1,720,982 research outputs found
Modelling approach for the evaluation of burial and erosion processes on Posidonia oceanica meadows
No full textSeagrass loss can be partially attributed to naturally- or anthropogenically-induced sediment dynamics that
involve excessive burial or erosion processes. The main goal of this work was to develop a modelling approach
for analysing bottom morphological changes on Sites of Community Importance (SCIs) characterized by the
presence of Posidonia oceanica meadows. Sediment dynamics (settling fluxes) and composition (grain size and
mineralogy) within the two SCIs of the Civitavecchia coastal zone (north-eastern Tyrrhenian, Italy) were
investigated using sediment traps and bottom sediment samples. Moreover structural, morphological, and dy namic parameters of P. oceanica meadows were analyzed. The results showed high reliability in reproducing the
settling fluxes of medium and coarser sands (the most abundant sediment fractions of the two SCIs) compared to
the corresponding fluxes estimated with sediment traps. To further confirm the accuracy of the proposed
approach, a significant relationship was shown to exist between bottom morphological changes reproduced by
the numerical model and plant rhizome growth as measured by in-situ sampling; this relationship attests to the
capacity of P. oceanica to withstand burial and erosion processes. The model allowed us to perform a high spatial
resolution evaluation of erosion levels and deposition processes that occur within the two SCIs, providing a
predictive and useful tool towards a more sustainable management and conservation strategy of P. oceanica
meadows in coastal zones
Preliminary Investigation of Microlitter Pollution in Low-Energy Hydrodynamic Basins Using Sabella spallanzanii (Polychaeta: Sabellidae) Tubes
No full textHarbor basins are strategically important and heavily impacted water bodies according to the water framework directive.
Due to constant trafc, variety of activities, and low-energy hydrodynamics, these areas can have high degrees of water
pollution. This study reports the results of the preliminary investigation of anthropogenic microlitter (AM) pollution in a
semi-enclosed basin (Civitavecchia harbor; northern Tyrrhenian Sea, Italy) using the tubes built by the polychaete Sabella
spallanzanii. The visual inspection showed AM particles within the tube structure as a result of its building process. The
total average AM abundance was 20.8±3.7 AM g−1. AM abundances and fushing time as the hydrodynamic parameter of
water renewal highlight the homogeneity of the sampling area. The suitability of S. spallanzanii tubes as a potential tool to
investigate the AM pollution level in sheltered and polluted environments is highlighte
A new approach to assess the effects of oil spills on phytoplankton community during the “Serious Game” experiment (MEDESS-4MS Project)
No full textThe “Serious Game” experiment was focused on the development of an integrated monitoring approach to oil spill events in the Mediterranean Sea; it was carried out in the Northern Tyrrhenian Sea, an area that is reported to have intense marine traffic often connected to operational oil discharges. Our experiment was designed in order to develop a rapid assessment of oil spill effects on phytoplankton community through the integration of satellite imagery, in situ sampling and new low-cost technologies. In particular, satellite images were frequently acquired to monitor the study area. When the oil slick was detected, a real time sampling survey was carried out with the support of the Italian Coast Guards, employed as Voluntary Observing Ships for the identification of the polluted area, as well as for sampling and measuring activities. During the experiment, numerous analyses were carried out on the controls (C1, C5, E1, E5) and oiled (M1, M2, M4) stations to assess the most useful methods to quantify the impact of oil slick on the phytoplankton community. Among the numerous methods used, phytoplankton qualitative and quantitative evaluation was indispensable to appreciate subtle changes among the different phytoplankton groups; it is therefore a crucial analysis to observe the short negative effects of oil exposure on microalgae. In addition, the C:N ratio was shown to be a reliable parameter to evaluate the presence of oil compounds in the particulate fraction. Also the new low-cost technology used (the vertical profiler T-FLaPpro) was proved to be an efficient support to the rapid assessment of the oil impact along the water column
Trophic, Chemo-Ecological and Sex-Specific Insights on the Relation Between Diplodus sargus (Linnaeus, 1758) and the Invasive Caulerpa cylindracea (Sonder, 1845)
No full textBiological invasions result in negative and unpredictable impacts on oceans worldwide.
