Roberto Bertoni

Italian National Research Council | CNR · Institute of Ecosystem Study ISE

LaBr3:Ce crystals have good scintillation properties for X-ray spectroscopy. Initially, they were introduced for radiation imaging in medical physics with either a photomultiplier or SiPM readout, and they found extensive applications in homeland security and gamma-ray astronomy. We used 1″ round LaBr3:Ce crystals to realize compact detectors with...

In the oligotrophic Lake Maggiore, the majority of picocyanobacteria are phycoerythrin-bearing Synechococcus-type belonging to cluster 5 (Pcy-5). Their distribution was followed in a seven-year study along a depth gradient from the surface down to 350 m in relation to Transparent Exopolymer Particles (TEP), Total Organic Carbon (TOC), Chlorophyll-a...

Beam hodoscopes based on 32 × 32 square polystyrene scintillating fibres along X/Y, having section 3 × 3 mm2 or 1 × 1 mm2, have been designed and characterised for monitoring low-energy charged particle beams. Each fibre is read by a SiPM and the signal is digitised and analysed off-line. Hodoscopes were exposed to the 60 MeV/c negative muon beam a...

Celebrating an anniversary is, at the same time, appreciation of past well-being and hope for a favourable future. However, celebrating the birthday of a scientific journal is not just an act of hope in the future, but rather an act of faith in research and in science as tools for the advancement of the human species....

Transparent Exopolymer Particles (TEP) play an important role in the organic carbon cycle of many aquatic systems but the production and distribution of TEP have been studied mainly in the marine environment, neglecting the large oligotrophic lakes. We selected Lake Maggiore, one of the most important freshwater reserve in Northern Italy, to study...

This article is simultaneously a call for, a study of, and a contribution to the preservation of scientific heritage. Focusing on the heritage of a disciplinary niche like that of limnology, we take the specific heritage of the Istituto Italiano di Idrobiologia ‘Dr. Marco De Marchi’ (Istituto) as a case study to illustrate the present challenges an...

This atlas aims to provide an overview of the picocyanobacteria cultures hold by the CNR-IRSA collection. These are monoclonal strains mostly of the genera Synechococcus and Cyanobium. These strains were mainly isolated from lakes of different trophic status around the globe and, so far, they are not available in other collections of algae and (pic...

Antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) are worldwide considered as emerging contaminants of large interest, and a primary threat to human health. It is becoming clear that the environment plays a central role in the transmission, spread, and evolution of antibiotic resistance. Although marine systems have been la...

Picocyanobacteria of the genus Synechococcus are major contributors to global primary production and nutrient cycles due to their oxygenic photoautotrophy, their abundance, and the extensive distribution made possible by their wide-ranging biochemical capabilities. The recent recovery and isolation of strains from the deep euxinic waters of the Bla...

The beta lactamase gene blaCTX-M, responsible of the resistance to cephalosporins, has been detected in microbes from hospitals to open waters. We studied the seasonality and stability of blaCTX-M in Lake Maggiore over 3 years and the role of potential inputs of allochthonous bacteria and/or antibiotic pollution in promoting its occurrence. blaCTX-...

The Black Sea is the largest meromictic sea with a reservoir of anoxic water extending from 100 to 1000 m depth. These deeper layers are characterised by a poorly understood fluorescence signal called “deep red fluorescence”, a chlorophyll a- (Chl a) like signal found in deep dark oceanic waters. In two cruises, we repeatedly found up to 103 cells...

Phytoplankton (PCC) and prokaryoplankton community compositions were studied in five perialpine lakes (Garda, Maggiore, Como, Iseo, and Lugano) of different trophic conditions and mixing regimes, using inverted microscopy and CARD-FISH technique. The aim of this research was to assess, for the first time in these lakes, the relationships among PCC,...

Planktonic cyanobacteria belonging to the genus Synechococcus are ubiquitously distributed in marine and fresh waters, substantially contributing to total carbon fixation on a global scale. While their ecological relevance is acknowledged, increasing resolution in molecular techniques allows disentangling cyanobacteria's role at the micro-scale, wh...

