Benthic oxygen exchange in a live coralline algal bed and an adjacent sandy habitat: an eddy covariance study

Karl M. Attard, Henrik Stahl, Nicholas A. Kamenos, Gavin Turner, Heidi L. Burdett, Ronnie N. Glud

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Coralline algal (maerl) beds are widespread, slow-growing, structurally complex perennial habitats that support high biodiversity, yet are significantly understudied compared to seagrass beds or kelp forests. We present the first eddy covariance (EC) study on a live maerl bed, assessing the community benthic gross primary productivity (GPP), respiration (R), and net ecosystem metabolism (NEM) derived from diel EC time series collected during 5 seasonal measurement campaigns in temperate Loch Sween, Scotland. Measurements were also carried out at an adjacent (?20 m distant) permeable sandy habitat. The O2 exchange rate was highly dynamic, driven by light availability and the ambient tidally-driven flow velocity. Linear relationships between the EC O2 fluxes and available light indicate that the benthic phototrophic communities were light - limited. Compensation irradiance (Ec ) varied seasonally and was typically ∼1.8-fold lower at the maerl bed compared to the sand. Substantial GPP was evident at both sites; however, the maerl bed and the sand habitat were net heterotrophic during each sampling campaign. Additional inputs of ∼4 and ∼7 mol m-2 yr-1 of carbon at the maerl bed and sand site, respectively, were required to sustain the benthic O2 demand. Thus, the 2 benthic habitats efficiently entrap organic carbon and are sinks of organic material in the coastal zone. Parallel deployment of 0.1 m2 benthic chambers during nighttime revealed O2 uptake rates that varied by up to ∼8-fold between replicate chambers (from -0.4 to -3.0 mmol O2 m-2 h-1 ; n = 4). However, despite extensive O2 flux variability on meter horizontal scales, mean rates of O2 uptake as resolved in parallel by chambers and EC were typically within 20% of one another.

Original languageEnglish
Pages (from-to)99-115
Number of pages17
JournalMarine Ecology Progress Series
Volume535
DOIs
Publication statusPublished - 15 Sep 2015

Keywords

  • Benthic chambers
  • Benthic oxygen exchange
  • Benthic primary production
  • Coastal carbon cycling
  • Coralline algae
  • Eddy covariance
  • Permeable sediment

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Aquatic Science

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