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Aims: Microalgae are ubiquitous in aquatic environments, including aquaculture farms, but few studies have delved into their phytoplankton diversity and bioremediation potential. In this study, the cultivable phytoplankton of a rainbow trout freshwater aquaculture farm was isolated, phylogenetically analysed and used to assemble a consortium to polish an aquaculture derived effluent, with low concentrations of ammonium, nitrite and nitrate. Methods and Results: Through standard plating in different selective media, a total of 15 microalgae strains were isolated from sludge from a rotary drum filtering system which removes suspended solids from the water exiting the facility. Based on 18S rRNA gene sequences, isolates were assigned to nine different genera of the Chlorophyta phylum: Asterarcys, Chlorella, Chloroccocum, Chlorosarcinopsis, Coelastrella, Desmodesmus, Micractinium, Parachlorella and Scenedesmus. Species from most of these genera are known to inhabit freshwater systems in Galicia and continental Spain, but the Coelastrella, Asterarcys or Parachlorella genera are not usually present in freshwater streams. In an onsite integrative approach, the capacity of a consortium of native microalgae isolates to grow on aquaculture derived effluents and its nutrient removal capacity were assessed using a raceway pond. After 7 days, removal efficiencies of approximately 99%, 92% and 49% for ammonium, nitrite and nitrate, respectively, were achieved concomitantly with a microalgae biomass increase of ca. 17%. Conclusions: Sludge from the aquaculture filtering system presents a high diversity of microalgae species from the Chlorophyta phylum, whose application in a consortial approach revealed to be efficient to polish aquaculture derived effluents with low nutrient content. Significance and Impact of the Study: The use of native microalgae consortia from aquaculture systems can contribute to the development of efficient treatment systems for low nutrient wastewater, avoiding nutrients release to the environment and promoting water recirculation. This may further strengthen the use of phycoremediation at the industrial scale, as an environment friendly strategy.

Rapidly accumulating genetic data from environmental sequencing approaches have revealed an extraordinary level of unsuspected diversity within marine phytoplankton, which is responsible for around 50% of global net primary production.However, the phenotypic identity of many of the organisms distinguished by environmental DNA sequences remains unclear. The rappemonads represent a plastid-bearing protistan lineage that to date has only been identified by environmental plastid 16S rRNA sequences.The phenotypic identity of this group, which does not confidently cluster in any known algal clades in 16S rRNA phylogenetic reconstructions, has remained unknown since the first report of environmental sequences over two decades ago. We show that rappemonads are closely related to a haptophyte microalga, Pavlomulina ranunculiformis gen. nov. et sp. nov., and belong to a new haptophyte class, the Rappephyceae. Organellar phylogenomic analyses provide strong evidence for the inclusion of this lineage within the Haptophyta as a sister group to the Prymnesiophyceae. Members of this new class have a cosmopolitan distribution in coastal and oceanic regions. The relative read abundance of Rappephyceae in a large environmental barcoding dataset was comparable to, or greater than, those of major haptophyte species, such as the bloom-forming Gephyrocapsa huxleyi and Prymnesium parvum, and this result indicates that they likely have a significant impact as primary producers. Detailed characterization of Pavlomulina allowed for reconstruction of the ancient evolutionary history of the Haptophyta, a group that is one of the most important components of extant marine phytoplankton communities., 20年以上謎だった生物の正体が判明 --光合成生物進化解明のカギに--. 京都大学プレスリリース. 2021-03-29.

