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Eutrophication in Portuguese estuaries evidenced by δ15N of macrophytes

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dc.contributor.author Castro, Paula
dc.contributor.author Valiela, Ivan
dc.contributor.author Freitas, Helena
dc.date.accessioned 2011-04-26T13:05:47Z
dc.date.available 2012-01-01T09:30:26Z
dc.date.issued 2007-12-06
dc.identifier.citation Marine Ecology Progress Series 351 (2007): 43-51 en_US
dc.identifier.uri http://hdl.handle.net/1912/4515
dc.description Author Posting. © Inter-Research, 2007. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 351 (2007): 43-51, doi:10.3354/meps07173. en_US
dc.description.abstract Terrestrial inputs of nitrogen in estuaries are increasing and altering salt marsh primary production, plant communities and associated biota. We used N isotope ratios and %N in Spartina maritima, Halimione portulacoides, Zostera noltii and below-canopy sediments to study eutrophication caused by anthropogenic land-derived nitrogen in the Mondego and Mira estuaries, Portugal. In spite of different land use practice intensities between estuaries, there were no marked differences in nitrate concentrations in the water column, but ammonium, total dissolved nitrogen and dissolved organic nitrogen concentrations were greater in the Mondego estuary. Sediment and shoot N contents suggest a general pattern of high nitrogen regimes in Mondego and Mira, and point to a somewhat higher delivery of nitrogen into the Mondego. However, these parameters were not sensitive indicators of level of eutrophication. In contrast, δ15N ratios in plant shoots differed significantly and were higher in Mondego for all 3 plant species. Plant δ15N signatures were therefore more sensitive sentinels of land-derived nitrogen load. The parallel increase of δ15N in shoots and sediments indicated that both shoots and sediments followed and reflected the level of eutrophication and some larger whole estuary difference in N loads. Thus, nitrogen isotopic signatures in macrophytes and sediments were useful indicators of land-derived nitrogen in estuaries. en_US
dc.format.mimetype application/pdf
dc.language.iso en en_US
dc.publisher Inter-Research en_US
dc.relation.uri http://dx.doi.org/10.3354/meps07173
dc.subject Land-derived nitrogen en_US
dc.subject N-15 en_US
dc.subject Rooted macrophytes en_US
dc.subject Mondego estuary en_US
dc.subject Mira estuary en_US
dc.title Eutrophication in Portuguese estuaries evidenced by δ15N of macrophytes en_US
dc.type Article en_US
dc.identifier.doi 10.3354/meps07173


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