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In 2013, the Italian Society of Nephrology joined forces with Nephrocare-Italy to create a clinical research cohort of patients on file in the data-rich clinical management system (EUCLID) of this organization for the performance of observational studies in the hemodialysis (HD) population. To see whether patients in EUCLID are representative of the HD population in Italy, we set out to compare the whole EUCLID population with patients included in the regional HD registries in Emilia-Romagna (Northern Italy) and in Calabria (Southern Italy), the sole regions in Italy which have systematically collected an enlarged clinical data set allowing comparison with the data-rich EUCLID system. An analysis of prevalent and incident patients in 2010 and 2011 showed that EUCLID patients had a lower prevalence of coronary heart disease, peripheral vascular disease, heart failure, valvular heart disease, liver disease, peptic ulcer and other comorbidities and risk factors and a higher fractional urea clearance (Kt/V) than those in the Emilia Romagna and Calabria registries. Accordingly, survival analysis showed a lower mortality risk in the EUCLID 2010 and 2011 cohorts than in the combined two regional registries in the corresponding years: for 2010, hazard ratio (HR) EUCLID vs. Regional registries: 0.80 [95% confidence interval: 0.71–0.90]; for 2011, HR: 0.76 [0.65–0.90]. However, this difference was nullified by statistical adjustment for the difference in comorbidities and risk factors, indicating that the longer survival in the EUCLID database was attributable to the lower risk profile of patients included in that database. This preliminary analysis sets the stage for future observational studies and indicates that appropriate adjustment for difference in comorbidities and risk factors is needed to generalize to the Italian HD population analyses based on the data-rich EUCLID database.

Silicoflagellate populations and fluxes were analyzed from water samples and sediment traps in several basins of the eastern Mediterranean and Black Sea, to show species distribution in response to ecological factors and compared with the Quaternary records of the region. In the eastern Mediterranean, Dictyocha stapedia was the most abundant species, represented by two varieties: var. stapedia, smaller and with an apex spine, that dominated in the pelagic settings, and var. aspinosa, larger and lacking an apex spine, that dominated in the north Adriatic Sea. Dictyocha aculeata was the second most abundant species, Octactis pulchra was seasonally dominant in the Adriatic Sea. Stephanocha speculum occurred sporadically in the Adriatic Sea with 6-sided normal-sized specimens, but was nearly absent from pelagic assemblages. In the Black Sea, assemblages and fluxes were characterized by larger 7-sided skeletons of D. speculum with apex spines and a lower abundance of O. pulchra. © 2019 Elsevier Ltd

Recent studies on ocean acidification due to the increase of carbon dioxide in the atmosphere have provided evidence on a possible impact on coccolithophore calcification. In the framework of the MedSeA (Mediterranean Sea Acidification in a changing climate, EU-FP7) project, we collected data from May 2011 to February 2013 to deepen knowledge on coccolithophore associations at a coastal site in the Gulf of Trieste, for which a long-term time series of plankton data is available (C1-LTER 1986-present). The main aims of this study were to assess the contribution of coccolithophores to the phytoplankton community, also in relation with the available time series for the site, to identify the seasonal distribution of different species, to evaluate the relationships with high quality measurements of the carbonate system and other environmental parameters, and to compare the results of the coccolithophore analyses obtained by different methods (phase contrast versus polarized light microscopy and scanning electron microscopy). Coccolithophores showed a high interannual variability and a typical seasonal pattern, with maxima in the autumn-winter and minima in summer. The seasonal pattern was mainly linked to [HCO3 -], which is the preferential form used by coccolithophores for calcification. During the analysed period, the coccolithophore community was characterized by species adapted to a variety of environmental conditions: in autumn-winter, Emiliania huxleyi dominated, followed by Acanthoica quattrospina, Syracosphaera pulchra and some minor species (only present in autumn, e.g. Ophiaster hydroideus, Calciopappus rigidus, Michaelsarsia adriaticus); in spring, the association was dominated by holococcolithophores and minor E. huxleyi; in summer, low overall abundances coincide with low E. huxleyi concentration and the dominance of small Syracosphaera species, Rhabdosphaera clavigera and holococcolithophores. The comparison between the total coccolithophore abundances obtained by phase contrast microscope with the Utermöhl method and those obtained by polarized light microscope revealed good correspondence in winter and autumn, and less in spring. In fact, the polarized light microscope counting, coupled with scanning electron microscope observations on selected samples, allowed us to recognize species with very small and/or less calcified coccoliths, that would be probably lumped with other flagellates with the Utermöhl method, improving the assessment of coccolithophore species diversity and their contribution to the total phytoplankton.