We collected live mixed natural samples from the northeastern Ross Sea during the austral summer of 2017 and isolated a novel Prorocentrum sp. (Dinophyceae) associated with mucilaginous Phaeocystis antarctica (Coccolithophyceae) colonies. The haptophyte P. antarctica is a key species of the phytoplankton community in the Ross Sea, where blooms are subjected to iron limitation and/or co-limitation with other micronutrients (e.g., vitamin B12) during the summer. We first performed preliminary genetic analyses to determine the specific identity of the novel Prorocentrum sp., which indicated that it represented a previously undescribed species. The formal description of this new species is in process. To further assess its relationship with P. antarctica, we obtained their monospecific and mixed cultures and evaluated their responses to different irradiance levels and iron and vitamin B12 limitation. Our results indicated differential susceptibility of the two species to iron limitation and differential photosynthetic plasticity under high irradiance. Iron limitation reduced colony formation in P. antarctica and decreased the chlorophyll-a content in Prorocentrum sp., whereas B12 limitation did not affect growth or photosynthetic efficiency in either species. In addition, P. antarctica could photosynthesize efficiently under different irradiance levels, due to its ability to modulate the light adsorption cross-section of PSII, whereas Prorocentrum sp. exhibited lower photosynthetic plasticity and an inability to modulate both the maximum photochemical efficiency and effective adsorption cross-section of PSII under high irradiance. The trophic interaction between Prorocentrum sp. and P. antarctica could present ecological implications for the food webs and biogeochemical cycles of the Antarctic ecosystem. Considering the predicted climate-driven shifts in global ocean surface light regimes and changes in iron or vitamin B12 transfer, which are most likely to impact changes in the phytoplankton community structure, our results present implications for carbon export to deeper waters, ecological functioning, and associated biogeochemical changes in the future.

In the present investigation, we aimed to study diversity and cell abundance of phytoplankton in the southwest of the Caspian Sea. This survey included 4 transects and 12 stations. A total of 48 samples were collected during spring 2012 and spring 2013. Finally, 72 species of phytoplankton were identified including phyla Diatoms (29 species), Chlorophyta (17 species), Pyrrophyta (16 species), Cyanophyta (6 species), and Euglenophyta (4 species). The total average of cell abundance was approximately 43.55 ± 5.10 × 104 cells/m3. The number of recorded species in spring, summer, autumn, and winter was 46, 50, 41 and 39, respectively. Diatoms had the highest species diversity and cell abundance in winter related to Thalassionema nitzschiodes at a depth of 10 m. Seasonal changes in diversity of phytoplankton significantly differed, showing maximum in autumn with high diversity index (2.532) and minimum in spring (2.201) on Shannon Diversity Index. Finally, the quality of water is classified according to this index in the middle level.

Kostryukova AM, Krupnova TG, Mashkova IV, Gavrilkina SV, Nikita O. Egorov NO. 2018. Phytoplankton diversity in three lakes of South Ural, Russia. Biodiversitas 19: 1459-1467. Preservation of water ecosystems in their natural state is of great significance. Phytoplankton is one of the biotic indicators of the lake trophic status and ecological state. This study deals with phytoplankton diversity of three lakes of South Ural, Russia. The studied lakes represented different trophic states: Lake Savelkul was oligo-mesotrophic, Lake Ilmenskoe was mesotrophic and Lake Argayash was eutrophic. The species composition of common phytoplankton was recorded in June-July months during 2015 and 2016. The Cyanophyta (blue-green algae) species were dominant in Lake Ilmenskoe(42-64%) and Lake Argayash(55-70%). The Bacillariophyta (diatom algae) species were dominant in the Lake Savelkul(40-66 %). The most common diversity indices namely the Shannon Index, Simpson Index and Margalef Index were determined and the data was also analysed using graphs. The graphs were constructed by the similarity calculating method on the basis of the Sorensen-Czekanowski coefficient. Diversity indices confirm the higher species richness of the microalgal community of Lake Ilmenskoe, classified as mesotrophic. It was shown that the lakes have sufficiently high biodiversity and high ecosystem resilience. Further, statistical analysis (CCA) revealed that orthophosphate-phosphorus, nitrite-nitrogen and pH were the most significant environmental factors influencing phytoplankton community of the lakes studied.

