Diet of bluefin tuna (Thunnus thynnus) and swordfish (Xhipias gladius) in the Adriatic Sea

The present issue analyses bluefin tuna (Thynnus thunnus) and swordfish (Xiphias glaudis) diet, caught by professional long-line fishing in the middle Adriatic Sea (Pomo pit). These species represent apex predators in pelagic environment that may play key roles in determining food web structure and ecosystem dynamics. The studies about their feedings habits, based upon stomach contents analysis, are important for the comprehension of biological and ecological interaction. Over the years, many studies have been performed on the diet of tuna and swordfish in the Mediterranean Sea. This research is based on a fairly wide number of analyzed stomach contents, in comparison with the previous ones. In this work, the analysis of 340 stomach contents of bluefin tuna caught by long-line in the central Adriatic sea confirms in general the opportunistic behaviour of this species. Finding support the hypothesis that Adriatic tuna and swordfish chase their food over a wide bathymetric zone and probably near the surface at night. No indication of food preference respect to size of predator or sample season are found. It seems that the two species are able to cohabit because their trophic niche are not overlapped, changing during the time and the vertical and horizontal space.

Global and regional sea level variations in the recent past and future: insight from observations and modeling

This work is focused on the analysis of sea–level change (last century), based mainly on instrumental observations. During this period, individual components of sea–level change are investigated, both at global and regional scales. Some of the geophysical processes responsible for current sea-level change such as glacial isostatic adjustments and current melting terrestrial ice sources, have been modeled and compared with observations. A new value of global mean sea level change based of tide gauges observations has been independently assessed in 1.5 mm/year, using corrections for glacial isostatic adjustment obtained with different models as a criterion for the tide gauge selection. The long wavelength spatial variability of the main components of sea–level change has been investigated by means of traditional and new spectral methods. Complex non–linear trends and abrupt sea–level variations shown by tide gauges records have been addressed applying different approaches to regional case studies. The Ensemble Empirical Mode Decomposition technique has been used to analyse tide gauges records from the Adriatic Sea to ascertain the existence of cyclic sea-level variations. An Early Warning approach have been adopted to detect tipping points in sea–level records of North East Pacific and their relationship with oceanic modes. Global sea–level projections to year 2100 have been obtained by a semi-empirical approach based on the artificial neural network method. In addition, a model-based approach has been applied to the case of the Mediterranean Sea, obtaining sea-level projection to year 2050.

Monitoring of Mediterranean marine benthic biodiversity through novel, standardized, and integrated approaches

Marine healthy ecosystems support life on Earth and human well-being thanks to their biodiversity, which is proven to decline mainly due to anthropogenic stressors. Monitoring how marine biodiversity changes trough space and time is needed to properly define and enroll effective actions towards habitat conservation and preservation. This is particularly needed in those areas that are very rich in species compared to their low surface extension and are characterized by strong anthropic pressures, such as the Mediterranean Sea. Subtidal rocky benthic Mediterranean habitats have a complex structural architecture, hosting a panoply of tiny organisms (cryptofauna) that inhabit crevices and caves, but that are still unknown. Different artificial standardized sampling structures (SSS) and methods have been developed and employed to characterize the cryptofauna, allowing for data replicability and comparability across regions. Organisms growing on these artificial structures can be identified coupling morphological taxonomy and DNA barcoding and metabarcoding. The metabarcoding allows for the identification of organisms in a bulk sample without morphological analysis, and it is based on comparing the genetic similarities of the assessed organisms with barcoding sequences present in online barcoding repositories. Nevertheless, barcoded species nowadays represent only a small portion of known species, and barcoding reference databases are not always curated and updated on a regular basis. In this Thesis I used an integrative approach to characterize benthic marine biodiversity, specifically coupling morphological and molecular techniques with the employment of SSS. Moreover, I upgraded the actual status of COI (cytochrome c oxidase subunit I) barcoding of marine metazoans, and I built a customized COI barcoding reference database for metabarcoding studies on temperate biogenic reefs. This work implemented the knowledge about diversity of Mediterranean marine communities, laying the groundworks for monitoring marine and environmental changes that will occur in the next future as consequences of anthropic and climate threats.

