Daily vertical migrations of Lake Baikal amphipods: Major players, seasonal dynamics and potential causes

Daily vertical migrations of hydrobionts are widespread in all water bodies, such as small wells and vast oceans. This phenomenon is most common among crustaceans, especially in amphipods. Lake Baikal is one of the most biodiverse freshwater centers containing 354 species and subspecies of amphipods, and almost all of them are endemics. The study’s goal was to follow the year-round dynamics of daily vertical migrations of amphipods and pinpoint various environmental factors that affect this process. Observations of amphipod migration were obtained using a remote video system. Based on the results, the vertical migratory activity of amphipods can be tracked during the year. The key factor that reduces migratory activity was found to be the start of the reverse stratification period. It is assumed that Lake Baikal amphipods have no single general reason for vertical migrations, and a few of the driving forces that make different amphipods groups migrate are accumulations of regions positive temperatures that facilitate sex development, food foraging, passive dispersal, search for a partner, and pairing.