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  • 1
    Electronic Resource
    Electronic Resource
    Secondary production of the brackish copepod communities and their contribution to the carbon fluxes in the Westerschelde estuary (The Netherlands) (1995)
    Springer
    Hydrobiologia 311 (1995), S. 103-114 
    Details
    ISSN: 1573-5117
    Keywords: secondary production ; copepod ; estuary ; Westerschelde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The zooplankton community of the brackish part of the Westerschelde estuary (November 1989–October 1990) was dominated by two calanoid copepods, Eurytemora affinis and Acartia tonsa. Eurytemora was present during a longer period of the year and was much more important in terms of total abundances and biomasses than Acartia. The secondary production of these species was estimated by means of the growth rate method, using weight-specific growth rates obtained from laboratory cultures (Eurytemora) or from the literature (Acartia). Due to the substantially higher growth rates of Acartia compared to Eurytemora, total yearly productions of both communities were comparable, notwithstanding the large discrepancies in biomass. They amounted to about 5 and 6 g C m−2 y−1 by Acartia and Eurytemora respectively. The food needed to realise this production was estimated to be about 14 and 17 g C m−2 y−1 by Acartia and Eurytemora respectively. Provided that the copepods are able to selectively ingest the phytoplankton, in situ net production provides sufficient carbon for zooplankton demands for a short period of the year only. As phytoplankton standing stock is very low and net phytoplankton productivity is negative from late fall to early spring, nutritional demands of the copepods have to be fulfilled by other than algal food at least during this period of the year. Although the copepods in the brackish part can have an important impact on some food items, their contribution to total carbon fluxes in the brackish zone is negligible: each year some 6% of all consumed carbon in the brackish part of the estuary passes through the copepod food web.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00008574
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Daily cycles of dissolved oxygen and nutrient content in a shallow fishpond: The impact of water renewal (1990)
    Springer
    Hydrobiologia 207 (1990), S. 131-136 
    Details
    ISSN: 1573-5117
    Keywords: dissolved oxygen ; nutrients ; daily cycles ; water renewal ; fishponds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study was conducted in a shallow fishpond located on the eastern side of Arcachon Bay, France. Dissolved oxygen, pH and nutrient content (NH4, NO2, NO3 and PO4) showed pronounced diel variations. These phenomena seemed to be directly controlled by biological processes. Microbially mediated degradation of organic matter constitutes the main source of nutrients in the water column and primary producers consume the major part of these products. These processes are closely coupled to the light-dark cycle. Man-induced water renewal caused low modifications in nutrient concentration and did not alter its temporal dynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041449
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of different N- and P-loading on primary and secondary production in an experimental marine ecosystem (1999)
    Springer
    Aquatic ecology 33 (1999), S. 65-81 
    Details
    ISSN: 1573-5125
    Keywords: eutrophication ; mesocosm ; phytoplankton ; zooplankton ; macrobenthos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of nutrient loading on phytoplankton, zooplankton and macrozoobenthos in experimental ecosystems was studied in a 7-month experiment. The mesocosms were designed to mimic the major physical characteristics (irradiance, temperature, mixing) of the Dutch coastal zone in the river Rhine plume. Three different nutrient loading scenarios were used, representing present and future conditions. The level of the spring phytoplankton bloom was determined by phosphorus loading, whereas during summer the nitrogen loading determined phytoplankton biomass. The differences in nutrient loading did not result in shifts in phytoplankton species composition. With exception of the early phase of the spring bloom, diatoms dominated phytoplankton biomass in all nutrient treatments. This was ascribed to microzooplankton grazing on smaller algal species. Microzooplankton biomass showed a positive correlation with primary production, and also significant differences between nutrient treatments. Copepod development was limited, probably due to competition with microzooplankton and predation by benthic fauna. Macrobenthos biomass correlated with primary production, and was lower in the lowest nutrient treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009929706903
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    Paper (German National Licenses)
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