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Full-Text Articles in Physical Sciences and Mathematics
Under-Ice Diel Vertical Migrations Of Oncorhynchus Nerka And Their Zooplankton Prey, G. B. Steinhart, Wayne A. Wurtsbaugh
Under-Ice Diel Vertical Migrations Of Oncorhynchus Nerka And Their Zooplankton Prey, G. B. Steinhart, Wayne A. Wurtsbaugh
Watershed Sciences Faculty Publications
We used stationary hydroacoustics and measures of environmental conditions (water temperature, dissolved oxygen, light levels, and zooplankton) to determine what factors, foraging or predation risk, influenced diel vertical migrations of Oncorhynchus nerka during winter in three high-mountain lakes. The Sawtooth Valley lakes are deep, oligotrophic, glacial lakes located in central Idaho, U.S.A., and historically contained populations of anadromous O. nerka. In general, low light intensities limited foraging opportunities of O. nerka under ice, especially at night. In Stanley Lake, O. nerka underwent diel vertical migrations to exploit available light to feed. Oncorhynchus nerka occupied shallow water at night, where there …
Ontogenetic Habitat Shifts Of Juvenile Bear Lake Sculpin, J. Ruzycki, Wayne A. Wurtsbaugh
Ontogenetic Habitat Shifts Of Juvenile Bear Lake Sculpin, J. Ruzycki, Wayne A. Wurtsbaugh
Watershed Sciences Faculty Publications
Bear lake sculpin Cottus extensus exhibit ontogenetic habitat shifts during their initial year of life. Distribution and habitat switching was measured with bimonthly bottom-trawl surveys repeated throughout the summer. Patterns of daily growth increments on otoliths were used to measure the history of habitat residence, individual size at the time of the habitat switch, and habitat-specific growth rates. Laboratory experiments and known-age fish confirmed daily increment formation of otoliths. After dispersing during an initial pelagic larval stage, postlarval juveniles settled in both the warm, food-rich littoral zone and the cold, unproductive profundal zone. During summer, initial profundal-zone inhabitants underwent a …