444 research outputs found

    The Presence of Lampreys in the Tyrrhenian Rivers of the Campania Region (Southern Italy): A New Record of the Sea Lamprey Petromyzon marinus (Linnaeus 1758).

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    The southern Italian peninsula has been suggested to be an important European district for lampreys’ genetic diversity. All lamprey species ever described throughout the Italian peninsula are protected within European legislation and listed in Annex II of the EU Habitats Directive (92/43/EEC)and Annex III of the Bern Convention (82/72/CEE) as species of conservation concern, and the Habitats Directive ensures the designation of “sites of community interest” (SICs) for threatened species. During a survey to collect preliminary data on lampreys’ presence in the Cilento, Vallo di Daino, and Alburni National Park (PNCV) located in the Campania region, where 28 sites of community interest (SICs) have been established by the EU Habitats Directive (92/43/EEC), two specimens of sea lamprey (Petromyzon marinus, Linnaeus, 1758) were detected for the first time. The specimens were genetically characterized through the sequencing of the mtDNA control region locus. The study highlighted the significant importance of the Campania region for lampreys, which,concerning Lampetra sp., was found to have peculiar genetic characteristics and unique alleles that have not been described elsewhere. Furthermore, the recognition of the sea lamprey, P. marinus, emphasized the value of this area, especially in terms of laying the groundwork for future habitat protection strategies

    Rimozione di sedimenti per fluitazione dal serbatoio di Sernio (SO)

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    Il presente lavoro descrive la rimozione di un ingente quantitativo di sedimenti (circa 100'000 tonnellate) dal serbatoio di Sernio, in provincia di Sondrio, effettuata tra maggio e luglio del 2009. Il sedimento \ue8 stato evacuato per fluitazione (flushing), nel sostanziale rispetto dei vincoli preventivamente stabiliti sulla concentrazione di solidi sospesi (CSS) delle acque scaricate. Tali limitazioni hanno lo scopo di contenere l\u2019impatto delle operazioni sugli ecosistemi acquatici coinvolti. La CSS \ue8 stata controllata regolando il livello nel serbatoio, la portata in uscita e, in un secondo tempo, mediante l\u2019utilizzo di escavatori meccanici. La gestione delle operazioni si \ue8 basata sul costante monitoraggio della CSS poco a valle dell\u2019area di intervento. La campagna di misura \ue8 stata ulteriormente estesa a valle, per un tratto di circa 40 km lungo l\u2019asta dell\u2019Adda, al fine di quantificare la riduzione della CSS per effetto combinato di diluizione e deposizione

    Considering mesohabitat scale in ecological impact assessment of sediment flushing

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    Benthic macroinvertebrates respond to several factors characterizing the physical habitats, as water depth, current and streambed substrate. Thus, anthropogenic disturbances altering these factors may have different effects on benthos, also depending on mesohabitats. These disturbances include sediment flushing operations, commonly carried out to recover reservoir capacity, and investigating their effects at mesohabitat scale could be relevant for an adequate ecological impact assessment of these operations. Here, we compared benthic macroinvertebrate communities sampled before and after a controlled sediment flushing operation in three different mesohabitats (a pool, a riffle and a step-pool) of an Alpine stream. Contrary from expectations, the composition of macroinvertebrate assemblages was not significantly different among mesohabitats. Moreover, the impact of sediment flushing was more significant in terms of density rather than in richness. Two stressor-specific indices were tested, but only one (the Siltation Index for LoTic EcoSystems - SILTES) clearly detected the impact of sediment flushing on the macroinvertebrate community structure. Finally, some differences in the temporal trajectories and recovery times to pre-flushing conditions were observed among mesohabitats, both if the three mesohabitats were considered separately and if all their possible combinations were accounted for. Particularly, riffle was the most sensitive mesohabitat, not fully recovering one year after the sediment disturbance

    Towards ecological flows: status of the benthic macroinvertebrate community during summer low-flow periods in a regulated lowland river

