Behaviour of Lake Baikal amphipods as a part of the night migratory complex in the Kluevka settlement region (south-eastern Baikal)

Abstract

The night migration complex in the bottom zone of the shallow-water slope on the east coast of southern Lake Baikal near the village of Kluevka was investigated. According to the observations, it was established that the pelagic fish of the suborder Cottoidei and the pelagic amphipod Macrohectopus branickii can sporadically participate in the migration complex. The mass presence of benthic amphipods was highest in the first minute of observations, with more than 250 individuals/freeze-frame, and then stabilized at 43-65 individuals/freeze-frame. The Juday net-collected amphipods comprised only one typically benthic species, Micruropus wohlii platycercus , which is known to be a nocturnal migrant. For the first time, the typically pelagic species M. branickii , was observed in the migratory complex over shallow coastal shoal, which species, according to all previous studies, was considered to inhabit only greater depths and to avoid areas with depths of less than 100 m, such as shallow-water slope bottom zones.