Nutrient enrichment and planktonic biomass ratios in lakes

Dag O. Hessen*, Bjørn A. Faafeng, Pål Brettum, Tom Andersen

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    26 Citations (Scopus)

    Abstract

    Phosphorus (P) to chlorophyll ratios and zooplankton-phytoplankton (Z:P) biomass ratios were assessed in 400 temperate lakes over a gradient of phosphorus (P) and with different fish communities. Most of the lakes in this survey were oligotrophic, with a median total P of 7.3 μg P L-1. Thus, the survey provided information on food web effects during the early phase of eutrophication. There was no tendency toward a reduced yield of autotrophs per unit of P over the gradient covered in this survey. The zooplankton yield per unit of P or chlorophyll a decreased slightly with increased nutrient concentrations, and Z:P biomass ratios decreased with fish community classes, reflecting increased fish predation pressure. However, the variability in biomass ratios within a given range of P and fish class was some 100 times higher than the difference over the gradients. This finding suggests that lake-specific properties, community composition, and food quality are by far the most important determinants of biomass ratios and probably also trophic efficiency in lakes; it further suggests that these factors are superimposed on the general effect of eutrophication, at least up to 30 μg P L-1.

    Original languageEnglish
    Pages (from-to)516-527
    Number of pages12
    JournalEcosystems
    Volume9
    Issue number4
    DOIs
    Publication statusPublished - Jun 2006

    Keywords

    • Fish
    • Lakes
    • Nutrient enrichment
    • Phytoplankton
    • Trophic levels
    • Zooplankton

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