Tidal controls on trace gas dynamics in a seagrass meadow of the Ria Formosa lagoon (southern Portugal)

Bahlmann, E.; Weinberg, I.; Lavric, J. V.; Eckhardt, T.; Michaelis, W.; Santos, Rui; Seifert, R.

http://hdl.handle.net/10400.1/12027

Use this identifier to reference this record.

Name:	Description:	Size:	Format:
12027.pdf		757.73 KB	Adobe PDF	Download

Send Feedback

Authors

Abstract(s)

Coastal zones are important source regions for a variety of trace gases, including halocarbons and sulfur-bearing species. While salt marshes, macroalgae and phyto-plankton communities have been intensively studied, little is known about trace gas fluxes in seagrass meadows. Here we report results of a newly developed dynamic flux chamber system that can be deployed in intertidal areas over full tidal cycles allowing for highly time-resolved measurements. The fluxes of CO2, methane (CH4) and a range of volatile organic compounds (VOCs) showed a complex dynamic mediated by tide and light. In contrast to most previous studies, our data indicate significantly enhanced fluxes during tidal immersion relative to periods of air exposure. Short emission peaks occurred with onset of the feeder current at the sampling site. We suggest an overall strong effect of advective transport processes to explain the elevated fluxes during tidal immersion. Many emission estimates from tidally influenced coastal areas still rely on measurements carried out during low tide only. Hence, our results may have significant implications for budgeting trace gases in coastal areas. This dynamic flux chamber system provides intensive time series data of community respiration (at night) and net community production (during the day) of shallow coastal systems.

Keywords

Intertidal sand flat Pore-water exchange Halogenated organic-compounds Biogenic sulfur-compounds Eastern english-channel Coastal salt marshes Methane production Marine-sediments Zostera-noltii Methyl-bromide