The FAMU experiment aims to measure precisely the hyperfine splitting of the muonic-hydrogen atom ground state. A preliminary measurement of the transfer rate of muons from hydrogen to heavier gases is needed. In June 2014, the FAMU pressurized gas target was exposed to the low energy pulsed muon beam at the RIKEN RAL (Rutherford Appleton Laborator...

Microgels such as transparent exopolymer particles (TEP) can be as important in freshwater as they are in the ocean because they constitute microenvironments of unique physical, chemical, and biological properties. Previous studies have shown that TEP concentrations can significantly contribute to the organic carbon pool in both marine and freshwat...

Freshwater cyanobacteria of the genus Synechococcus are ubiquitous and organized either as single cells of diverse morphology or as microcolonies of different size. We studied the formation of microcolonies induced by the mixotrophic nanoflagellate Poterioochromonas sp. grazing on two Synechococcus strains belonging to phylotypes with different con...

In spite of the title, this is not the beginning of a long and boring family saga. I simply need to take a few minutes of your time to explain the history of this journal: where it is coming from, why it is changing and where it is going...

In spite of the title, this is not the beginning of a long and boring family saga. I simply need to take a few minutes of your time to explain the history of this journal: where it is coming from, why it is changing and where it is going...

The presence of the mesophilic Thaumarchaeota (Thaum) in deep lakes seems to be restricted to oligotrophic lakes, where they have been found in the deep hypolimnion. We evaluated the vertical distribution of Thaum in six subalpine deep lakes, in spring and summer, to ascertain if there was a Thaum vertical gradient common to all the lakes in the re...

Limnologists 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’s increased ability to change the biosphere. Such alterations often came with unplanned and noticeably negative side effects mushrooming from la...

The impact of human activities on the spread and on the persistence of antibiotic resistances in the environment is still far from being understood. The natural background of resistances is influenced by human activities, and the wastewater treatment plants (WWTPs) are among the main sources of the release of antibiotic resistance into the environm...

Freshwater cyanobacteria of the genus Synechococcus are ubiquitous and organized either as single cells of diverse morphology or as microcolonies of different size. We studied the formation of microcolonies induced by the mixotrophic nanoflagellate Poterioochromonas sp. grazing on two Synechococcus strains belonging to phylotypes with different con...

The fate of antibiotic resistance genes (ARGs) in environmental microbial communities is of primary concern as prodromal of a potential transfer to pathogenic bacteria. Although of diverse origin, the persistence of ARGs in aquatic environments is highly influenced by anthropic activities, allowing potential control actions in well-studied environm...

Global warming has been shown to strongly influence inland water systems, producing noticeable increases in water temperatures. Rising temperatures, especially when combined with widespread nutrient pollution, directly favour the growth of toxic cyanobacteria. Climate changes have also altered natural water level fluctuations increasing the probabi...

The limnological research conducted at the Istituto Italiano di Idrobiologia over the last 75 years has taken an ecological and interdisciplinary approach, addressing the interdependence of chemical, physical and biological aspects of freshwaters. In this paper we have tried to reconstruct the evolution of this historic institute's activities, anal...

The interest for microorganisms inhabiting the hypolimnion and for their role in biogeochemical cycles of lakes is considerable, but knowledge is far from complete. The presence of chemolithoautotrophic Bacteria and mesophilic Archaea ( e.g ., Thaumarchaeota) assimilating inorganic carbon in the deep hypolimnion of lakes has been ascertained. We me...

In recent years, phenology has been proposed as an indicator to monitor systematically the state of the ecosystem and to detect changes triggered by perturbation of the environmental conditions. Recorded changes in the seasonal timing allowed to evaluate re-organizations of communities and drastic alterations of the ecosystem structure. The Europea...

The microbial diversity of moonmilk, a hydrated calcium carbonate speleothem, was evaluated from two Italian caves to provide context for the food web of highly-specialized troglobitic beetles, Cansiliella spp. (Leptodirinae), with distinctive carbon and nitrogen isotope values indicative of a novel food source. The moonmilk and associated percolat...

We studied the phylogenetic diversity of non-marine picocyanobacteria broadening the sequence data set with 43 new sequences of the 16S rRNA gene. The sequences were derived from monoclonal strains isolated from four volcanic high altitude athalassohaline lakes in Mexico, five glacial ultraoligotrophic North Patagonian lakes and six Italian lakes o...