Catchability and survival of the resources during fishing operation

The present Ph.D. thesis aims to test and evaluate by-catch reduction devices (BRDs) that minimize the retention of undersized fish and do not penalize revenues of the fishing industry. Considering that a fraction of fish that escape from fishing gear or that are rejected at the sea probably does not survive (unaccounted mortality), it is a major concern for sustainable fisheries management, as unaccounted mortality may lead to biased stock assessment since they will tend to underestimate fishing mortality and overestimate stock size. In this context, in the present Ph.D. thesis, the escape survival (i.e. survival of the fish escaped through the trawl net codend) of the Mullus barbatus Linnaeus 1758 and the discard survival (survival of fish rejected at the sea after being hauled on deck) of Trachurus trachurus were evaluated for the first time in the central Mediterranean Sea. In conclusion, the use of underwater lights in Mediterranean trawl fisheries should be carefully regulated through ad hoc measures that are currently lacking, to minimize the potential impacts of artificial light on some already overexploited stocks. Even if further works should be carried out in the future to test BRDs performances in different areas and seasons, the T90 50 mm codend and the Grid-T45 40 mm seem promising tools to reduce the catch of undersized individuals and contribute to mitigating the current overfishing of Parapenaeus longirostris and Merluccius merluccius. The escape survival of M. barbatus was high and thanks to an improved methodology the bias in the sampling was minimized. However, for improved stock assessment of M. barbatus, the experiment should be repeated to provide accurate escape mortality estimates. While the discard survival of T. trachurus was very low and according to the landing obligation (Reg. EU 1380/2013) all the juveniles of the species should be landed.

Acoustic backscatter of small pelagic fish species in the Adriatic Sea

The aim of the present study is to apply a broad range of techniques to increase the knowledge of acoustic properties of Sprattus sprattus, Scomber colias and Trachurus mediterraneus in the Adriatic Sea. A novel study using tethered live fish but not involving hooks and anesthetic was tested on T. mediterraneus and S. colias through several ex situ experiments using a split-beam scientific echosounder operating at 38, 120, and 200 kHz. The mean TS was estimated for 29 live specimens, resulting in a conversion factor b20 value of -71.4 dB re 1 m2 and -71.6 dB re 1 m2 respectively which is ~3 dB lower than the current one in use in the Mediterranean Sea. Successively, two monospecific trawl hauls were analyzed through the application of in situ approach for the computation of TS values of S. sprattus which led to six b20 values for sprat (range, -68.8 dB re 1 m2 to -65.6 dB re 1 m2), all higher than the current known value of -71.7 dB re 1 m2. The high difference up to 4.2 dB compared to the current value translates in a significant decrease of absolute sprat biomass along the time series un to 20%. Finally, 149 specimens of the three species were collected for backscattering model application(i.e. Kirchhoff-ray mode model (KRM) and Finite Element Method (FEM)) from digital images of the fish body and swimbladder obtained from Computer Tomography (CT) and X-Ray scans. The values resulting from the application of KRM and FEM are in agreement with empirical results. In general terms the present work proposes the acoustic backscatter characterization of S. colias, S. sprattus and T. mediterraneus in the Mediterranean Sea.

Methylmercury and polycyclic aromatic hydrocarbons in Mediterranean seafood: a molecular anthropological perspective

