Effects of Paramuricea clavata (Risso, 1826) (Anthozoa: Plexauridae) forests on settlement of benthic species: an experimental approach

Rationale: Coralligenous habitat is considered the second most important subtidal “hot spot” of species diversity in the Mediterranean Sea after the Posidonia oceanica meadows. It can be defined as a typical Mediterranean biogenic hard bottom, mainly produced by the accumulation of calcareous encrusting algae that, together with other builder organisms, form a multidimensional framework with a high micro-spatial variability. The development of this habitat depends on physical factors (i.e. light, hydrodynamism, nutrients, etc.), but also biologic interactions can play a relevant role in structuring the benthic assemblages. This great environmental heterogeneity allows several different assemblages to coexist in a reduced space. One of the most beautiful is that characterised by the Mediterranean gorgonian Paramuricea clavata (Risso, 1826) that can contribute to above 40% of total biomass of the community and brings significant structural complexity into the coralligenous habitat. In sites moderately exposed to waves and currents, P. clavata can form high-density populations (up to 60 colonies m-2) between 20 – 70 m in depth. Being a suspension feeder, where it forms dense populations, P. clavata plays a significant role in transferring energy from planktonic to benthic system. The effects of the branched colonies of P. clavata could be comparable to those of the forests on land. They can affect the micro scale hydrodynamism and light, promoting or inhibiting the growth of other species. Unfortunately, gorgonians are threatened by several anthropogenic disturbance factors (i.e. fishing, pollution, tourism) and by climatic anomalies, linked to the global changes, that are responsible of thermal stress, development of mucilage and enhanced pathogens activity, leading to mass mortality events in last decades. Till now, the possible effects of gorgonian forest loss are largely unknown. Our goal was to analyse the ecological role of these sea fan forests on the coralligenous benthic assemblages. Experimental setup and main results: The influence of P. clavata in the settlement and recruitment of epibenthic organisms was analysed by a field experiment carried out in two randomly selected places: Tavolara island and Portofino promontory. The experiment consisted in recreate the presence and absence of the gorgonian forest on recruitment panels, arranged in four plots per type (forested and non-forested), interspersed each other, and deployed at the same depth. On every forested panel 3 gorgonian colonies about 20 cm height were grafted with the use of Eppendorf tubes and epoxy resin bicomponent simulating a density of 190 sea fans per m-2. This density corresponds to a mean biomass of 825 g DW m-2,3 which is of the same order of magnitude of the natural high-density populations. After about 4 months, the panels were collected and analysed in laboratory in order to estimate the percent cover of all the species that have colonized the substrata. The gorgonian forest effects were tested by multivariate and univariate permutational analyses of the variance (PERMANOVA). Recruited assemblages largely differed between the two study sites, probably due to different environmental conditions including water quality and turbidity. On overall, the presence of P. clavata reduced the settlement and recruitment of several algae: the shadow caused by the gorgonian might reduce light availability and therefore their growth. This effect might be greater in places where the waters are on average more clear, since at Portofino it is less visible and could be masked by the high turbidity of the water. The same pattern was registered for forams, more abundant outside gorgonian forest, probably linked with algal distribution, shadowing effect or alimentary competition. The last one hypothesis could be valid also for serpulids polychaetes that growth mainly on non-forested panels. An opposite trend, was showed by a species of bryozoan and by an hydroid that is facilitated by the presence of P. clavata, probably because it attenuates irradiance level and hydrodynamism. Species diversity was significantly reduced by the presence of P. clavata forests at both sites. This seems in contrast with what we expected, but the result may be influenced by the large algal component on non-forested panels. The analysis confirmed the presence of differences in the species diversity among plots and between sites respectively due to natural high variability of the coralligenous system and to different local environment conditions. The reduction of species diversity due to the presence of gorgonians appeared related to a worst evenness rather than to less species richness. With our experiment it is demonstrated that the presence of P. clavata forests can significantly alter local coralligenous assemblages patterns, promoting or inhibiting the recruitment of some species, modifying trophic relationships and adding heterogeneity and complexity to the habitat. Moreover, P. clavata could have a stabilising effect on the coralligenous assemblages.

