Freshwater monitoring reveals unknown midge diversity

Náttúra

19 Mar

*Thousands of Chironomid pupal exuviae collecting in the foam on the shore of Toftavatn. Mynd: Agnes-Katharina Kreiling*

Tjóðsavnið is conducting ecological monitoring on land and in freshwater. One of the routine monitoring methods for freshwater habitats is the collection of Chironomid pupal exuviae. These are the skins the midges leave behind when hatching out of the pupae and which float on the water surface and can easily be collected. At least seven new species records for the Faroese fauna have been made based on pupal exuviae collected from lakes in 2025 alone. Among the new records, there are even two new genera, Stictochironomus and Paratendipes.

Chironomidae are the most species-rich (and often most abundant) invertebrate group in aquatic habitats in Greenland, Iceland and the Faroes. They are good indicators for water quality and are used for freshwater monitoring worldwide, but are especially important in sub-Arctic and island countries where diversity in other aquatic groups is much lower.

Up to 2020, around 85 species of Chironomidae were recorded from the Faroes, but collection efforts during the past few years have revealed a much greater diversity in this group. Some examples of spectacular new finds during the past years are Metriocnemus carmencitabertarum, identified last year from a pupal exuviae collected from a rain water filled barrel, and the marine midge Telmatogeton murrayi, identified during a large Diptera collection effort in the Faroes in 2023. Furthermore, some species were added to the faunistic checklist during the Koltur baseline study and barcoding sequences from insects collected in the Faroes during the international LIFEPLAN project 2022-2025 suggests an additional seven new records. Together with the seven recent new records made during Tjóðsvanið’s regular freshwater monitoring scheme, the Chironomid list for the Faroes grew to well beyond 100 species. And we are sure that we will find many more in the years to come!