1. Xosé Anxelu G. Morán 1, Laura Díaz-Pérez 1, Enrique Nogueira 1 and Antonio Bode 2 1 Instituto Español de Oceanografía (IEO), Xixón, Spain 2 Instituto Español de Oceanografía (IEO), A Coruña, Spain More microbes with warming? Analysis of planktonic time-series in the southern Bay of Biscay continental shelf

2. Ocean plankton and temperature Ocean plankton and temperature Li et al. (2006) Rodríguez (1994) Richardson and Schoeman (2004)

3. FL3 SSC Prochlorococcus Synechococcus Large picoeukaryotes Small picoeukaryotes ~0.7 µm ~1.0 µm ~1.5 µm ~2.0 µm Vaulot 2004 SSC FL1 HNA bacteria LNA bacteria ~0.4 µm ~0.5 µm Beads What are microbes? What are microbes? Heterotrophic bacteria Picophytoplankton

4. Study site Study site Bay of Biscay A Coruña Xixón Approx. monthly samplings since 2002 and 2003

5. Seasonal patterns Seasonal patterns Abundance Structure Picophytoplankton Heterotrophicbacteria Cells ml -1 Cyanobacteria (%) HNA bacteria (%) Month

6. Seasonal patterns Seasonal patterns Month HNA bacteria (%) Depth Xixón Coherent temporal and vertical patterns in the contribution of HNA bacteria (the ones more dependent on phytoplankton) Morán et al. (2011)

7. Xixón AbundanceStructure Long-term variability – Picophytoplankton Long-term variability – Picophytoplankton Log abundance (cells ml -1 ) A Coruña Cyanobacteria (%) Date

8. Xixón A Coruña AbundanceStructure Long-term variability – Heterotrophic bacteria Long-term variability – Heterotrophic bacteria Log abundance (cells ml -1 ) HNA cells (%) Date

9. Xixón Biomass (mg C m -2 ) Long-term variability – Integrated biomass Long-term variability – Integrated biomass picophytoplankton bacteria

10. Surface0-75 m averages Picoph%CyanBact%HNAPicoph%cyanBact%HNA Temperature surf–0.40***–– 0.26**–– Stratif. index–0.32**––0.34**––– [NO 3 ] surf––-0.20*-0.37***–––-0.21* Chl int–-0.30**–– Chl int <2 µm–––– Relationships with other variables Relationships with other variables

11. More microbes with warming? More microbes with warming? NWr 2 = 0.66, p <0.0001, n=154 & NE Atlantic NWr 2 = 0.39, p <0.0001, n=152 & NE Atlantic NWr 2 = 0.73, p <0.0001, n=152 & NE Atlantic Morán et al. (2010)

12. Marked seasonal patterns in picoplankton abundance and structure were observed at both sites, more marked in Xixón, presumably linked to lower nutrient load. Heterotrophic bacterial abundance showed contrasting long-term trends, decreasing in A Coruña and increasing in Xixón. Thanks! Conclusions Conclusions Time-series data suggest an association of the smallest components of plankton with ocean warming.