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