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  • bream  (1)
  • fish yields  (1)
  • 1
    Digitale Medien
    Digitale Medien
    The food of bream (Abramis brama L.) in two basins of Lake Balaton of different trophic status (1991)
    Springer
    Hydrobiologia 209 (1991), S. 51-58 
    Details
    ISSN: 1573-5117
    Schlagwort(e): food composition ; food selectivity ; bream ; Lake Balaton
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Contrary to earlier observations the food composition of bream (Abramis brama L.) in Lake Balaton has changed in parallel with eutrophication. These changes were probably caused by increased population density and connected with density dependent growth as well as sharpened inter- and intraspecific competition in the cyprinid community. According to the frequency of occurrence, zooplankton followed by benthic invertebrates comprised the majority of the bream's food. By weight, however, benthic food dominated in both basins. Size-related dietary changes were pronounced, but statistically not always significant, suggesting the overall importance of the most abundant and available prey types. Bream did not strongly select any of the zooplankton groups, however, seasonal changes in food composition alternated in parallel with the trophic gradient along the longitudinal axis of the lake.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00006717
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
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  • 2
    Digitale Medien
    Digitale Medien
    Trophic relationships between primary producers and fish yields in Lake Balaton (1990)
    Springer
    Hydrobiologia 191 (1990), S. 213-221 
    Details
    ISSN: 1573-5117
    Schlagwort(e): chlorophyll a ; morphometry ; fish yields ; energy transfer ; Lake Balaton
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Relationships between chlorophyll a content of the water, the shoreline-length: water area ratio and the annual total fish yield as catch per unit effort (CUE: kg ha−1 100 h−1 as annual mean values) have been calculated by multivariable regression. The determination coefficient (r 2 = 0.913) showed a significant dependence of fish yield on morphometry of different lake areas. Accordingly, fish carrying capacity of the open water areas, calculated from chlorophyll a content and S/A, ranged from 12 to 34%, but that of the littoral zone between 66 and 88%. These findings have also been supported by echo-sounding records of the horizontal distribution of fish. Bream (Abramis brama L.) contributes the majority (70–80%) of fish stock and yield. Its food mainly consists of zooplankton and benthic invertebrates in ratios that are widely variable with season and depend on the age of fish. Average daily food consumption of individuals (age group 3 + and over) varies between 2 and 5 g. Bream consumes two- to three-times more food in the SW basin than in the NE one. This means that the present stocks inhabiting areas from NE to SW consume annually 13249–20085 t yr−1 of food. According to estimated calorific values, the annual energy consumption of local populations along the longitudinal axis of the lake varies between 93 and 141 kJ m−2 yr−1. The efficiency of energy transfer from primary producers to fish is low and varies from 0.04 to 0.1%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00026054
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
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