@article {strauss_bay_2023, title = {The Bay of Bengal exposes abundant photosynthetic picoplankton and newfound diversity along salinity-driven gradients}, journal = {Environmental Microbiology}, year = {2023}, abstract = {The Bay of Bengal (BoB) is a 2,600,000 km2 expanse in the Indian Ocean upon which many humans rely. However, the primary producers underpinning food chains here remain poorly characterized. We examined phytoplankton abundance and diversity along strong BoB latitudinal and vertical salinity gradients-which have low temperature variation (27-29{\textdegree}C) between the surface and subsurface chlorophyll maximum (SCM). In surface waters, Prochlorococcus averaged 11.7 {\textpm} 4.4 {\texttimes} 104 cells ml-1 , predominantly HLII, whereas LLII and {\textquoteright}rare{\textquoteright} ecotypes, HLVI and LLVII, dominated in the SCM. Synechococcus averaged 8.4 {\textpm} 2.3 {\texttimes} 104 cells ml-1 in the surface, declined rapidly with depth, and population structure of dominant Clade II differed between surface and SCM; Clade X was notable at both depths. Across all sites, Ostreococcus Clade OII dominated SCM eukaryotes whereas communities differentiated strongly moving from Arabian Sea-influenced high salinity (southerly; prasinophytes) to freshwater-influenced low salinity (northerly; stramenopiles, specifically, diatoms, pelagophytes, and dictyochophytes, plus the prasinophyte Micromonas) surface waters. Eukaryotic phytoplankton peaked in the south (1.9 {\texttimes} 104 cells ml-1 , surface) where a novel Ostreococcus was revealed, named here Ostreococcus bengalensis. We expose dominance of a single picoeukaryote and hitherto {\textquoteright}rare{\textquoteright} picocyanobacteria at depth in this complex ecosystem where studies suggest picoplankton are replacing larger phytoplankton due to climate change.}, keywords = {RCC393, RCC809}, issn = {1462-2920}, doi = {10.1111/1462-2920.16431}, author = {Strauss, Jan and Choi, Chang Jae and Grone, Jonathan and Wittmers, Fabian and Jimenez, Valeria and Makareviciute-Fichtner, Kriste and Bachy, Charles and Jaeger, Gualtiero Spiro and Poirier, Camille and Eckmann, Charlotte and Spezzano, Rachele and L{\"o}scher, Carolin R. and Sarma, V. V. S. S. and Mahadevan, Amala and Worden, Alexandra Z.} } @article {cruz_bioprospecting_2023, title = {Bioprospecting for industrially relevant exopolysaccharide-producing cyanobacteria under Portuguese simulated climate}, journal = {Scientific Reports}, volume = {13}, number = {1}, year = {2023}, note = {Number: 1 Publisher: Nature Publishing Group}, pages = {13561}, abstract = {Cyanobacterial exopolysaccharides (EPS) are potential candidates for the production of sustainable biopolymers. Although the bioactive and physicochemical properties of cyanobacterial-based EPS are attractive, their commercial exploitation is limited by the high production costs. Bioprospecting and characterizing novel EPS-producing strains for industrially relevant conditions is key to facilitate their implementation in various biotechnological applications and fields. In the present work, we selected twenty-five Portuguese cyanobacterial strains from a diverse taxonomic range (including some genera studied for the first time) to be grown in diel light and temperature, simulating the Portuguese climate conditions, and evaluated their growth performance and proximal composition of macronutrients. Synechocystis and Cyanobium genera, from marine and freshwater origin, were highlighted as fast-growing (0.1{\textendash}0.2~g~L-1~day-1) with distinct biomass composition. Synechocystis sp. LEGE 07367 and Chroococcales cyanobacterium LEGE 19970, showed a production of 0.3 and 0.4~g~L-1 of released polysaccharides (RPS). These were found to be glucan-based polymers with high molecular weight and a low number of monosaccharides than usually reported for cyanobacterial EPS. In addition, the absence of known cyanotoxins in these two RPS producers was also confirmed. This work provides the initial steps for the development of cyanobacterial EPS bioprocesses under the Portuguese climate.}, keywords = {Biochemistry, Biotechnology, Microbiology, rcc2380}, issn = {2045-2322}, doi = {10.1038/s41598-023-40542-6}, url = {https://www.nature.com/articles/s41598-023-40542-6}, author = {Cruz, Jos{\'e} Diogo and Delattre, C{\'e}dric and Felpeto, Aldo Barreiro and Pereira, Hugo and Pierre, Guillaume and Morais, Jo{\~a}o and Petit, Emmanuel and Silva, Joana and Azevedo, Joana and Elboutachfaiti, Redouan and Maia, In{\^e}s B. and Dubessay, Pascal and Michaud, Philippe and Vasconcelos, Vitor} } @article {edullantes_comparison_2023, title = {Comparison of thermal traits between non-toxic and potentially toxic marine phytoplankton: Implications to their responses to ocean warming}, journal = {Journal of Experimental Marine Biology and Ecology}, volume = {562}, year = {2023}, pages = {151883}, abstract = {Understanding the effect of temperature on growth in marine phytoplankton is crucial in predicting the biogeography and phenology of algal blooms in the warming ocean. Here, we investigated the temperature dependence of the growth of non-toxic and potentially toxic marine phytoplankton. Using non-toxic strains (Prorocentrum sp. NRR 188, Prorocentrum micans CCAP 1136/15, and Alexandrium tamutum PARALEX 242) and potentially toxic strains (Prorocentrum minimum Poulet, Prorocentrum lima CCAP 1136/11, and Alexandrium minutum PARALEX 246) of dinoflagellates as test organisms, we measured their growth rates along a wide temperature gradient and estimated their maximum growth rates, thermal traits (e.g. thermal optima (Topt), critical thermal minima (CTmin), critical thermal maximum (CTmax), fundamental thermal niche (FTN), and skewness), thermal sensitivity, and warming vulnerability. To allow a comparison of these traits with an adequate number of observations, we independently analyzed datasets compiled from published laboratory experiments. Our experiments revealed that the temperature traits were independent of the toxicity of phytoplankton, except for Topt and CTmax. Also, the results of the analysis of the published datasets showed that maximum growth rates and thermal traits were comparable between non-toxic and potentially toxic phytoplankton. Our findings suggest that non-toxic and potentially toxic phytoplankton have generally comparable temperature traits that they can use to respond to climate change. However, depending on the climate scenario, non-toxic phytoplankton may be more vulnerable to warming than potentially toxic phytoplankton. Further studies are needed to improve our understanding of the response of marine phytoplankton to temperature, which can advance our ability to predict algal blooms in response to ongoing climate change.