Amelie Berger, Peter Berg, Karen McGlathery, Lillian Aoki,

Matthew Oreska, Marie Lise Delgard

Temperate seagrass bed metabolism and carbon

sequestration

acb4rk@virginia.edu

OCB 2019 Summer

Workshop

Slime moldwasting disease

VCR loss due to pandemic wasting disease and “Great

Storm” of 1933CheapeakeBay

VCR

Atlantic Ocean

OCB 2019 Summer

Workshop

Landscape-scale restorationseeds

Orth Lab, VIMS; The Nature Conservancy

500 acres seeded70 million seeds6200 acres meadow

= 25 km2

OCB 2019 Summer

Workshop

South BaySouth Bay0.5 – 1 acre plots100k seeds acre-1

http://web.vims.edu/bio/sav/

Landscape-scale restoration

OCB 2019 Summer

Workshop

Long-term seagrass study

2014

2015

2017

2016

High temperatures in June 2015 caused large-scale die-off

Meadow development

Mature meadow

Die-off Parti

al re

cove

ry

OCB 2019 Summer

Workshop

VCR

Atlantic Ocean

Photo: AWI Sea Ice Physics group

Aquatic eddy covariance technique

OCB 2019 Summer

Workshop

Aquatic eddy covariance technique

Berger et al. (in review)

OCB 2019 Summer

Workshop

Aquatic eddy covariance technique

24 hours

Berger et al. (in review)

• R = !"# ∑ flux%&'( + ∑flux*+,-

h*+,- h./012

• GPP = !"# ∑ flux./012 +

∑flux*+,-h*+,- h./012

Hume et al. (2011) L&O

• R = !"# ∑ flux%&'( + ∑flux*+,-

h*+,-h./012

• GPP = !"# ∑ flux./012 +

∑flux*+,-h*+,- h./012

OCB 2019 Summer

Workshop

2015

2014

Highly dynamic, but overall balanced seagrass metabolism

Berger et al. (in review)

heterotrophic

autotrophic

OCB 2019 Summer

Workshop

Long-term record of seagrass metabolism

2015

2014

Berger et al. (in review)Hume et al. 2011 Rheuban et al. 2014

OCB 2019 Summer

Workshop

2015

2014 NEM = 1.0 mmol O2 m-2 d-1

Highly dynamic, but overall balanced seagrass metabolism

Berger et al. (in review)

OCB 2019 Summer

Workshop

Annual carbon budget

Berger et al. (in review)

OCB 2019 Summer

Workshop

Restoration reinstates C storage in sediments

0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14

Density

(sho

otsm

-2)

MeadowAge(yr)

• Within 12 years, C burial within range of natural systems

• ~half seagrass C; half algal C produced in situ

CO2

Buried Carbon

ParticulateOrganic C

Greiner et al. 2013, Greiner et al. 2016, Oreska et al. 2017a,b

Meadow development

Mature meadow

050100150200250300350400450500

0 9-14 15 16 17

BulkC(gm

-2)

Meadowage(y)

050

100150200250300350400450500

0 9-14 15 16 17

BulkC(gm

-2)

Meadowage(y)

Restoration reinstates C sequestration in plant biomass

Berger et al. (in review)

OCB 2019 Summer

Workshop

Disturbance caused a shift in trophic status

Berger et al. (in review)

Trophic status: balanced

2014

OCB 2019 Summer

Workshop

Disturbance caused a shift in trophic status

Berger et al. (in review)

2014

2015

Trophic status: heterotrophic

OCB 2019 Summer

Workshop

Disturbance caused a shift in trophic status

Berger et al. (in review)2017

2016

2014

2015

Trophic status: autotrophic

OCB 2019 Summer

Workshop

050

100150200250300350400450500

0 9-14 15 16 17

Carbon

storage(gm

-2)

Meadowage(y)

Seagrass loss affects C storage

Nice to meet you. I’m a Zostera.Nice to meet you. I’m a Zostera.Nice to meet you. I’m a Zostera.Nice to meet you. I’m a Zostera.

Restor

ation Loss

Nice to meet you. I’m a Zostera.

Nice to meet you. I’m a Zostera.Nice to meet you. I’m a Zostera.

Nice to meet you. I’m a Zostera.Nice to meet you. I’m a Zostera.Nice to meet you. I’m a Zostera.

Recovery

OCB 2019 Summer

Workshop

0

50

100

150

200

250

300

350

400

450

NearInlet Mid-meadow

Carbon

storage(gm

-2)

2013

2017

2018

2017

Landscape-scale variation affects C loss

No carbon loss near inlet

Near Inlet

Mid-meadow

Link to exposure to temperature stress

High flushing,Short

residence time

Higher resilience

+

Berger et al. (in prep)

OCB 2019 Summer

Workshop

bathymetry

Limitation by low CO2 or high O2?

Berg et al. (2019) L&O

OCB 2019 Summer

Workshop

bathymetry

No limitation by low CO2 or high O2

Berg et al. (2019) L&O

OCB 2019 Summer

Workshop

• Restoration reinstates C storage and sequestration

• Sediment C stocks are vulnerable to shoot losses fromtemperature stress

• Seagrass loss and recovery causes shifts in trophicstatus, but the meadow is metabolically balanced overallà most C retention = in sediment

• Meadows are resilient at the landscape scale

• No stimulation of photosynthesis at high CO2concentrations

Conclusions

OCB 2019 Summer

Workshop

Dieback and C loss is patchy at plot scale

0

50

100

150

200

250

300

Seagrass Bare

C (g

/m2)

OCB 2019 Summer

Workshop