Benthic nitrogen metabolism in a macrophyte meadow (Vallisneria spiralis L.) under increasing sedimentary organic matter loads
Number of Authors: 8
2015 (English)In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 124, no 1-3, 387-404 p.Article in journal (Refereed) Published
Organic enrichment may deeply affect benthic nitrogen (N) cycling in macrophyte meadows, either promoting N loss or its recycling. This depends upon the plasticity of plants and of the associated microbial communities, as those surrounding the rhizosphere. Rates of denitrification, dissolved inorganic N fluxes and N uptake were measured in sediments vegetated by the submerged macrophyte Vallisneria spiralis L. under increasing organic matter loads. The aim was to investigate how the combined N assimilation and denitrification, which subtract N via temporary retention and permanent removal, respectively, do vary along the gradient. Results showed that V. spiralis meadows act as regulators of benthic N cycling even in organic enriched sediments, with negative feedbacks for eutrophication. A moderate organic load stimulates N uptake and denitrification coupled to nitrification in the rhizosphere. This is due to a combination of weakened competition between macrophytes and N cycling bacteria and enhanced radial oxygen loss by roots. An elevated organic enrichment affects N uptake due to hostile conditions in pore water and plant stress and impairs N mineralisation and its removal via denitrification coupled to nitrification. However, the loss of plant performance is almost completely compensated by increased denitrification of water column nitrate, resulting in a shift between the relative relevance of temporary and permanent N removal processes.
Place, publisher, year, edition, pages
2015. Vol. 124, no 1-3, 387-404 p.
Organic enrichment, Vallisneria spiralis, Radial oxygen loss, N fluxes, Denitrification, N uptake
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:su:diva-119082DOI: 10.1007/s10533-015-0104-5ISI: 000355620200025OAI: oai:DiVA.org:su-119082DiVA: diva2:843380