Seafood carries several contaminants, among which mercury and polycyclic aromatic hydrocarbons are those that cause major concern. Evidence exists that human populations are exposed to these environmental chemicals since ancient times, which may have driven the positive selection of specific genetic polymorphisms related to chemicals toxicokinetic. Both mercury and polycyclic aromatic hydrocarbons are able to cause DNA methylation changes in humans. Some Mediterranean populations may be particularly exposed to these contaminants, being the Mediterranean Sea at a high-risk for contamination by toxic compounds, and because of their traditionally high consumption of locally caught seafood. Starting from these premises the present thesis aims to contribute to the understanding of the molecular impact of seafood consumption on the biology of the Mediterranean population. To this end the work has been divided into four main parts: (1) the development and meta-analysis of a georeferenced database on polycyclic aromatic hydrocarbons in Mediterranean seafood aimed at identifying geographical patterns of contamination and trends that could be related to the biology of the marine organisms, to the physico-chemical properties of each hydrocarbon and to the oceanographic characteristic of the Mediterranean; (2) the development and validation of a food frequency questionnaire to estimate the intake of mercury through seafood consumption among a population living in a geographic area that is usually considered a contamination hotspot; (3) the creation of a biobank made of biological samples from members of several Italian communities together with information on their dietary habits, lifestyle and general health; (4) a review of the literature on the genetic component of individual susceptibility to methylmercury and polycyclic aromatic hydrocarbons exposure in humans, to the effects that these pollutants have on human DNA methylation, and to the evidence that Mediterranean coastal communities represent an informative case study to investigate the potential molecular impact of these chemicals.

Consequences of plant population size for pollinator visitation and plant reproductive success

Habitat loss and fragmentation have a prominent role in determining the size of plant populations, and can affect plant-pollinator interactions. It is hypothesized that in small plant populations the ability to set seeds can be reduced due to limited pollination services, since individuals in small populations can receive less quantity or quality of visits. In this study, I investigated the effect of population size on plant reproductive success and insect visitation in 8 populations of two common species in the island of Lesvos, Greece (Mediterranean Sea), Echium plantagineum and Ballota acetabulosa, and of a rare perennial shrub endemic to north-central Italy, Ononis masquillierii. All the three species depended on insect pollinators for sexual reproduction. For each species, pollen limitation was present in all or nearly all populations, but the relationship between pollen limitation and population size was only present in Ononis masquillierii. However, in Echium plantagineum, significant relationships between both open-pollinated and handcrossed-pollinated seed sets and population size were found, being small populations comparatively less productive than large ones. Additionally, for this species, livestock grazing intensity was greater for small populations and for sparse patches, and had a negative influence on productivity of the remnant plants. Both Echium plantagineum and Ballota acetabulosa attracted a great number of insects, representing a wide spectrum of pollinators, thereby can be considered as generalist species. For Ballota acetabulosa, the most important pollinators were megachilid female bees, and insect diversity didn’t decrease with decreasing plant population size. By contrast, Ononis masquillierii plants generally received few visits, with flowers specialized on small bees (Lasioglossum spp.), representing the most important insect guild. In Echium plantagineum and Ballota acetabulosa, plants in small and large populations received the same amount of visits per flower, and no differences in the number of intraplant visited flowers were detected. On the contrary, large Ononis populations supported higher amounts of pollinators than small ones. At patch level, high Echium flower density was associated with more and higher quality pollinators. My results indicate that small populations were not subject to reduced pollination services than large ones in Echium plantagineum and Ballota acetabulosa, and suggest that grazing and resource limitation could have a major impact on population fitness in Echium plantagineum. The absence of any size effects in these two species can be explained in the light of their high local abundance, wide habitat specificity, and ability to compete with other co-flowering species for pollinators. By contrast, size represents a key characteristic for both pollination and reproduction in Ononis masquillierii populations, as an increase in size could mitigate the negative effects coming from the disadvantageous reproductive traits of the species. Finally, the widespread occurrence of pollen limitation in the three species may be the result of 1) an ongoing weakening or disruption of plantpollinator interactions derived from ecological perturbations, 2) an adaptive equilibrium in response to stochastic processes, and 3) the presence of unfavourable reproductive traits (for Ononis masquillierii).

