Autotrofia ed eterotrofia in un sistema fluviale e lacustre eutrofico: bilanci di massa dei gas disciolti e dei nutrienti, ruolo della vegetazione macrofitica sommersa ed elofitica, del fitoplancton e dei tempi di residenza idraulica.

Il sistema fluviale del Mincio comprende segmenti a diverso grado di naturalità, morfometria e regime idrologico. Sono stati considerati in questo lavoro un segmento settentrionale caratterizzato da integrità ecologica e simile allo stato di riferimento, un segmento meridionale parzialmente bacinizzato a scorrimento lento ed un segmento centrale, assimilabile ad un lago per i tempi di ricambio lunghi e la velocità dell’acqua trascurabile. Obiettivi generali del lavoro sono stati: 1) confrontare le funzioni interne ai due segmenti fluviali in relazione al loro stato di conservazione e in particolare in relazione alle attività dei produttori primari dominanti (rispettivamente una macrofita radicata sommersa nel tratto nord ed il fitoplancton nel tratto sud); 2) evidenziare l’importanza degli scambi di gas disciolti (O2 e CO2) all’interfaccia acqua-atmosfera nel metabolismo complessivo di questi due sistemi; 3) quantificare l’importanza relativa del fitoplancton e di una prateria monospecifica di una pleustofita (Trapa natans) nell’evoluzione stagionale del chimismo e nei bilanci di massa di ossigeno, anidride carbonica e nutrienti in un sistema lacustre poco profondo. Le ipotesi generali associate a questi macrobiettivi sono: 1) la bacinizzazione può determinare la distrofia di sistemi fluviali eutrofici caratterizzati da un eccessivo arricchimento organico a livello dei sedimenti e dall’eccessiva proliferazione del fitoplancton; 2) l’idrodinamismo ha un ruolo fondamentale nel regolare i tenori dei gas e mantenere oscillazioni contenute nelle percentuali di saturazione; 3) le comunità a pleustofite favoriscono l’insorgenza dell’anossia con implicazioni sul metabolismo complessivo del sistema che le ospita. In estrema sintesi i risultati ottenuti permettono di affermare che: 1) Il sistema fluviale analizzato è una sorgente di CO2 verso l’atmosfera, in linea con quanto riportato dalla letteratura. I risultati di questo lavoro indicano però che i flussi sono fortemente regolati da aspetti idrologici e dalle comunità dei produttori primari dominanti e variano significativamente a seconda delle scale spaziali e temporali adottate nelle indagini. 2) La velocità dell’acqua nei segmenti fluviali eutrofici di alta pianura non permette la strutturazione di comunità fitoplanctoniche ed assume un’importante funzione regolatrice dei tassi di crescita, colonizzazione e sviluppo delle macrofite sommerse, garantendo buona ossigenazione e trasparenza. La disponibilità dei nutrienti simultaneamente determina un eccesso di proliferazione macrofitica con implicazioni a cascata per i segmenti a valle a causa del trasporto di materiale particellato. Nel segmento meridionale, la bacinizzazione si riflette in estremi valori di sovrasaturazione della CO2 e nella sottosaturazione dell’O2 in prossimità del fondo. Le densità di cellule microalgali sono inoltre tipiche di sistemi ipertrofici/distrofici. 3) Sorprendentemente, nonostante il carattere maggiormente distrofico del segmento fluviale meridionale, è il segmento a maggiore naturalità ad essere una maggiore sorgente di anidride carbonica per l’atmosfera. Questo a causa della maggiore velocità dell’acqua, che favorisce il rilascio del gas in eccesso, ma anche per i maggiori tassi di mineralizzazione del particellato. Nel segmento sud, invece, grandi quantità di CO2 disciolta vengono trasferiti a valle e tendono ad accumularsi in acqua (>400% di saturazione). 4) In un sistema eutrofico come il lago di Mezzo i bilanci dei gas indicano un metabolismo complessivo al netto autotrofo. In questo sistema viene ridimensionato il ruolo della pleustofita dominante rispetto al fitoplancton quale trappola di C, N e P. L’ombreggiamento della colonna d’acqua da parte di T. natans ha però implicazioni negative per i bilanci dell’ossigeno. 5) L’alterazione, indotta dalle attività antropiche, di aspetti idrologici quali i tempi di ricambio o la velocità dell’acqua inducono transizioni nelle comunità vegetali, nella zonazione dei processi e, in definitiva, nello stato trofico dei sistemi fluviali.The Mincio River is composed by adjacent reaches characterized by different levels of ecological integrity, morphology, and hydrological regime. This study considered a high plain reach (northern trait), similar to its reference status, a channelized low plain reach (southern trait), and a central reach, similar to a lake due to longer water retention-time (few days) and slow current velocity. The main objectives of this study were: 1) compare internal functions of two fluvial segments based on their conservation state and on the role of the dominant primary producers community (submerged macrophyte and phytoplankton in the northern and in the southern traits, respectively); 2) highlight the importance of dissolved gas (O2 e CO2) exchanges at the water-atmosphere interface on the whole metabolism of the two traits; 3) quantify the relative importance of phytoplankton community and of a pleustophyte stand (Trapa natans) on the seasonal evolution of the oxygen, carbon dioxide and nutrient mass balances in a shallow lake. The general hypotheses at the base of these objectives are: 1) the rectification and channelization could determine the dystrophy of eutrophic fluvial segments, characterized by nutrient and organic enrichment at sediment level and by microalgal blooms; 2) the hydrodynamism has a fundamental role as gas exchange regulator, and avoids excess super or undersaturation; 3) pleustophytic communities favor hypoxic events with implications for the whole ecosystem metabolism. In brief, the results obtained suggest that: 1) The Mincio River is a source of CO2 to the atmosphere, in accordance with the recent literature on river metabolism. Simultaneously, the results of this study show also that fluxes are strongly regulated by hydrological aspects and by the dominant communities of primary producers. Sharp variations in CO2 saturation, as those evidenced in the northern segment, suggest that the choice of adequate spatial and temporal scales, is of paramount importance. 2) The current velocity of the high plain river reach does not allow the structuring of phytoplankton communities and has an important role on regulating growth rates, colonization and development of submerged macrophytes, ensuring good water oxygenation and transparency. At the same time the high nutrients availability favoures the macrophytic development with cascade implications for downstream river reaches, mainly due to downwards particle transport. In the southern trait, the channelization results in extreme values of CO2 supersaturation and pronounced O2 decline at sediment level. Further, the microalgal biomass is typical of hypertrophic/dystrophic systems. 3) Surprisingly, the northern trait, characterized by high ecological integrity, is a major source of CO2 to the atmosphere. This is due to the higher current velocity which favours the release of the gas in excess, but also to the major mineralization rates of the particulate material. At the southern trait the CO2 excess is transferred downstream or accumulate into the water column (>400% of saturation). 4) In a eutrophic system, as the Lago di Mezzo, the gas mass balances demonstrate the net autotrophy of the whole system. In this shallow Lake, the dominant pleustophyte has a minor role as C, N and P trap compared to phytoplankton. The water column shading by T. natans has negative implications on oxygen balances and promotes anoxia. 6) The human modifications of hydrological aspects, as water retention time or current velocity, determines the shift of primary producer communities and of the metabolic processes. This modifies the slow fading of adjacent river reaches along longitudinal gradients, described in the River Continuum Concept. Human impacts induce local transitions of the trophic status in altered river reaches

