Metabarcoding and microscopy characterization of phytoplankton from frontal areas of the Argentine Sea

The Argentine Sea is worldwide recognized as a highly productive area, characterized by extensive phytoplankton blooms during spring and summer. Despite the well-known importance of frontal areas for biomass accumulation, phytoplankton diversity remains poorly studied. In an unprecedented approach for the Argentine Sea, we combined microscopy and 18Sv4 metabarcoding analyses for a refined assessment of summer phytoplankton composition in three understudied frontal areas of the Argentine Sea (≈43°−55°S), with contrasting oceanographic conditions. Metabarcoding and microscopy analyses agreed on the detection of the dominant phytoplanktonic groups in the different frontal areas studied; chlorophytes in Valdés Peninsula, dinoflagellates in waters off Blanco Cape, and diatoms in de los Estados Island. The analysis of the phytoplankton community was significantly enriched by combining both techniques, microscopy provided cell abundances and biomass data and metabarcoding provided greater detail on species composition, revealing an important specific richness of dinoflagellates, diatoms and other delicate groups, such as chlorophytes. However, we also considered differences between the methods for certain taxa at a lower taxonomic level (species/genus) of the dominant taxa, such as the underestimation of the diatoms Asterionellopsis glacialis and Pseudo-nitzschia spp. and the overestimation of Chaetoceros contortus by metabarcoding in comparison to microscopic counts. The detection of several taxa belonging to small and delicate groups, previously overlooked due to the lack of distinct morphological features, establishes a baseline for future studies on phytoplankton diversity in the Argentine Sea

Correction to: Detection of the phycotoxin pectenotoxin-2 in waters around King George Island, Antarctica

A correction to this paper has been published: https://doi.org/10.1007/s00300-021-02834-3</jats:p

Detection of the phycotoxin pectenotoxin-2 in waters around King George Island, Antarctica

In order to set a base line for the observation of planktonic community changes due to global change, protistan plankton sampling in combination with phycotoxin measurements and solid phase adsorption toxin tracking (SPATT) was performed in two bays of King George Island (KGI) in January 2013 and 2014. In addition, SPATT sampling was performed in Potter Cove during a one-year period from January 2014 until January 2015. Known toxigenic taxa were not firmly identified in plankton samples but there was microscopical evidence for background level presence of Dinophysis spp. in the area. This was consistent with environmental conditions during the sampling periods, especially strong mixing of the water column and low water temperatures that do not favor dinoflagellate proliferations. Due to the lack of significant abundance of thecate toxigenic dinoflagellate species in microplankton samples, no phycotoxins were found in net tow samples. In contrast, SPATT sampling revealed the presence of dissolved pectenotoxin-2 (PTX-2) and its hydrolyzed form PTX-2 seco acid in both bays and during the entire one-year sampling period. The presence of dissolved PTX in coastal waters of KGI is strong new evidence for the presence of PTX-producing species, i.e., dinoflagellates of the genus Dinophysis in the area. The presence of phycotoxins and their respective producers, even at the low background concentrations found in this study, may be the seed of possible proliferations of these species under changing environmental conditions. Furthermore, phycotoxins can be used as chemotaxonomic markers for a very specific group of plankton thus allowing to track the presence of this group over time.Fil: Krock, Bernd. Alfred Wegener Institut-Helmholtz Zentrum für Polarund Meeresforschung; AlemaniaFil: Schloss, Irene Ruth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Universidad Nacional de Tierra del Fuego; ArgentinaFil: Trefault, Nicole. Universidad de Santiago de Chile; ChileFil: Tillmann, Urban. Alfred Wegener Institut-Helmholtz Zentrum für Polarund Meeresforschung; AlemaniaFil: Hernando, Marcelo Pablo. Comisión Nacional de Energía Atómica; ArgentinaFil: Deregibus, Dolores. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Antoni, Julieta Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Almandoz, Gaston Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Hoppenrath, Mona. Alfred Wegener Institut-Helmholtz Zentrum für Polarund Meeresforschung; Alemani

Response of a natural Antarctic phytoplankton assemblage to changes in temperature and salinity

The climate around the Western Antarctic Peninsula (WAP) is rapidly changing and dramatically affecting marine coastal waters. Increases in air and seawater temperatures, not matter how small, can alter coastal biological communities due to both temperature increases as well as salinity reduction from glacier melting. The aim of this study was to evaluate the individual and combined effects of elevated sea surface temperature (+4 °C) and decreased salinity (−4) on growth and assemblage composition of natural summer phytoplankton from Potter Cove (King George Island, South Shetlands, northern WAP), using an outdoor microcosm experiment. Pigment composition was analyzed by high performance liquid chromatography (HPLC/Chemtax) and species composition by light and electron microscopy. Increases in phytoplankton biomass during the first 3 days at elevated-temperatures coincided with an increase in the abundance and the specific growth rate of small centric diatoms (Chaetoceros socialis and Shionodiscus gaarderae, mostly observed in temperate waters) and unidentified small phytoflagellates &lt;5 μm. In contrast, pennate diatoms significantly decreased. At the end of the experiment on day 7, under nitrate and phosphate limitation, chlorophytes abundances increased under low salinity whereas prasinophytes decreased in all treatments. This study suggests that climate change could notably affect Antarctic phytoplankton composition by favouring temperate-water species previously undetected in Antarctic waters, such us S. gaarderae. Moreover, the observed changes in phytoplankton structure, associated with an increase of nano- over micro-size taxa, could have important implications for future Antarctic food webs

Detection of the phycotoxin pectenotoxin-2 in waters around King George Island, Antarctica