International audience; This study investigated the genetic diversity of phytoplankton communities in six shallow lagoons located on the French coast of the northwestern Mediterranean Sea that represented a trophic gradient ranging from oligotrophic to hypereutrophic. The phytoplankton communities were sampled once a month from spring (May) to the beginning of autumn (September/early October) in 2012 and fractionated by size. Metabarcodes were generated from cDNAs by targeting the D1-D2 region of the 28S rRNA gene and pyrosequenced using Roche 454 technology. Examination of the annotated barcodes revealed harmful algal species not previously documented in these lagoons. Three ichthyotoxic species belonging to Pfiesteriaceae were detected: Luciella masanensis was relatively widespread and abundant in many samples, whereas Pfiesteria piscicida and Stoeckeria changwonensis were found as single barcode sequences. Furthermore, a phylogenetic analysis of barcodes annotated as belonging to Pfiesteriaceae suggested the existence of two previously undescribed clades. The other toxic or potentially harmful dinoflagellates detected through rare barcodes were Dinophysis acuminata, Vulcanodinium rugosum, Alexandrium andersonii and A. ostenfeldii. The two most abundant dinoflagellate taxa were Gymnodinium litoralis and Akashiwo sanguinea with respect to sequence numbers. Four diatom species from the genus Pseudo-nitzschia that potentially produce domoic acid were identified (P. galaxiae, P. delicatissima, P. brasiliana and P. calliantha). These observations are discussed in terms of the literature and monitoring records related to the identified taxa in this Mediterranean area.

International audience; Studies on phytoplankton and in particular Harmful Algal Blooms (HABs) species in southern Mediterranean waters are scarce. We performed from April 2008 to June 2009 weekly investigations on microphytoplankton community structure and abundance in two contrasted marine ecosystems located in the western Moroccan Mediterranean coast, M'diq Bay and Oued Laou Estuary. Simultaneously, we measured the main physico-chemical parameters. Globally, the two studied areas showed comparable values of the assessed abiotic environmental factors. Temperature and salinity followed seasonal variation with values ranging from 13.5°C to 21.4°C and 31 to 36.8, respectively. Average nutrient values in surface water ranged from 0.7 to 45.76 μM for dissolved inorganic nitrogen, 0.02-2.10 μM for PO 4 and 0.23-17.46 μM for SiO 4 in the study areas. A total of 92 taxa belonging to 8 taxonomic classes were found. The highest number of microphytoplankton abundance reached 1.2 × 10 6 cells L −1 with diatoms being the most abundant taxa. Factorial Discriminant Analysis (FDA) and Spearman correlation test showed a significant seasonal discrimination of dominant microphytoplankton species. These microorganisms were associated with different environmental variables, in particular temperature and salinity. Numerous HABs species were encountered regularly along the year. Although Dinophysis species and Prorocentrum lima were present in both sites, no Lipophilic Shellfish Poisoning was detected for the analyzed bivalve mollusks. Domoic acid (DA), produced by toxic species of Pseudo-nitzschia was found with concentrations up to 18 µg DA g −1 in the smooth clam Callista chione. Data showed that the observed persistent and dramatic Paralytic Shellfish Poisoning (PSP) intoxication of mollusks resulted probably of Gymnodinium catenatum pro-liferations in both studied areas. Contrary to C. chione, the cockle Achanthocardia tuberculatum showed a permanent and extremely high toxicity level during the 15 months survey with up to 7545 µg Equivalent Saxitoxin kg −1 flesh (ten times higher than the sanitary threshold of 800 µg eqSTX Kg −1 flesh). The present work highlights for the first time the dynamic of microphytoplankton including HABs species and their associated toxin accumulation in the commercially exploited shellfish in the southern western Mediterranean waters of Morocco. Furthermore, the acquired data will help us to improve the monitoring of HABs species and related toxins in these coastal marine systems.

