MEPS 471:11-22 (2012)  -  doi:10.3354/meps10013

Impacts of long-term fertilization on salt marsh tidal creek benthic nutrient and N2 gas fluxes

Amanda M. Vieillard1,*, Robinson W. Fulweiler1,2

1Department of Earth and Environment and 2Department of Biology, Boston University, 675 Commonwealth Avenue, Boston, Massachusetts 02215, USA

ABSTRACT: Salt marsh ecosystems serve as critical nutrient filters by removing reactive nitrogen (N) through denitrification. We examined the influence of long-term fertilization on N transformation and removal in a salt marsh tidal creek ecosystem fringing the Plum Island Sound estuary in northern Massachusetts, USA. Sediment oxygen demand was within the range of other marsh systems (1271.9 to 7855.0 µmol m−2 h−1) and was not significantly different between the fertilized and reference creek. Net N2 fluxes ranged from net N fixation of −402.7 µmol N2-N m−2 h−1 in the reference creek to net denitrification of 524.9 µmol N2-N m−2 h−1 in the fertilized creek. Net N2 flux and nitrate uptake were significantly higher in the fertilized creek, and in both creeks, net denitrification appeared to be nitrate limited. We calculated rates of dissimilatory nitrate reduction to ammonium (DNRA) and found it to be significantly higher in the fertilized creek, representing 45 and 11% of the total nitrate uptake in the fertilized and reference creeks, respectively. Additionally, there was a strong relationship between ammonium and nitrite fluxes in both creeks. These results suggest that DNRA may outcompete denitrification at high nitrate concentrations. Increased anthropogenic nutrient loading may therefore have a detrimental effect on the N removal capacity of salt marsh ecosystems.


KEY WORDS: Denitrification · DNRA · Salt marsh ecosystem · Fertilization · Nitrogen loading


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Cite this article as: Vieillard AM, Fulweiler RW (2012) Impacts of long-term fertilization on salt marsh tidal creek benthic nutrient and N2 gas fluxes. Mar Ecol Prog Ser 471:11-22

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