}, keywords = {Growth experiment, Growth models, Microalgal ecophysiology, RCC2649, RCC291, RCC3034, Thermal performance, Thermal physiology, Toxic microalgae}, issn = {0022-0981}, doi = {10.1016/j.jembe.2023.151883}, url = {https://www.sciencedirect.com/science/article/pii/S0022098123000151}, author = {Edullantes, Brisneve and Low-Decarie, Etienne and Steinke, Michael and Cameron, Tom} } @article {ebenezer_elemental_2022, title = {Elemental and macromolecular composition of the marine Chloropicophyceae, a major group of oceanic photosynthetic picoeukaryotes}, journal = {Limnology and Oceanography}, volume = {n/a}, number = {n/a}, year = {2022}, note = {_eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12013}, abstract = {Chloropicophyceae (Prasinophyte Clade VII) are small nonmotile coccoid cells with cell diameters ranging from 1 to 3 μm. Molecular surveys indicate they are relatively high in abundance in moderately oligotrophic oceanic waters and may substantively contribute to biogeochemical cycling in the sea. Here, we quantify the elemental and macromolecular composition of three subtropical Chloropicophyceae strains: Chloropicon mariensis, Chloropicon maureeniae, and Chloropicon roscoffensis under nutrient-sufficient exponential growth and nitrate starvation. Under nutrient-sufficient conditions the Chloropicophyceae are high in C : N and quite low in C : P and N : P relative to the canonical Redfield ratio, reflecting their relatively high nucleic acid composition compared to many other phytoplankton taxa. Nitrate starvation causes increases in C : N and C : P and decreases in N : P, primarily due to increases in carbohydrate and lipid and decreases in protein and RNA. There is genetic evidence that unlike most other green algae, Chloropicophyceae are diploid. The high nucleic acid content in the Chloropicon is consistent with the hypothesis that the nucleus, as a nonscalable component, takes up a larger and substantial proportion of cell mass in diploid picoeukaryotes. The elemental and macromolecular composition of these Chloropicophyceae, and relatively homeostatic response to N-starvation compared to diatoms, provides some insight into their success in the moderately oligotrophic ocean.}, keywords = {RCC138, RCC3374, RCC3375}, issn = {1939-5590}, doi = {10.1002/lno.12013}, url = {http://onlinelibrary.wiley.com/doi/abs/10.1002/lno.12013}, author = {Ebenezer, Vinitha and Hu, Yingyu and Carnicer, Olga and Irwin, Andrew J. and Follows, Michael J. and Finkel, Zoe V.} } @article {leblond_galactolipids_2022, title = {Galactolipids of the genus Amphidinium (Dinophyceae): an hypothesis that they are basal to those of other peridinin-containing dinoflagellates}, journal = {European Journal of Phycology}, year = {2022}, note = {Publisher: Taylor \& Francis _eprint: https://doi.org/10.1080/09670262.2022.2092215}, pages = {1{\textendash}10}, abstract = {The genus Amphidinium is shown in many phylogenies to be basal to other peridinin-containing, photosynthetic dinoflagellates as one of the first photosynthetic genera to arise after the evolution of heterotrophic genera. As part of our continuing examination of the plastid-associated galactolipids, namely mono- and digalactosyldiacylglycerol (MGDG and DGDG, respectively), in dinoflagellates, we here examine the galactolipid composition of members of the genus Amphidinium. We show that this genus is characterized by an abundance of 20:5(n-3)/18:5(n-3) and 20:5(n-3)/18:4(n-3) forms of MGDG and DGDG (with sn-1/sn-2 regiochemical specificity of fatty acids), but also sometimes with generally lesser amounts of some polyunsaturated C18/C18 forms, thus placing the examined species within a previously identified cluster of C20/C18 MGDG- and DGDG-containing, peridinin-containing dinoflagellates. We also show that Testudodinium testudo, previously known as Amphidinium testudo, conversely falls within a previously identified C18/C18 cluster, indicating a distinct difference in galactolipid biosynthesis capability. While it is likely that further revision of the genus may occur in the future and/or more basal peridinin-containing, photosynthetic genera may be discovered, at the current time Amphidinium is the currently agreed-upon most basal dinoflagellate genus for which isolates are available for biochemical characterization such as what we describe in this paper. Thus, because of the presumed basal position of the genus Amphidinium, we present a hypothesis that its galactolipids currently represent those that are ancestral to other genera of peridinin-containing dinoflagellates, including those within the C18/C18 cluster.}, keywords = {Amphidinium, chloroplast, Dinoflagellate, Dinophyceae, lipid, RCC1981, Testudodinium}, issn = {0967-0262}, doi = {10.1080/09670262.2022.2092215}, url = {https://doi.org/10.1080/09670262.2022.2092215}, author = {Leblond, Jeffrey D. and Elkins, Lindsey C. and Graeff, Jori E. and Sabir, Kyra} } @article {falciatore_light-driven_2022, title = {Light-driven processes: key players of the functional biodiversity in microalgae}, journal = {Comptes Rendus. Biologies}, volume = {345}, number = {2}, year = {2022}, pages = {1{\textendash}24}, doi = {10.5802/crbiol.80}, url = {https://comptes-rendus.academie-sciences.fr/biologies/articles/10.5802/crbiol.80/}, author = {Falciatore, Angela and Bailleul, Benjamin and Boulouis, Alix and Bouly, Jean-Pierre and Bujaldon, Sandrine and Cheminant-Navarro, Soizic and Choquet, Yves and Vitry, Catherine de and Eberhard, Stephan and Jaubert, Marianne and Kuras, Richard and Lafontaine, Ingrid and Landier, Sophie and Selles, Julien and Vallon, Olivier and Wostrikoff, Katia} } @article {leblond_sterols_2022, title = {Sterols of Testudodinium testudo (formerly Amphidinium testudo): Production of the Δ8(14) sterol gymnodinosterol and chemotaxonomic relationship to the Kareniaceae}, journal = {Journal of Eukaryotic Microbiology}, volume = {n/a}, number = {n/a}, year = {2022}, note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/jeu.12929}, pages = {e12929}, abstract = {Testudodinium testudo is a peridinin-containing dinoflagellate recently renamed from Amphidinium testudo. While T. testudo has been shown via phylogenetic analysis of small subunit ribosomal RNA genes to reside in a clade separate from the genus Amphidinium, it does possess morphological features similar to Amphidinium sensu stricto. Previous studies of Amphidinium carterae and Amphidinium corpulentum have found the sterols to be enriched in Δ8(14) sterols, such as 4α-methyl-5α-ergosta-8(14),24(28)-dien-3β-ol (amphisterol), uncommon to most other dinoflagellate taxa and thus considered possible biomarkers for the genus Amphidinium. Here, we provide an examination of the sterols of T. testudo and show they are dominated not by amphisterol, but rather by a different Δ8(14) sterol, (24R)-4α-methyl-5α-ergosta-8(14),22-dien-3β-ol (gymnodinosterol), previously thought to be a major sterol only within the Kareniaceae genera Karenia, Karlodinium, and Takayama. Also found to be present at low levels were 4α-methyl-5α-ergosta-8,14,22-trien-3β-ol, a sterol previously observed in Karenia brevis to be an intermediate in the production of gymnodinosterol, and cholesterol, a sterol common to many other dinoflagellates. The presence of gymnodinosterol in T. testudo is the first report of this sterol as the sole major sterol in a dinoflagellate outside of the Kareniaceae. The implication of this chemotaxonomic relationship to the Kareniaceae is discussed.