Since March 1986, there has been a monthly time series collected through water sampling in the Gulf of Trieste. The sampling station (C1-LTER, 45º42'30"N 13º42'36"E) is located 200 m from the coastline with a water depth of 18 m. Water-column samples (0.5, 5, 10, and 15 m) were analyzed from the 1986-2010 time series (Cabrini et al., 2012) in order to identify phytoplankton seasonal evolution and community structure. The analysis of total phytoplankton composition showed a clear seasonal cycle with peak concentration values in late winter to early spring due to monospecific diatom blooms, and low values in late spring to summer when the phytoplankton is dominated by small flagellates. There is a second smaller peak in the fall that is dominated by diatoms, and low values occur in early winter, when nanoflagellates dominate. In addition, Cabrini et al. (2012) detected an important regime shift within the analyzed time series: a period from 1986 to 1994 that is characterized by high phytoplankton abundance values and dominated by phytoflagellates, and a second period from 1995 to 2007 with low cell concentrations that is dominated by diatoms. In this work, we analyzed the time series from August 2011 to July 2012, specifically addressing the vertical and seasonal distribution of selected phytoplankton groups – those possessing a mineralized skeleton and thus potentially preserved in the sediments and able to leave a fossil record. Coccolithophores are a major group in the oligotrophic eastern Mediterranean, and Cabrini et al. (2012) showed that they also can be seasonally important in the shallow areas of the Gulf of Trieste. In the present dataset, coccolithophores showed a primary abundance peak (up to 3.2x105 coccospheres/liter) from November to February and a second smaller peak (up to 1x105 coccospheres/ liter) in May to June. Emiliania huxleyi was the most abundant species throughout the analyzed time series, but Acanthoica quattrospina also made an important contribution in January, while holococcolithophores (A. quattrospina HOL, Corisphaera gracilis, C. strigilis, and C. mediterranea HOL) and small Syracosphaera species were the most important group within the May to June peak. In addition, there was a widespread occurrence, especially in the subsurface layer, of species inhabiting the intermediate photic zone during the late summer to fall period (Algirosphaera robusta, Calciopappus rigidus, Ophiaster hydroideus, and Calciosolenia spp.), while Rhabdosphaera clavigera and Syracosphaera pulchra were most important during the summer months. Among the flagellate groups, Cabrini et al. (2012) reported silicoflagellates and ebridians from the Gulf of Trieste. Worldwide, these silicifying groups make a minor contribution to phytoplankton, and little is known about their specific vertical and seasonal distribution because only a few studies have dealt with their occurrence in water samples. An improved knowledge of their ecological characteristics would be of great value, considering their potential use in paleoecological reconstructions. In the present dataset, the occurrence of silicoflagellates was restricted to the fall-winter-spring period. Octactis pulchra was the dominant species, occurring throughout the water column from September to March, with peak values (8x104 cells/liter) in January. Dictyocha species were present from September to January, primarily in the subsurface layers, while Distephanus speculum occurred only sporadically at different times and depths. Ebridians also showed a very clear seasonality, with Ebria tripartita occurring from January to March in the sub-surface layers and Hermesinum adriaticum occurring throughout the water column from June to August.

I coccolitoforidi sono microalghe nanoplanctoniche che producono uno scheletro esterno di minute placche carbonatiche. Sono presenti in tutti gli oceani, dalle zone equatoriali a quelle sub-polari, e in condizioni favorevoli possono proliferare in dense ed estese fioriture. Sono considerati tra i principali produttori primari marini, rappresentando circa il 15% della biomassa totale del fitoplancton. Inoltre, rivestono un ruolo importante nel controllo delle variazioni climatiche, giocando un ruolo fondamentale nel ciclo dello zolfo per la produzione di dimetilsolfuro e in quello del carbonio grazie ai processi di fotosintesi e calcificazione. Studi recenti sull’acidificazione degli oceani, dovuta all’aumento di anidride carbonica in atmosfera, hanno messo in evidenza un possibile impatto sulla calcificazione dei coccolitoforidi. Nell’ambito del progetto MedSea (Mediterranean Sea Acidification in a changing climate, EU-FP7, 2011-in corso), si è proposto di approfondire le conoscenze sulle associazioni a coccolitoforidi in un sito costiero del golfo di Trieste, dove esiste una serie temporale (C1-LTER, 1986-2013) di dati sul plancton. Scopi principali del lavoro sono valutare il contributo dei coccolitoforidi all’interno della comunità fitoplanctonica, anche in relazione alla serie storica disponibile per il sito, identificare la distribuzione stagionale delle diverse specie durante un anno di campionamento (agosto 2011-agosto 2012) e confrontare i risultati dell’analisi dei coccolitoforidi ottenuti attraverso diverse metodologie (microscopia ottica a contrasto di fase e a luce polarizzata e microscopia elettronica a scansione). I coccolitoforidi mostrano un’alta variabilità interannuale e un tipico andamento stagionale, con concentrazioni massime in autunno-inverno e minime in estate. Nell’intervallo analizzato, l’associazione a coccolitoforidi è dominata in autunno-inverno da Emiliania huxleyi, seguita da Acanthoica quattrospina, Syracosphaera pulchra e alcune specie minori (presenti solo in autunno, e.g. Ophiaster hydroideus, Calciosolenia brasiliensis, C. murrayi, Michaelsarsia adriaticus); in primavera l’associazione è dominata da olo-coccolitoforidi e subordinata E. huxleyi; in estate sono presenti principalmente E. huxleyi, Syracosphaera spp., Rhabdosphaera clavigera e olo-coccolitoforidi.

