Thumbnail Image
Item

Differential effects of bivalves on sediment nitrogen cycling in a shallow coastal bay

Smyth, Ashley
; 
Murphy, Anna E.
; 
Anderson, Iris C.
; 
Song, BK
Abstract
In coastal ecosystems, suspension-feeding bivalves can remove nitrogen though uptake and assimilation or enhanced denitrification. Bivalves may also retain nitrogen through increased mineralization and dissimilatory nitrate reduction to ammonium (DNRA). This study investigated the effects of oyster reefs and clam aquaculture on denitrification, DNRA, and nutrient fluxes (NOx, NH4 6 +, O2). Core incubations were conducted seasonally on sediments adjacent to restored oyster reefs (Crassostrea virginica), clam aquaculture beds (Mercenaria mercenaria) which contained live clams, and bare sediments from Smith Island Bay, Virginia, USA. Denitrification was significantly higher at oyster reef sediments and clam aquaculture site than bare sediment in the summer; however DNRA was not enhanced. The clam aquaculture site had the highest ammonium production due to clam excretion. While oyster reef and bare sediments exhibited seasonal differences in rate processes, there was no effect of season on denitrification, DNRA or ammonium flux at the clam aquaculture site. This suggests that farm management practices or bivalve metabolism and excretion may override seasonal differences. When water column nitrate concentration was elevated, denitrification increased in clam aquaculture site and oyster reef sediments but not in bare sediment; DNRA was only stimulated at the clam aquaculture site. This, along with a significant and positive relationship between denitrification and sediment organic matter, suggests that labile carbon limited nitrate reduction at the bare sediment site. Bivalve systems can serve as either net sinks or sources of nitrogen to coastal ecosystems, depending mainly on the type of bivalve, location and management practices.
Description
Date
2017-01-01
Journal Title
Journal ISSN
Volume Title
Publisher
Collections
Publications, Presentations, & Events
Show all metadata
Download Dataset
Files
Thumbnail Image
Smyth_et_al_ESCO_2017.pdf
Adobe PDF, 1.59 MB
Rights Holder
Usage License
Embargo
Research Projects
Organizational Units
Journal Issue
Keywords
Biological Sciences Peer-Reviewed Articles, denitrification, DNRA, Mercenaria mercenaria, Crassostrea virginica, nitrogen, eutrophication
Citation
Advisor
Department
Virginia Institute of Marine Science
DOI
https://doi.org/10.1007/s12237-017-0344-9
URI
https://scholarworks.wm.edu/handle/internal/18494
Embedded videos