Eelgrass meadows, Zostera marina (L.), facilitate the ecosystem service of nitrogen removal during simulated nutrient pulses in Shinnecock Bay, New York, USA

• Published in: Marine pollution bulletin Vol. 124; no. 1; pp. 376 - 387
• Main Authors: Zarnoch, Chester B., Hoellein, Timothy J., Furman, Bradley T., Peterson, Bradley J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15-11-2017
• Subjects: Bays; Coastal filter; Denitrification; Environmental Monitoring; Eutrophication; Grassland; Groundwater; New York; Nitrification; Nitrogen - metabolism; Nitrogen fixation; Stoichiometry; Zosteraceae; Denitrification; Nitrogen fixation; Stoichiometry; Groundwater; Coastal filter; Eutrophication
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2017.07.061

Seagrass meadows are important sites of nitrogen (N) transformations in estuaries, however, the role of N loading in driving relative rates of N fixation and denitrification in seagrass habitats is unclear. The current study quantified N fluxes in eelgrass meadows (Zostera marina (L.)) and nearby unvegetated sand in trials representing in situ and N enriched conditions. Net N2 fluxes were low or negative under in situ conditions in both eelgrass and sand. Under N enriched conditions, denitrification was higher than N-fixation, and denitrification in eelgrass was significantly higher than sand. Denitrification of water column NO3− was more significant than coupled nitrification-denitrification in the eelgrass. Denitrification was likely supported by greater organic carbon and N within the eelgrass sediment compared to sand. Eelgrass meadows in Shinnecock Bay may facilitate the ecosystem service of N removal and retention during short-term nutrient pulses that can originate from groundwater discharge and stormwater runoff.
•Eelgrass meadows can be hotspots for nitrogen cycling.•Mechanisms that favor nitrogen fixation or denitrification are unclear.•N2 fluxes were low or negative in eelgrass meadows with low water column nitrogen.•Denitrification was high in eelgrass habitat under nitrogen enriched conditions.•Denitrification was supported by water column nitrate and sediment carbon.