@article {56655, title = {Community-Level Responses to Iron Availability in Open Ocean Plankton Ecosystems}, journal = {GLOBAL BIOGEOCHEMICAL CYCLES}, volume = {33}, year = {2019}, month = {03/2019}, pages = {391-419}, abstract = {

Predicting responses of plankton to variations in essential nutrients is hampered by limited in situ measurements, a poor understanding of community composition, and the lack of reference gene catalogs for key taxa. Iron is a key driver of plankton dynamics and, therefore, of global biogeochemical cycles and climate. To assess the impact of iron availability on plankton communities, we explored the comprehensive bio-oceanographic and bio-omics data sets from Tara Oceans in the context of the iron products from two state-of-the-art global scale biogeochemical models. We obtained novel information about adaptation and acclimation toward iron in a range of phytoplankton, including picocyanobacteria and diatoms, and identified whole subcommunities covarying with iron. Many of the observed global patterns were recapitulated in the Marquesas archipelago, where frequent plankton blooms are believed to be caused by natural iron fertilization, although they are not captured in large-scale biogeochemical models. This work provides a proof of concept that integrative analyses, spanning from genes to ecosystems and viruses to zooplankton, can disentangle the complexity of plankton communities and can lead to more accurate formulations of resource bioavailability in biogeochemical models, thus improving our understanding of plankton resilience in a changing environment.

Plain Language Summary Marine phytoplankton require iron for their growth and proliferation. According to John Martin{\textquoteright}s iron hypothesis, fertilizing the ocean with iron could dramatically increase photosynthetic activity, thus representing a biological means to counteract global warming. However, while there is a constantly growing knowledge of how iron is distributed in the ocean and about its role in cellular processes in marine photosynthetic groups such as diatoms and cyanobacteria, less is known about how iron availability shapes plankton communities and how they respond to it. In the present work, we exploited recently published Tara Oceans data sets to address these questions. We first defined specific subcommunities of co-occurring organisms that co-vary with iron availability in the oceans. We then identified specific patterns of adaptation and acclimation to iron in different groups of phytoplankton. Finally, we validated our global results at local scale, specifically in the Marquesas archipelago, where recurrent phytoplankton blooms arc believed to be a result of iron fertilization. By integrating global data with a localized response, we provide a framework for understanding the resilience of plankton ecosystems in a changing environment.

}, doi = {10.1029/2018GB006022}, author = {Caputi, L and Carradec, Q and Eveillard, D and Kirilovsky, A and Pelletier, E and Karlusich, J and Vieira, Fabio Rocha Jimenez and (Villar, E and Chaffron, S and Malviya, Shruti and Scalco, E and Acinas, Silvia G. and Alberti, A and Aury, Jean-Marc and Benoiston, Anne-Sophie and Bertrand, A and Biard, T and Bittner, L and Boccara, M and Brum, Jennifer R and Brunet, C and Busseni, G and Carratala, A and Claustre, H and Coelho, Luis Pedro and Colin, S and D{\textquoteright}Aniello, S and Da Silva, Corinne and Del Core, Marianna and Dore, H and Gasparini, S and Kokoszka, F and Jamet, Jean-Louis and Lejeusne, C and Lepoivre, C and Lescot, M and Lima-Mendez, Gipsi and Lombard, F and Lukes, J and Maillet, N and Madoui, Mohammed-Amin and Martinez, E and Mazzocchi, Maria Grazia and Neou, Mario B and Paz-Yepes, Javier and Poulain, Julie and Ramondenc, S and Romagnan, Jean-Baptiste and Roux, S and Manta, DS and Sanges, R and Speich, S and Sprovieri, M and Sunagawa, S and Taillandier, V and Tanaka, A and Tirichine, L and Trottier, C and Uitz, J and Veluchamy, A and Vesela, J and Vincent, F and Yau, S and Kandels-Lewis, Stefanie and Searson, S and Dimier, C and Picheral, M and Bork, P and Boss, E and De Vargas, C and Follows, M and Grimsley, N and Guidi, L and Hingamp, P and Karsenti, E and Sordino, P and Stemmann, L and Sullivan, MB and Tagliabue, A and Zingone, A and Garczarek, L and d{\textquoteright}Ortenzio, F and Testor, P and Not, F and d{\textquoteright}Alcala, MR and Wincker, P and Bowler, C and Iudicone, D and Gorsky, G and Jaillon, O and Karp-Boss, Lee and Krzic, U and Ogata, H and Pesant, S and Raes, J and Reynaud, EG and Sardet, C and Sieracki, M and Velayoudon, D and Weissenbach, J} } @article {31051, title = {Nanoplanktonic diatoms are globally overlooked but play a role in spring blooms and carbon export.}, journal = {Nat Commun}, volume = {9}, year = {2018}, month = {2018 Mar 05}, pages = {953}, abstract = {

