Effect of Artificial Illumination on the Intensity of Nocturnal Vertical Migrations of Amphipods in Lake Baikal

Сентябрь 21, 2013 3:18

Key words: amphipods, Baikal, daily vertical migrations, artificial illumination, video observations.Daily vertical migrations (DVMs) of pelagic and even many benthic organisms are characteristic of both marine and continental aquatic ecosystems. The causes of such migrations and factors relevant to them are of great interest of the involved factors is highly interest-ing. For several years, we investigated DVMs of Baikal amphipods (Crustacea, Amphipoda), namely, the noc-turnal migration of many shallow-water benthic species to the pelagic zone. We identified the main life forms of amphipods involved in DVMs, dominant species of the nocturnal migratory complex in several areas of Baikal, and rejected the defense–feeding hypothesis of DVMs traditionally used to explain the vertical migrations of plankton (Takhteev et al., 2000; Mekhanikova and Takhteev, 2001).The prevalence of immature juveniles in the nocturnal migratory aggregations also led to a conclusion that DVMs in most species are not related to reproduction and mating (Govorukhina, 2001). We pro-posed that daily migrations provide for the accumula-tion of a certain sum of temperatures (if a vertical tem-perature gradient is present) or for activation of metab-olism via motion proper in order to complete maturation in due time under conditions of a cold-water lake (Mekhanikova and Takhteev, 2001).

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