Photosynthetic picoeukaryotes (PPEs) are fundamental contributors to oceanic primary production and form diverse communities dominated by prymnesiophytes, chlorophytes, pelagophytes and chrysophytes. Here, we studied the vertical distribution of these major groups in two offshore regions of the northern Iberian Peninsula during summer stratification. We performed a fine-scale vertical sampling (every ∼2 m) across the DCM and used fluorescence in situ hybridization (FISH) to determine the PPE composition and to explore the possible segregation of target groups in the light, nutrient and temperature gradients. Chlorophytes, pelagophytes and prymnesiophytes, in this order of abundance, accounted for the total PPEs recorded by flow cytometry in the Avilés canyon, and for more than half in the Galicia Bank, whereas chrysophytes were undetected. Among the three detected groups, often the prymnesiophytes were dominant in biomass. In general, all groups were present throughout the water column with abundance peaks around the DCM, but their distributions differed: pelagophytes were located deeper than the other two groups, chlorophytes presented two peaks and prymnesiophytes exhibited surface abundances comparable to those at the DCM. This study offers first indications that the vertical distribution of different PPE groups is heterogeneous within the DCM. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Financial support has been provided by projects FAMOSO (CTM2008-06261-C03-01/MAR) to ML, MEFISTO (CTM2013-43767-P) to RM and MICRO-3B (FP7-OCEAN-2011 287589, EU). AM Cabello was recipient of a Spanish FPI grant (BES-2009-027194). We are also grateful for the financial support of the Generalitat de Catalunya to the "Grup de Diversitat Microbiana en Ecosistemes Aquatics" (2014SGR/1591)." We thank F. Sanchez for inviting us to participate in the INDEMARES 0710 cruises and the chief scientists, technicians, researchers and crew for their collaboration. We thank C. Gonzalez-Pola for providing the hydrographic data. We thank G. Salazar and FM. Cornejo-Castillo for data treatment advice.