Effects of habitat characteristics on cryptic fish assemblages

Habitat structure is known to influence the abundance of fishes on temperate reefs. Biotic interactions play a major role in determining the distribution and abundance of species. The significance of these forces in affecting the abundance of fishes may hinge on the presence of organisms that either create or alter habitat. On temperate reefs, for example, macroalgae are considered autogenic ecosystem engineers because they control resource availability to other species through their physical structure and provide much of the structure used by fish. On both coral and temperate reefs, small cryptic reef fishes may comprise up to half of the fish numbers and constitute a diverse community containing many specialized species. Small cryptic fishes (<100 mm total length) may be responsible for the passage of 57% of the energy flow and constitute ca. 35% of the overall reef fish biomass on coral reefs. These benthic fish exploit restricted habitats where food and shelter are obtained in, or in relation to, conditions of substrate complexity and/or restricted living space. A range of mechanisms has been proposed to account for the diversity and the abundance of small fishes: (1) lifehistory strategies that promote short generation times, (2) habitat associations and behaviour that reduce predation and (3) resource partitioning that allows small species to coexist with larger competitors. Despite their abundance and potential importance within reef systems, little is known of the community ecology of cryptic fishes. Specifically on habitat associations many theories suggested a not clear direction on this subject. My research contributes to the development of marine fish ecology by addressing the effects of habitat characteristics upon distribution of cryptobenthic fish assemblages. My focus was on the important shallow, coastal ecosystems that often serve as nursery habitat for many fish and where different type of habitat is likely to both play important roles in organism distribution and survival. My research included three related studies: (1) identification of structuring forces on cryptic fish assemblages, such as physical and biological forcing; (2) macroalgae as potential tools for cryptic fish and identification of different habitat feature that could explain cryptic fish assemblages distribution; (3) canopy formers loss: consequences on cryptic fish and relationship with benthos modifications. I found that: (1) cryptic fish assemblages differ between landward and seaward sides of coastal breakwaters in Adriatic Sea. These differences are explained by 50% of the habitat characteristics on two sides, mainly due to presence of the Codium fragile, sand and oyster assemblages. Microhabitat structure influence cryptic fish assemblages. (2) Different habitat support different cryptic fish assemblages. High heterogeneity on benthic assemblages reflect different fish assemblages. Biogenic components that explain different and diverse cryptic fish assemblages are: anemonia bed, mussel bed, macroalgal stands and Cystoseira barbata, as canopy formers. (3) Canopy forming loss is not relevant in structuring directly cryptic fish assemblages. A removal of canopy forming algae did not affect the structure of cryptic fish assemblages. Canopy formers algae on Conero cliff, does not seem to act as structuring force, probably due to its regressive status. In conclusion, cryptic fish have been shown to have species-specific associations with habitat features relating to the biological and non biological components afforded by fish. Canopy formers algae do not explain cryptic fish assemblages distribution and the results of this study and information from the literature (both from the Mediterranean Sea and elsewhere) show that there are no univocal responses of fish assemblages. Further exanimations on an non regressive status of Cystoseira canopy habitat are needed to define and evaluate the relationship between canopy formers and fish on Mediterranean sea.

Dati geochimici ed ecologici di foraminiferi planctonici. Implicazioni paleoceanografiche in due aree chiave: Oceano Meridionale e Mare Mediterraneo.

