Prokaryotic abundance, activity and community structure in relation to the quality of dissolved organic matter in the deep waters off the Galician Coast (NW Spain). Elisa Guerrero-Feijóo, Mar Nieto-Cid, Xosé-Antón Álvarez-Salgado, Marta Álvarez, Víctor Hernando-Morales, Eva Sintes, Eva Teira, Gerhard J. Herndl, Marta M. Varela

I. Introduction The prokaryotes are an important component in marine plankton Arístegui et al. 2009

I. Introduction The prokaryotes are an important component in marine plankton Herndl and Reinthaler, 2013

II. Aims 1. Determine the abundance, activity and the prokaryotic community structure (Bacteria & Archaea) 2. Study the relationship between prokaryotic community structure and environmental variables environmental variables biologic organic matter physico-chemical

III: Study area Sampling site (NW Spain) St 111St 108St 16St 11 Two cruises: In 2011  BIOPROF-1 In 2012  BIOPROF-2

IV: Methods Prokaryotic abundance (PA) Prokaryotic heterotrophic production (PHP) Smith and Azam (1992) Prokaryotic community structure FingerprintingCARD-FISH

V. Results: Properties Water masses EZ ENACW-OMZ MW LSW ENADW LDW ENADW MW LSW OMZ BIOPROF-1BIOPROF-2

Results V.Results: PA & PHP

Results V.Results: CARD-FISH ThaumarchaeotaBacteria

V.Results: CARD-FISH Ʃ =97.82%

Results Relationship: CARD-FISH and quality DOM V.Results: CARD-FISH Quality DOMBacteria Thaumarchaeota FDOM M FDOM T CDOM CDOM CDOM S DOM DOC0.53-

Archaeal Community Structure (ACS) Results Euphotic zone Deep waters Mesopelagic waters V.Results: T-RFLPs

Euphotic zone Deep waters Mesopelagic waters Bacterial Community Structure (BCS) V.Results: ARISA

Results: DisTLM analysis For running the model:Best procedure SetsVariables Physico-Chemical Temperature Salinity Oxygen Nitrate Silicate Phosphate Dissolved Organic Matter FDOM M FDOM T CDOM 254 CDOM 340 CDOM 365 S DOM DOC Biologic Prokaryotic abundance Prokaryotic heterotrophic activity

Results: DisTLM analysis For running the model:Best procedure SetsVariables Physico-Chemical Temperature Salinity Oxygen Nitrate Silicate Phosphate Dissolved Organic Matter FDOM M FDOM T CDOM 254 CDOM 340 CDOM 365 S DOM DOC Biologic Prokaryotic abundance Prokaryotic heterotrophic activity

Results: DisTLM analysis For running the model:Best procedure SetsVariables Physico-Chemical Temperature Salinity Oxygen Nitrate Silicate Phosphate Dissolved Organic Matter FDOM M FDOM T CDOM 254 CDOM 340 CDOM 365 S DOM DOC Biologic Prokaryotic abundance Prokaryotic heterotrophic activity

Results V.Results: DistLM T-RFLPs ACS = Physico-chemical ( 20%) + Organic matter ( 26% ) + Biological ( 17% )

Results V.Results: DisTLM ARISA BCS = Physico-chemical ( 38% ) + Organic matter (30% )+ Biological ( 18% )

VI. Conclusions Prokaryotic abundance and prokaryotic heterotrophic production decrease with depth. Thaumarchaeota relative abundance was higher in deep waters than surface layer, while Bacterial abundance tends to decrease with depth. SAR-11 and Alteromonas dominated the prokaryotic community structure inhabiting surface waters. SAR-202 and SAR-324 increased with depth. SAR-406 did not show any clear trend. The prokaryotic community assemblages clearly clustered according to the different water masses. DisTLM analysis explained that only 29% of the variation of ACS can be modeled by the environmental variables tested in this study. DOM represented the primary factor driving the ACS. On the other hand, the analysis explained 49% of the variation for the BCS to the variables included in this work. The physico-chemical set was the most representative to modeling the BCS.

Acknowledgment Fátima Eiroa Elena Rey Ángel Lamas Rebeca Alvariño Vladimir Dobal Other important members Crew of the R/V Cornide de Saavedra Co-authors Marta M Varela Mar Nieto Cid Pepe Álvarez Salgado Victor Hernando Morales Eva Sintes Eva Teira Gerhard Herndl Marta Álvarez Funding: BIO-PROF MODUPLAN Elisa Guerrero-Feijóo is supported by Project BIO-PROF THANK FOR YOUR ATTENTION!!