The influence of abiotic and biotic factors on the concentration of dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) was investigated and compared during two annual cycles in 2016 and 2018 in the Belgian coastal zone (BCZ) in the southern North Sea at five fixed stations. These stations covered a near-offshore gradient from stations close to the mouth of the Scheldt estuary to most offshore stations. Significant differences of Chlorophyll-a (Chl-a) concentrations were observed between the two years with higher values in early spring 2018 (due to better light and nutrient conditions coupled to colder temperatures) and in summer 2018 (due to warmer conditions) compared to 2016. Nevertheless, the seasonal and spatial DMSP and DMSO (DMS(P,O))patterns, as well as the yearly average were nearly identical in 2016 and 2018. This can be explained by the fact that the phytoplankton groups responsible for the large differences in Chl-a in 2018 and 2016 were low DMSPproducers characterized by several diatom and dinoflagellate species, occurring in early spring and summer. Further, the Prymnesiophyceae Phaeocystis globosa, occurring in late spring and responsible of most of DMS(P,O) measured in the area, reached similar biomass both years. The DMSP:Chl-a ratio obtained from the field measurements were similar to those previously published for the main observed phytoplankton groups, but more differences were observed for the DMSO:Chl-a ratio. DMS(P,O) estimations based on Chl-a linear regressions for the whole dataset need to account on two relationships discriminating the low and high-DMSP producing species., info:eu-repo/semantics/published

International audience; This study assesses the ability of hyperspectral optical measurements to discriminate changes in the composition of phytoplankton communities in open-ocean non-bloom environments. A large set of in situ near-surface measurements, comprising phytoplankton pigment determinations and hyperspectral optical data of phytoplankton absorption coefficient, aph(λ), and remote-sensing reflectance, Rrs(λ), are used in the analysis. Measurements were collected in different ecological provinces in the Pacific and Atlantic Oceans with chlorophyll-a concentrations ranging from about 0.02 to 1.5mgm-3. Hierarchical cluster analysis was applied to measured spectra of aph(λ) and Rrs(λ) and the second-derivative spectra of these optical variables. The resulting optical-based classifications of the examined stations compared favorably (similarity index≥0.73) with a classification of phytoplankton community composition calculated from pigment measurements. Similarities between pigment-based and optically-based classifications were better for the optical data of aph(λ) than Rrs(λ), with only slight improvements resulting from the use of the second derivative spectra as opposed to the non-differentiated spectra. An Empirical Orthogonal Function (EOF) analysis was applied to the optical spectra to examine the correlation of dominant modes of variability with several bio-optical and biogeochemical properties. This analysis supports the notion that the performance of the optical approach is strongly associated with the effects of differences in pigment composition, cell size, and intracellular pigment concentration among different phytoplankton communities on the optical properties of the ocean

10 páginas, 5 figuras, 3 tablas, The use of pigment data to map microalgal populations in natural waters has become an established and convenient way of studying phytoplankton. However, the chromatographic analysis of algal pigments is a major challenge due to the diversity of molecules spanning a wide range of polarities, but also including many that have closely similar chemical structures. Among these sets of compounds of similar structure, the separation of mono and divinylic pairs of chlorophylls is of particular importance due to their relevance as chemotaxonomical biomarkers. In this work, we have taken advantage of the special type of solute–stationary phase interactions provided by pentafluorophenyl phases together with the high retention values resulting from an octadecyl spacer in the column to develop a method for the joined analysis of chlorophylls and carotenoids. The mobile phase contains organic solvents of low toxicity, methanol and ethanol and ammonium acetate buffer, in a simple binary elution gradient. More than seventy photosynthetic pigments (chlorophylls, carotenes and xanthophylls) can be determined in the same chromatographic analysis employing the method here presented. The complete resolution of mono and divinylic forms of chlorophylls a, b and c is achieved in less than 42 min. The same analysis allows the separation of most chemotaxonomically important carotenoids, including positional isomers. The method can successfully be applied to the characterization of the pigment composition of members of different classes in the main chloroplast lineages (red and green) of the evolution of photosynthetic eukaryotes, in the study of biosynthetic processes of chlorophylls and especially in the description of plankton populations in natural waters. It is particularly suited for the simultaneous detection of green algae and the cyanobacteria of outstanding global importance Prochlorococcus marinus, This work was co-financed by Spanish Ministerio de Economía y Competitividad (MINECO) and FEDER through project CTM2012-32181. A.G.O. is funded by a MINECO doctoral grant (BES-2013-065752)

