MEPS 661:97-114 (2021)  -  DOI: https://doi.org/10.3354/meps13616

ABSTRACT: Sediment resuspension is a common process in dynamic coastal settings, but its implications for remineralization and carbon turnover in seagrass meadows are poorly understood. Here, we assessed eelgrass Zostera marina metabolism in the Baltic Sea (SW Finland) using benthic flume-chambers and aquatic eddy covariance to critically evaluate the drivers of benthic O₂ exchange during dynamic flow conditions. During quiescent weather conditions, the 2 methods resolved similar metabolic rates and net ecosystem autotrophy (±11% of each other). However, elevated flow speeds and sediment resuspension halfway through the study induced a 5-fold increase in the O₂ uptake rates measured by eddy covariance, whereas chamber fluxes remained relatively unchanged. Following particle resettlement, instruments were redeployed and the benthic O₂ uptake resolved by both techniques was just ~30% of the values measured before resuspension. Laboratory investigations revealed sediment resuspension could potentially increase benthic O₂ uptake up to 6fold, mainly due to the reoxidation of reduced compounds (e.g. FeS_x). This process was fully captured by the eddy O₂ fluxes, but not by the chamber incubation. Consequently, the chamber and eddy net ecosystem metabolism amounted to -17 and -824 mmol C m^-2, respectively, throughout the study period. The rapid reoxidation and long-term effects of resuspension on benthic O₂ dynamics highlight the importance of fully capturing dynamic conditions when assessing the overall carbon turnover in coastal habitats. Future studies on the biogeochemical functioning of coastal environments should aim to capture the natural frequency and duration of resuspension events.

KEY WORDS: Benthic oxygen exchange · Seagrass · Oxygen storage · Wind waves · Sediment resuspension

Full text in pdf format Supplementary material

Cite this article as: Camillini N, Attard KM, Eyre BD, Glud RN (2021) Resolving community metabolism of eelgrass Zostera marina meadows by benthic flume-chambers and eddy covariance in dynamic coastal environments. Mar Ecol Prog Ser 661:97-114. https://doi.org/10.3354/meps13616 Export citation Share:    Facebook - - linkedIn