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    Climate change along with the increasing exploitation of water resources exacerbates low-flow periods, causing detrimental effects on riverine communities. The main mitigation measure currently adopted to counteract hydrological alterations induced by off-stream diversion is the release of minimum flows (MFs), even if within the European Union Water Framework Directive an upgrade towards ecological flows is urgently required to achieve good ecological status (GES). In this study, we investigated the temporal evolution of the benthic macroinvertebrate community in an Italian regulated lowland river (Ticino River) to clarify the ecological effects of summer low flows, and we evaluated the current MFs in the perspective of meeting GES standard. Biomonitoring was carried out for four consecutive years (2019-2022), in a river site immediately below a large off-stream diversion. The four study years were characterized by different streamflow patterns, thus allowing us to compare the temporal trajectories of the community under different flow conditions. Moreover, the interruption of the low-flow periods due to overflow spilled by the upstream dam gave us the opportunity to assess the effects of experimental flow peaks. Contrary to the expectation, the macroinvertebrate assemblage kept almost unvaried across the years, showing great resistance and resilience to hydrological changes. Even in extraordinarily dry 2022, the community composition varied only slightly, with a reduction of mayflies and an increase of mollusks. However, a deterioration of the ecological status below GES standard was recorded that summer, indicating the need for an upgrading of the current MFs. This upgrade would include experimental flow peaks in critical periods, which act as intermediate disturbances, enhancing community richness, diversity, and overall quality, as well as compliance with a threshold of an index specifically developed for the hydrological pressure

    Beta-diversity and stressor specific index reveal patterns of macroinvertebrate community response to sediment flushing

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    Anthropogenic increase of fine sediment loading is one of the main pressures for rivers worldwide. Particularly, Alpine streams are increasingly facing this issue due to sediment flushing operations from hydropower reservoirs, aimed at recovering storage for preserving electricity generation. Although Controlled Sediment Flushing Operations (CSFOs) are becoming increasingly frequent, ecological indicators to adequately assess and monitor their impact on the stream ecosystem have been poorly developed. In this work, we aimed to perform a screening of currently available biomonitoring tools to evaluate the CSFO effects on the riverine biota and adequately assess its recovery, starting from the recognition of the main ecological mechanisms triggered by the mentioned activities on benthic macroinvertebrate communities. We used two independent datasets concerning two reservoirs in the central Italian Alps to investigate the temporal effects of CSFOs repeated for four consecutive years (case-study I), and the impact of a single CSFO at a seasonal scale through a before/after-control/impact approach (case-study II). Initially, we quantified the CSFO impact on the richness and beta-diversity of macroinvertebrate communities by combining multivariate and univariate statistical techniques. Then, we compared the performance of the Siltation Index for LoTic EcoSystems (SILTES), recently developed for detecting siltation impact in Alpine streams, with that of the generic index currently adopted to assess the ecological status (sensu Water Framework Directive) of the Italian rivers, and of another sediment-specific index, but developed for a different bio-geographical area. The analysis of the two case-studies demonstrated that the nestedness (i.e. taxa loss) is the primary source of biological impairment caused by CSFOs. Moreover, we found that SILTES was more effective than the other indices because of its strong correlation with the nestedness, and since it properly discriminated impaired and pristine conditions, at both multi-annual and seasonal scale. In the first case-study, a threshold in the temporal trend of this index was detected, indicating a recovery within three months. In the second one, SILTES showed a recovery to pre-event seasonal values after nine months from the CSFO, due to larger and more persistent sediment deposition. This study demonstrates that SILTES could be adopted as a benchmark to improve the management of CSFOs from an ecological viewpoint. Our findings can be extended to the management of other sediment-related activities affecting mountainous streams worldwide, and, more generally, the adopted approach can be replicated for developing new ecological tools to manage other disturbances to river environments

    Morphologic and genetic variability in the Barbus fishes (Teleostei, Cyprinidae) of Central Italy

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    © 2019 Royal Swedish Academy of Sciences Italian freshwaters are highly biodiverse, with species present including the native fishes Barbus plebejus and Barbus tyberinus that are threatened by habitat alteration, fish stocking and invasive fishes, especially European barbel Barbus barbus. In central Italy, native fluvio-lacustrine barbels are mainly allopatric and so provide an excellent natural system to evaluate the permeability of the Apennine Mountains. Here, the morphologic and genetic distinctiveness was determined for 611 Barbus fishes collected along the Padany–Venetian (Adriatic basins; PV) and Tuscany–Latium (Tyrrhenian basins; TL) districts. Analyses of morphological traits and mitochondrial DNA sequence data explored the natural and anthropogenic factors that have shaped their distribution ranges. Over 100 alien B. barbus were recorded in the Tiber basin (TL district) and Metauro basin (PV district). Comparisons of genetic and morphometric data revealed that morphometric data could identify alien B. barbus from native Barbus, but could not differentiate between B. tyberinus and B. plebejus. Genetic analyses revealed ~50 D-loop mtDNA haplotypes and identified a distinct Barbus lineage present only in the Vomano River at the southern boundary of PV district. Demographic expansion and molecular variance analyses revealed a lack of geographic structuring across the sampling regions. While the contemporary B. plebejus distribution has been driven primarily by anthropogenic fish translocations, the dispersal of B. tyberinus has been via natural dispersion, including their crossing of the Apennine Mountains via temporary river connectivity. The results also revealed that the Barbus fishes of the mid-Adriatic region of Europe have a complex pattern of local endemism. To conserve these patterns of genetic uniqueness, especially in the mid-Adriatic basins, Barbus fishes should be managed by treating them as unique evolutionary units and ceasing translocations of all Barbus fishes between river basins