Bacterial size and morphology are controlled by several factors including predation, viral lysis, UV radiation, and inorganic nu-trients. We observed that bacterial biovolume from the hypolimnion of two oligotrophic lakes is larger than that of bacteria living in the layer from surface to 20 m, roughly corresponding to the euphotic/epilimnetic zone...

We investigated the community structure of freshwater picocyanobacteria (Pcy) in the oligotrophic subalpine Lake Maggiore (North-ern Italy) using the least conserved sequences of the Internal Transcribed Spacer (ITS-1) fragment. The aim was to characterize the succession of Pcy Operational Taxonomic Units (OTUs) during a seasonal cycle at two envir...

La Rete Italiana di Ricerche Ecologiche a Lungo Termine (LTER–Italia) è costituita da enti e da scienziati che si occupano di ricerca ecologica in ecosistemi terrestri, d’acqua dolce e marini. Essi utilizzano lunghe serie temporali di dati ambientali e biologici come strumento diagnostico e prognostico per comprendere lo stato, il funzionamento e l...

UV radiation (UVR) has different effects on prokaryotic cells, such as, for instance, filamentation and aggregation in bacteria. Here we studied the effect of UVR on microcolony formation in two freshwater Synechococcus strains of different ribotypes (group B and group I) and phycobiliprotein compositions (phycoerythrin [PE] and phycocyanin [PC])....

The scaling of the solar ultraviolet radiation (UVR, 280–400nm) effect on phyto- and bacterio-plankton at the ecosystem level is difficult since its estimate is often based on short-time incubation experiments performed at fixed depths, neglecting the previous days’ radiation history and the variable radiation caused by vertical mixing. To examine...

In surface blooms, cell density is not evenly distributed with depth but shows a vertical abundance gradient, dependent on the hydrodynamics of water body and on cell buoyancy. To sample reproducibly and quantitatively cyanobacteria and algae blooms a simple Surface Bloom Sampler (SUBS) was designed. This instrument collects a known volume of water...

Through laboratory experiments, we tested whether UV radiation (UVR) induces filamentation in natural bacteria assemblages from North Andean Patagonian lakes. We incubated water from three different lakes for 72 h in four separate treatments: (1) UVR + PAR (photosynthetically active radiation), (2) 50% UVR + PAR, (3) PAR and (4) 50% PAR. The irradi...

The study of the hydrodynamics of the hypolimnion of a deep holo-oligomictic lake (Lake Maggiore, Northern Italy, z max = 370 m) during the last 28 years showed that hypolimnetic waters remained isolated, not exchanging with the mixing zone even in winter when the full overturn conditions are most likely. The thickness of the isolated layer can ran...

We analysed the long-term dynamics (1980–2007) of hypolimnetic and epilimnetic bacterial abundances and organic carbon concentrations, both dissolved (DOC) and particulate (POC), in the deep holo-oligomictic Lake Maggiore, included in the Southern Alpine Lakes Long-Term Ecological Research (LTER) site. During the 28 years of investigation, bacteria...

Picocyanobacteria (Pcy) diversity was studied in a set of ultraoligotrophic North Patagonian Andean lakes. The glacial lake system includes a central lake (Lake Nahuel Huapi, with its side basin, Lake Moreno) and four satellite lakes (Lakes Espejo, Correntoso, Gutiérrez and Mascardi) derived from a larger paleolake. Automated ribosomal intergenic s...

Pelagic food webs, with particular emphasis on microbial loops, were investigated in European alpine lakes. During two ice-free seasons (1996-1997) investigations of biomass structure in pelagic food webs were performed at 7 lakes in low-alkalinity mountain regions (Lake Districts). In 2000 (in some cases, 2001), late-summer (autumn) samples from 3...

The shallow Andean North Patagonian lakes are suitable environments for the evaluation of autotrophic and heterotrophic production under a scenario of high radiation in high dissolved organic matter (DOM) systems. We aimed to study the balance between primary and bacterial production in three shallow Andean lakes, in a summer sampling (high irradia...

In a deep, subalpine holo-oligomictic lake, the relative abundance of Archaea and Crenarchaeota, but not that of Bacteria, increases significantly with depth and varies seasonally. Cell-specific prokaryotic productivity is homogeneous along the water column. The concept of active Archaea observed in the deep ocean can therefore be extended to a dee...