daily and seasonal variability of co2 saturation and evasion in a free flowing and in a dammed river reach

The daily and seasonal evolution of O2 and CO2 saturation, water-atmosphere fluxes and budgets were measured in two fluvial reaches of the Mincio River (Italy). The northern reach is free flowing and is dominated by macrophytes while the southern reach is dammed, hypertrophic and phytoplankton dominated. We hypothesized short term regulation of gas saturation and fluxes by primary producers and the reversal of CO2 off-gassing in the southern reach. Results indicated that both reaches were always CO2 supersaturated. Higher CO2 evasion rates in the northern compared to the southern reach depended on reaeration coefficient, in turn depending on water velocity. In the northern reach dissolved inorganic carbon (DIC) production was one order of magnitude higher than oxygen consumption, likely due to a combination of anoxic heterotrophic activity in the hyporheic zone and carbonate dissolution. The activity of macrophytes influenced CO2 saturation on short time scales. A net summer abatement of DIC occurred in the southern reach, probably due to fixation by phytoplankton, which attenuated supersaturation but not reversed CO2 efflux. This study demonstrates how in small rivers CO2 evasion can undergo rapid and significant changes due to eutrophication, altered hydrology and shift in primary producer communities

Aspects of Invasiveness of Ludwigia and Nelumbo in Shallow Temperate Fluvial Lakes

