order to better predict future climate changes

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Sylt Benthocosms - North Sea Relevance

• Increasing human activities and CO₂ release to the atmosphere cause global ocean warming and acidification, as well as local oxygen depletion and eutrophication.

• Laboratory experiments with single species and single stressors show variable responses between and within species and different stress combinations can have synergistic, additive or antagonistic effects on species.

• Thus, only near natural multi-species and multi-stressor experiments can predict future community responses.

Andreas Pansch

¹

, Stefanie Sokol

²

, Harald Asmus

¹

, Ragnhild Asmus

¹

, Martin Wahl

²

1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung - Wadden Sea Station List, Germany

2GEOMAR Helmholtz Zentrum for Ocean Rsearch, Kiel, Germany

Leibniz Institute for Baltic Sea Research www.io-warnemuende.de – BIOACID II Meeting Warnemünde 2013

Multi-stressors and multi-community approaches in order to better predict future climate changes

Consortium 2: Direct and indirect effects of environmental stress: shifts in macrophyte interactions WP 2.1: with consumers and epibionts and ensuing community re-structering

cooler and heaters

for each unit

6 multi parameter measurement systems:

- temperature - pH

- oxygen

- conductivity

tide simulation 12 experimental

units of 1800 L

computerized setting and monitoring

of pH, temperature, tides, currents…

current simulation, changing direction with tides

outlets for water samples

CO₂ mixing facility

Kiel Benthocosms - Baltic Sea

Growth of Fucus

Spring 2013

1Ambient 2Warming 4Warming+Acidification

-50050100150200

Treatment

Increase in Biomass [%]

16

Increase in Biomass (%)

Epiphytes on Fucus

# of Littorina

Summer 2013

-80-60-40-2002040

Treatment

17

Increase in Biomass (%)

0.00.20.40.60.81.0

Treatment

10

# of Barnacles on Fucus

T * T *

T **

0200400600800

Treatment

Ambient Warm Acid Warm+Acid

# of Idotea per Benthocosms

0100200300400500600

Treatment

T p=0.065

010203040506070

Treatment

k

0200400600800

Treatment

k

0200400600800

Treatment

k

050100150200

Treatment

k

# of Idotea

# of Idotea per Benthocosms

# of Gammarus

# of Littorina per Benthocosm

1Ambient 3Acidification

050100150

Treatment

k

7

Volume of Epiphytes on on Fucus

Ambient Warm Acid Warm+Acid Ambient Warm Acid Warm+Acid

# of Gammarus

# of Idotea

# of Littorina per Benthocosm

# of Gammarus per Benthocosm

# of Amphibalanusml Fucus

# of Idotea per Benthocosm

Growth of Fucus # of Littorina

T ***

T ** T *

• Fucus vesiculosus + it’s associated community (Idotea sp., Littorina sp., Gammarus sp., Mytilus edulis and Asterias rubens)

• Incubated for 3-months at future warming (ambient +5 °C) &

ocean acidification (ambient +600 ppm) in 12 2000 l benthocosms

• Red lines indicate the biomass or the number of specimens at the beginning of the experiments

Outlook

• Further experiments will be conducted with Fucus vesiculosus and Zostera marina/noltii at the AWI-Sylt for comparisons of North- and Baltic Sea communities

• Organisms will be exposed to new combinations of stress regimes, including eutrophication, hypoxia, desiccation and sedimentation

• Analysis of the data with ecological network analysis

First Results

• Warming inhibited Fucus growth in both experiments and supported growth of epiphytes

• Warming increased the abundance of Idotea in spring while it largely decreased it´s abundance in summer

• Warming did not effect Gammarus abundance in spring but reduced it´s abundance in summer, and increased the amount of settled

barnacles

• Littorina seemed to be less impacted by warming and acidification



Warming had a much higher impact than acidification

Andreas Pansch

andreas.pansch@awi.de