2 research outputs found

    Contrasts among macrophyte riparian species in their use of stream water nitrate and ammonium: insights from 15N natural abundance

    No full text
    13 páginas, 4 figuras, 4 tables.We examined the relevance of dissolved inorganic nitrogen (DIN) forms (nitrate and ammonium) in stream water as N sources for different macrophyte species. To do this, we investigated the variability and relationships between 15N natural abundance of DIN forms and of four different macrophyte species in five different streams influenced by inputs from wastewater treatment plants and over time within one of these streams. Results showed that 15N signatures were similar in species of submersed and amphibious macrophytes and in stream water DIN, whereas 15N signatures of the riparian species were not. 15N signatures of macrophytes were generally closer to 15N signatures of nitrate, regardless of the species considered. Our results showed significant relationships between 15N signatures of DIN and those of submersed Callitriche stagnalis and amphibious Veronica beccabunga and Apium nodiflorum, suggesting stream water DIN as a relevant N source for these two functional groups. Moreover, results from a mixing model suggested that stream water DIN taken up by the submersed and amphibious species was mostly in the form of nitrate. Together, these results suggest different contribution to in-stream N uptake among the spatially-segregated species of macrophytes. While submersed and amphibious species can contribute to in-stream N uptake by assimilation of DIN, macrophyte species located at stream channel edges do not seem to rely on stream water DIN as an N source. Ultimately, these results add a functional dimension to the current use of macrophytes for the restoration of stream channel morphology, indicating that they can also contribute to reduce excess DIN in streams.Financial support was provided by the Spanish Ministry of Science and Innovation through the ISONEF (ref: CGL2008-05504-C02-02/ BOS) and MED_FORESTREAM (ref: CGL2011-30590-C02-02) projects and by the European Science Foundation project COMIX (EuroDiversity Collaborative Research program, ref: 05_EDIV_FP065-COMIX). M. Peipoch and M. Ribot were funded through a FPI PhD fellowship and a technical training contract, respectively, from the Spanish Ministry of Science and Innovation through the ISONEF project. A. Blesa was granted a FPI PhD fellowship associated to grant BIO2010-18875 from the Spanish Ministry of Science and Innovation.Peer reviewe
    corecore