Boersma, Maarten

Lange, Julia

Schwenk, Klaus

OceanRep

GEOMAR Helmholtz Centre for Ocean Research Kiel – www.geomar.de – BIOACID Phase II Meeting Kiel 10 – 11 Sept. 2014 Evolutionary response to ocean acidification Introduction Mesozooplankton / Metabarcoding Consortium 1:  Pelagic ecosystems WP 1.14:        Adaptations to ocean acidification in mesozooplankton Very few studies exist dealing with the evolutionary responses of species to ocean acidification (OA), even though the selective forces of OA are potentially strong. Hence, we investigate selection processes in zooplankton. Potential patterns of adaptation to OA will be uncovered by integrating field observations, laboratory experiments and genetic analyses. Transplantation experiments Results To investigate the adaptability of mesozooplankton to OA  a long-term selection experiment with Acartia tonsa a common copepod in the North Sea were set-up .  • 100 l plastic tanks with artificial sea water (ASW; 32 psu) at     18°C and constant darkness • 15.000-20.000 individuals per tank • pCO2 selection lines (SL): 800 µatm A, B, C; 200 µatm D, E, F • ph-value: 200 tanks: 8.5 ±0.2; 800 tanks: 8.0 ±0.2 • running time until now: 12 months / 24 generations A. tonsa developed much slower under high CO2 conditions but there was no difference between the SLs and thus no detectable adaptations to CO2 regarding the developmental speed. Furthermore there was no detectable difference between the high and low CO2 treatments and selection lines according the amount of produced eggs. Additionally the hatching rate did not vary between the CO2 treatments whereby the nauplii from the high CO2 selection lines hatched significantly faster in the first 24 hours. Long-term selection experiment Set up To test if the copepods adapted to their selection line conditions within 6 month / 12 generations transplantation experiments were conducted (4 treatments, 3 replicates). The copepods from both CO2 SLs were cross incubated with different water pCO2 concentrations in connection with the corresponding food. Developmental rate, egg production and hatching rate were measured. Gene expression 1Julia A. F. Lange, 1Maarten Boersma, 2Klaus Schwenk 1Alfred-Wegener-Institut Helmholtz-Zentrum for Polar and Marine Research, Biologische Anstalt Helgoland   2Institute of Environmental Science University Koblenz-Landau Fig.1 (a-c) Copepod and food cultures. 1(a) Pyrenomonas salina cultures bubbled with different CO2 concentrations 1(b) Chemostats of the backup algae cultures 1(c) Aeration system of the copepod tanks  1a 1c 1b We plan to carry out an lab experiment with A. tonsa to investigate gene expression pattern in various CO2 environments. From previous experiments we already known that copepods suffer most under a low food quality due to a changed stoichiometry of the algae. Under high CO2 conditions (800 µatm pCO2) they spend most of their energy in reproduction and therefore develop slower. We therefore focus on genes which are involved in growth processes, moulting and reproduction.   Differences in species composition and genotype frequency between experimental populations (suffering under ocean acidification compared to  present-day CO2 conditions) were detected by metabarcoding. Samples were taken during a mesocosm experiment in the Gullmarsfjord in Sweden 2012. 0 20 40 60 80 100 800SL / 200T 200SL / 200T 200SL / 800T 800SL / 800T Percentage distribution of stages Nauplii C1 - C3 C4 - C6 Fig.2 (a,b) Transplantation experiments results. The x-axis shows the experimental treatments; (800 SL) selection line manipulated with 800 µatm CO2, (200 SL) selection line manipulated with 200 µatm CO2, (800 T) treatment with  800 µatm CO2 manipulated water and food, (200 T) treatment with  200 µatm CO2  manipulated water and food. (a) Diagram of the developmental stage distribution. The left y-axis shows the percentage of the respective stages. The legend shows the developmental stages; (Nauplii) nauplii stages 1-6, (C1 - C3) copepodite stages 1-3, (C4 - C6) copepodite stages 4-6. The ANOVA showed only a significant treatment effect (p < 0.05), but none for the selection line nor for an interaction (Data pooled from N = 3 replicates). (b) Diagram of the percentage of hatched nauplii. The left y-axis shows the percentage of the hatched nauplii. The legend shows the two sampling points; The ANOVA showed only a significant selection line effect (p < 0.05), but none for the treatment nor for an interaction (Data pooled from N = 3 replicates). On going studies and future plans 0 20 40 60 80 100 800 SL / 200 T 200 SL / 200 T  200 SL / 800 T 800 SL / 800 T Percentage of hatched nauplii after 24h after 48h (a) (b) 

Evolutionary response to ocean acidification

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