La studio della distribuzione spaziale e temporale della associazioni a foraminiferi planctonici, campionati in zone con differente regime idrografico, ha permesso di comprendere che molte specie possono essere diagnostiche della presenza di diverse masse d’acqua superficiali e sottosuperficiali e di diversi regimi di nutrienti nelle acque oceaniche. Parte di questo lavoro di tesi si basa sullo studio delle associazioni a foraminiferi planctonici attualmente viventi nel Settore Pacifico dell’Oceano Meridionale (Mare di Ross e Zona del Fronte Polare) e nel Mare Mediterraneo (Mar Tirreno Meridionale). L’obiettivo di questo studio è quello di comprendere i fattori (temperatura, salinità, nutrienti etc.) che determinano la distribuzione attuale delle diverse specie al fine di valutarne il valore di “indicatori” (proxies) utili alla ricostruzione degli scenari paleoclimatici e paleoceanografici succedutisi in queste aree. I risultati documentano che la distribuzione delle diverse specie, il numero di individui e le variazioni nella morfologia di alcuni taxa sono correlate alle caratteristiche chimico-fisiche della colonna e alla disponibilità di nutrienti e di clorofilla. La seconda parte del lavoro di tesi ha previsto l’analisi degli isotopi stabili dell’ossigeno e del rapporto Mg/Ca in gusci di N. pachyderma (sin) prelevati da pescate di micro zooplancton (per tarare l’equazione di paleo temperatura) da un box core e da una carota provenienti dalla zona del Fronte Polare (Oceano Pacifico meridionale), al fine di ricostruire le variazioni di temperatura negli ultimi 13 ka e durante la Mid-Pleistocene Revolution. Le temperature, dedotte tramite i valori degli isotopi stabili dell’ossigeno, sono coerenti con le temperature attuali documentate in questa zona e il trend di temperatura è paragonabile a quelli riportati in letteratura anche per eventi climatici come lo Younger Dryas e il mid-Holocene Optimum. I valori del rapporto Mg/Ca misurato tramite due diverse tecniche di analisi (laser ablation e analisi in soluzione) sono risultati sempre molto più alti dei valori riportati in letteratura per la stessa specie. La laser ablation sembra carente dal punto di vista del cleaning del campione e da questo studio emerge che le due tecniche non sono comparabili e che non possono essere usate indifferentemente sullo stesso campione. Per quanto riguarda l’analisi dei campioni in soluzione è stato migliorato il protocollo di cleaning per il trattamento di campioni antartici, che ha permesso di ottenere valori veritieri e utili ai fini delle ricostruzioni di paleotemperatura. Tuttavia, rimane verosimile l’ipotesi che in ambienti particolari come questo, con salinità e temperature molto basse, l’incorporazione del Mg all’interno del guscio risenta delle condizioni particolari e che non segua quindi la relazione esponenziale con la temperatura ampiamente dimostrata ad altre latitudini.

Studies of the atmospheric muon flux with the ANTARES detector

The thesis main topic is the determination of the vertical component of the atmospheric muon flux as a function of the sea depth at the ANTARES site. ANTARES is a Cherenkov neutrino telescope placed at 2500m depth in the Mediterranean Sea at 40 km from the southern cost of France. In order to retrieve back the physical flux from the experimental data a deconvolution algorithm has been perform which takes into consideration the trigger inefficiensies and the reconstruction errors on the zenith angle. The obtained results are in good agreement with other ANTARES indipendent analysis.

Composti organostannici nell'ambiente marino e membrane biologiche: risposte molecolari e biochimiche nei molluschi bivalvi

