Nutrient cycling relative to δ15N and δ13C natural abundance in a coastal wetland with long-term nutrient additions
Bernot, M.J.; Bernot, R.J.; Morris, J.T. (2009). Nutrient cycling relative to δ15N and δ13C natural abundance in a coastal wetland with long-term nutrient additions. Aquat. Ecol. 43(4): 803-813. https://dx.doi.org/10.1007/s10452-008-9221-8
In: Aquatic Ecology. Springer: Dordrecht; London; Boston. ISSN 1386-2588; e-ISSN 1573-5125, more
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Coastal wetland; delta C-13; delta N-15; Natural abundance; Nitrogen;Nutrient loading; Nutrient uptake; Phosphorus |
| Authors | | Top |
- Bernot, M.J.
- Bernot, R.J.
- Morris, J.T.
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| Abstract |
Because nitrogen and phosphorus are primary resources for plant, algal, and microbial production, increases in nutrient inputs can markedly alter aquatic ecosystems. Coastal wetland plots at Belle W. Baruch Marine Field Laboratory (South Carolina, USA) have been amended with nitrogen and phosphorus for similar to 20 years to determine the effects of nutrient loading on coastal wetlands. We conducted a survey of delta N-15 and delta C-13 natural abundance in coastal wetland organic pools (sediment, vegetation) with long-term nutrient amendments (control, no addition; nitrogen; phosphorus; and nitrogen + phosphorus additions). Additionally, we conducted laboratory assays to quantify pore water nutrient availability and nitrification rates. Marsh vegetation (Spartina alterniflora) had enriched delta C-13 values (mean -14aEuro degrees) relative to bulk sediment samples (mean -18aEuro degrees). Nitrogen-amended plots (alone and in combination with phosphorus) had enriched delta C-13 values in the surface sediment (0-5 cm; mean -16.1aEuro degrees) relative to control (mean -16.5aEuro degrees) and phosphorus-amended plots (mean -16.8aEuro degrees). Nitrogen-amended plots also had depleted delta N-15 in S. alterniflora leaf tissues (-3.3aEuro degrees) and surface sediment samples (mean 2.1aEuro degrees) relative to leaf tissues (mean 2.1aEuro degrees) or sediment samples (mean 5.8aEuro degrees) from control or phosphorus-only amended plots. Nitrate availability (as increased pore water concentration) was higher in N-amended plots although ammonium availability did not differ. Phosphorus availability was higher only in phosphorus-only amended plots. Overall, we found that long-term nutrient amendments to coastal wetlands significantly altered nutrient availability and uptake rates as well as natural abundance of delta C-13 and delta N-15 in multiple organic matter sources. |
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