KM Myrvold
Fish in seasonal habitats
Norway has 33 species of freshwater fish and represents the northern extent for many species that exist in Europe. The most diverse communities occur in the south-eastern part of the country in the Glomma and Haldenvassdraget basins up to Lake Mjøsa at 61 °N, the largest lake in Norway. Barriers to immigration, history of disturbance, access to refugia, and suitability of environments all determine the number of species present on the landscape today, and understanding the mechanisms that explain the local persistence of species is important for conservation and management.
We are currently working on understanding how fish make use of the seasonal habitats that form in summer where the Gudbrandsdalslågen River flows into Lake Mjøsa in Lillehammer. We hypothesize that favorable microclimates on the floodplain can explain – at least in part – how many species persist in an otherwise less suitable area.
The length of the summer season is of particular importance to spring-spawning species, because it drives the development from eggs to free-swimming stages. In snowmelt-driven systems, access to habitat patches that are relatively warmer than the local average temperature can be important for the local persistence of species. Here, off channel habitats such as flooded wetlands and side channels can be particularly important because they provide physical shelter from the current and higher temperatures than the main channel.
Ongoing work includes temperature monitoring, a tagging study with acoustic tags, underwater video, and timelapse photography.
Publications:
See several posts (with video) at blogg.forskning.no/ferskvannbloggen
Timelapse video here:
Myrvold, KM. 2024. A complete homogenization of temperatures during widespread flooding. River Research and Applications 40:1621-1625.
Myrvold, KM, TH Holter, AO Syverhuset, in prep. Time-lapse photography as a tool for visualizing seasonal floodplain habitats.