Diatoms are one of the major primary producers in the ocean, responsible annually for ~20\% of photosynthetically fixed COon Earth. In oceanic models, they are typically represented as large (\>20 {\textmu}m) microphytoplankton. However, many diatoms belong to the nanophytoplankton (2-20 {\textmu}m) and a few species even overlap with the picoplanktonic size-class (\<2 {\textmu}m). Due to their minute size and difficulty of detection they are poorly characterized. Here we describe a massive spring bloom of the smallest known diatom (Minidiscus) in the northwestern Mediterranean Sea. Analysis of Tara Oceans data, together with literature review, reveal a general oversight of the significance of these small diatoms at the global scale. We further evidence that they can reach the seafloor at high sinking rates, implying the need to revise our classical binary vision of pico- and nanoplanktonic cells fueling the microbial loop, while only microphytoplankton sustain secondary trophic levels and carbon export.

}, issn = {2041-1723}, doi = {10.1038/s41467-018-03376-9}, author = {Leblanc, Karine and Qu{\'e}guiner, Bernard and Diaz, Fr{\'e}d{\'e}ric and Cornet, V{\'e}ronique and Michel-Rodriguez, M{\'o}nica and Durrieu de Madron, Xavier and Bowler, Chris and Malviya, Shruti and Thyssen, Melilotus and Gr{\'e}gori, G{\'e}rald and Rembauville, Mathieu and Grosso, Olivier and Poulain, Julie and de Vargas, Colomban and Pujo-Pay, Mireille and Conan, Pascal} } @article {30155, title = {Neobodonids are dominant kinetoplastids in the global ocean.}, journal = {Environ Microbiol}, volume = {20}, year = {2018}, month = {2018 Feb}, pages = {878-889}, abstract = {

Kinetoplastid flagellates comprise basal mostly free-living bodonids and derived obligatory parasitic trypanosomatids, which belong to the best-studied protists. Due to their omnipresence in aquatic environments and soil, the bodonids are of ecological significance. Here, we present the first global survey of marine kinetoplastids and compare it with the strikingly different patterns of abundance and diversity in their sister clade, the diplonemids. Based on analysis of 18S rDNA V9 ribotypes obtained from 124 sites sampled during the Tara Oceans expedition, our results show generally low to moderate abundance and diversity of planktonic kinetoplastids. Although we have identified all major kinetoplastid lineages, 98\% of kinetoplastid reads are represented by neobodonids, namely specimens of the Neobodo and Rhynchomonas genera, which make up 59\% and 18\% of all reads, respectively. Most kinetoplastids have small cell size (0.8-5 {\textmu}m) and tend to be more abundant in the mesopelagic as compared to the euphotic zone. Some of the most abundant operational taxonomic units have distinct geographical distributions, and three novel putatively parasitic neobodonids were identified, along with their potential hosts.

}, issn = {1462-2920}, doi = {10.1111/1462-2920.14034}, author = {Flegontova, Olga and Flegontov, Pavel and Malviya, Shruti and Poulain, Julie and de Vargas, Colomban and Bowler, Chris and Luke{\v s}, Julius and Hor{\'a}k, Ale{\v s}} } @article {36659, title = {Ubiquitous abundance distribution of non-dominant plankton across the global ocean.}, journal = {Nat Ecol Evol}, year = {2018}, month = {2018 Jun 18}, abstract = {

Marine plankton populate 70\% of Earth{\textquoteright}s surface, providing the energy that fuels ocean food webs and contributing to global biogeochemical cycles. Plankton communities are extremely diverse and geographically variable, and are overwhelmingly composed of low-abundance species. The role of this rare biosphere and its ecological underpinnings are however still unclear. Here, we analyse the extensive dataset generated by the Tara Oceans expedition for marine microbial eukaryotes (protists) and use an adaptive algorithm to explore how metabarcoding-based abundance distributions vary across plankton communities in the global ocean. We show that the decay in abundance of non-dominant operational taxonomic units, which comprise over 99\% of local richness, is commonly governed by a power-law. Despite the high spatial turnover in species composition, the power-law exponent varies by less than 10\% across locations and shows no biogeographical signature, but is weakly modulated by cell size. Such striking regularity suggests that the assembly of plankton communities in the dynamic and highly variable ocean environment is governed by large-scale ubiquitous processes. Understanding their origin and impact on plankton ecology will be important for evaluating the resilience of marine biodiversity in a changing ocean.

}, issn = {2397-334X}, doi = {10.1038/s41559-018-0587-2}, author = {Ser-Giacomi, Enrico and Zinger, Lucie and Malviya, Shruti and de Vargas, Colomban and Karsenti, Eric and Bowler, Chris and De Monte, Silvia} }