acidification on benthic communities

Effects of global warming and ocean acidification on benthic communities

in the German Wadden Sea

-

BIOACID Annual Meeting, September 2014, Kiel

Andreas Pansch¹, Harald Asmus¹, Ragnhild Asmus¹, Birte Mensch², Vera Winde³, Martin Wahl⁴

1Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Wadden Sea Station Sylt

2Christian-Albrechts-University Kiel

3IOW, Leibnitz Institute for Baltic Research Warnemünde

4GEOMAR, Helmholz Centre for Ocean Research Kiel

Why mesocosm studies ?

 Close the gap between small scale lab experiments and field studies

 Experiments with communities instead of single species under controlled conditions

 Investigation of species interactions and community structure under climate change

AWI Wadden Sea Station

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Mesocosms facilities - Sylt

 Constructed by 4H-Jena Engineering

 Finished in August 2013

 12 mesocosms  12 independent experimental units

 Non filtered seawater from the Wadden Sea Station

 Connected with the CO₂-gas mixing facility of the institute

Made for climate change experiments at the ecosystem level

Single mesocosm

 170 cm in diameter x 80 cm height

 1800 l volume

 Insulated wall construction

 Translucent lid

 Temperature regulation

 Multiparameter measurement system

 Flow through

 Tide simulation

 Software

Tide simulation

 IMG_0946.JPG

Tide simulation

low tide

Tide simulation

high tide

Temperature regulation

Aqua medic^® Titanium heater

3 x 500 W

Aqua medic^® Titan 2000 cooler

550 W

Software:

 yearly max/min

 daily max/min

 adjusted by measured

temperatures in the field

Temperature regulation

+ 5 °C

CO ₂ -gas mixing facility

Seawater in each mesocosm is directly

aerated with pre- mixed gas

Seawater acidification

380 ppm

1000 ppm

Multi-parameter measurements

One system for two mesocosms:

Hydrolab DS5X

 Parameters measured at the moment

• temperature

• pH

• oxygen (Clark cell)

• conductivity

 Possible adjustments in the future

• chlorophyll

• turbidity

• Ammonium etc.

Software

First experiments

autumn 2013 + spring 2014

 Macro algal community (Fucus vesiculosus)

 3 month

 CO₂ x temperature

 4 treatments (3 replicates)

 Ambient

 Warm  Ambient + 5 °C

 Acid  1000 ppm

 Warm + Acid  + 5 °C, 1000 ppm

Fucus vesiculosus

Ambient Warm Acid Warm+Acid

280300320340

Increase in Biomass (%)

Ambient Warm Acid Warm+Acid

106108110112114

Increase in Biomass (%)

Autumn 2013 Spring 2014

• Warming inhibited Fucus growth

• Elevated pCO₂ increased Biomass

• Stress combination acted antagonistically

p= 0.007 ** p= 0.092

Gammarus sp.

• Warming increased the number of Gammarus offspring

Ambient Warm Acid Warm+Acid

50010001500200025003000

# of Gammarus per Benthocosm

Abundance p= 0.073

Ambient Warm Acid Warm+Acid

0.0040.0060.0080.0100.012

Gammarus (mg Dryweight/Individual)

Dry weight per Individual p= 0.288 Spring 2014

Gammarus sp.

• Warming increased the number of Gammarus offspring

Ambient Warm Acid Warm+Acid

468101214

Gammarus (mg Dryweight per Benthocosm)

Dry weight per Benthocosm p= 0.424

Spring 2014

Corophium sp.

• Warming and acidification as well the combination of both increased the abundance of Corophium sp.

Ambient Warm Acid Warm+Acid

100200300400

# of Corophium per Benthocosm

Ambient Warm Acid Warm+Acid

0.00040.00060.00080.00100.00120.00140.0016

Corophium (mg Dryweight/Individual

Abundance Dry weight per Individual

p= 0.624 p= 0.650

Spring 2014

Hydrobia ulvae

• Warming and acidification as well the combination of both increased the abundance and growth of Hydrobia ulvae

Ambient Warm Acid Warm+Acid

200400600800

# of Hydrobia per Benthocosm

Ambient Warm Acid Warm+Acid

0.0020.0030.0040.005

Hydrobia (mg Dryweight/IndividualHydrobia (mg Dryweight/Individual)

Abundance Dry weight per Individual

p= 0.365 p= 0.226

Spring 2014

Juvenile Littorina littorea

• Warming and acidification as well the combination of both increased the abundance of L. littorea offspring

• Warming increased the growth of juvenile L. littorea

Ambient Warm Acid Warm+Acid

50100150200250300

# of juvenile Littorina littorea per Benthocosm

Ambient Warm Acid Warm+Acid

0.0050.0100.0150.020

juvenile Littorina littorea (mg Dryweight/Individual)

Abundance Dry weight per Individual

p= 0.647 p= 0.012 *

Spring 2014

adult Littorina littorea

• Warming reduced the biomass of adult L. littorea

Ambient Warm Acid Warm+Acid

1.81.92.02.12.22.3

Littorina littorea (mg/Ind)

Abundance

• No change in abundance

Dry weight per Individual p= 0.370

Spring 2014

Littorina mariae

• Warming and acidification as well the combination of both increased the abundance of L. mariae

• Growth increased under the combination of warning and high pCO₂

Ambient Warm Acid Warm+Acid

500100015002000

# of Littorina mariae per Benthocosm

Ambient Warm Acid Warm+Acid

0.0050.0100.0150.0200.0250.030

Littorina mariae (mg Dryweight/Individual)

Abundance Dry weight per Individual

p= 0.331 p= 0.617

Spring 2014

Mytilus edulis

• Warming decreased the abundance of M. edulis offspring and growth of M. edulis adults

• Elevated CO₂ increased the abundance of offspring

Ambient Warm Acid Warm+Acid

30405060708090

# of Mytilus offspring

Ambient Warm Acid Warm+Acid

-10123456

Increase in shell length (%)

Abundance Shell length

p= 0.575 p= 0.002 **

Spring 2014

Crassostrea gigas

• Elevated CO₂ decreased growth of C. gigas

• The combination of warming and elevated CO₂ led to control growth

Ambient Warm Acid Warm+Acid

5101520

Increase in shell length (%)

Abundance

Shell length

• No settled oysters were found p= 0.333

Spring 2014

Summary

Warm Acid Warm+Acid

Fucus vesiculosus Gammarus sp.

Corophium sp.

Hydrobia ulvae Juv. L. littorea Adult L. littorea Littorina mariae Mytilus edulis Crassostrea gigas

Conclusions

 No obvious negative effects at elevated pCO₂

 Warming impacted Fucus and Mytilus negatively

 Combination of warming and acidification acted antagonistically

 Importance of multiple stressor experiments

 Important to differentiate between direct and indirect effects

 First results show higher impact of acidification on Wadden Sea community than on Baltic Sea communities

Although single species effects were shown widely in the literature, two of the main predicted future threats, warming

and acidification, do not negatively impact benthic Wadden Sea assemblages

Future plans

Summer 2014 (still running)

 Fucus vesiculosus community

(CO₂ x temperature) x eutrophication

 Test with Ecological Network Analysis

 Experiments on Seagrass communities

 Test of more stressors, stress combinations, species, life stages and communities

• fish larvae, small fish

• turbidity, deoxygenation, hyposalinity, sedimentation, micro plastics

Thanks for your

attention