The relationship between invasive plant functional traits and their invasiveness is still the subject of scientific investigation, and the backgrounds of transition from non-native to invasive species in ecosystems are therefore poorly understood. Furthermore, our current knowledge on species invasiveness is heavily biased toward terrestrial species; we know much less about the influence of allochthonous plant traits on their invasiveness in aquatic ecosystems. In this paper, we present the results of a study on physiological and ecological traits of two introduced and three native macrophyte species in the Mantua lakes system (northern Italy). We compared their photophysiology, pigment content, leaf reflectance, and phenology in order to assess how the invasive Nelumbo nucifera and Ludwigia hexapetala perform compared to native species, Nuphar lutea, Nymphaea alba, and Trapa natans. We found L. hexapetala to have higher photosynthetic efficiency and to tolerate higher light intensities than N. nucifera and the native species especially at extreme weather conditions (prolonged exposure to high light and higher temperatures). Chlorophyll a and b, and carotenoids content of both allochthonous species were substantially higher than those of native plants, suggesting adaptive response to the ecosystem of Mantua lakes system. Higher variability of recorded data in invasive species was also observed. These observations suggest advanced photosynthetic efficiency of the invasive species, especially L. hexapetala, resulting in faster growth rates and higher productivity. This was supported by the evaluation of seasonal dynamics mapped from satellite remote sensing data. This study provides empirical evidence for the relationship between specific plant physiological traits and invasiveness of aquatic plant species, highlighting the importance of trait studies in predicting ecosystem-level impacts of invasive plant species

Leaf reflectance can surrogate foliar economics better than physiological traits across macrophyte species

Abstract Background Macrophytes are key players in aquatic ecosystems diversity, but knowledge on variability of their functional traits, among and within species, is still limited. Remote sensing is a high-throughput, feasible option for characterizing plant traits at different scales, provided that reliable spectroscopy models are calibrated with congruous empirical data, but existing applications are biased towards terrestrial plants. We sampled leaves from six floating and emergent macrophyte species common in temperate areas, covering different phenological stages, seasons, and environmental conditions, and measured leaf reflectance (400–2500 nm) and leaf traits (dealing with photophysiology, pigments, and structure). We explored optimal spectral band combinations and established non-parametric reflectance-based models for selected traits, eventually showing how airborne hyperspectral data could capture spatial–temporal macrophyte variability. Results Our key finding is that structural—leaf dry matter content, leaf mass per area—and biochemical—chlorophyll-a content and chlorophylls to carotenoids ratio—traits can be surrogated by leaf reflectance with normalized error under 17% across macrophyte species. On the other hand, the performance of reflectance-based models for photophysiological traits substantively varies, depending on macrophyte species and target parameters. Conclusions Our main results show the link between leaf reflectance and leaf economics (structure and biochemistry) for aquatic plants, thus envisioning a crucial role for remote sensing in enhancing the level of detail of macrophyte functional diversity analysis to intra-site and intra-species scales. At the same time, we highlighted some difficulties in establishing a general link between reflectance and photosynthetic performance under high environmental heterogeneity, potentially opening further investigation directions

Shorter blooms expected with longer warm periods under climate change: an example from a shallow meso-eutrophic Mediterranean lake

AbstractSatellite data from the Climate Change Initiative (CCI) lakes project were used to examine the influence of climate on chlorophyll-a (Chl-a). Nonparametric multiplicative regression and machine learning were used to explain Chl-a concentration trend and dynamics. The main parameters of importance were seasonality, interannual variation, lake level, water temperature, the North Atlantic Oscillation, and antecedent rainfall. No evidence was found for an earlier onset of the summer phytoplankton bloom related to the earlier onset of warmer temperatures. Instead, a curvilinear relationship between Chl-a and the temperature length of season above 20°C (LOS) was found with longer periods of warmer temperature leading to blooms of shorter duration. We suggest that a longer period of warmer temperatures in the summer may result in earlier uptake of nutrients or increased calcite precipitation resulting in a shortening of the duration of phytoplankton blooms. The current scenario of increasing LOS of temperature with climate change may lead to an alteration of phytoplankton phenological cycles resulting in blooms of shorter duration in lakes where nutrients become limiting. Satellite-derived information on lake temperature and Chl-a concentration proved essential in detecting trends at appropriate resolution over time

Remote sensing of macrophyte morphological traits: Implications for the management of shallow lakes

