Four researchers from the AQUATERR project (see more at our homepage, Twitter, and ResearchGate) embarked on a journey mid-June 2022 to the Finnish Laplands to collect Arctic emergent aquatic insects. We, Dr. Martin Kainz (Austria), Prof. Dominik Martin-Creuzburg (Germany), Dr. Margaux Mathieu-Resuge (France), and PhD candidate Tarn Preet Parmar (Germany) arrived in Kilpisjärvi to the midnight sun (Figure 1). The Kilpisjärvi Biological Station (Figure 2) is located near Lake Kilpisjärvi, in Finland’s northern “arm” near the very northwesternmost point of Finland. The village has a small local population of a few hundred but is a popular tourist destination during both summer and winter months!

Figure 1: Margaux (left) and Dominik (right) looking for potential sampling ponds on our arrival around the Kilpisjärvi Biological Station (Finland). Photo taken just before midnight, with the midnight sun about to hide behind Saana (Photo: Tarn Preet Parmar).

Figure 2: The main building of the Kilpisjärvi Biological Station which has accommodations, laboratories, offices, a staffed kitchen, and a library. Reindeer are seen regularly around the area including right in front of the station (Photo: Tarn Preet Parmar).

We were interested in studying the role small Arctic ponds may have in supplying important dietary energy and nutrients to terrestrial predators via emerging aquatic insects. Anyone who spends outdoor time during the Lapland summers will have their best strategy to avoid the swarm of mosquitos. Mosquitos, along with other aquatic emergent insects, represent a key vector of aquatic-derived energy and nutrient transfer to terrestrial food webs. Aquatic insects typically contain higher content of long-chain polyunsaturated fatty acids (LC-PUFA) than terrestrial insects. Small Arctic ponds may only be productive for a few weeks in a year, but the aquatic insects that emerge may be a crucial nutrient source of physiologically important LC-PUFA for terrestrial predators such as spiders and birds. Accelerated Arctic warming will likely influence the production and export of emerging insects leading to a potential phenological mismatch with terrestrial consumers. Little is known about emergent insect and LC-PUFA export in Arctic ponds but with the help of INTERACT we wanted to change that!

During the 9 days we stayed at the Kilpisjärvi Biological Station, we built and deployed our floating emergence traps (Figure 3). We looked at the invertebrate community of several ponds before sampling aquatic insects emerging from 5 small Arctic ponds (Figure 4). The floating emergence traps were sampled every few days to make sure the insects were alive, and we were able to see some real-time aquatic to terrestrial nutrient transfer via the spider webs in the vegetation surrounding our sampling ponds (Figure 5). Collected insects were frozen as soon as possible, freeze dried in preparation for lipid analysis and identified using stereo microscopes available at the station. We even got to celebrate a birthday during our stay in Kilpisjärvi (Figure 6). We replicated the sampling design at NIBIO Svanhovd Station (Norway; see other blog post for more information).

Figure 3: Assembling floating emergent insect traps with Kilpisjärvi reindeer casually walking by our assembly line (Photo: Dominik Martin-Creuzburg).

Figure 4: Dominik (left) and Martin (right) looking at the invertebrate community of a potential sampling pond with Lake Kilpisjärvi (background left) and Saana’s peak (background right; Photo: Tarn Preet Parmar).

Figure 5: Aquatic insects (Chironomidae; foreground) caught in a spider web in the vegetation around one of our sampling ponds (floating emergence trap; background) demonstrating aquatic to terrestrial nutrient transfer from Arctic ponds to surrounding terrestrial food webs. Floating emergence traps deployed on one of the five ponds selected. Emergence traps allow us to quantify the insect emergence biomass and LC-PUFA export per m2/day (Photo: Dominik Martin-Creuzburg).

The Kilpisjärvi Biological Station was a well-equipped field station with super friendly staff (see their website for details). We would gladly come back to continue our project or for any future collaborations! We want to thank all the staff of the Kilpisjärvi Biological Station for their support, especially to Pirjo Hakala, Hannu Autto, and Oula Kalttopää. “Kiitos paljon” to Milla Mäkinen and Maija Sujala for all their tremendous help sampling!

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