The response of experimental rocky shore communities to nutrient additions

TL Bokn, CM Duarte, MF Pedersen, N Marba, FE Moy, C Barron, B Bjerkeng, J Borum, H Christie, S Engelbert, FL Fotel, EE Hoell, R Karez, K Kersting, Patrik Kraufvelin, C Lindblad, M Olsen, KA Sanderud, U Sommer, K Sorensen

    Tutkimustuotos: LehtiartikkeliArtikkeliTieteellinenvertaisarvioitu

    54 Sitaatiot (Scopus)

    Abstrakti

    The aim of this study was to determine whether the experimental nutrient enrichment of littoral rocky shore communities would be followed by a predicted accumulation of fast-growing opportunistic algae and a subsequent loss of perennial benthic vegetation. Inorganic nitrogen (N) and potassium (P) was added to eight concrete mesocosms inhabited by established littoral communities dominated by fucoids. The response to nutrient enrichment was followed for almost 2 1/2 years. Fast-growing opportunistic algae (periphyton and ephemeral green algae) grew significantly faster in response to nutrient enrichment, but the growth of red filamentous algae and large perennial brown algae was unaffected. However, these changes were not followed by comparable changes in the biomass and composition of the macroalgae. The biomass of opportunistic algae was stimulated only marginally by the nutrient enrichment, and perennial brown algae (fucoids) remained dominant in the mesocosm regardless of nutrient treatment level. Established rocky shore communities thus seem able to resist the effects of heavy nutrient loading. We found that the combined effects of the heavy competition for space and light imposed by canopy-forming algae, preferential grazing on opportunistic algae by herbivores, and physical disturbance, succeeded by a marked export of detached opportunistic algae, prevented the fast-growing algae from becoming dominant. However, recruitment studies showed that the opportunistic algae would become dominant when free space was available under conditions of high nutrient loading and low grazing pressure. These results show that established communities of perennial algae and associated fauna in rocky shore environments can prevent or delay the accumulation of bloom-forming opportunistic algae and that the replacement of long-lived macroalgae by opportunistic species at high nutrient loading may be a slow process. Nutrient enrichment may not, in itself, be enough to stimulate structural changes in rocky shore communities.
    AlkuperäiskieliEi tiedossa
    Sivut577–594
    Sivumäärä18
    JulkaisuEcosystems
    Vuosikerta6
    Numero6
    DOI - pysyväislinkit
    TilaJulkaistu - 2003
    OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

    Keywords

    • algae
    • benthic vegetation
    • coastal eutrophication
    • hard-bottom organisms
    • intertidal communities
    • mesocosm
    • nutrient enrichment
    • rocky shore communities

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