The dynamics of the phytoplankton assemblage, the physical, chemical and biologi- cal parameters, and primary productivity and production were monitored in the central English Channel along a transect between Ouistreham and Portsmouth from January to December 2010. The spatial patterns of the phytoplankton assemblage were controlled by the hydrological charac- teristics of the water masses, and the annual structure of the phytoplankton assemblage was char- acteristic of the central English Channel and was controlled by seasonality. The spring bloom was dominated by a single species, Chaetoceros socialis, and associated with low microphytoplankton evenness and Shannon-Wiener indices, whereas the evenness index was high from late spring to winter and associated with the proliferation of pico- and nanophytoplankton cells. We identified 2 species responsible for harmful algal blooms, Phaeocystis globosa, which dominated the commu- nity in the northern part of the Seine Bay in May, and Lepidodinium chlorophorum, which domi- nated the community near the French coast in September. We examined the relationship between microphytoplankton diversity and maximum primary production and productivity. We found a negative parabolic relationship between the diversity indices (evenness and Shannon-Wiener) and maximum primary production, and a positive parabolic relationship between the number of taxa (richness) and maximum primary production. However, we found no relationship between maximum productivity and the evenness or richness indices. High levels of productivity were measured during the increasing abundance of pico and nanophytoplankton cells, highlighting the importance of taking the dominant functional group into account, rather than the degree of diver- sity, when explaining the level of productivity.

11 pages, 5 figures, 1 table, The aim of our study was to describe the diversity and dynamics of size-fractionated phytoplankton at a fixed station (P2, Ría de Pontevedra, NW Spain) from late spring to early winter. Phytoplankton successions were assessed weekly from May to November 2004 using pigment analyses, light microscopy and fluorescence in situ hybridization coupled with tyramide signal amplification (FISH-TSA). Periodic upwelling events triggered the development of diatom populations followed by periods of relaxation/downwelling conditions where remineralization processes (maxima of NH4 +), raised temperatures and/or low salinity waters from rainfall favored the increase of picophytoplankton. Marked differences were observed between diversity and dynamics of the micronano (>3 μm) and pico (, F.R. was supported by a postdoctoral fellowship from Caixanova Foundation

The phytoplanktonic samples were collected from the Gharni Reservoir of Latur district of Maharashtra for a period of one year, from June 2013 to May 2014. Totally 18 species of phytoplankton belonging to different taxonomic groups were identified. Among these 7 species belong to Chlorophyceae, 5 species to Cyanophyceae, 3 species to Bacillariophyceae and 3 species to Euglenophyceae. The phytoplankton productivity fluctuated seasonally and the maximum number of 560 units/liter was recorded during month of February and March and minimum number of 95 units/liter during the month of September.

