2018 Ocean Sciences Meeting, Portland, Oregon, USA Session EP43A Aquatic Flux Studies: New Ecological Findings and In Situ Approaches
Importance of macroalgal beds (Fucus vesiculosus) for carbon cycling and oxygen dynamics Karl Attard, Postdoctoral Researcher Tvärminne Zoological Station, University of Helsinki Department of Biology, University of Southern Denmark
[email protected]
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The ‘breathing seascape’ project Resolving ecosystem metabolism and habitat‐function relationships acrosscoastalhabitats
Macroalgal canopies
Seagrass beds
Soft sediments
Mussel reefs
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The ‘breathing seascape’ project Resolving ecosystem metabolism and habitat‐function relationships acrosscoastalhabitats
(1) Eddy fluxes + env. parameters
(2) Biodiversity measurements
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The ‘breathing seascape’ project Resolving ecosystem metabolism and habitat‐function relationships acrosscoastalhabitats
Macroalgal canopies
Seagrass beds
Soft sediments
Mussel reefs
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Macroalgal canopies: Fucus vesiculosus
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Fucus vesiculosus Linnaeus 1753, Finnish Archipelago, Baltic Sea
Study site: Spikarna, Finnish Archipelago
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50m x 50m F. vesiculosus canopy 2 m water depth AEC deployed from small boats by divers Deployments 3‐4 d in duration 5 field campaigns (Aug, Oct, Dec, Mar, Jun)
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Seasonal metabolism measurements
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35‐72 hr of eddy flux data per season
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High flow velocities and rough seabed surface
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Flux footprint: 35‐56 m2
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Seabed PAR: 1‐31 mol quanta m‐2 d‐1
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Light‐response detected year‐round
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High oxygen production rates from late winter to late summer
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Autotrophic in 4/5 of the campaigns Attard et al. In prep
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Seasonal metabolism measurements
(A) Daily NEM Coral reefs: McGillis et al. 2011, Long et al. 2013, Takeshita et al. 2016; Bare sediments: Hume et al. 2011, Berg et al. 2013, Attard et al. 2014, Rheuban et al. 2014a, Attard et al. 2015, Walpersdorf et al. 2017; Macroalgae: Gruber et al. 2017, this study; Seagrass: Moriarty et al. 1990, Pollard & Moriarty 1991, Hume et al. 2011, Rheuban et al. 2014b, Long et al. 2015b, Olive et al. 2016, Ganguly et al. 2017, Gruber et al. 2017, Lee et al. 2017). (B) Annual NEM Maerl beds: Martin et al. 2007, Attard et al. 2015; Bare sediments: Rheuban et al. 2014a, Attard et al. 2015; Seagrass: Rheuban et al. 2014a; Macroalgae: this study).
Attard et al. In prep
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Annual NEM and organic C export potential
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Org C export ~0.3 kg C m‐2 yr‐1 (Global average ≈ 0.4 kg C m‐2 yr‐1, Krause‐Jensen & Duarte 2016)
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Habitat connectivity
Attard et al. In prep
Oxygen flux dynamics
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Eddy flux offset w/ respect to PAR
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Consistent between days
10 August 2016 Attard et al. In prep
Oxygen storage within macroalgae gas spaces
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(1) Nighttime oxygen flux: very low uptake or even positive fluxes (release)
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(2) Sunrise: offset of ~5 h w/ PAR
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(3) Sunset: High oxygen release rates under very low PAR
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Attard et al. In prep
Oxygen flux dynamics
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Consistent across seasons (spring‐autumn)
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Tests to constrain effects of known potential issues
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Attard et al. In prep
Oxygen storage within macroalgae gas spaces
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1% gas space ≈ 25% of O2
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Oxygen accumulation within gas spaces under illumination (400 µmol PAR m‐2 s‐1)
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Exponential decrease in the dark, but still above water saturation levels for ~12 h
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Attard et al. In prep
Impacts of gas storage on oxygen fluxes?
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Gas storage dynamics consistent with eddy flux dynamics
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Impacts on GPP and R estimates, NEM?
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Implications for biogeochemical functioning of canopies?
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Attard et al. In prep
Thank you
Collaborators
Funding
Iván Rodil, Alf Norkko, Joanna Norkko (University of Helsinki) Peter Berg (University of Virginia) Ronnie N. Glud (University of Southern Denmark) Walter and Andrée de Nottbeck Foundation Academy of Finland
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