Coccolithophores are globally important marine calcifying phytoplankton that utilize a haplo-diplontic life cycle. The haplo-diplontic life cycle allows coccolithophores to divide in both life cycle phases and potentially expands coccolithophore niche volume. Research has, however, to date largely overlooked the life cycle of coccolithophores and has instead focused on the diploid life cycle phase of coccolithophores. Through the synthesis and analysis of global scanning electron microscopy (SEM) coccolithophore abundance data (n=2534), we find that calcified haploid coccolithophores generally constitute a minor component of the total coccolithophore abundance (≈ 2 %–15 % depending on season). However, using case studies in the Atlantic Ocean and Mediterranean Sea, we show that, depending on environmental conditions, calcifying haploid coccolithophores can be significant contributors to the coccolithophore standing stock (up to ≈30 %). Furthermore, using hypervolumes to quantify the niche of coccolithophores, we illustrate that the haploid and diploid life cycle phases inhabit contrasting niches and that on average this allows coccolithophores to expand their niche by ≈18.8 %, with a range of 3 %–76 % for individual species. Our results highlight that future coccolithophore research should consider both life cycle stages, as omission of the haploid life cycle phase in current research limits our understanding of coccolithophore ecology. Our results furthermore suggest a different response to nutrient limitation and stratification, which may be of relevance for further climate scenarios. Our compilation highlights the spatial and temporal sparsity of SEM measurements and the need for new molecular techniques to identify uncalcified haploid coccolithophores. Our work also emphasizes the need for further work on the carbonate chemistry niche of the coccolithophore life cycle.

Silicoflagellate populations and fluxes were analyzed from water samples and sediment traps in several basins of the eastern Mediterranean and Black Sea, to show species distribution in response to ecological factors and compared with the Quaternary records of the region. In the eastern Mediterranean, Dictyocha stapedia was the most abundant species, represented by two varieties: var. stapedia, smaller and with an apex spine, that dominated in the pelagic settings, and var. aspinosa, larger and lacking an apex spine, that dominated in the north Adriatic Sea. Dictyocha aculeata was the second most abundant species, Octactis pulchra was seasonally dominant in the Adriatic Sea. Stephanocha speculum occurred sporadically in the Adriatic Sea with 6-sided normal-sized specimens, but was nearly absent from pelagic assemblages. In the Black Sea, assemblages and fluxes were characterized by larger 7-sided skeletons of D. speculum with apex spines and a lower abundance of O. pulchra.

Fibrocapsa japonica resting cysts were detected in coastal sediments of the Marche region (northern Adriatic Sea, Italy), where summer blooms regularly occur. Sampling was carried out along 18 transects (2 stations each) during May–June 2007. The identification and counting of raphidophyte cysts were carried out under the inverted microscope and molecular analyses were applied to sediment samples to confirm species-specific identification. Raphidophyte cysts were recorded in almost all stations with maximum abundance of 9 ± 5 and 12 ± 3 cysts g−1 dw for cysts of F. japonica and undetermined Raphidophyceae, respectively. Cyst formation was induced in F. japonica monoclonal cultures under different conditions: shadow-optimal temperature and dark-low temperature treatment; both experiments were performed at two salinity values (30 and 35). Cyst formation (preliminary cysts) was observed in both experiments, although with different encystment rates. However, only a further permanence in the dark at 15 °C in microplates led to the formation of mature cysts, probably supported by the possibility to adhere to solid surfaces. Before pre-cyst formation, vegetative cells showed a cytoplasmatic “brown body”.