Organotin compounds are worldwide diffused environmental contaminants, mainly as consequence of their extensive past use as biocides in antifouling paints. In spite of law restrictions, due to unwanted effects, organotin still persist in waters, being poorly degraded, easily resuspended from sediments and bioaccumulated in exposed organisms. The widespread toxicity and the possible threat to humans, likely to be organotin-exposed through contaminated seafood, make organotin interactions with biomolecules an intriguing biochemical topic, apart from a matter of ecotoxicological concern. Among organotins, tributyltin (TBT) is long known as the most dangerous and abundant chemical species in the Mediterranean Sea. Due to its amphiphilic nature, provided by three lipophilic arms and an electrophilic tin core, TBT can be easily incorporated in biomembranes and affect their functionality. Accordingly, it is known as a membrane-active toxicant and a mitochondrial poison. Up to now the molecular action modes of TBT are still partially unclear and poorly explored in bivalve mollusks, even if the latter play a not neglectable role in the marine trophic chain and efficiently accumulate organotins. The bivalve mollusk Mytilus galloprovincialis, selected for all experiments, is widely cultivated in the Mediterranean and currently used in ecotoxicological studies. Most work of this thesis was devoted to TBT effects on mussel mitochondria, but other possible targets of TBT were also considered. A great deal of literature points out TBT as endocrine disrupter and the masculinization of female marine gastropods, the so-called imposex, currently signals environmental organotin contamination. The hormonal status of TBT-exposed mussels and the possible interaction between hormones and contaminants in modulating microsomal hydroxilases, involved in steroid hormone and organotin detoxification, were the research topics in the period spent in Barcelona (Marco Polo fellowship). The variegated experimental approach, which consisted of two exposure experiments and in vitro tests, and the choice of selected tissues of M. galloprovincialis, the midgut gland for mitochondrial and microsomal preparations for subsequent laboratory assays and the gonads for the endocrine evaluations, aimed at drawing a clarifying pattern on the molecular mechanisms involved in organotin toxicity. TBT was promptly incorporated in midgut gland mitochondria of adult mussels exposed to 0.5 and 1.0 μg/L TBT, and partially degraded to DBT. TBT incorporation was accompanied by a decrease in the mitochondrial oligomycin-sensitive Mg-ATPase activity, while the coexistent oligomycin-insensitive fraction was unaffected. Mitochondrial fatty acids showed a clear rise in n-3 polyunsaturated fatty acids after 120 hr of TBT exposure, mainly referable to an increase in 22:6 level. TBT was also shown to inhibit the ATP hydrolytic activity of the mitochondrial F1FO complex in vitro and to promote an apparent loss of oligomycin sensitivity at higher than 1.0 μM concentration. The complex dose-dependent profile of the inhibition curve lead to the hypothesis of multiple TBT binding sites. At lower than 1.0 μM TBT concentrations the non competitive enzyme inhibition by TBT was ascribed to the non covalent binding of TBT to FO subunit. On the other hand the observed drop in oligomycin sensitivity at higher than 1.0 μM TBT could be related to the onset of covalent bonds involving thiolic groups on the enzyme structure, apparently reached only at high TBT levels. The mitochondrial respiratory complexes were in vitro affected by TBT, apart from the cytocrome c oxidase which was apparently refractory to the contaminant. The most striking inhibitory effect was shown on complex I, and ascribed to possible covalent bonds of TBT with –SH groups on the enzyme complexes. This mechanism, shouldered by the progressive decrease of free cystein residues in the presence of increasing TBT concentrations, suggests that the onset of covalent tin-sulphur bonds in distinct protein structures may constitute the molecular basis of widespread TBT effects on mitochondrial complexes. Energy production disturbances, in turn affecting energy consuming mechanisms, could be involved in other cellular changes. Mussels exposed to a wide range of TBT concentrations (20 - 200 and 2000 ng/L respectively) did not show any change in testosterone and estrogen levels in mature gonads. Most hormones were in the non-biologically active esterified form both in control and in TBT-treated mussels. Probably the endocrine status of sexually mature mussels could be refractory even to high TBT doses. In mussel digestive gland the high biological variability of microsomal 7-benzyloxy-4-trifluoromethylcoumarin-O-Debenzyloxylase (BFCOD) activity, taken as a measure of CYP3A-like efficiency, probably concealed any enzyme response to TBT exposure. On the other hand the TBT-driven enhancement of BFCOD activity in vitro was once again ascribed to covalent binding to thiol groups which, in this case, would stimulate the enzyme activity. In mussels from Barcelona harbour, a highly contaminated site, the enzyme showed a decreased affinity for the 7-benzyloxy-4-trifluoromethylcoumarin (BCF) substrate with respect to mussel sampled from Ebro Delta, a non-polluted marine site. Contaminant exposure may thus alter the kinetic features of enzymes involved in detoxification mechanisms. Contaminants and steroid hormones were clearly shown to mutually interact in the modulation of detoxification mechanisms. The xenoestrogen 17α-ethylenyl estradiol (EE2) displayed a non-competitive mixed inhibition of CYP3A-like activity by a preferential bond to the free enzyme both in Barcelona harbour and Ebro Delta mussels. The possible interaction with co-present contaminants in Barcelona harbour mussels apparently lessened the formation of the ternary complex enzyme-EE2-BCF. The whole of data confirms TBT as membrane toxicant in mussels as in other species and stresses TBT covalent binding to protein thiols as a widespread mechanism of membrane-bound-enzyme activity modulation by the contaminant.

