Coupled nitrification–denitrification measured in situ in a Spartina alterniflora marsh with a 15NH4+ tracer
MetadataShow full item record
Measurements of N losses by denitrification from saltmarsh sediments have proved difficult because of the importance of plant metabolism and tidal cycles to sediment N cycling. In vitro approaches often do not measure the dominant coupled nitrification–denitrification pathway and/or alter in situ plant growth and redox conditions. We developed an in situ 15NH4+ tracer approach to measure coupled nitrification–denitrification fluxes in an undisturbed New England Spartina alterniflora saltmarsh. The tracer was line-injected into sediments underlying natural S. alterniflora stands and in similar areas receiving long-term N amendment (up to 11.2 mol organic N m–2 yr–1 for 16 to 23 yr), and 15N retention and loss routes were followed for 1 to 5 d. Denitrification losses in unfertilized grass stands ranged from 0.4 to 11.9 mmol N m–2 d–1 (0.77 ± 0.18 mol N m–2 yr–1). Denitrification in unfertilized sediments remained low until late summer, but underwent a ca. 4-fold increase in August and September, although sediment temperatures and respiration rates were high throughout the summer. Plant N uptake may limit the availability of N to support denitrification during the early summer, and denitrification may be released from competition with plant uptake in late summer, when plant growth slows. Denitrification rates in fertilized areas ranged from 22 to 77 mmol N m–2 d–1 (10.5 ± 4.9 mol N m–2 yr–1), and denitrification was likely controlled by the availability of fertilizer N rather than by competition with plants, since N was added in excess of plant demand. Our results emphasize the importance of in situ measurements of denitrification in understanding the dynamics of saltmarsh N cycling.
Author Posting. © Inter-Research, 2005. 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 299 (2005): 123-135, doi:10.3354/meps299123.
Suggested CitationMarine Ecology Progress Series 299 (2005): 123-135
Showing items related by title, author, creator and subject.
Perez, Tibisay; Garcia-Montiel, Diana; Trumbore, Susan E.; Tyler, Stanley; de Camargo, Plinio; Moreira, Marcelo; Piccolo, Marisa C.; Cerri, Carlos C. (Ecological Society of America, 2006-12)The isotopic signatures of 15N and 18O in N2O emitted from tropical soils vary both spatially and temporally, leading to large uncertainty in the overall tropical source signature and thereby limiting the utility of isotopes ...
Plant nitrogen dynamics in fertilized and natural New England salt marshes : a paired 15N tracer study Drake, Deanne C.; Peterson, Bruce J.; Deegan, Linda A.; Harris, Lora A.; Miller, E. E.; Warren, R. Scott (Inter-Research, 2008-02-07)We examined the effects of increased nutrient availability on nitrogen (N) dynamics in dominant New England salt marsh plants (tall and stunted Spartina alterniflora and S. patens) using paired large-scale nutrient and ...
Effects of regular salt marsh haying on marsh plants, algae, invertebrates and birds at Plum Island Sound, Massachusetts Buchsbaum, Robert N.; Deegan, Linda A.; Horowitz, Julie; Garritt, Robert H.; Giblin, Anne E.; Ludlam, John P.; Shull, David H. (2008-10)The haying of salt marshes, a traditional activity since colonial times in New England, still occurs in about 400 ha of marsh in the Plum Island Sound estuary in northeastern Massachusetts. We took advantage of this haying ...