Macrophytes are important elements of freshwater ecosystems, fulfilling a pivotal role in biogeochemical cycles. The synoptic capabilities provided by remote sensing make it a powerful tool for monitoring aquatic vegetation characteristics and the functional status of shallow lake systems in which they occur. The latest generation of airborne and spaceborne imaging sensors can be effectively exploited for mapping morphologically – and physiologically – relevant vegetation features based on their canopy spectral response. The objectives of this study were to calibrate semi-empirical models for mapping macrophyte morphological traits (i.e., fractional cover, leaf area index and above-water biomass) from hyperspectral data, and to investigate the capabilities of remote sensing in supporting macrophyte monitoring and management. We calibrated spectral models using in situ reflectance and morphological trait measures and applied them to airborne hyperspectral imaging data, acquired over two shallow European water bodies (Lake Hídvégi, in Hungary, and Mantua lakes system, in Italy) in two key phenological phases. Maps of morphological traits were produced covering a broad range of aquatic plant types (submerged, floating, and emergent), common to temperate and continental regions, with an error level of 5.4% for fractional cover, 0.10 m2 m-2 for leaf area index, and 0.06 kg m-2 for above-water biomass. Based on these maps, we discuss how remote sensing could support monitoring strategies and shallow lake management with reference to our two case studies: i.e., by providing insight into spatial and species-wise variability, by assessing nutrient uptake by aquatic plants, and by identifying hotspot areas where invasive species could become a threat to ecosystem functioning and service provision

Cognitive Syndromes and C9orf72 Mutation Are Not Related to Cerebellar Degeneration in Amyotrophic Lateral Sclerosis

ObjectiveThe notion that cerebellar pathology may contribute to cognitive impairment in ALS, especially in patients with C9orf72 repeated expansion, has been inconsistently reported. This study aimed exploring the relationship between cerebellar involvement, cognitive impairment and C9orf72 repeated expansion of patients with ALS.MethodsQuantitative in vivo assessment of cerebellar lobules has been investigated in 66 non-demented patients with ALS and 28 healthy controls (HCs). Pathologic C9orf72 repeated expansion was found in 13 patients. Mild cognitive and/or behavioral impairment was diagnosed in 22 C9orf72 negative ALS patients. Measures of cortical volume (CV) and cortical thickness (CT) of cerebellar lobules of all participants were used for Principal Component Analysis (PCA) to identify clusters of lobular measures highly correlated with each other. PCA outcomes were used for between group comparisons and correlation analyses with neuropsychological and clinical features.ResultsDisease severity measured with ALS functional rating scale and index of disease progression rate significantly correlated with CV reduction of the second PCA cluster loading CV measures of anterior lobules. In all patients, cognitive impairment, measured with verbal fluency, was related to CV reduction of the third cluster comprising posterior lobules. No specific cortical thinning or volume reduction of cerebellar clustering patterns could be detected in ALS subgroups.ConclusionOur data show that specific patterns of subregional cerebellar involvement are associated with physical disability or cognitive impairment in ALS, in line with the topographic organization of the cerebellum. However, there was no specific correlation between cerebellar degeneration and cognitive syndromes or C9orf72 mutations

