1. Picoeukaryotes (< 3 µm) diversity coastal site of the English Channel Khadidja Romari & Daniel Vaulot PICODIV meeting Oslo - March 2003

2. Roscoff Station: Astan Year 2000 April June September December Year 2001 April May June Year 2001 May Sampling strategy

3. RFLP Analysis of environmental clone libraries June 2001 Sept.2001 Dourd. May 2001 May 2001 Apri. 2000 Apri. 2001 Dec. 2000 June 2000

4. Clone library Astan Dourduff Date 12 April 200065 35 9 June 200054 46 7 Sept 200068 32 19 Dec 2000 60 40 12 April 2001 54 46 16 May 2001 65 35 13 June 2001 41 59 # of RFLP typesCoverage value (%) 17 May 2001 52 48 * 100 positives clones were screened by RFLP for each clone library * Coverage value (C) = 1- n/N, (n = number of RFLP type; N = number of clone analysed) RFLP-Analysis of environmental clone libraries

5. Clones  99.5 % sequence simil. OTU OTU with similarity  98 % Phylotype OTU OTU : Operational taxonomic unit Phylotype : Genus/species level OTU: Ecotype level

7. Groups # phylotypes # OTUs Prasinophyceae 9 28 Cryptophyceae 6 22 Prymnesiophyceae 3 6 Dinophyceae 7 11 Cercozoa 19 25 Choanoflagellates 5 6 Stramenopiles 26 40 Alveolate group I 4 7 Alveolate group II 25 42 Ciliates 23 38 Rosko II 6 12 Rosko I (Telonema ) 4 8 Total137 245 Diversity inside the groups OTUs : Clones with similarity  98% and < 99,5 % Phylotypes : OTUs with similarity < 98 %

8. Phylotype level: Heterotrophs are more diverse than phototrophs Groups# Phylotypes Heterotrophs 108 Phototrophs 21 # OTUs 164 83 Diversity : Phototrophs vs heterotrophs OTU level: Phototrophs are relatively more diverse than heterotrophs

9. Photosynthetic groups Prasinophyceae Micromonas, Bathycoccus, Ostreococcus also Pyramimonas, CCMP 1205 Cryptophyceae (nucleus and nucleomorph) Geminigera Prymnesiophyceae uncultivated group, Chrysochromulina Dinophyceae Gymnodinium, Prorocentrum, Dinophysis Ostreococcus

10. Non photosynthetic groups Stramenopiles all clades defined by Ramon plus a new one Cafeteria Uncultivated alveolates mostly group II (Amoebophrya) Ciliates no strong identity with known species Cercozoa Cryothecomonas, Cercomonas Picture from S. Kuhn Cryothecomonas Choanoflagellates no strong identity with known species Telonema

11. Temporal and spatial variability

12. Astan Station Sporadic phylotypes (appearing only once)

13. Conclusions High diversity (not fully covered by clone sampling) Confirm ubiquity of novel alveolates and stramenopiles Specificity of coastal areas (temperate ?) Mamiellales Cryptophyceae Ciliates Cercozoa Two novel groups ? Diatom bloom library has unique features low diversity mostly sporadic phylotypes Estuarine library very different from Astan library dominated by Ciliates some groups absent (Cryptophyceae)

14. Acknowledgements PICODIV CNRS-Aventis Foundation BIOSOPE (funded by CNRS) PICOMANCHE (Brittany region program) The Mysis crew Fabrice Not (Collecting samples)