The Orbetello lagoon consists of two coastal ponds, Laguna di Ponente and Laguna di Levante, characterized by high nutrient concentrations, very poor exchanges with the sea and subjected to recurrent eutrophication crisis mainly in the past decades. To assess its current trophic status, from 1995 to 2001 the temporal evolution and spatial distribution of environmental factors, phytoplankton biomass and composition have been investigated. In this paper, the mean annual cycles of phytoplankton abundance, community structure and diversity are discussed. The seasonal cycles of micro- and nanophytoplankton densities are characterized by high frequency oscillations with fast increasing and decreasing blooms, but generally the lowest densities occur in winter, except for the peaks of December, and the highest ones during spring and summer. Despite the variability at short time scale of phytoplankton density, composition and diversity, a recurrent pattern was evidenced. Nanoplanktonic flagellates were the dominant fraction, mainly cryptophyceans during winter and early spring, while diatoms showed high summer blooms of nanoplanktonic centric genera and were very scarce during the other seasons, mainly with pennate genera. The phytoplankton community structure appeared to be more diversified from early summer to fall with the variable contribution of diatoms, dinoflagellates and other flagellates. Phytoplankton diversity, computed by means of the Shannon index, was relatively low (mean of 1.96 bit per cell) and two phases, common to the whole lagoon, have been evidenced: a first phase of lower diversity during winter and early spring, followed by an increasing trend that reached the highest diversity in late summer-fall. The pattern of nutrients' (DIN and DIP) availability and depletion leads to a seasonal change of the N/P ratio that seems to play a role as regards the phytoplankton community succession and then diversity, favoring or limiting the growth of the different groups., La lagune d'Orbetello est formée de deux étendues d'eau côtières, la lagune du Ponent et la lagune du Levant caractérisées par des concentrations élevées de sels nutritifs, de faibles échanges avec la mer et soumises à des crises dystrophiques récurrentes dans les dernières décennies. Pour connaître son état trophique, l'évolution spatiale et temporelle des facteurs de l'environnement, de la biomasse et de la composition phytoplanctonique a été suivie de 1995 à 2001. Cet article présente les cycles annuels moyens de l'abondance du phytoplancton, de la structure des communautés et de la diversité. Les variations saisonnières du micro- et du nanophytoplancton présentent des oscillations à haute fréquence avec des floraisons apparaissant puis disparaissant rapidement. Généralement, les densités les plus faibles apparaissent en hiver, à l'exception de pics en décembre, et les plus élevées au printemps et en été. Malgré la variabilité haute fréquence, un schéma d'organisation peut être mis en évidence. Les flagellés nanoplanctoniques constituent la fraction dominante, principalement les cryptophycées, durant l'hiver et au début du printemps tandis que les diatomées sont à l'origine de floraisons importantes en été ; le reste de l'année, elles sont rares, le groupe des pennés dominant alors. La communauté phytoplanctonique est plus diversifiée du début de l'été à l'automne avec des contributions variables des diatomées, des dinoflagellés et autres flagellés. La diversité du phytoplancton, exprimée par l'indice de Shannon, est relativement basse (en moyenne 1.96 bit cell–1) et deux phases, communes à l'ensemble de la lagune, sont mises en lumière : la première de basse diversité en hiver et au début du printemps, suivie d'un accroissement qui atteint un pic en fin d'été et à l'automne. La distribution des sels nutritifs (azote inorganique dissous et phosphore inorganique dissous) souligne un changement saisonnier du rapport N/P qui paraît jouer un rôle sur la succession des espèces et donc la diversité favorisant ou limitant la croissance de tel ou tel groupe.

To advance our understanding of competition and coexistence in phytoplankton species within a functional group, such as a diatom group, we developed a numerical model composed of 240 within tropic-level virtual species that can actually or potentially compete. We then explored how the phytoplankton assembly is structured by deterministic or stochastic processes, where the former process is typically represented using the traditional niche theory and the latter process is highlighted using the neutral theory. Because we used eddy-resolving resolution, phytoplankton dispersion and the resultant dispersal limitation were explicitly represented, where the dispersal limitation prevents the most competitive species from using its appropriate niche and subsequently enhances stochastic effects. In the simulation results, all surviving species have an oceanic volume in which the phytoplankton species has the highest specific growth rate in all the 240 species. The abundance in the most competitive space has a strong, positive correlation with the relative species abundance. Moreover, of the phytoplankton types whose abundances in the most competitive space are nearly equal, the survival of a species is affected by its residence time within its habitat; the surviving phytoplankton species tend to have larger residence times compared to the non-persistent species. These results led us to conclude that deterministic processes had significant contributions to a formation of phytoplankton assembly. This was supported by the result that a structure of phytoplankton assembly represented by species rank in abundance was invariant with time and hardly dependent on initial conditions of phytoplankton composition. (C) 2016 The Author(s). Published by Elsevier B.V.