Struttura di popolazione in gamberi aristeidi (Decapoda, Aristeidae) nel Mediterraneo occidentale mediante l'utilizzo di loci microsatelliti

Il lavoro svolto durante il dottorato di ricerca ha permesso lo sviluppo e la verifica della attendibilità di marcatori molecolari neutrali (loci microsatelliti) specifici per Aristeus antennatus. Tali marcatori sono stati poi utilizzati per studiare la struttura genetica di popolazione della specie del Mediterraneo occidentale e i risultati ottenuti sono stati confrontati con quelli di un progetto di ricerca parallelo su Aristeaomorpha foliacea, analizzando differenze ed analogie fra le due specie. I risultati delle analisi su Aristeus antennatus hanno evidenziato una completa assenza di struttura di popolazione e come i due sessi contribuiscano in modo diverso al flusso genico. La specie infatti presenta un sex-ratio a favore dei maschi oltre gli 800m, mentre tale rappoorto è a favore delle femmine in strati più superficiali, dove sono probabilmente soggette a condizioni oceanografiche più dispersive. Tramite test genetici appropriati è stato possibile valutare indirettamente il grado di dospersione dei sessi dimostrando che nell'area analizzati i maschi erano rappresentati maggiormente da individui stanziali, mentre gli individui di sesso femminile erano migranti. Le femmine appaiono pertanto giocare un ruolo preminente rispetto ai maschi nel determinare l'entità del flusso genico. Il confronto dei risultati ottenuti in Aristeus antennatus con quelli di Aristaeomorpha foliacea ha evidenziato la relazione fra alta capacità dispersiva, sia allo stato larvale che adulto, e completo rimescolamento genetico nei gamberi aristeidi nel Mediterraneo occidentale anche se in quest'ultima specie non ci sono evidenze di dispersione genetica mediata dal sesso. E' pertanto di forte interesse (dato anche il valore economico di questi organismi) come una struttura di popolazione qualitativamente e quantitavamente comporabile venga raggiunta con dinamiche di popolazione molto diverse.

Wide-scale population genomics of Atlantic bluefin tuna (Thunnus thynnus) inferred by novel high-throughput technology

My PhD project was focused on Atlantic bluefin tuna, Thunnus thynnus, a fishery resource overexploited in the last decades. For a better management of stocks, it was necessary to improve scientific knowledge of this species and to develop novel tools to avoid collapse of this important commercial resource. To do this, we used new high throughput sequencing technologies, as Next Generation Sequencing (NGS), and markers linked to expressed genes, as SNPs (Single Nucleotide Polymorphisms). In this work we applied a combined approach: transcriptomic resources were used to build cDNA libreries from mRNA isolated by muscle, and genomic resources allowed to create a reference backbone for this species lacking of reference genome. All cDNA reads, obtained from mRNA, were mapped against this genome and, employing several bioinformatics tools and different restricted parameters, we achieved a set of contigs to detect SNPs. Once a final panel of 384 SNPs was developed, following the selection criteria, it was genotyped in 960 individuals of Atlantic bluefin tuna, including all size/age classes, from larvae to adults, collected from the entire range of the species. The analysis of obtained data was aimed to evaluate the genetic diversity and the population structure of Thunnus thynnus. We detect a low but significant signal of genetic differentiation among spawning samples, that can suggest the presence of three genetically separate reproduction areas. The adult samples resulted instead genetically undifferentiated between them and from the spawning populations, indicating a presence of panmictic population of adult bluefin tuna in the Mediterranean Sea, without different meta populations.

Materiale epigrafico per la ricostruzione dei contatti nel Mediterraneo tra il 1200 a.C. e il 500 a.C.