    Bradyrhizobium japonicum senses iron through the status of haem to regulate iron homeostasis and metabolism

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    The Irr protein from the bacterium Bradyrhizobium japonicum is expressed under iron limitation to mediate iron control of haem biosynthesis. The regulatory input to Irr is the status of haem and its precursors iron and protoporphyrin at the site of haem synthesis. Here, we show that Irr controls the expression of iron transport genes and many other iron-regulated genes not directly involved in haem synthesis. Irr is both a positive and negative effector of gene expression, and in at least some cases the control is direct. Loss of normal iron responsiveness of those genes in an irr mutant, as well as a lower total cellular iron content, suggests that Irr is required for the correct perception of the cellular iron status. Degradation of Irr in iron replete cells requires haem. Accordingly, control of Irr-regulated genes by iron was aberrant in a haem-defective strain, and iron replete mutant cells behave as if they are iron-limited. In addition, the haem mutant had an abnormally high cellular iron content. The findings indicate that B. japonicum senses iron via the status of haem biosynthesis in an Irr-dependent manner to regulate iron homeostasis and metabolism

    The karyotype of Nothoscordum arenarium Herter (Gilliesioideae, Alliaceae): A populational and cytomolecular analysis

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    The genus Nothoscordum Kunth comprises approximately 20 species native to South America. Karyologically, the genus is remarkable for its large chromosomes and Robertsonian translocations. Variation in chromosome number has been recorded in a few polyploid species and it is unknown among diploids. This study presents the chromosome number and morphology of 53 individuals of seven populations of N. arenarium Herter (2n = 10). In addition, karyotype analyses after C-banding, staining with CMA and DAPI, and in situ hybridization with 5S and 45S rDNA probes were performed in six individuals from one population. All individuals exhibited 2n = 10 (6M + 4A), except for one tetraploid (2n = 20, 12M + 8A) and one triploid (2n = 15, 9M + 6A) plant. C-banding revealed the presence of CMA+ /DAPI - heterochromatin in the short arm and in the proximal region of the long arm of all acrocentric chromosomes. The 45S rDNA sites co-localized with the CMA + regions of the acrocentrics short arms, while the 5S rDNA probe only hybridized with the subterminal region of a pair of metacentric chromosomes. A change in the pattern of CMA bands and rDNA sites was observed in only one individual bearing a reciprocal translocation involving the long arm of a metacentric and the long arm of an acrocentric chromosome. These data suggest that, despite isolated cases of polyploidy and translocation, the karyotype of N. arenarium is very stable and the karyotypic instability described for other species may be associated with their polyploid condition

    Genetic and phenotypic displacement of an endemic Barbus complex by invasive European barbel Barbus barbus in central Italy

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    Invasions of alien fishes can result in considerable consequences for native biodiversity, including local extinctions of native species through genetic introgression. In Italy, the alien European barbel Barbus barbus was first detected in 1994. It has since undergone range expansion, raising conservation concerns on their impacts on endemic Barbus species, including Barbus plebejus and Barbus tyberinus. Here, the genetic and phenotypic consequences of B. barbus invasion in the Tyrrhenian and Adriatic basins of central Italy were assessed by comparing ‘invaded’ with ‘uninvaded’ river sections that remain free of B. barbus due to barriers preventing their upstream dispersal. In both basins, uninvaded sites were confirmed as B. barbus free, but the endemic populations had low genetic variability. In the invaded sections, haplotype and nucleotide diversity was relatively high, with introgression skewed towards B. barbus genes, with the barbel populations comprising of only 4% and 23% of pure B. tyberinus and B. plebejus respectively. Relatively high morphological differentiation was apparent between pure B. tyberinus and hybrid forms, whilst differences were less apparent between pure B. plebejus and their hybrid forms. Thus, the endemic Barbus species only persist in areas that remain free of invasive B. barbus, with this only due to river structures that impede their upstream movements. As these structures also limit the effective population size of the endemic species, conservation plans must reconcile B. barbus dispersal prevention with the need to increase the population connectivity of the endemics
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