Distribuzione spazio-temporale di Stenella coeruleoalba (Meyen, 1833) e Tursiops truncatus (Montagu, 1821) nel Golfo di Taranto

Il Golfo di Taranto è una baia storica all’interno del Mar Ionio Settentrionale, Mar Mediterraneo Orientale. Sebbene il Mar Mediterraneo rappresenti meno dell’1% della superficie oceanica, presenta un alto livello di diversità biologica e si inserisce tra i primi 25 Biodiversity Hot Spot a livello globale. Esso purtroppo è anche uno dei bacini più antropizzati del mondo; tali pressioni mettono a serio rischio la conservazione di numerose specie, tra cui i Cetacei. Attualmente non sono presenti lavori riportanti dati di abbondanza dei Cetacei nel Golfo di Taranto: la mia ricerca vuole contribuire a colmare questo vuoto conoscitivo ed aggiungere nuove conoscenze sull’abbondanza dei Cetacei nel Mar Mediterraneo. Le aree di studio prese in esame si trovano nel Golfo di Taranto, sono contigue ed hanno la stessa superficie. Utilizzando il metodo del transetto lineare ed il software Distance 6.0 è stato possibile, raccogliere i dati di abbondanza dei delfinidi Stenella coeruleoalba e Truncatus truncatus ed analizzarli, ottenendo delle stime di abbondanza da confrontare con la serie storica disponibile (2009-2014). L’utilizzo del metodo del Distance Sampling, applicato per la prima volta nel Golfo di Taranto, è stato fondamentale perché ha permesso di colmare una lacuna conoscitiva sulla consistenza numerica associata alla nota presenza dei Cetacei nel Mar Ionio Settentrionale. I risultati ottenuti hanno reso possibile il confronto delle stime di abbondanza ottenute nel Golfo di Taranto con quelle del bacino ligure-corso-provenzale del Mediterraneo (Santuario Pelagos). Infatti è stato possibile rilevare che S. coeruleoalba presenta abbondanze generalmente inferiori ed un trend in diminuzione nel Santuario Pelagos, in netto contrasto con le maggiori abbondanze ed il trend in incremento evidenziato nel Golfo di Taranto e sintetizzato in questa tesi. Si evince, quindi la massima urgenza nell’implementare lo studio nel Golfo di Taranto, laddove la presenza di differenti specie di Cetacei e le stime di abbondanza di S. coeruleoalba e T. truncatus evidenziano la necessità di interventi di gestione finalizzati alla conservazione del patrimonio di diversità biologica del Mediterraneo.

Multifrequency VLBA observations of two compact symmetric objects

In this thesis the results of the multifrequency VLBA observations of the GPS 1944+5448 and the HFP J0111+3906 are presented. They are compact objects smaller than about 100 pc, completely embedded in the host galaxy. The availability of multi-epoch VLBI observations spanning more than 10 years, allowed us to compute the hot spot advance speed in order to obtain the kinematic age of both sources. Both radio sources are young, in agreement with the idea that they are in an early evolutionary stage. The spectral analysis of each source component, such as the lobes, the hot spots, the core and the jets, making a comparison with the theoretical ones is described. In addition the physical parameters derived from VLBA images as the magnetic field, the luminosity, the energy and the ambient medium density of both sources are discussed.

Integrazione di dati antropometrici e termografici per l'analisi della distribuzione di temperatura all'interfaccia moncone-protesi d'arto inferiore

Le immagini termiche all’ infrarosso sono utilizzate da molte decadi per monitorare la distribuzione di temperatura della pelle umana. Anormalità come infiammazioni ed infezioni causano un aumento locale della temperatura, visibile sulle immagini sotto forma di hot spot. In tal senso la termografia ad infrarossi può essere utilizzata nel campo ortopedico per rilevare le zone sovra-caricate dalla protesi. Per effettuare una valutazione precisa dell’interfaccia moncone-invasatura può essere utile combinare i dati termografici e i dati antropometrici (superficie tridimensionale del moncone), relativi ai singoli pazienti. Di ciò si occupa tale studio, che dopo aver fornito una panoramica sulla termografia e sulla reverse engineering, sperimenta delle tecniche semplici e low-cost per combinare i dati termici e i dati antropometrici. Buoni risultati si riescono ad ottenere utilizzando un Kinect come scanner e un software open-source per il texture mapping. I termogrammi 3D ricreati costituiscono un ottimo strumento di valutazione, per medici e tecnici ortopedici, circa il design dell’invasatura.