Mesocosm tracer studies. 1. Zooplankton as sources and sinks in the pelagic phosphorus cycle of a mesotrophic lake

Anne Lyche*, Tom Andersen, Kirsten Christoffersen, Dag O. Hessen, Paul H. Berger Hansen, Annette Klysner

*Corresponding author for this work

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    33 Citations (Scopus)

    Abstract

    The impact of various zooplankton groups on the cycling and retention of phosphorus in a mesotrophic lake in late summer was estimated in a 10-d mesocosm experiment with addition of 33P. Specific assimilation rates for various dissolved and particulate fractions and individual zooplankton species were estimated by application of tracer models. By means of mathematical inverse methods, these estimates were used to construct a balanced P budget that included the different zooplankton groups. Altogether, the consumers (including the mixotrophic Dinobryon) were responsible for >60% of the estimated P sedimentation (~1% d- 1). The microconsumers had the largest specific P assimilation (0.28 d- 1) and regenerated 45% of assimilated P; Daphnia had an intermediate P assimilation (0.17 d-1), but regenerated <20%, whereas Cyclops assimilated P quite slowly (0.07 d-1) and regenerated 230% of its assimilation of algal P <20 μm, due to its feeding on microconsumers. The microconsumers, and the daphnids in particular, thus act mainly as sinks for P, whereas the cyclopoids act mainly as sources of P by assimilating and regenerating P otherwise trapped in the microconsumers. The mechanisms responsible for these different roles seem related to growth rate and P content of the consumers relative to that of their diet.

    Original languageEnglish
    Pages (from-to)460-474
    Number of pages15
    JournalLimnology and Oceanography
    Volume41
    Issue number3
    Publication statusPublished - May 1996

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    Lyche, A., Andersen, T., Christoffersen, K., Hessen, D. O., Berger Hansen, P. H., & Klysner, A. (1996). Mesocosm tracer studies. 1. Zooplankton as sources and sinks in the pelagic phosphorus cycle of a mesotrophic lake. Limnology and Oceanography, 41(3), 460-474.