Ocean acidification effects on plankton communities, ecosystem structure and carbon cycling

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1 Ocean acidification effects on plankton communities, ecosystem structure and carbon cycling Monika Winder Department of Ecology, Environment and Plant Sciences Stockholm University

2 What does a more acidic ocean mean for marine life? Feely et al. (2009) Oceanogr

3 Strong CO 2 effects on calcifying organisms Corals Pteropods Sea urchin Coccolithophores Decrease in calcification rates Difficulty maintaining their external calcium carbonate skeletons Coccolithophor bloom

4 Response of non-calcifying organisms and communities Strong indirect effects Shift in species composition Species-specific differences in uptake rates of carbon sources (CO 2 vs. HCO 3 ) Different sensitivities to high CO 2 Shift in food quality Increase in C:N or C:P ratio Essential biomolecules (fatty acids) Zooplankton Bacteria HNF Ciliates DOC Phytoplankton

5 CO 2 -induced food quality change in a phytoplankton species Thalassiosira pseudonana Decrease in essential biomolecules (Polyunsaturated fatty acids, PUFA) at high CO 2 Rossoll et al. (2012) PlosOne

6 Deleterious CO 2 -induced food quality change reduced copepod reproduction Egg production low CO 2 high Rossoll et al. (2012) PlosOne

7 Do natural plankton communities compensate for adverse acidification effects observed at single species level? Natural communities include structural complexity, ecophysiological variability and genetic diversity

8 ph How does acidification affect coastal plankton communities? Baltic Sea, Kiel Fjord Indoor mesocosms CO 2 (matm)

9 High resistance to increasing CO 2 levels Phytoplankton Nutrient ratio (C:P, C:N) Copepod abundance Copepod egg production Egg female -1 day Egg female -1 day CO 2 level Rossoll et al. (2013) MEPS

10 Coastal communities encounter often large amplitudes in ph and pco 2 Seasonal variation in hypoxic Western Baltic Sea adapted to extreme ph and CO 2 values IPCC predictions by 2100 Melzner et al. (2012) Mar Biol

11 North Sea open ocean plankton community 390 ppm 840 ppm 3000 ppm

12 Biomass (mg C L -1 ) Ciliophora Protozoa Nanophytopl Picophytopl Biomass (mg C L -1 ) Shift in micro-plankton species composition Coccolithophores Emiliania low CO 2 level CO high low CO 2 level CO 2 high Bermudez et al. (submitted)

13 Biomass (mg C L -1 ) Ciliophora Protozoa Nanophytopl Picophytopl What does this mean for the ecosystem? Ciliates Zooplankton HNF Phytoplankton low Bermudez et al. (submitted) 2000 CO 2 level CO high Increased carbon recycling within the microbial loop reduced carbon transfer

14 PUFA (%) Decline of essential fatty acids in a key zooplankton copepod at high CO 2 Calanus finmarchicus Bermudez et al. (submitted)

15 Gelatinous zooplankton (appendicularians) perform better in warmer, more acidified environments Appendicularian (Oikopleura) North Sea, land-based mesocosms

16 Increase in gelatinous zooplankton alter the directions of carbon flow CO 2 Temp Present conditions Higher temperature and CO 2 Phytoplankton Fish Phytoplankton Fish DOC Zooplankton Appendicularians Copepods Ciliates DOC + + Zooplankton Appendicularians + - Ciliates Copepods - Sinking particles Sinking particles Carbon flux + Carbon flux

17 Ocean acidification induced shifts in plankton communities transfer to higher trophic levels Fish Zooplankton Bacteria HNF Ciliates DOC Phytoplankton

18 Conclusions Sensitivity to high CO 2 differs between organisms and communities --> we cannot extrapolate from one species and location to another Gelatinous zooplankton perform better under warmer and more acidic ocean --> alter the carbon cycling Shifts in plankton composition affects energy and food quality for consumers --> indirect effects of ocean acidification may compromise fish production

19 Acknowledgements GEOMAR, Kiel Dennis Rossol Rafael Bermudez Ulf Riebesell Thomas Hansen Daniela Freese Andrea Ludwig University of Bergen Eric Thompson Jean-Marie Bouquet Chris Toredsson Stella Berger Rafael Bermudez Dennis Rossoll