from the far North. Before starting, can you tell me what is the first memory that comes to your mind if you think about the Arctic expedition?

The first memory is a feeling. The feeling of being far away from civilization, in a place so vast, so wild, so unexplored, and realising that you are nothing more than nature’s guest. That humans are not the mightiest of species. This perception is infinitely humbling. 

What did you find up North that you didn’t expect?

A huge amount of trash. I knew that we were going to find some, but I was not prepared for the unbelievable amount of trash pushed onto the Arctic beaches by ocean currents. Plastic, fishnets, clothes, even a kids’ tractor, were left there for the millennia to come. It was very dystopian to imagine that these human objects – which represented lives, dreams, expectations – would be lying in the northern unexplored territories unbeknownst to anyone else in the world. 

Anything else?

Well, we were there in August, but I still had expected the Arctic to be more white. And colder – the temperature was around 7 degrees during the day. I was also surprised by the amount of tourists we bumped into in the coastal towns we visited before taking off. While sailing, I was impressed by an old, burnt down, German military station from the 2nd World War that we found, a remnant from a distant past.

What was your mission in the Arctic?

Monitoring the impact of climate change on biodiversity through eDNA sampling. eDNA is the genetic material present in environmental sampling. We wanted to study how fresh water input from the glacier affected the biodiversity distribution along the fjord. The actual sampling was done through filters and it only took around 3 days. Since the sailing time lasted about three weeks, I had plenty of time to help the other researchers on the boat; I would say this was the most interesting part of the journey, as I learnt a lot from others. Everybody was on a different scientific mission. Some were doing cartography, others drone mapping. I was also asked by my professor to collect some lake water samples, as we had time. The overarching mission was finding the wreckage of Umberto Nobile’s airship, but the conditions were too harsh to finalise the search. 

How did you get engaged in the expedition?

I was in the right place at the right time. I was just an undergraduate student when one of my professors, Kristy Deiner, asked me if I wanted to join an expedition to collect some eDNA data in the Arctic. Strangely enough, they were struggling to find some Master students interested in the program. I immediately was in for the adventure. After the expedition, I continued my Master studies, and only then I found out a paper was on the way of being published with the data we had collected two years prior. 

How was the data for the paper collected?

We had some standardised kits produced by an established French laboratory, SpyGen. The set-up consisted of a glass cylinder with a filter in it. Around 30 litres of water at a time were pumped through the filters. Each filter retains some eDNA and is later put into a buffer, which stabilises the eDNA. Then you can send it back to the laboratory, and efficiently perform downstream analyses. As concerns the water samples containing information on the salinity, temperature and chlorophyll-a abundance, we used a CTD device directly at the fjord. 

What is chlorophyll-a and why is it important?

It is photosynthetic material, and is therefore the first part of the food chain. It is an indicator for biodiversity and organic activity.

What were the challenges related to data taking?

We took much longer than expected, as the boat was drifting, continuously changing location. There was also a lot of ice melting and falling down, which contributed to slowing down the process. 

How heavy was the data you collected?

Difficult question, it depends so much on the specificity of the used primer. The water parameters can be stored and processed on a portable computer. The eDNA samples, on the contrary, contain a lot of parameters and have to be run on supercomputers. Imagine that in a little water sample the metabarcoding could identify 1*3 to 10*4 species of organism. As of today, we do not even know all the bacteria that exist in the world, so this number is probably higher. 

Right. And why was the Lilliehöök fjord a good place to collect environmental data?

The conditions of the Lilliehöök Arctic fjord were special because the glacier is directly melting into the fjord. Environmentally, fresh water input into the sea is the driver of how the natural system works. If the glacier dimensions reduce so much that the glacier doesn’t reach the sea anymore, what would the effects on the living species be? The water melting structures the fjord’s environmental gradients and therefore its biodiversity. Next to the glacier, the cold water sinks, and the sea water flows in, therefore the surface water next to the glacier is saltier compared to the rest of the fjord. We wanted to assess how the biodiversity of fish and eukaryotic plankton communities relate with environmental conditions. We did a complete study of how these parameters changed as a function of depth of the water, salinity, presence of chlorophyll-a and distance to the glacier. We did not find a particular trend, although we saw a peak of diversity in the intermediate position of the fjord. We also chose this fjord because we got the permission to perform a scientific sample collection on it. 

Biodiversity of fish and eukaryotic plankton at different positions and depths of the fjiord.

Lilliehöök fjord, Svalbard (79 N).

The feeling of being far away from civilization, in a place so vast, so wild, so unexplored, and realising that you are nothing more than nature’s guest. That humans are not the mightiest of species. This perception is infinitely humbling.

Elias Meier

Why is eukaryotic plankton important?

It is the first part of the food chain after chlorophyll-a. Its abundance is directly related to the amount of chlorophyll-a present in the water. The same could be said about the proportion of plankton to fish, but the relation is harder to describe as many other complex parameters come into place, as fish is a more complex living organism that moves faster through space. 

Can you explain what meta-barcoding is?

You can imagine eDNA as a huge library. With meta-barcoding techniques, you take the whole information present in water through filters, and afterwards you decide which information to extrapolate. Meta-barcoding aims to determine the  species composition within a sample, which is a component of biodiversity. 

How was living on the boat?

I had been on sailing boats before, but never for 3 weeks. I created tight bonds with everyone on board, and the environment was always friendly. I received a warm welcome, and a lot of useful tips on life on board. The fact that you cannot leave the small space that the boat offers you leads you to accepting to share everything with others, and I felt very comfortable with it. I love the wilderness and the simplicity of living in nature, and I am very comfortable with the mountains, having grown up in Switzerland. At first, the huge, infinite, homogeneous amount of water surrounding us scared me, and I was afraid of being seasick. However, I quickly got used to it. 

How did this experience influence your future?

It instilled me with curiosity for the Arctic. It is an environment that changes faster than others in the world, although it is so remote and inaccessible to human life. I find it interesting how heavily we influence places that we do not inhabit, and this trip convinced me that I would love to do some research on the Svalbard soil. If I will start a PhD in the future, it will have to be related to the harsh and icy environment of the wild northern lands.

[1] Marques, V., Hassler, C., Deiner, K. et al. Environmental drivers of eukaryotic plankton and fish biodiversity in an Arctic fjord. Polar Biol 46, 1083–1096 (2023). https://doi.org/10.1007/s00300-023-03187-9.

Interview by Elena Gazzarrini.

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