}, keywords = {Amphidinium, Dinoflagellate, Dinophyceae, lipid, RCC1981, sterol, Testudodinium}, issn = {1550-7408}, doi = {10.1111/jeu.12929}, url = {http://onlinelibrary.wiley.com/doi/abs/10.1111/jeu.12929}, author = {Leblond, Jeffrey D. and Elkins, Lindsey C. and Sabir, Kyra and Graeff, Jori E.} } @article {arin_taxonomic_2022, title = {Taxonomic relationship between two small-sized Chaetoceros species (Bacillariophyta): C. tenuissimus and C. salsugineus , and comparison with C. olympicus sp. nov. from Catalan coastal waters (NW Mediterranean)}, journal = {European Journal of Phycology}, volume = {57}, number = {3}, year = {2022}, pages = {277{\textendash}296}, abstract = {
The majority of species of the highly diverse genus Chaetoceros are described as chain-forming, although several species are described as strictly solitary (such as C. tenuissimus) or having an alternate solitary and a chain-forming phase during their life history (such as C. salsugineus). In this study, the diversity of small forms of Chaetoceros from the NW Mediterranean coastal waters was explored through the morphological and molecular characterization of four different strains belonging to two distinct species. Based on their morphology, three of the strains were identified as C. salsugineus (Takano, 1983). The SSU and LSU rDNA sequences represented the first available for well-characterized C. salsugineus strains and were 96.6{\textendash}100\% similar to publicly available C. tenuissimus (Meunier, 1913) sequences. Both species share the same morphological features, such as setae and ultrastructure of the valves, as well as the rimoportula characteristics. In addition, the morphology of the solitary form of C. salsugineus matched with that of C. tenuissimus. Here, we propose the two species as synonyms (the name C. tenuissimus prevailing as it has priority for this taxon), emend the original description and designate an epitype. The fourth strain was identified as C. olympicus sp. nov., a new species, which alternates solitary and chain-forming forms within its life history. The main differential characteristics of this species are the absence of rimoportula both in terminal and intercalary valves, the setae ultrastructure, which is thin and circular in cross-section with a few, slightly twisted, rows of small rectangular poroids and some spirally arranged spines, and the morphology of the resting spores, with primary valve vaulted and covered with short to medium-sized spines, and secondary valve smaller, rounded and smooth. A comparison of C. tenuissimus and C. olympicus with other species as well as information on their life cycle and ecology is also provided.
}, keywords = {RCC3007, RCC3008, RCC5795}, issn = {0967-0262, 1469-4433}, doi = {10.1080/09670262.2021.1966838}, url = {https://www.tandfonline.com/doi/full/10.1080/09670262.2021.1966838}, author = {Arin, Laura and Re{\~n}{\'e}, Albert and Gallisai, Rachele and Sarno, Diana and Garc{\'e}s, Esther and Estrada, Marta} } @article {eyal_variability_2022, title = {The variability in the structural and functional properties of coccolith base plates}, journal = {Acta Biomaterialia}, volume = {148}, year = {2022}, pages = {336{\textendash}344}, abstract = {Biomineralization processes exert varying levels of control over crystallization, ranging from poorly ordered polycrystalline arrays to intricately shaped single crystals. Coccoliths, calcified scales formed by unicellular algae, are a model for a highly controlled crystallization process. The coccolith crystals nucleate next to an organic oval structure that was termed the base plate, leading to the assumption that it is responsible for the oriented nucleation of the crystals via stereochemical interactions. In recent years, several works focusing on a well-characterized model species demonstrated a fundamental role for indirect interactions that facilitate coccolith crystallization. Here, we developed the tools to extract the base plates from five different species, giving the opportunity to systematically explore the relations between base plate and coccolith properties. We used multiple imaging techniques to evaluate the structural and chemical features of the base plates under native hydrated conditions. The results show a wide range of properties, overlaid on a common rudimentary scaffold that lacks any detectable structural or chemical motifs that can explain direct nucleation control. This work emphasizes that it is the combination between the base plate and the chemical environment inside the cell that cooperatively facilitate the exquisite control over the crystallization process. Statement of significance Biological organic scaffolds can serve as functional surfaces that guide the formation of inorganic materials. However, in many cases the specific interactions that facilitate such tight regulation are complex and not fully understood. In this work, we elucidate the architecture of such amodel biological template, an organic scale that directs the assembly of exquisite crystalline arrays of marine microalgae. By using cryo electron microscopy, we reveal the native state organization of these scales from several species. The observed similarities and differences allow us to propose that the chemical microenvironment, rather than stereochemical matching, is the pivotal regulator of the process.