By Phoenix Rogers
The opportunity LOREX provided to spend the summer in Sweden working in a brand-new environment with a team of collaborators was an incredible experience. A big thanks goes out to everyone who helped make this trip possible. Now that I’ve returned from Sweden, I would like to share some stories about the challenges our team and I faced during my 19 days in the field this summer and also elaborate on the research project that I took on while working there.
Umea, Sweden is 30 degrees north from my home institution in Tuscaloosa, Alabama, resulting in a drastically different climate from what I’ve become accustomed to. During the summer, Sweden is relatively dry and cold, but there are some days that can get surprisingly hot. This can be exacerbated by the long summer days in northern Sweden when the relief of night never seems to come. Even after a tough day in the field, it was difficult to fall asleep at a reasonable time since at midnight it could still be light outside (example in image below). Sleeping in was almost impossible too since the sun rises so early in the morning that the field tent quickly became a sauna. On the flip side, the long summer days aren’t all that bad since you don’t have to worry about your workday getting cut short due to nightfall and the accompanying darkness. Plus, it almost always made it possible to do a little fishing after work! Pro tip: don’t forget a blindfold before making plans to visit a place like Sweden in the summer and give your body time to adapt to the long summer days.
Our research group was primarily interested in brown trout population dynamics in pristine systems, which brought us to the remote mountains near Stekenjokk, Sweden for our field work. This mountainous region is primarily undeveloped, so we had to reach our field sites by helicopter. Don’t get me wrong, the aerial views from the helicopter rides were unforgettable but relying on a helicopter for transportation had some challenges. We needed to bring sampling gear and enough food and supplies to last 5 people for up to two weeks, resulting in a huge mess of things that we needed to transport in a helicopter. This forced us to be very considerate about what we decided to bring since it wasn’t possible to bring everything we might need nor was it easy for items to get brought to us once we were out in the field. We learned this lesson the hard way when we had pieces of equipment fail, requiring replacement parts flown in – this not only gets expensive but also slows down productivity and extending our stay in the mountains. Long story short: using a helicopter to move between field sites can be so fun, but it does add a new, challenging element to the logistics.
The midnight sun and helicopter rides were unique experiences, but the real reason I flew halfway across the world to Sweden was for a research project I had spent months developing and tweaking. The big-picture question I was trying to answer was: does the input of drifting invertebrates entering lakes support lake-dwelling brown trout? To address this question, I deployed drift nets for 24 hours at the end of stream inlets, right before they entered the lake. I also collected kicknet samples from the same streams so I could compare drift rates between streams. The inlets containing brown were also electrofished and a sub-sample of those fish were kept for gut content analysis. Gill nets were also deployed in the lakes and the guts will be analyzed by all fish captured. Inspiration for this study came from some work done by Jack Dendy in 1939, who investigated the fate of invertebrates drifting into lakes. Dendy’s results did not show support for drifting invertebrates being an important flux of energy for lake-living fish, but his work was limited to a single lake inlet in Michigan and his sampling efforts didn’t include fish diets. Our approach expands on Dendy’s initial study by attempting to identify if the flux of invertebrates entering lakes supports lake-living brown trout, which could change our understanding of food web dynamics in lakes.
A summer in Sweden sounds like loads of fun (and it really was) but I also went there with a job to do. Some of our data has been processed, but there is still a lot of work to be done, including another summer of sampling. I’m excited to continue working with my collaborators in Sweden to increase our understanding of brown trout population dynamics and the role of invertebrate drift in supporting lake-living brown trout. To keep up with how this project progresses, check out my research website (http://progers.people.ua.edu/) or follow me on twitter (@phoenix_rogers).