Extensive diel fish migrations in a deep ultraoligotrophic lake of Patagonia Argentina |
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Authors: | Magalí Rechencq Alejandro Sosnovsky Patricio Jorge Macchi Pablo Andrés Alvear Pablo Horacio Vigliano |
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Institution: | 1.Grupo de Evaluación y Manejo de Recursos ícticos (GEMARI), Centro Regional Universitario Bariloche (CRUB),Universidad Nacional del Comahue (UNCo),S. C. de Bariloche,Argentina;2.Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA),Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET),S. C. de Bariloche,Argentina |
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Abstract: | Andean Patagonian lakes are ultraoligotrophic, highly transparent water bodies with very low densities of organisms at the
different levels of their trophic food webs. Little is known about spatial distribution and habitat use by fish in these lakes.
Hydroacoustic and active sampling techniques were used to study the distribution, composition, and displacement of organisms
in an Andean lake throughout the diel cycle on two different moon phase days. Sound scattering layers (SSLs) were found both
in the near-shore and pelagic habitats at different times of the day. These SSLs, formed by galaxiid larvae and adults, underwent
displacement during the time periods of dawn and dusk, giving rise to the redistribution of organisms in the different habitats.
The organisms show high sensitivity to light intensity, displaying different behaviors depending on moon phases. Extensive
diel vertical migrations show that the deep pelagic habitats provide diurnal refuge for native galaxiids in Andean Patagonian
lakes. Due to the high densities of galaxiid larvae and adults, it is likely that diel migrations generate an active flow
of energy and matter between habitats, which could have a profound influence on whole lake dynamics. |
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