}, keywords = {biomineralization, Calcite, Coccoliths, Cryo electron tomography, Crystallization, RCC1130, RCC1181, RCC190, RCC3777}, issn = {1742-7061}, doi = {10.1016/j.actbio.2022.06.027}, url = {https://www.sciencedirect.com/science/article/pii/S174270612200366X}, author = {Eyal, Zohar and Krounbi, Leilah and Ben Joseph, Oz and Avrahami, Emanuel M. and Pinkas, Iddo and Peled-Zehavi, Hadas and Gal, Assaf} } @article {park_bioluminescence_2021, title = {Bioluminescence capability and intensity in the dinoflagellate Alexandrium species}, journal = {ALGAE}, volume = {36}, year = {2021}, abstract = {Some species in the dinoflagellate genus Alexandrium are bioluminescent. Of the 33 formally described Alexandrium species, the bioluminescence capability of only nine species have been tested, and eight have been reported to be bioluminescent. The present study investigated the bioluminescence capability of seven Alexandrium species that had not been tested. Alexandrium mediterraneum, A. pohangense, and A. tamutum were bioluminescent, but A. andersonii, A. hiranoi, A. insuetum, and A. pseudogonyaulax were not. We also measured the bioluminescent intensity of A. affine, A. fraterculus, A. mediterraneum, A. ostenfeldii, A. pacificum, A. pohangense, A. tamarense, and A. tamutum. The mean 200-second-integrated bioluminescence intensity per cell ranged from 0.02 to 32.2 {\texttimes} 104 relative luminescence unit per cell (RLU cell-1), and the mean maximum bioluminescence intensity per cell per second (BLMax) ranged from 0.01 to 10.3 {\texttimes} 104 RLU cell-1 s-1. BLMax was significantly correlated with the maximum growth rates of Alexandrium species, except for A. tamarense. A phylogenetic tree based on large subunit ribosomal DNA (LSU rDNA), showed that the bioluminescent species A. affine, A. catenella, A. fraterculus, A. mediterraneum, A. pacificum, and A. tamarense formed a large clade. However, the toxicity or mixotrophic capability of these species was split. Thus, their bioluminescence capability in this clade was more consistent than their toxicity or mixotrophic capability. Phylogenetic trees based on LSU rDNA and the luciferase gene of Alexandrium were consistent except for A. pohangense. The results of the present study can provide a basis for understanding the interspecific diversity in bioluminescence of Alexandrium.}, keywords = {RCC4104}, doi = {10.4490/algae.2021.36.12.6}, author = {Park, Sang Ah and Jeong, Hae Jin and Ok, Jin and Kang, Heechang and You, Jihyun and Eom, Se and Yoo, Yeong and Lee, Moo Joon} } @booklet {marc_dinophyceae_2021, title = {Dinophyceae use exudates as weapons against the parasite Amoebophrya sp. (Syndiniales)}, year = {2021}, note = {Company: Cold Spring Harbor Laboratory Distributor: Cold Spring Harbor Laboratory Label: Cold Spring Harbor Laboratory Section: New Results Type: article}, month = {jan}, pages = {2021.01.05.425281}, abstract = {Parasites of the genus Amoebophrya sp. are important contributors to marine ecosystems and can be determining factors in the demise of blooms of Dinophyceae, including microalgae commonly responsible for toxic red tides. Yet they rarely lead to the total collapse of Dinophyceae blooms. The addition of resistant Dinophyceae (Alexandrium minutum or Scrippsiella donghaienis) or their exudate into a well-established host-parasite culture (Scrippsiella acuminata-Amoebophrya sp.) mitigated the success of the parasite and increased the survival of the sensitive host. Effect were mediated via water-borne molecules without the need of a physical contact. Severity of the anti-parasitic defenses fluctuated depending on the species, the strain and its concentration, but never totally prevented the parasite transmission. The survival time of Amoebophrya sp. free-living stages (dinospores) decreased in presence of A. minutum but not of S. donghaienis. The progeny drastically decreased with both species. Integrity of the membrane of dinospores was altered by A. minutum which provided a first indication on the mode of action of these anti-parasitic molecules. These results demonstrate that extracellular defenses are an effective strategy against parasites that does not only protect the resistant cells but also have the potential to affect the whole surrounding community.}, keywords = {rcc, RCC1627, RCC4383, RCC4714, RCC749}, doi = {10.1101/2021.01.05.425281}, url = {https://www.biorxiv.org/content/10.1101/2021.01.05.425281v1}, author = {Marc, Long and Dominique, Marie and Jeremy, Szymczak and Jordan, Toullec and Estelle, Bigeard and Marc, Sourisseau and Mickael, Le Gac and Laure, Guillou and C{\'e}cile, Jauzein} } @article {eich_effects_2021, title = {Effects of UV Radiation on the Chlorophyte Micromonas polaris Host{\textendash}Virus Interactions and MpoV-45T Virus Infectivity}, journal = {Microorganisms}, volume = {9}, year = {2021}, pages = {2429}, abstract = {Polar seas are under threat of enhanced UV-radiation as well as increasing shipping activities. Considering the ecological importance of marine viruses, it is timely to study the impact of UV-AB on Arctic phytoplankton host{\textendash}virus interactions and also test the efficacy of ballast water (BW) UV-C treatment on virus infectivity. This study examined the effects of: (i) ecologically relevant doses of UV-AB radiation on Micromonas polaris RCC2258 and its virus MpoV-45T, and (ii) UV-C radiation (doses 25{\textendash}800 mJ cm-2) on MpoV-45T and other temperate algal viruses. Total UV-AB exposure was 6, 12, 28 and 48 h (during the light periods, over 72 h total). Strongest reduction in algal growth and photosynthetic efficiency occurred for 28 and 48 h UV-AB treatments, and consequently the virus production rates and burst sizes were reduced by more than half (compared with PAR-only controls). For the shorter UV-AB exposed cultures, negative effects by UV (especially Fv/Fm) were overcome without impacting virus proliferation. To obtain the BW desired log-4 reduction in virus infectivity, a UV-C dose of at least 400 mJ cm-2 was needed for MpoV-45T and the temperate algal viruses. This is higher than the commonly used dose of 300 mJ cm-2 in BW treatment.}, keywords = {RCC2258}, doi = {10.3390/microorganisms9122429}, author = {Eich, Charlotte} } @article {pinto_features_2021, title = {Features of the Opportunistic Behaviour of the Marine Bacterium Marinobacter algicola in the Microalga Ostreococcus tauri Phycosphere}, journal = {Microorganisms}, volume = {9}, year = {2021}, pages = {1777}, abstract = {Although interactions between microalgae and bacteria are observed in both natural environment and the laboratory, the modalities of coexistence of bacteria inside microalgae phyco-spheres in laboratory cultures are mostly unknown. Here, we focused on well-controlled cultures of the model green picoalga Ostreococcus tauri and the most abundant member of its phycosphere, Marinobacter algicola. The prevalence of M. algicola in O. tauri cultures raises questions about how this bacterium maintains itself under laboratory conditions in the microalga culture. The results showed that M. algicola did not promote O. tauri growth in the absence of vitamin B12 while M. algicola depended on O. tauri to grow in synthetic medium, most likely to obtain organic carbon sources provided by the microalgae. M. algicola grew on a range of lipids, including triacylglycerols that are known to be produced by O. tauri in culture during abiotic stress. Genomic screening revealed the absence of genes of two particular modes of quorum-sensing in Marinobacter genomes which refutes the idea that these bacterial communication systems operate in this genus. To date, the {\textquoteright}opportunistic{\textquoteright} behaviour of M. algicola in the laboratory is limited to several phytoplanktonic species including Chlorophyta such as O. tauri. This would indicate a preferential occurrence of M. algicola in association with these specific microalgae under optimum laboratory conditions.