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Mechanisms underlying recovery of zooplankton in Lake Orta after liming
Get PDFThe goal of this study was to improve the understanding of the large-scale mechanisms underlying the recovery of the zooplankton of Lake Orta from historical contamination, following reduced input of ammonia and metals and the subsequent 1989/90 liming intervention. The industrial pollution had been severe and long-lasting (1929-1990). Zooplankton biodiversity has improved, but most of the new taxa appearing in our counts are rotifers, while many calanoids and the large cladoceran predators (Bythotrephes and Leptodora) that are common in the nearby Lake Maggiore, were still absent from Lake Orta 17 years after liming. To aid understanding of the large-scale mechanisms controlling changes in annual richness, we assessed the annual persistence (P) of Crustacea and Rotifera taxa as an estimator of whether propagules that survived introduction, as result of the natural recolonization process, also thrived. We found that the rate of introduction of zooplankton colonists and their persistence in the water column of Lake Orta changed from 1971 to 2007. New rotifer taxa appeared in the lake after the mid-1980s, when discharge of toxic substances decreased, but their annual persistence was low (P<0.5) until the turn of the century. The numerical values of rotifer and crustacean persistence in Lake Orta were unexpectedly high in 2001 and 2007 (0.55 and 0.72 for rotifers, 0.85 and 0.86 for crustacean, respectively), much higher than in limed lakes in Sudbury, Canada, and in adjacent Lake Maggiore. We hypothesize this could be related to the lack of Cladoceran predators and zooplanktivorous fish in the pelagic waters of Lake Orta
A non-deterministic approach to forecasting the trophic evolution of lakes
Get PDFLimnologists have long recognized that one of the goals of their discipline is to increase its predictive capability. In recent years, the role of prediction in applied ecology escalated, mainly due to man\u27s increased ability to change the biosphere. Such alterations often came with unplanned and noticeably negative side effects mushrooming from lack of proper attention to long-term consequences. Regression analysis of common limnological parameters has been successfully applied to develop predictive models relating the variability of limnological parameters to specific key causes. These approaches, though, are biased by the requirement of a priori cause-relation assumption, oftentimes difficult to find in the complex, nonlinear relationships entangling ecological data. A set of quantitative tools that can help addressing current environmental challenges avoiding such restrictions is currently being researched and developed within the framework of ecological informatics. One of these approaches attempting to model the relationship between a set of inputs and known outputs, is based on genetic algorithms and programming (GP). This stochastic optimization tool is based on the process of evolution in natural systems and was inspired by a direct analogy to sexual reproduction and Charles Darwin\u27s principle of natural selection. GP works through genetic algorithms that use selection and recombination operators to generate a population of equations. Thanks to a 25-years long time-series of regular limnological data, the deep, large, oligotrophic Lake Maggiore (Northern Italy) is the ideal case study to test the predictive ability of GP. Testing of GP on the multi-year data series of this lake has allowed us to verify the forecasting efficacy of the models emerging from GP application. In addition, this non-deterministic approach leads to the discovery of non-obvious relationships between variables and enabled the formulation of new stochastic models
Reduction in camera-specific variability in [123I]FP-CIT SPECT outcome measures by image reconstruction optimized for multisite settings: impact on age-dependence of the specific binding ratio in the ENC-DAT database of healthy controls
Get PDFPurpose Quantitative estimates of dopamine transporter availability, determined with [123I]FP-CIT SPECT, depend on the SPECT equipment, including both hardware and (reconstruction) software, which limits their use in multicentre research and clinical routine. This study tested a dedicated reconstruction algorithm for its ability to reduce camera-specific intersubject variability in [123I]FP-CIT SPECT. The secondary aim was to evaluate binding in whole brain (excluding striatum) as a reference for quantitative analysis. Methods Of 73 healthy subjects from the European Normal Control Database of [123I]FP-CIT recruited at six centres, 70 aged between 20 and 82 years were included. SPECT images were reconstructed using the QSPECT software package which provides fully automated detection of the outer contour of the head, camera-specific correction for scatter and septal penetration by transmission-dependent convolution subtraction, iterative OSEMreconstruction including attenuation correction, and camera-specific Bto kBq/ml^ calibration. LINK and HERMES reconstruction were used for head-to-head comparison. The specific striatal [123I]FP-CIT binding ratio (SBR) was computed using the Southampton method with binding in the whole brain, occipital cortex or cerebellum as the reference. The correlation between SBR and age was used as the primary quality measure. Results The fraction of SBR variability explained by age was highest (1) with QSPECT, independently of the reference region, and (2) with whole brain as the reference, independently of the reconstruction algorithm. Conclusion QSPECT reconstruction appears to be useful for reduction of camera-specific intersubject variability of [123I]FP-CIT SPECT in multisite and single-site multicamera settings. Whole brain excluding striatal binding as the reference provides more stable quantitative estimates than occipital or cerebellar binding
Considerazioni generali sulla evoluzione a lungo termine delle caratteristiche chimiche del Lago Maggiore, con particolare riferimento al triennio 2013-2015
No full textNot availableRicerche sull\u27evoluzione del Lago Maggiore. Aspetti limnologici. Programma triennale 2013-2015. Campagna 2015 e rapporto triennale 2013-2015. Considerazioni generali sulla evoluzione a lungo termine delle caratteristiche chimiche del Lago Maggiore, con particolare riferimento al triennio 2013-2015. Riscaldamento delle acque ed effetti sull\u27idrochimica, variazioni nel contenuto ionico delle acque, dinamiche a lungo termine dei nutrienti algali
Indagini sull\u27evoluzione del popolamento zooplanctonico: confronto con i dati pregressi anche alla luce delle mutate condizioni meteo-climatiche. Sintesi del triennio 2013-2015
No full textNot availableRicerche sull\u27evoluzione del Lago Maggiore. Aspetti limnologici. Programma triennale 2013-2015. Campagna 2015 e rapporto triennale 2013-2015. Indagini sull\u27evoluzione del popolamento zooplanctonico: confronto con i dati pregressi anche alla luce delle mutate condizioni meteo-climatiche. Sintesi del triennio 2013-201
Il mescolamento invernale del lago: dipendenza dalla meteorologia locale, dalle oscillazioni oceaniche nord-atlantiche (NAO) e dai cambiamenti climatici globali
No full textNot availableCONTENUTI CALORICI, TEMPERATURA, OSSIGENO E STABILIT? TERMICA NELLE ACQUE DEL LAGO MAGGIORE NELL\u27ANNO 2015: Profondit? di mescolamento. ASPETTI DELLA DINAMICA DEL LAGO MAGGIORE CONDIZIONATI DAL CLIMA: Rapporto tra temperatura dell\u27aria e dell\u27acqua ; Contenuto di calore; Profondit? di mescolamento; Concentrazioni dell\u27 ossigeno ipolimnico; Stabilit? termica ; Rapporti tra gli indici M, NAOW e Trend. General Lake Mode
The assessment of quality standards in eu groundwater dependent ecosystems: the case of ionized ammonia (NH4+)
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Comparative genomics and phylogenetic analyses of non-marine picocyanobacteria
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