116 research outputs found
Phytoplankton metabolism in a stratified nearshore ecosystem with recurrent harmful algal blooms (HABs)
No full textThe coastal ocean is experiencing changes in its physical and chemical properties that strongly affect planktonic metabolism assemblages and, in some cases, favor the occurrence of harmful algal blooms (HABs). Here we analyze the variations in phytoplankton biomass, gross and net primary production (NCP) as well as community respiration (CR) at two nearshore sampling sites (P1 and P2) located at a Mediterranean beach where high biomass HABs are recurrent. At P1, the most exposed site, phytoplankton chlorophyll was generally low, whereas dinoflagellates outbreaks of the genus Gymnodinium and Alexandrium were recurrent during summer at P2 spanning for 10-20 days. During bloom episodes, NCP increased up to 10-fold (>80 mmol O2 m-3 day-1). Contrastingly, variation in CR only reached an average of 1.8-fold the rates of non-bloom conditions. Remarkably, although the enhanced NCP:CR ratio suggests net autotrophic population growth, production per unit biomass at P1 and P2 was not significantly different. Our results indicate that although summer conditions favor the necessary primary production enhancement leading to HAB occurrences, the short-term dynamics driving high biomass episodes are not driven by metabolic variations but instead are governed by subtle accumulative processes of some flagellate species in the nutrient-rich nearshore environment.This research was financed by HYDROALGAL (RTC-2016-4812-5) project and partially carried out within the framework of the activities of the Spanish Government through the “María de Maeztu Centre of Excellence” accreditation to IMEDEA (CSIC-UIB) (CEX2021-001198-M). A.R-de-G. was supported by a post-doctoral fellowship “Incorporacion de personal investigador” funded by the Ministry of Innovation, Research and Tourism of the Balearic Island Government.With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001198-M).Peer reviewe
Patterns in planktonic metabolism in the Mediterranean Sea
No full textPlanktonic gross community production (GPP), net community production (NCP) and community respiration (CR) across the Mediterranean Sea was examined in two cruises, Thresholds 2006 and 2007, each crossing the Mediterranean from West to East to test for consistent variation along this longitudinal gradient in late spring to early summer. GPP averaged 2.4±0.4 mmol O2 m−3 d−1, CR averaged 3.8±0.5 mmol O2 m−3 d−1, and NCP averaged – 0.8±0.6 mmol O2 m−3 d−1 across the studied sections, indicative of a tendency for a net heterotrophic metabolism in late spring to early summer, prevalent across studied sections of the Mediterranean Sea as reflected in 70% of negative NCP estimates. The median P/R ratio was 0.6, also indicating a strong prevalence of heterotrophic communities (P/R0.05). The net heterotrophy of the studied sections of the Mediterranean Sea indicates that allochthonous carbon should be important to subsidise planktonic metabolism during the late spring.This research was funded by the THRESHOLDS integrated project (003933-2), funded by the Framework Program 6 of the EU, and a complementary action (CTM2005- 24238-E) funded by the Plan Nacional de I+D, Spanish Ministry of Science and Innovation. A. Regaudie-de-Gioux was supported by the EU Marie Curie EST project METAOCEANS (MEST-CT-2005- 019678).Peer Reviewe
Compensation irradiance for planktonic community metabolism in the ocean
No full text9 páginas, 5 figuras, 2 tablas.The light compensation irradiance for planktonic metabolic balance, defined as the irradiance where gross planktonic primary production equals community respiration, is an important property describing ecosystem dynamics. Planktonic communities receiving irradiances above the compensation irradiance or compensation depth (i.e., the depth at which the compensation irradiance is received) are autotrophic and act as CO2 sinks, whereas those at lower irradiances or located deeper in the water column act as CO2 sources. However, this property is undefined for heterotrophic communities in which metabolic balance is not set by light availability. The compensation irradiance for planktonic metabolism in the ocean was quantified experimentally and calculated using data available in the literature to assess its variability and possible controls. Gross primary production by the oceanic planktonic communities examined here meet their respiratory requirements at irradiances of about 1.1 ± 0.4 mol quanta m−2 d−1 and tend to be autotrophic above a depth of 36 ± 9 m, on average. The depth of nitracline is closely correlated with the compensation depth for community metabolism across the studied areas, but the compensation depth tends to be located above the depth of the nitracline. This is expected from the facts that the underlying, net heterotrophic communities should act as sources of inorganic nutrients and that the nitracline cannot develop within the mixed layer where the compensation depth is often located. These results imply that the planktonic communities examined extending from 36 m depth, on average, to the bottom of the euphotic layer tend to be heterotrophic, acting as CO2 and inorganic nutrient sources.Esta investigación ha sido financiada gracias a los proyectos RODA (CTM-2004-06842-CO3-O2) y ATOS (POL2006-00550/CTM), proyecto Humboldt-2009 (CTM2008-02497-E), y la expedición del proyecto Malaspina-2010 financiado por el programa CONSOLIDER Ingenio-2010(CSD2008-00077), todos ellos subvencionados por el Plan Nacional de I+D del Ministerio de España de Ciencia e Innovación. Aurore Regaudie-de-Gioux ha sido financiada por el programa de la Unión Europea Marie Curie EST, proyecto Metaoceans (MEST-CT-2005-019678).Peer reviewe
Plankton Metabolism in the Ocean
No full textThis live data set reports gross primary production (GPP), community respiration (CR) and net community production (NCP) of oceanic plankton communities. The methods used to measure GPP, CR, and NCP varied; these include oxygen evolution in dark-light bottles (Carpenter 1965; Carrit and Carpenter 1966),tracer additions (14C additions, SteemanNielsen 1952, and 18O-labeled H2O, Bender etal. 1987), incubation-free methods, including analyses of triple oxygen isotopes (Luz etal. 2000), O2:Ar ratios (Emerson 1987; Spitzer and Jenkins 1989; Emerson et al. 1993),non-intrusivebio-optical (OPT) methods (Claustre et al. 2008), fast repetition rate fluorometry (FRRF, Kolber and Falkowski 1993), and oxygen sensors mounted on gliders (Tengberg et al. 2006; Nicholson et al. 2008) and buoys (Boutin and Merlivat2009). Characteristics of each method are discussed by Robinson and Williams (2005)and Duarte et al.(2013). The article Global patterns in oceanic planktonic metabolism by Regaudie de Gioux, A. and Duarte, C.M. is currently in press to be published in Limnology and Oceanography in 2013. This dataset is subject to a Creative Commons License Attribution-Noncommercial-ShareAlike 3.0 Unported.This data set includes recently published data and our own unpublished data on plankton community metabolism using both incubation and incubation-free techniques from 92 individual reports published between 1981 and 2011, from stations across the open ocean, including the Mediterranean Sea.Peer reviewe
Surgical Models of Liver Regeneration in Pigs. A Practical Review of the Literature for Researchers
No full textThe remarkable capacity of regeneration of the liver is well known, although the involved mechanisms are far from being understood. Furthermore, limits concerning the residual functional mass of the liver remain critical in both fields of hepatic resection and transplantation. The aim of the present study was to review the surgical experiments regarding liver regeneration in pigs to promote experimental methodological standardization. The Pubmed, Medline, Scopus, and Cochrane Library databases were searched. Studies evaluating liver regeneration through surgical experiments performed on pigs were included. A total of 139 titles were screened, and 41 articles were included in the study, with 689 pigs in total. A total of 29 studies (71% of all) had a survival design, with an average study duration of 13 days. Overall, 36 studies (88%) considered partial hepatectomy, of which four were an associating liver partition and portal vein ligation for staged hepatectomy (ALPPS). Remnant liver volume ranged from 10% to 60%. Only 2 studies considered a hepatotoxic pre-treatment, while 25 studies evaluated additional liver procedures, such as stem cell application, ischemia/reperfusion injury, portal vein modulation, liver scaffold application, bio-artificial, and pharmacological liver treatment. Only nine authors analysed how cytokines and growth factors changed in response to liver resection. The most used imaging system to evaluate liver volume was CT-scan volumetry, even if performed only by nine authors. The pig represents one of the best animal models for the study of liver regeneration. However, it remains a mostly unexplored field due to the lack of experiments reproducing the chronic pathological aspects of the liver and the heterogeneity of existing studies
Single snapshot imaging of optical properties (SSOP) for perfusion assessment during gastric conduit creation for esophagectomy: An experimental study on pigs
No full textAnastomotic leakage (AL) is a serious complication occurring after esophagectomy. The current knowledge suggests that inadequate intraoperative perfusion in the anastomotic site contributes to an increase in the AL rate. Presently, clinical estimation undertaken by surgeons is not accurate and new technology is necessary to improve the intraoperative assessment of tissue oxygenation. In the present study, we demonstrate the application of a novel optical technology, namely Single Snapshot imaging of Optical Properties (SSOP), used to quantify StO2% in an open surgery experimental gastric conduit (GC) model. After the creation of a gastric conduit, local StO2% was measured with a preclinical SSOP system for 60 min in the antrum (ROI-A), corpus (ROI-C), and fundus (ROI-F). The removed region (ROI-R) acted as ischemic control. ROI-R had statistically significant lower StO2% when compared to all other ROIs at T15, T30, T45, and T60 (p < 0.0001). Local capillary lactates (LCLs) and StO2% correlation was statistically significant (R = -0.8439, 95% CI -0.9367 to -0.6407, p < 0.0001). Finally, SSOP could discriminate resected from perfused regions and ROI-A from ROI-F (the future anastomotic site). In conclusion, SSOP could well be a suitable technology to assess intraoperative perfusion of GC, providing consistent StO2% quantification and ROIs discrimination
Extrapolation of ex-situ bacterial production and community respiration rates at 22°C from incubations with water bottle samples from METEOR cruise M156
No full textThis dataset includes measured and calculated data over the epipelagic layer (0-200 m depth) of 25 stations with 14 of them inside or in the vicinity of a cyclonic eddy that formed off Mauritania along the ∼ 900 km zonal corridor between Mauritania and the Cabo Verde islands in the eastern Tropical North Atlantic during the M156 cruise on the RV Meteor from July 3rd to August 1st 2019. To extrapolate BP and CR rates to 22°C, we used equations from López-Urrutia and Morán for BP (BPU; 2007) and from Regaudie de Gioux and Duarte for CR (CRRG; 2012). we compared the rates of BP and CR measured ex-situ (BP_ex-situ and CR_ex-situ) with the rates obtained from BPU (BPU_14°C) and CRRG (CRRG_average temperature) at the temperature set during the incubations. References: López-Urrutia and Morá ,2007(https://doi.org/10.1890/06-1641); Regaudie de Gioux and Duarte, 2012 (https://doi.org/10.1029/2010GB003907
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