}, keywords = {RCC4221}, doi = {10.3390/microorganisms9081777}, author = {Pinto, Jordan and Lami, Rapha{\"e}l and Krasovec, Marc and Grimaud, R{\'e}gis and Urios, Laurent and Lupette, Josselin and Escande, Marie-Line and Sanchez, Fr{\'e}d{\'e}ric and Intertaglia, Laurent and Grimsley, Nigel and Piganeau, Gwenael and Sanchez, Sophie} } @article {Dore2020, title = {Evolutionary mechanisms of long-term genome diversification associated with niche partitioning in marine picocyanobacteria}, journal = {Frontiers in Microbiology}, volume = {11}, number = {September}, year = {2020}, note = {tex.mendeley-tags: RCC1084,RCC1085,RCC1086,RCC1087,RCC156,RCC158,RCC162,RCC2033,RCC2035,RCC2319,RCC2366,RCC2368,RCC2369,RCC2374,RCC2376,RCC2378,RCC2379,RCC2380,RCC2381,RCC2382,RCC2383,RCC2385,RCC2433,RCC2436,RCC2438,RCC2527,RCC2528,RCC2533,RCC2534,RCC2535,RCC2553,RCC2554,RCC2555,RCC2556,RCC2571,RCC2673,RCC278,RCC296,RCC307,RCC328,RCC3377,RCC407,RCC515,RCC539,RCC555,RCC556,RCC752,RCC753,RCC791}, month = {sep}, pages = {1{\textendash}23}, keywords = {amino-acid substitutions, comparative genomics, evolution, genomic islands, marine cyanobacteria, niche adaptation, Prochlorococcus, rcc1084, RCC1085, RCC1086, RCC1087, RCC156, RCC158, rcc162, RCC2033, RCC2035, RCC2319, RCC2366, RCC2368, RCC2369, RCC2374, RCC2376, RCC2378, RCC2379, rcc2380, RCC2381, rcc2382, RCC2383, RCC2385, RCC2433, RCC2436, RCC2438, RCC2527, RCC2528, RCC2533, RCC2534, RCC2535, RCC2553, RCC2554, RCC2555, RCC2556, RCC2571, RCC2673, RCC278, rcc296, RCC307, RCC328, RCC3377, RCC407, RCC515, rcc539, rcc555, RCC556, rcc752, RCC753, rcc791, Synechococcus}, issn = {1664-302X}, doi = {10.3389/fmicb.2020.567431}, url = {https://www.frontiersin.org/article/10.3389/fmicb.2020.567431/full}, author = {Dor{\'e}, Hugo and Farrant, Gregory K. and Guyet, Ulysse and Haguait, Julie and Humily, Florian and Ratin, Morgane and Pitt, Frances D. and Ostrowski, Martin and Six, Christophe and Brillet-Gu{\'e}guen, Loraine and Hoebeke, Mark and Bisch, Antoine and Le Corguill{\'e}, Gildas and Corre, Erwan and Labadie, Karine and Aury, Jean-Marc and Wincker, Patrick and Choi, Dong Han and Noh, Jae Hoon and Eveillard, Damien and Scanlan, David J. and Partensky, Fr{\'e}d{\'e}ric and Garczarek, Laurence} } @article {Barton2020, title = {Evolutionary temperature compensation of carbon fixation in marine phytoplankton}, journal = {Ecology Letters}, year = {2020}, note = {tex.mendeley-tags: RCC1303,RCC1512,RCC1773,RCC4221,RCC623,RCC626,RCC652,RCC80,RCC834}, month = {feb}, pages = {ele.13469}, abstract = {The efficiency of carbon sequestration by the biological pump could decline in the coming decades because respiration tends to increase more with temperature than photosynthesis. Despite these differences in the short-term temperature sensitivities of photosynthesis and respiration, it remains unknown whether the long-term impacts of global warming on metabolic rates of phytoplankton can be modulated by evolutionary adaptation. We found that respiration was consistently more temperature dependent than photosynthesis across 18 diverse marine phytoplankton, resulting in universal declines in the rate of carbon fixation with short-term increases in temperature. Long-term experimental evolution under high temperature reversed the short-term stimulation of metabolic rates, resulting in increased rates of carbon fixation. Our findings suggest that thermal adaptation may therefore have an ameliorating impact on the efficiency of phytoplankton as primary mediators of the biological carbon pump.}, keywords = {climate change, evolutionary ecology, metabolism, phytoplankton physiology, RCC1303, rcc1512, RCC1773, RCC4221, RCC623, RCC626, RCC652, RCC80, RCC834, thermal performance curves}, issn = {1461-023X}, doi = {10.1111/ele.13469}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.13469}, author = {Barton, Samuel and Jenkins, James and Buckling, Angus and Schaum, C.-Elisa and Smirnoff, Nicholas and Raven, John A. and Yvon-Durocher, Gabriel}, editor = {Ezenwa, Vanessa} } @article {bottini_high_2020, title = {High resolution spatial analyses of trace elements in coccoliths reveal new insights into element incorporation in coccolithophore calcite}, journal = {Scientific Reports}, volume = {10}, number = {1}, year = {2020}, note = {Number: 1 Publisher: Nature Publishing Group}, pages = {9825}, abstract = {Coccolithophores are phytoplanktonic algae which produce an exoskeleton made of single platelets of calcite named coccoliths. They are widespread in all oceans and directly impact the short- and long-term C cycle. The study of coccolith size, morphology and elemental composition reveals important information regarding the ability of the cell to calcify and on the factors that influence this process. In this regard, very little is known about coccolith composition and its changes under altered environmental conditions. Here, we present high resolution (50 {\texttimes} 50 nm) elemental spatial distribution in pristine coccoliths of Coccolithus pelagicus and Gephyrocapsa oceanica reconstructed via X-ray fluorescence analyses at synchrotron. The studied specimens are from control culture and metal-enriched (V, Ni, Zn and Pb) experiments. The analysed specimens produced under stress conditions, display an irregular shape and are thinner, especially in the external rim, with ca. 1/3 lower Ca concentrations compared to specimens from the control. The same specimens also have higher Sr/Ca ratio with highest values in the coccolith external rim, suggesting that difficulty in calcification is additionally reflected in increased Sr/Ca ratios. Selenium is found in the coccolith as possible substitute of carbonate in the calcite. V and Pb apparently did not interact with the coccoliths while Zn and Ni were deposited on the coccolith surface.}, keywords = {Environmental chemistry, Environmental impact, Marine chemistry, Pollution remediation, RCC1198, RCC1303}, issn = {2045-2322}, doi = {10.1038/s41598-020-66503-x}, url = {http://www.nature.com/articles/s41598-020-66503-x}, author = {Bottini, Cinzia and Dapiaggi, Monica and Erba, Elisabetta and Faucher, Giulia and Rotiroti, Nicola} } @article {Guyet2020, title = {Synergic effects of temperature and irradiance on the physiology of the marine synechococcus strain WH7803}, journal = {Frontiers in Microbiology}, volume = {11}, year = {2020}, note = {Publisher: Frontiers Media S.A. tex.mendeley-tags: RCC752}, month = {jul}, pages = {1707}, abstract = {Understanding how microorganisms adjust their metabolism to maintain their ability to cope with short-term environmental variations constitutes one of the major current challenges in microbial ecology. Here, the best physiologically characterized marine Synechococcus strain, WH7803, was exposed to modulated light/dark cycles or acclimated to continuous high-light (HL) or low-light (LL), then shifted to various stress conditions, including low (LT) or high temperature (HT), HL and ultraviolet (UV) radiations. Physiological responses were analyzed by measuring time courses of photosystem (PS) II quantum yield, PSII repair rate, pigment ratios and global changes in gene expression. Previously published membrane lipid composition were also used for correlation analyses. These data revealed that cells previously acclimated to HL are better prepared than LL-acclimated cells to sustain an additional light or UV stress, but not a LT stress. Indeed, LT seems to induce a synergic effect with the HL treatment, as previously observed with oxidative stress. While all tested shift conditions induced the downregulation of many photosynthetic genes, notably those encoding PSI, cytochrome b6/f and phycobilisomes, UV stress proved to be more deleterious for PSII than the other treatments, and full recovery of damaged PSII from UV stress seemed to involve the neo-synthesis of a fairly large number of PSII subunits and not just the reassembly of pre-existing subunits after D1 replacement. In contrast, genes involved in glycogen degradation and carotenoid biosynthesis pathways were more particularly upregulated in response to LT. Altogether, these experiments allowed us to identify responses common to all stresses and those more specific to a given stress, thus highlighting genes potentially involved in niche acclimation of a key member of marine ecosystems. Our data also revealed important specific features of the stress responses compared to model freshwater cyanobacteria.}, keywords = {light stress, marine cyanobacteria, rcc752, Synechococcus, temperature stress, transcriptomics, UV radiations}, issn = {1664302X}, doi = {10.3389/fmicb.2020.01707}, url = {www.frontiersin.org}, author = {Guyet, Ulysse and Nguyen, Ngoc A. and Dor{\'e}, Hugo and Haguait, Julie and Pittera, Justine and Conan, Ma{\"e}l and Ratin, Morgane and Corre, Erwan and Le Corguill{\'e}, Gildas and Brillet-Gu{\'e}guen, Loraine and Hoebeke, Mark and Six, Christophe and Steglich, Claudia and Siegel, Anne and Eveillard, Damien and Partensky, Fr{\'e}d{\'e}ric and Garczarek, Laurence} } @article {GerikasRibeiro2020, title = {Taxonomic reassignment of \textit{Pseudohaptolina birgeri comb. nov . (Haptophyta)}, journal = {Phycologia}, volume = {in press}, year = {2020}, note = {tex.mendeley-tags: RCC5268,RCC5270}, month = {oct}, pages = {1{\textendash}10}, keywords = {RCC5268, RCC5270}, issn = {0031-8884}, doi = {10.1080/00318884.2020.1830255}, url = {https://www.biorxiv.org/content/10.1101/2020.05.06.081489v1 https://www.tandfonline.com/doi/full/10.1080/00318884.2020.1830255}, author = {G{\'e}rikas Ribeiro, Catherine and Lopes dos Santos, Adriana and Probert, Ian and Vaulot, Daniel and Edvardsen, Bente} } @mastersthesis {Edullantes2020, title = {Thermal responses of marine phytoplankton : Implications to their biogeography in the present and future oceans}, year = {2020}, note = {Number: September tex.mendeley-tags: RCC2649,RCC291,RCC3404}, type = {phd}, keywords = {RCC2649, RCC291, RCC3404}, author = {Edullantes, Brisneve} } @article {Yau2020, title = {Virus-host coexistence in phytoplankton through the genomic lens}, journal = {Science Advances}, volume = {6}, number = {14}, year = {2020}, note = {tex.mendeley-tags: RCC2590,RCC2596}, month = {apr}, pages = {eaay2587}, abstract = {Virus-microbe interactions in the ocean are commonly described by {\textquotedblleft}boom and bust{\textquotedblright} dynamics, whereby a numerically dominant microorganism is lysed and replaced by a virus-resistant one. Here, we isolated a microalga strain and its infective dsDNA virus whose dynamics are characterized instead by parallel growth of both the microalga and the virus. Experimental evolution of clonal lines revealed that this viral production originates from the lysis of a minority of virus-susceptible cells, which are regenerated from resistant cells. Whole-genome sequencing demonstrated that this resistant-susceptible switch involved a large deletion on one chromosome. Mathematical modeling explained how the switch maintains stable microalga-virus population dynamics consistent with their observed growth pattern. Comparative genomics confirmed an ancient origin of this {\textquotedblleft}accordion{\textquotedblright} chromosome despite a lack of sequence conservation. Together, our results show how dynamic genomic rearrangements may account for a previously overlooked coexistence mechanism in microalgae-virus interactions.}, keywords = {RCC2590, RCC2596}, issn = {2375-2548}, doi = {10.1126/sciadv.aay2587}, url = {https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aay2587}, author = {Yau, Sheree and Krasovec, Marc and Benites, L. Felipe and Rombauts, Stephane and Groussin, Mathieu and Vancaester, Emmelien and Aury, Jean-Marc and Derelle, Evelyne and Desdevises, Yves and Escande, Marie-Line and Grimsley, Nigel and Guy, Julie and Moreau, Herv{\'e} and Sanchez-Brosseau, Sophie and Van de Peer, Yves and Vandepoele, Klaas and Gourbi{\`e}re, S{\'e}bastien and Piganeau, Gwenael} } @article {Granata2019, title = {The influence of bio-optical properties of Emiliania huxleyi and Tetraselmis sp. on biomass and lipid production when exposed to different light spectra and intensities of an adjustable LED array and standard light sources}, journal = {SN Applied Sciences}, volume = {1}, number = {6}, year = {2019}, note = {ISBN: 0123456789 Publisher: Springer International Publishing tex.mendeley-tags: RCC1210,RCC2604}, month = {jun}, pages = {524}, keywords = {Bio-optical properties, Biomass and lipid production, jel classification q42, mathematics subject classification 92c99, rcc1210, RCC2604, Spectral irradiance}, issn = {2523-3963}, doi = {10.1007/s42452-019-0529-x}, url = {http://link.springer.com/10.1007/s42452-019-0529-x}, author = {Granata, Tim and Habermacher, Patrick and H{\"a}rri, Vinzenz and Egli, Marcel} } @article {Gafar2019, title = {Particulate inorganic to organic carbon production as a predictor for coccolithophorid sensitivity to ongoing ocean acidification}, journal = {Limnology and Oceanography Letters}, volume = {4}, number = {3}, year = {2019}, note = {Publisher: John Wiley \& Sons, Ltd tex.mendeley-tags: RCC1130,RCC1141,RCC1168,RCC1198,RCC1200,RCC1323,RCC1334}, month = {jun}, pages = {62{\textendash}70}, abstract = {Ocean acidification (OA) can induce shifts in plankton community composition, with coccolithophores being mostly negatively impacted. This is likely to change particulate inorganic and organic carbon (PIC and POC, respectively) production, with impacts on the biological carbon pump. Hence, assessing and, most importantly, understanding species-specific sensitivities of coccolithophores is paramount. In a multispecies comparison, spanning more than two orders of magnitude in terms of POC and PIC production rates, among Calcidiscus leptoporus, Coccolithus pelagicus subsp. braarudii, Emiliania huxleyi, Gephyrocapsa oceanica, and Scyphosphaera apsteinii, we found that cellular PIC : POC was a good predictor for a species{\textquoteright} OA sensitivity. This is likely related to the need for cellular pH homeostasis, which is challenged by the process of calcification producing protons internally, especially when seawater pH decreases in an OA scenario. With higher PIC : POC, species and strains being more sensitive to OA coccolithophores may shift toward less calcified varieties in the future.}, keywords = {RCC1130, RCC1141, RCC1168, RCC1198, RCC1200, RCC1323, RCC1334}, issn = {2378-2242}, doi = {10.1002/lol2.10105}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10105}, author = {Gafar, N. A. and Eyre, B. D. and Schulz, K. G.} } @article {Engesmo2018, title = {Development of a qPCR assay to detect and quantify ichthyotoxic flagellates along the Norwegian coast, and the first Norwegian record of Fibrocapsa japonica (Raphidophyceae)}, journal = {Harmful Algae}, volume = {75}, year = {2018}, note = {Publisher: Elsevier B.V. tex.mendeley-tags: RCC1501,RCC1502}, pages = {105{\textendash}117}, abstract = {Blooms of ichthyotoxic microalgae pose a great challenge to the aquaculture industry world-wide, and there is a need for fast and specific methods for their detection and quantification in monitoring programs. In this study, quantitative real-time PCR (qPCR) assays for the detection and enumeration of three ichthyotoxic flagellates: the dinoflagellate Karenia mikimotoi (Miyake \& Kominami ex Oda) Hansen \& Moestrup and the two raphidophytes Heterosigma akashiwo (Hada) Hada ex Hara \& Chihara and Fibrocapsa japonica Toriumi \& Takano were developed. Further, a previously published qPCR assay for the dinoflagellate Karlodinium veneficum (Ballantine) Larsen was used. Monthly samples collected for three years (Aug 2009{\textendash}Jun 2012) in outer Oslofjorden, Norway were analysed, and the results compared with light microscopy cell counts. The results indicate a higher sensitivity and a lower detection limit (down to 1 cell L-1) for both qPCR assays. Qualitative and semi-quantitative results were further compared with those obtained by environmental 454 high throughput sequencing (HTS, metabarcoding) and scanning electron microscopy (SEM) examination from the same samplings. All four species were detected by qPCR and HTS and/or SEM in outer Oslofjorden (Aug 2009{\textendash}Jun 2012); Karlodinium veneficum was present year-round, whereas Karenia mikimotoi, Heterosigma akashiwo and Fibrocapsa japonica appeared mainly during the autumn in all three years. This is the first observation of Fibrocapsa japonica in Norwegian coastal waters. This species has previously been recorded off the Swedish west coast and German Bight, which may suggest a northward dispersal.}, keywords = {454 high throughput environmental sequencing, Heterosigma akashiwo, Karenia mikimotoi, Karlodinium veneficum, Molecular monitoring, rcc1501, rcc1502, RDNA, SEM}, issn = {15689883}, doi = {10.1016/j.hal.2018.04.007}, url = {https://doi.org/10.1016/j.hal.2018.04.007}, author = {Engesmo, Anette and Strand, David and Gran-Stadnicze{\~n}ko, Sandra and Edvardsen, Bente and Medlin, Linda K. and Eikrem, Wenche} } @article {Smallwood2018, title = {Integrated systems biology and imaging of the smallest free-living eukaryote Ostreococcus tauri}, journal = {bioRxiv}, year = {2018}, note = {tex.mendeley-tags: RCC745}, keywords = {? No DOI found, RCC745}, author = {Smallwood, Authors Chuck R and Chen, Jian-hua and Kumar, Neeraj and Chrisler, William and Samuel, O and Kyle, Jennifer E and Nicora, Carrie D and Boudreau, Rosanne and Ekman, Axel and Kim, K and Moore, Ronald J and Mcdermott, Gerry and Cannon, William R and Evans, James E} } @article {Delmont2018, title = {Linking pangenomes and metagenomes: the Prochlorococcus metapangenome}, journal = {PeerJ}, volume = {6}, year = {2018}, note = {ISBN: 2167-8359 tex.mendeley-tags: RCC156,RCC158,RCC162,RCC269,RCC278,RCC296,RCC3377,RCC407}, pages = {e4320}, abstract = {Pangenomes offer detailed characterizations of core and accessory genes found in a set of closely related microbial genomes, generally by clustering genes based on sequence homology. In comparison, metagenomes facilitate highly resolved investigations of the relative distribution of microbial genomes and individual genes across environments through read recruitment analyses. Combining these complementary approaches can yield unique insights into the functional basis of microbial niche partitioning and fitness, however, advanced software solutions are lacking. Here we present an integrated analysis and visualization strategy that provides an interactive and reproducible framework to generate pangenomes and to study them in conjunction with metagenomes. To investigate its utility, we applied this strategy to a Prochlorococcus pangenome in the context of a large-scale marine metagenomic survey. The resulting Prochlorococcus metapangenome revealed remarkable differential abundance patterns between very closely related isolates that belonged to the same phylogenetic cluster and that differed by only a small number of gene clusters in the pangenome. While the relationships between these genomes based on gene clusters correlated with their environmental distribution patterns, phylogenetic analyses using marker genes or concatenated single-copy core genes did not recapitulate these patterns. The metapangenome also revealed a small set of core genes that mostly occurred in hypervariable genomic islands of the Prochlorococcus populations, which systematically lacked read recruitment from surface ocean metagenomes. Notably, these core gene clusters were all linked to sugar metabolism, suggesting potential benefits to Prochlorococcus from a high sequence diversity of sugar metabolism genes. The rapidly growing number of microbial genomes and increasing availability of environmental metagenomes provide new opportunities to investigate the functioning and the ecology of microbial populations, and metapangenomes can provide unique insights for any taxon and biome for which genomic and sufficiently deep metagenomic data are available.