La Tesi Materiale epigrafico per la ricostruzione dei contatti nel Mediterraneo tra il 1200 a.C. e il 500 a.C. si propone di illustrare i complessi rapporti instauratisi tra i vari popoli che si affacciarono sulle rive del Mediterraneo e nelle sue vicinanze, tra il 1200 e il 500 a.C. circa, quali emergono dalle iscrizioni disponibili, principalmente greche e semitiche (soprattutto fenicie, ebraiche, aramaiche e assire), prendendo tuttavia in esame anche iscrizioni ittite, egiziane, frigie, etrusche e celtiche. Le date suddette riguardano due eventi cruciali, che sconvolsero il Mediterraneo: gli attacchi dei Popoli del Mare, che distrussero l'Impero Ittita e indebolirono l'Egitto, e le guerre Persiane. Le iscrizioni riportate sono 1546, quasi sempre traslitterate, tradotte, e accompagnate da un'immagine, da riferimenti bibliografici essenziali e da una breve motivazione del collegamento proposto. Il quadro che si delinea ben testimonia la complessità dei rapporti che si intrecciarono in quel periodo: si pensi alle centinaia di graffiti greci trovati a Naucrati, in Egitto, o alle decine di iscrizioni greche trovate a Gravisca. Anche le iscrizioni aramaiche e assire attestano gli stretti rapporti che si formarono tra Siria e Mesopotamia; ugualmente Iran e Arabia sono, direttamente o indirettamente, collegati a Etruria e Grecia; così troviamo un'iscrizione greca nel cuore dell'Impero Persiano, e un cratere laconico nel centro della Gallia. In realtà lo scopo di questo lavoro è anche quello di mettere in contatto due mondi sostanzialmente separati, ossia quello dei Semitisti e quello dei Grecisti, che solo apparentemente si conoscono e collaborano. Inoltre vorrei soavemente insinuare l'idea che la tesi di Joseph Naveh, che ipotizzò che gli alfabeti greci abbiano tratto origine in prima istanza dalle iscrizioni protocananaiche, nel XII sec. a.C., è valida, e che solo in un secondo tempo i Fenici abbiano dato il loro apporto.

Valutazione della presenza di contaminanti perfluoroalchilici in alimenti destinati al consumo umano

Le sostanze perfluoralchiliche (PFAS), composti fluorurati ampiamente utilizzati negli ultimi anni in diverse applicazioni industriali e commerciali, sono ritrovati diffusamente nell’ambiente e in diverse specie animali. Recentemente i PFAS hanno destato preoccupazione anche per la salute umana. Il rischio di esposizione è principalmente legato alla dieta (i prodotti ittici sembrano essere gli alimenti più contaminati). Lo scopo di questo lavoro è stato quello di valutare la presenza del perfluorottanosulfonato (PFOS) e dell’acido perfluorottanoico (PFOA), in diverse matrici alimentari: latte vaccino commercialmente disponibile in Italia, latte materno italiano, diverse specie di pesce commercialmente disponibili in Italia e 140 branzini di diverse aree (principalmente Mediterraneo). I campioni di latte sono stati trattati con estrazione liquido-liquido seguita da due fasi di purificazione mediante cartucce SPE prima dell’iniezione nell’UPLC-MS/MS. L’analisi del latte vaccino ha evidenziato una contaminazione diffusa di PFOS, ma a basse concentrazioni (fino a 97 ng/L), mentre il PFOA è stato ritrovato raramente. In questo studio, in grado di individuare anche i livelli delle ultra-tracce, sono state osservate nel latte materno concentrazioni di 15-288 ng/L per il PFOS e di 24-241 ng/LPFOA. Le concentrazioni e le frequenze più alte, per entrambi i PFAS, sono stati ritrovate in campioni di latte forniti da donne primipare, suggerendo un rischio di esposizione per i primogeniti. Il metodo utilizzato per i campioni di pesce era basato su un’estrazione con solvente organico seguita da due fasi di purificazione: una con i sali e una con fase solida dispersiva. L’estratto, analizzato in UPLC-MS/MS, ha confermato la contaminazione di questa matrice a livelli significativi, ma anche l’alta variabilità delle concentrazioni misurate. Il monitoraggio monospecie ha mostrato una contaminazione rilevante (PFOS 11,1- > 10000 ng/L; PFOA < 9-487 ng/L), soprattutto nei branzini pescati, rispetto a quelli allevati.