We investigated the community composition and the relative size-shape distribution of bacterial assemblages in deep transparent lakes, where bacteria may be affected by harmful ultraviolet radiation (UVR). Summer samples of the euphotic zones of nine ultraoligotrophic lakes located in different drainage basins between 40u279 and 42u499S in the Nort...

We carried out laboratory experiments in one ultraoligotrophic pristine Andean lake (Lake Gutiérrez, Argentina) and in one subalpine lake that is now at the edge of the oligo-to mesotrophic condition (Lake Maggiore, Italy). Lake water was amended with phosphorus (+P), organic carbon (+C), alone or in combination (+CP), to test for short-term change...

We designed microcosm experiments to study the response of bacterial communities to altered predation pressure, in phosphorus-limited conditions. Different-sized predators were removed through filtration, yielding the following treatments: bacteria only (no predation, NP; <1 µm filtrate); small-sized predators (10P, <10µm filtrate) and small-to med...

We studied the vertical distribution of two mixotrophic ciliates, "Ophrydium naumanni" and "Stentor araucanus" in two contrasting summer seasons (strong vs. mild windy years) to determine whether differences in vertical mixing affect their success by changes in light availability for their endosymbiotic algae. Field experiments were done to evaluat...

The most remote regions of globe represent some of the least disturbed ecosystems, yet they are threatened by air pollution and by climatic change. The Himalaya is one of the most isolated regions in the world and least explored wildernesses outside the Polar Regions; and it is for this reason that the Tibetan Plateau is often referred to as the ‘T...

We measured biomass and primary production of picophytoplankton (PicoPhy: 0.2–2μm) and of autotrophic size fraction >2μm in six deep ultraoligotrophic lakes in the Andean-Patagonian region (around 41°S) during summer stratification. Surface Photosynthetically Active Radiation (PAR) ranged from 1277 to 1849μmol photons m−2s−1, and the euphotic zone,...

We studied the photosynthetic characteristics and genetic diversity of Synechococcus assemblages at two different light and mixing conditions in a deep oligotrophic lake (Lake Maggiore, Northern Italy). Sampling was performed at the beginning of summer stratification, when the base of the photic zone was isolated by the presence of a shallower ther...

The most remote regions of globe represent some of the least disturbed ecosystems, yet they are threatened by air pollution and by climatic change. The Himalaya is one of the most isolated regions in the world and least explored wildernesses outside the Polar Regions; and it is for this reason that the Tibetan Plateau is often referred to as the 'T...

I laghi sono ecosistemi complessi che, per essere compresi, devono essere studiati in un’ottica interdisciplinare. Questo testo è nato per offrire gli strumenti di base per capire e valutare le interazioni tra le diverse componenti dell’ecosistema lacustre e gli effetti di tali interazioni sulla sua evoluzione. Gli specialisti delle diverse discipl...

We compared the bacterivory of mixotrophic flagellates (MxFl) and of Daphnia longispina in a fishless high altitude lake with a simple food web. During the ice-free period of Lago Paione Superiore (LPS, Italian Central Alps) we measured species-specific direct uptake of fluores- cently labelled bacteria (FLB) by MxFl and D. longispina. Bacterial pr...

Stentor araucanus is a mixotrophic ciliate that, in Andean lakes, inhabits the upper epilimnetic levels, which are commonly avoided by other planktonic organisms. This freshwater heterotrich has dark pigmented cortical granules and lives autotrophically with endosymbiotic algae. The effect of photosynthetically active radiation (PAR) and ultraviole...

Stentor araucanus is a mixotrophic ciliate that, in Andean lakes, inhabits the upper epilimnetic levels, which are commonly avoided by other planktonic organisms. This freshwater heterotrich has dark pigmented cortical granules and lives autotrophically with endosymbiotic algae. The effect of photosynthetically active radiation (PAR) and ultraviole...

Research on the impact of natural radiation on aquatic biota requires novel instruments and methods enabling realistic tests of the effects of changing radiation on communities. This article describes an instrument devised to expose samples maintained in incubation flasks to the variable conditions experienced by the water masses in motion in the m...