In order to set a base line for the observation of planktonic community changes due to global change, protistan plankton sampling in combination with phycotoxin measurements and solid phase adsorption toxin tracking (SPATT) was performed in two bays of King George Island (KGI) in January 2013 and 2014. In addition, SPATT sampling was performed in Potter Cove during a one-year period from January 2014 until January 2015. Known toxigenic taxa were not firmly identified in plankton samples but there was microscopical evidence for background level presence of Dinophysis spp. in the area. This was consistent with environmental conditions during the sampling periods, especially strong mixing of the water column and low water temperatures that do not favor dinoflagellate proliferations. Due to the lack of significant abundance of thecate toxigenic dinoflagellate species in microplankton samples, no phycotoxins were found in net tow samples. In contrast, SPATT sampling revealed the presence of dissolved pectenotoxin-2 (PTX-2) and its hydrolyzed form PTX-2 seco acid in both bays and during the entire one-year sampling period. The presence of dissolved PTX in coastal waters of KGI is strong new evidence for the presence of PTX-producing species, i.e., dinoflagellates of the genus Dinophysis in the area. The presence of phycotoxins and their respective producers, even at the low background concentrations found in this study, may be the seed of possible proliferations of these species under changing environmental conditions. Furthermore, phycotoxins can be used as chemotaxonomic markers for a very specific group of plankton thus allowing to track the presence of this group over time.Este artículo tiene una corrección (ver "Documentos relacionados").Facultad de Ciencias Naturales y Muse

Response of a natural Antarctic phytoplankton assemblage to changes in temperature and salinity

The climate around the Western Antarctic Peninsula (WAP) is rapidly changing and dramatically affecting marine coastal waters. Increases in air and seawater temperatures, not matter how small, can alter coastal biological communities due to both temperature increases as well as salinity reduction from glacier melting. The aim of this study was to evaluate the individual and combined effects of elevated sea surface temperature (+4 °C) and decreased salinity (−4) on growth and assemblage composition of natural summer phytoplankton from Potter Cove (King George Island, South Shetlands, northern WAP), using an outdoor microcosm experi-ment. Pigment composition was analyzed by high performance liquid chromatography (HPLC/Chemtax) and species composition by light and electron microscopy. Increases in phytoplankton biomass during the first 3 days at elevated-temperatures coincided with an increase in the abundance and the specific growth rate of small centric diatoms (Chaetoceros socialis and Shionodiscus gaarderae, mostly observed in temperate waters) and unidentified small phytoflagellates &lt; 5 μm. In contrast, pennate diatoms significantly decreased. At the end of the experiment on day 7, under nitrate and phosphate limitation, chlorophytes abundances increased under low salinity whereas prasinophytes decreased in all treatments. This study suggests that climate change could notably affect Antarctic phytoplankton composition by favouring temperate-water species previously undetected in Antarctic waters, such us S. gaarderae. Moreover, the observed changes in phytoplankton structure, associated with an increase of nano- over micro-size taxa, could have important implications for future Antarctic food webs.Facultad de Ciencias Naturales y Muse

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Ensayos de toxicidad de zinc sobre la diatomea bentónica Halamphora luciae (Amphipleuraceae, Ochrophyta)

Se evaluó el efecto del zinc en cultivos axénicos de la diatomea bentónica Halamphora luciae aislada a partir de los sedimentos superficiales del estuario de Bahía Blanca. Las hipótesis que se pusieron a prueba fueron: a) la exposición al zinc produce una alteración en la tasa de crecimiento y composición de pigmentos fotosintéticos, b) la exposición al metal desencadena un estado de estrés oxidativo que provoca daño en los lípidos, aumento de compuestos fenólicos y aumento de la actividad superóxido dismutasa, c) en presencia del metal aumenta la movilidad celular conjuntamente con la producción de mucílago extracelular, d) las células crecidas en presencia de zinc exhiben cambios en la morfología y tamaño de los frústulos. Todos los bioensayos se hicieron por cuadruplicado en cristalizadores inoculados con 200 x 103 células e incubados a 12°C y con un fotoperíodo 12:12. Se seleccionaron dos puntos finales para los bioensayos (4 y 9 días, fase aguda y crónica, respectivamente).Se aplicó un ANOVA de dos factores (tratamiento y tiempo), considerando significativas las diferencias para p<0,05. Para determinar la CI50, se hicieron cultivos por triplicado en medio marino f/2 adicionados con dosis crecientes del metal y se determinó un valor de 50 μM. La exposición a la CI50 no modificó la tasa de crecimiento exponencial pero redujo a la mitad la densidad final de células. Tanto la cantidad de hidratos de carbono solubles en el medio de cultivo como la relación entre la concentración de clorofila a y de los pigmentos antena no varió luego de la exposición al zinc en ambos puntos finales. La etapa aguda se caracterizó por un aumento en el porcentaje de células en movimiento, una mayor producción de mucílago y la duplicación de la actividad superóxido dismutasa. Hacia la fase crónica solo se detectó un aumento significativo en la velocidad de desplazamiento de las células tratadas con zinc. En ambos tiempos, no se registró un incremento en los compuestos fenólicos ni en la peroxidación de lípidos. El análisis de sustancias poliméricas extracelulares solubles mostró una mayor heterogeneidad en los productos aislados de los cultivos con metal pero en ambos casos la glucosa fue el monosacárido mayoritario. La morfología del frústulo no presentó teratologías, pero disminuyó la relación superficie/volumen y el tamaño de las areolas en las células expuestas al metal. De los resultados observados se concluye que la biomasa celular, la movilidad, la relación superficie/volumen de las células, el tamaño de las areolas y la cuantificación de la actividad superóxido dismutasa resultan buenos indicadores de la toxicidad del zinc en bioensayos incubados durante 96 horas para la diatomea Halamphora luciae.Fil:Antoni, Julieta Silvina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina