Eutrophication in Portuguese estuaries evidenced by δ15N of macrophytes
MetadataShow full item record
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.
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.
Suggested CitationMarine Ecology Progress Series 351 (2007): 43-51
Showing items related by title, author, creator and subject.
Nutrient gradients in Panamanian estuaries : effects of watershed deforestation, rainfall, upwelling, and within-estuary transformations Valiela, Ivan; Giblin, Anne E.; Barth-Jensen, Coralie; Harris, Carolynn; Stone, Thomas A.; Fox, Sophia E.; Crusius, John (Inter-Research, 2013-05-22)To test whether deforestation of tropical forests alters coupling of watersheds, estuaries, and coastal waters, we measured nutrients in 8 watershed-estuarine systems on the Pacific coast of Panama where watershed forest ...
Evolution of Mid-Atlantic coastal and back-barrier estuary environments in response to a hurricane : implications for barrier-estuary connectivity Miselis, Jennifer L.; Andrews, Brian D.; Nicholson, Robert S.; Defne, Zafer; Ganju, Neil K.; Navoy, Anthony (Springer, 2015-12-29)Assessments of coupled barrier island-estuary storm response are rare. Hurricane Sandy made landfall during an investigation in Barnegat Bay-Little Egg Harbor estuary that included water quality monitoring, geomorphologic ...
Lai, Zhigang; Ma, Ronghua; Gao, Guangyin; Chen, Changsheng; Beardsley, Robert C. (John Wiley & Sons, 2015-08-21)Impacts of the multichannel river network on plume dynamics in the Pearl River estuary were examined using a high-resolution 3-D circulation model. The results showed that during the dry season the plume was a distinct ...