Direct and indirect effects of tides on ecosystem-scale CO2 exchange in a brackish tidal marsh in Northern California

Journal of Geophysical Research: Biogeosciences
By: , and 

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Abstract

We investigated the direct and indirect influence of tides on net ecosystem exchange (NEE) of carbon dioxide (CO2) in a temperate brackish tidal marsh. NEE displayed a tidally driven pattern with obvious characteristics at the multiday scale, with greater net CO2uptake during spring tides than neap tides. Based on the relative mutual information between NEE and biophysical variables, this was driven by a combination of higher water table depth (WTD), cooler air temperature, and lower vapor pressure deficit (VPD) during spring tides relative to neap tides, as the fortnightly tidal cycle not only influenced water levels but also strongly modulated water and air temperature and VPD. Tides also influenced NEE at shorter timescales, with a reduction in nighttime fluxes during growing season spring tides when the higher of the two semidiurnal tides caused inundation at the site. WTD significantly influenced ecosystem respiration (Reco), with lower Reco during spring tides than neap tides. While WTD did not appear to affect ecosystem photosynthesis (gross ecosystem production, GPP) directly, the impact of tides on temperature and VPD influenced GPP, with higher daily light‐use efficiency and photosynthetic activity during spring tides than neap tides when temperature and VPD were lower. The strong direct and indirect influence of tides on NEE across the diel and multiday timescales has important implications for modeling NEE in tidal wetlands and can help inform the timing and frequency of chamber measurements as annual or seasonal net CO2 uptake may be underestimated if measurements are only taken during nonflooded periods.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Direct and indirect effects of tides on ecosystem-scale CO2 exchange in a brackish tidal marsh in Northern California
Series title Journal of Geophysical Research: Biogeosciences
DOI 10.1002/2017JG004048
Volume 123
Issue 3
Year Published 2019
Language English
Publisher Wiley
Contributing office(s) California Water Science Center, WMA - Earth System Processes Division
Description 20 p.
First page 787
Last page 806
Country United States
State California
Other Geospatial San Francisco Bay National Estuarine Research Reserve, Suisun Bay