Non-indigenous macrophytes often synthesize secondary metabolites for defensive
purposes and increased competition efficiency: this is the case of Caulerpa cylindracea,
which has entered the Mediterranean Sea in 1990 and competed against local flora
and fauna since. It was demonstrated that the white seabream Diplodus sargus (i) has
included the algae into its diet, (ii) is subject to the peculiar Abnormally Tough Specimen
(ATS) condition post-cooking, and (iii) suffers physiological and behavioral disturbances
from caulerpin, one of the three major algal secondary metabolites. This paper confirms
a feeding relationship between the fish and the algae, quantifies caulerpin accumulation
in the liver, suggests a possible mollusk- and echinoderm-driven biomagnification, and
highlights the fact that all ATS specimens were males. Multivariate analyses on a
multi-biomarker panel reveals differential correlations to key cellular processes such
as oxidative stress, metabolism, neurotoxicity, and lipid peroxidation as well as to
condition indexes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Sediment dynamics and resuspension processes in a shallow-water Posidonia oceanica meadow
No full textIn the study, we describe the sedimentary dynamics in a shallow-water seagrass meadow. We examined the dynamics
of vertical sedimentation flux over a Posidonia oceanica meadow during the course of a one-year investigation. Total
sedimentary flux was monitored off the northern Latium coast (Italy) in the central Tyrrhenian Sea using sediment traps
from October 2015 to December 2016 at three stations established on bare sand, in the P. oceanica meadow, and on
a sand patch within the meadow. The traps were deployed during 11 surveys planned on the basis of the weather
conditions and seagrass growth phase. The trap content was analysed for the amount of mass trapped and grain-size
statistics, useful for describing sedimentary processes during storms. The meteorological data, P. oceanica
parameters, and sand patch evolution during the year were analysed to determine their relation to the vertical
sedimentation flux. The resuspension process dominated the shallow-water dynamics, but P. oceanica buffers the
resuspension, especially during calm sea conditions. The sedimentological tracers showed that when high energy-flow
regimes were present, the vegetation near the bottom enhanced the deposition of particles transported from adjacent
unvegetated areas. During late Summer, leaf litter deposited on the unvegetated seafloor buffered the seabed
sediment particles, preventing resuspension. We also detected the active transport of material from the sand patch to
the meadow that was dependent on the energy flow regime, showing that the vegetation plays two roles: preventing
resuspension and promoting deposition
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
PLASTICHE E MICROPLASTICHE: EFFETTI DANNOSI, SOLUZIONI E ATTIVITÀ DEL CORPO DELLE CAPITANERIE DI PORTO
No full textLa plastica è un materiale importante di cui la nostra economia fa ampio uso. Non solo semplifica la vita in vari modi, ma spesso è più leggera e meno costosa rispetto ai materiali alternativi. Tuttavia, se non la si smaltisce o ricicla correttamente dopo l’uso, spesso viene rilasciata nell’ambiente, dove può persistere per lunghi periodi e disgregarsi in frammenti sempre più piccoli, noti con il nome di microplastica, che sono motivo di preoccupazione.
Le plastiche vanno incontro a processi di degradazione, possono subire una frammentazione meccanica causata dalle onde e dalle maree che portano alla frammentazione di pezzi di plastica via via più piccoli e che possono avere un effetto diretto e indiretto sugli ecosistemi marini e sulla salute umana. Le esposizioni per ingestione, inalazione e contatto cutaneo sono tutte considerate vie di esposizione importanti per la popolazione generale. Le nanoplastiche possono raggiungere gli alveoli, entrare nel sistema circolatorio e raggiungere qualsiasi organo o tessuto del corpo ormano.
È plausibile quindi che le microplastiche e le nanoplastiche possano rivelarsi dei vettori capaci di veicolare in ogni tessuto dell’organismo umano e animale sostanze tossiche, quelle assorbite nell’ambiente e gli additivi utilizzati nei materiali plastici.
È evidente la necessità di dover ridurre la quantità di rifiuti plastiche che entrano negli ambienti naturali attraverso un migliore smaltimento dei rifiuti e una migliore gestione dei materiali. Centrale è il ruolo del Corpo delle Capitanerie di Porto - Guardia Costiera su questo tema, che da sempre considera la sicurezza dell’ambiente marino e costiero come uno degli obiettivi prioritari da perseguire
INQUINAMENTO MARINO DA PLASTICHE: RICERCA SCIENTIFICA, LEGISLAZIONE E RUOLO DEL CORPO DELLE CAPITANERIE DI PORTO
No full textDai primi anni del ventesimo secolo viviamo in un’epoca in cui la plastica svolge un ruolo sempre più importante nella nostra quotidianità. Il motivo di questa dipendenza risiede nelle proprietà chimico fisiche dei materiali polimerici, unici per resistenza, versatilità e longevità. Sonoproprio tali caratteristiche, che, come un boomerang, rendono la plastica tra i materiali più persistenti, duraturi e pericolosi nell’ambiente, causando danni quasi irreversibili agli ecosistemi marini.
Nella prima parte del lavoro di tesi vengono analizzate le caratteristiche fisiche e chimiche delle plastiche, , le diverse fonti di inquinamento da e la dispersione in mare. Vengono sottolineate le tecniche utilizzate per il monitoraggio della qualità ambientale e vengono analizzati dei metodi innovativi di previsione per localizzare le aree di maggiore accumulo su scala globale e in particolar modo nel Mediterraneo.
Successivamente è stato esaminato l’impatto effettivo e potenziale derivato dalla presenza della plastica in mare, la quale provoca danni all’ecosistema marino e, in secondo luogo, alla salute umana.
Una volta presa coscienza dell’impatto ambientale dell’inquinamento, sono analizzati i sistemi legislativi e scientifici per prevenire, ridurre, arginare e rimuovere la plastica dai mari. Sono quindi passate in rassegna le debolezze degli strumenti internazionali a tutela dell’inquinamento, le normative comunitarie, grazie a cui l’Unione Europea si pone come organizzazione trainante in materia ambientale e gli strumenti legislativi con cui lo Stato italiano ha adattato la propria normativa a quella comunitaria e alla realtà interna.
A conclusione sono delineate le attività istituzionali e operative del Corpo delle capitanerie di porto per la tutela degli ecosistemi marini dalla proliferazione delle plastiche.
Il fine dell’elaborato è quello di rendere consapevole il lettore del pericolo presente e futuro derivato dalla presenza della plastica in mare, sensibilizzando la popolazione verso un corretto uso di tale materiale e al rispetto dell’ambiente
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