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The importance of various habitats for fish in reservoirs
Šmejkal, Marek ; Prchalová, Marie (advisor) ; Vašek, Mojmír (referee)
Fish distribution in reservoirs is not homogeneous. Fish usually occur in upper parts of reservoirs on the longitudinal axis, where is also the greatest concentration of nutrients. Fish abundance and biomass as well as the trophy are declining towards the dam part. On the vertical axis, most fish occur above the thermocline, where temperature and concentration of dissolved oxygen reach the highest values. Fish community is changing also in time. Shortly after impoundment, the riverine species are dominating the community and later, generalist species prevail. Generally, we can distinguish pelagic and bentic habitats within the reservoir. There are species in reservoirs that occur almost strictly in pelagic habitat like asp and bleak and benthic species like ruffe and perch. Most species occur in both types of habitats (bream, roach, pikeperch, European catfish, white bream). Migrations between habitats occur on daily and on seasonal basis. On daily basis, we distinguish diel horizontal migration, in which fish shift between pelagic and benthic habitats. Diel vertical migration, when fish change depths, is not so significant in Czech reservoirs. Motivations for these diel migrations are food aviability, predation pressure and water temperature. Seasonal migrations comprise spawning migrations and winter...
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The importance of various habitats for fish in reservoirs
Šmejkal, Marek ; Vašek, Mojmír (referee) ; Prchalová, Marie (advisor)
Fish distribution in reservoirs is not homogeneous. Fish usually occur in upper parts of reservoirs on the longitudinal axis, where is also the greatest concentration of nutrients. Fish abundance and biomass as well as the trophy are declining towards the dam part. On the vertical axis, most fish occur above the thermocline, where temperature and concentration of dissolved oxygen reach the highest values. Fish community is changing also in time. Shortly after impoundment, the riverine species are dominating the community and later, generalist species prevail. Generally, we can distinguish pelagic and bentic habitats within the reservoir. There are species in reservoirs that occur almost strictly in pelagic habitat like asp and bleak and benthic species like ruffe and perch. Most species occur in both types of habitats (bream, roach, pikeperch, European catfish, white bream). Migrations between habitats occur on daily and on seasonal basis. On daily basis, we distinguish diel horizontal migration, in which fish shift between pelagic and benthic habitats. Diel vertical migration, when fish change depths, is not so significant in Czech reservoirs. Motivations for these diel migrations are food aviability, predation pressure and water temperature. Seasonal migrations comprise spawning migrations and winter...
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