}, keywords = {RCC156, RCC158, rcc162, RCC269, RCC278, rcc296, RCC3377, RCC407}, issn = {2167-8359}, doi = {10.7717/peerj.4320}, url = {https://peerj.com/articles/4320}, author = {Delmont, Tom O. and Eren, A. Murat} } @article {Muller2018, title = {Stable isotope fractionation of strontium in coccolithophore calcite: Influence of temperature and carbonate chemistry}, journal = {Geobiology}, volume = {16}, number = {3}, year = {2018}, note = {Publisher: John Wiley \& Sons, Ltd (10.1111) tex.mendeley-tags: RCC1200}, month = {may}, pages = {297{\textendash}306}, abstract = {Abstract Marine calcifying eukaryotic phytoplankton (coccolithophores) is a major contributor to the pelagic production of CaCO3 and plays an important role in the biogeochemical cycles of C, Ca and other divalent cations present in the crystal structure of calcite. The geochemical signature of coccolithophore calcite is used as palaeoproxy to reconstruct past environmental conditions and to understand the underlying physiological mechanisms (vital effects) and precipitation kinetics. Here, we present the stable Sr isotope fractionation between seawater and calcite (?88/86Sr) of laboratory cultured coccolithophores in individual dependence of temperature and seawater carbonate chemistry. Coccolithophores were cultured within a temperature and a pCO2 range from 10 to 25{\textdegree}C and from 175 to 1,240 ?atm, respectively. Both environmental drivers induced a significant linear increase in coccolith stable Sr isotope fractionation. The temperature correlation at constant pCO2 for Emiliania huxleyi and Coccolithus braarudii is expressed as ?88/86Sr = ?7.611 ? 10?3 T + 0.0061. The relation of ?88/86Sr to pCO2 was tested in Emiliania huxleyi at 10 and 20{\textdegree}C and resulted in ?88/86Sr = ?5.394 ? 10?5 pCO2 ? 0.0920 and ?88/86Sr = ?5.742 ? 10?5 pCO2 ? 0.1351, respectively. No consistent relationship was found between coccolith ?88/86Sr and cellular physiology impeding a direct application of fossil coccolith ?88/86Sr as coccolithophore productivity proxy. An overall significant correlation was detected between the elemental distribution coefficient (DSr) and ?88/86Sr similar to inorganic calcite with a physiologically induced offset. Our observations indicate (i) that temperature and pCO2 induce specific effects on coccolith ?88/86Sr values and (ii) that strontium elemental ratios and stable isotope fractionation are mainly controlled by precipitation kinetics when embedded into the crystal lattice and subject to vital effects during the transmembrane transport from seawater to the site of calcification. These results provide an important step to develop a coccolith ?88/86Sr palaeoproxy complementing the existing toolbox of palaeoceanography.}, keywords = {coccolithophores, paleoproxy calibration, phytoplankton, RCC1200, stable Sr isotope fractionation}, issn = {1472-4677}, doi = {10.1111/gbi.12276}, url = {https://doi.org/10.1111/gbi.12276}, author = {M{\"u}ller, M N and Krabbenh{\"o}ft, A and Vollstaedt, H and Brandini, F P and Eisenhauer, A} } @article {LopesdosSantos2017, title = {Chloropicophyceae, a new class of picophytoplanktonic prasinophytes}, journal = {Scientific Reports}, volume = {7}, number = {1}, year = {2017}, note = {tex.mendeley-tags: 2017,RCC1019,RCC1021,RCC1032,RCC1043,RCC1124,RCC138,RCC15,RCC1871,RCC19,RCC227,RCC2335,RCC2337,RCC2339,RCC287,RCC297,RCC3368,RCC3373,RCC3374,RCC3375,RCC3376,RCC3402,RCC4429,RCC4430,RCC4434,RCC4572,RCC4656,RCC696,RCC700,RCC701,RCC712,RCC713,RCC717,RCC719,RCC722,RCC726,RCC856,RCC857,RCC887,RCC917,RCC996,RCC997,RCC998,RCC999,sbr?hyto$_\textrmd$ipo}, month = {dec}, pages = {14019}, keywords = {2017, RCC1019, RCC1021, RCC1032, RCC1043, RCC1124, RCC138, RCC15, RCC1871, RCC19, RCC227, RCC2335, RCC2337, RCC2339, RCC287, RCC297, RCC3368, RCC3373, RCC3374, RCC3375, RCC3376, RCC3402, RCC4429, RCC4430, RCC4434, RCC4572, RCC4656, RCC696, RCC700, RCC701, RCC712, RCC713, RCC717, RCC719, RCC722, RCC726, RCC856, RCC857, RCC887, RCC917, RCC996, RCC997, RCC998, RCC999, sbr?hyto$_\textrmd$ipo}, issn = {2045-2322}, doi = {10.1038/s41598-017-12412-5}, url = {http://www.nature.com/articles/s41598-017-12412-5}, author = {Lopes dos Santos, Adriana and Pollina, Thibaut and Gourvil, Priscillia and Corre, Erwan and Marie, Dominique and Garrido, Jos{\'e} Luis and Rodr{\'\i}guez, Francisco and No{\"e}l, Mary-H{\'e}l{\`e}ne and Vaulot, Daniel and Eikrem, Wenche} } @article {faucher_impact_2017, title = {Impact of trace metal concentrations on coccolithophore growth and morphology: laboratory simulations of Cretaceous stress}, journal = {Biogeosciences}, volume = {14}, number = {14}, year = {2017}, note = {Publisher: Copernicus GmbH}, month = {jul}, pages = {3603{\textendash}3613}, abstract = {Abstract. The Cretaceous ocean witnessed intervals of profound perturbations such as volcanic input of large amounts of CO$_\textrm2$, anoxia, eutrophication and introduction of biologically relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes of a few calcareous nannofossil species. The correspondence between intervals of high trace metal concentrations and coccolith dwarfism suggests a negative effect of these elements on nannoplankton biocalcification processes in past oceans. In order to test this hypothesis, we explored the potential effect of a mixture of trace metals on growth and morphology of four living coccolithophore species, namely \textitEmiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and \textitCoccolithus pelagicus. The phylogenetic history of coccolithophores shows that the selected living species are linked to Mesozoic species showing dwarfism under excess metal concentrations. The trace metals tested were chosen to simulate the environmental stress identified in the geological record and upon known trace metal interactions with living coccolithophore algae.
Our laboratory experiments demonstrated that elevated trace metal concentrations, similarly to the fossil record, affect coccolithophore algae size and/or weight. Smaller coccoliths were detected in \textitE. huxleyi and \textitC. pelagicus, while coccoliths of \textitG. oceanica showed a decrease in size only at the highest trace metal concentrations. \textitP. carterae coccolith size was unresponsive to changing trace metal concentrations. These differences among species allow discriminating the most- (\textitP. carterae), intermediate- (\textitE. huxleyi and \textitG. oceanica) and least-tolerant (\textitC. pelagicus) taxa. The fossil record and the experimental results converge on a selective response of coccolithophores to metal availability.
These species-specific differences must be considered before morphological features of coccoliths are used to reconstruct paleo-chemical conditions.