The mediterranean sea we want

open58siThis paper presents major gaps and challenges for implementing the UN Decade of Ocean Science for Sustainable Development (2021-2030) in the Mediterranean region. The authors make recommendations on the scientific knowledge needs and co-design actions identified during two consultations, part of the Decade preparatory-phase, framing them in the Mediterranean Sea’s unique environmental and socio-economic perspectives. According to the ‘Mediterranean State of the Environment and Development Report 2020’ by the United Nations Environment Programme Mediterranean Action Plan and despite notable progress, the Mediterranean region is not on track to achieve and fully implement the Sustainable Development Goals of Agenda 2030. Key factors are the cumulative effect of multiple human-induced pressures that threaten the ecosystem resources and services in the global change scenario. The basin, identified as a climate change vulnerability hotspot, is exposed to pollution and rising impacts of climate change. This affects mainly the coastal zones, at increasing risk of extreme events and their negative effects of unsustainable management of key economic assets. Transitioning to a sustainable blue economy is the key for the marine environment’s health and the nourishment of future generations. This challenging context, offering the opportunity of enhancing the knowledge to define science-based measures as well as narrowing the gaps between the Northen and Southern shores, calls for a joint (re)action. The paper reviews the state of the art of Mediterranean Sea science knowledge, sets of trends, capacity development needs, specific challenges, and recommendations for each Decade’s societal outcome. In the conclusions, the proposal for a Mediterranean regional programme in the framework of the Ocean Decade is addressed. The core objective relies on integrating and improving the existing ocean-knowledge, Ocean Literacy, and ocean observing capacities building on international cooperation to reach the “Mediterranean Sea that we want”.openCappelletto M.; Santoleri R.; Evangelista L.; Galgani F.; Garces E.; Giorgetti A.; Fava F.; Herut B.; Hilmi K.; Kholeif S.; Lorito S.; Sammari C.; Lianos M.C.; Celussi M.; D'alelio D.; Francocci F.; Giorgi G.; Canu D.M.; Organelli E.; Pomaro A.; Sannino G.; Segou M.; Simoncelli S.; Babeyko A.; Barbanti A.; Chang-Seng D.; Cardin V.; Casotti R.; Drago A.; Asmi S.E.; Eparkhina D.; Fichaut M.; Hema T.; Procaccini G.; Santoro F.; Scoullos M.; Solidoro C.; Trincardi F.; Tunesi L.; Umgiesser G.; Zingone A.; Ballerini T.; Chaffai A.; Coppini G.; Gruber S.; Knezevic J.; Leone G.; Penca J.; Pinardi N.; Petihakis G.; Rio M.-H.; Said M.; Siokouros Z.; Srour A.; Snoussi M.; Tintore J.; Vassilopoulou V.; Zavatarelli M.Cappelletto M.; Santoleri R.; Evangelista L.; Galgani F.; Garces E.; Giorgetti A.; Fava F.; Herut B.; Hilmi K.; Kholeif S.; Lorito S.; Sammari C.; Lianos M.C.; Celussi M.; D'alelio D.; Francocci F.; Giorgi G.; Canu D.M.; Organelli E.; Pomaro A.; Sannino G.; Segou M.; Simoncelli S.; Babeyko A.; Barbanti A.; Chang-Seng D.; Cardin V.; Casotti R.; Drago A.; Asmi S.E.; Eparkhina D.; Fichaut M.; Hema T.; Procaccini G.; Santoro F.; Scoullos M.; Solidoro C.; Trincardi F.; Tunesi L.; Umgiesser G.; Zingone A.; Ballerini T.; Chaffai A.; Coppini G.; Gruber S.; Knezevic J.; Leone G.; Penca J.; Pinardi N.; Petihakis G.; Rio M.-H.; Said M.; Siokouros Z.; Srour A.; Snoussi M.; Tintore J.; Vassilopoulou V.; Zavatarelli M

COVID-19 Severity in Multiple Sclerosis: Putting Data Into Context

Background and objectives: It is unclear how multiple sclerosis (MS) affects the severity of COVID-19. The aim of this study is to compare COVID-19-related outcomes collected in an Italian cohort of patients with MS with the outcomes expected in the age- and sex-matched Italian population. Methods: Hospitalization, intensive care unit (ICU) admission, and death after COVID-19 diagnosis of 1,362 patients with MS were compared with the age- and sex-matched Italian population in a retrospective observational case-cohort study with population-based control. The observed vs the expected events were compared in the whole MS cohort and in different subgroups (higher risk: Expanded Disability Status Scale [EDSS] score > 3 or at least 1 comorbidity, lower risk: EDSS score ≤ 3 and no comorbidities) by the χ2 test, and the risk excess was quantified by risk ratios (RRs). Results: The risk of severe events was about twice the risk in the age- and sex-matched Italian population: RR = 2.12 for hospitalization (p < 0.001), RR = 2.19 for ICU admission (p < 0.001), and RR = 2.43 for death (p < 0.001). The excess of risk was confined to the higher-risk group (n = 553). In lower-risk patients (n = 809), the rate of events was close to that of the Italian age- and sex-matched population (RR = 1.12 for hospitalization, RR = 1.52 for ICU admission, and RR = 1.19 for death). In the lower-risk group, an increased hospitalization risk was detected in patients on anti-CD20 (RR = 3.03, p = 0.005), whereas a decrease was detected in patients on interferon (0 observed vs 4 expected events, p = 0.04). Discussion: Overall, the MS cohort had a risk of severe events that is twice the risk than the age- and sex-matched Italian population. This excess of risk is mainly explained by the EDSS score and comorbidities, whereas a residual increase of hospitalization risk was observed in patients on anti-CD20 therapies and a decrease in people on interferon