Daphnia hyalina was used to assess the impact of zooplankton on the photosynthetic activity of picocyanobacteria. A phosphorus-limited laboratory system was designed, composed of 3-� m filtered lake water with natural assemblages to which non-axenic Synechococcus sp. was added. Different treatments with and without Daphnia were arranged; aliquots f...

The horizontal heterogeneity of seston, dissolved (DOC) and particulate (POC) organic matter, Chlorophyll-a (Chl) and of autotrophic (APP) and heterotrophic (HPP) picoplankton was evaluated seasonally during a two-year period in Lago Maggiore, a large deep oligotrophic lake in Northern Italy. The dissolved fraction resulted homogeneously distribute...

1. The photosynthetic efficiencies of the mixotrophic ciliate Ophrydium naumanni and the autotrophic dinoflagellate Gymnodinium paradoxum were investigated using laboratory and field experiments in Lake Moreno Oeste (41°5′S and 71°33′W, 758 m a.s.l.), in the Nahuel Huapi System (North Patagonia, Argentina). 2. The effect of different underwater lig...

In aquatic microbial ecology, it has been considered that most extracellular enzymes except phosphatases are of bacterial origin. We tested this paradigm by evaluating the relationship between bacterial cell number and the activity of three glycolytic enzymes from 17 fresh waters and also from a laboratory experiment. Our large sets of pooled data...

In a fishless oligotrophic Alpine lake (Lago Paione Superiore: LPS), with a simple trophic food web, the relationships between microorganisms and zooplankton have been studied. During the ice-free period 1999, bacterial grazing by mixotrophic flagellates (MxFl), autotrophic carbon fixation and excretion (EOC), bacterial production, and zooplankton...

Picoplankton, both autotrophic (APP) and heterotrophic (HPP), ciliates and heterotrophic nanoflagellates (HNF) were counted and their biovolume measured monthly over a 3 year period in Lake Paione Superiore (LPS), a high mountain lake in the Italian a l- pine region. Analyses of organic carbon, particulate and dissolved, were performed at the same...

The effects of UVB radiation on the activity of heterotrophic (HPP) and autotrophic (APP) picoplankton (0.2-2 μm) and of autotrophic assemblages >2 μm has been measured and compared. Under natural UVB irradiance in a large, deep, oligotrophic subalpine lake (Lago Maggiore, 45°55'N) with mean dissolved organic carbon (DOC) concentrations of I mg C 1...

Picocyanobacterial abundance and their contribution to the total phytoplankton biomass, estimated as chlorophyll a, was investigated in 32 deep and shallow lakes. The lake series covered a wide range of natural and artificial lakes, from high altitude clear lakes and deep, large subalpine lakes through large shallow lakes, small reservoirs and fish...

In Lake Piramide Superiore (LPS) and Inferiore (LPI), situated in the Khumbu Valley (Nepalese Himalayas), organic particulate carbon (POC) forms a considerable part of the total seston (33% and 21% in LPI and LPS), never exceeding a concentration of 200 μgC l-1. LPS has a higher seston concentration, of which 58% is made up of inorganic matter, pro...

Picocyanobacterial abundance and their contribution to the total phytoplankton biomass, estimated as chlorophyll a, was investigated in 32 deep and shallow lakes. The lake series covered a wide range of natural and artificial lakes, from high altitude clear lakes and deep, large subalpine lakes through large shallow lakes, small reservoirs and fish...

Autotrophic (APP) and heterotrophic (HPP) picoplankton, heterotrophic nanoflagellates (HNF), ciliates and total organic carbon (TOC) were counted and measured for two years in Lakes Como, Garda, Iseo and Maggiore during the spring overturn. HPP and HNF constitute the most important carbon contributors among the organisms of the microbial loop. Lake...

The organic carbon dynamics of Lake Cadagno, a meromictic alpine lake, was studied considering the POC, DOC and chlorophyll spatial and temporal distribution in the whole water column during the ice-free period in 1994, 1995 and 1996. A well defined layer of purple sulphur bacteria was the source of 63-83% of total organic carbon which was therefor...

There are certain drawbacks involved in the routine use of Anodisc filters (0.2 µm pore size) in the analysis of particulate organic carbon (POC) from environmental samples. These filters are hard and brittle and consequently difficult to use in the autosampler of CHN ana- lysers. This paper describes a technique for grinding Anodisc filters with t...