Host-associated and Environmental Microbiomes in an Open-Sea Mediterranean Gilthead Sea Bream Fish Farm

Gilthead seabream is among the most important farmed fish species in the Mediterranean Sea. Several approaches are currently applied to assure a lower impact of diseases and higher productivity, including the exploration of the fish microbiome and its manipulation as a sustainable alternative to improve aquaculture practices. Here, using 16S rRNA gene high-throughput sequencing, we explored the microbiome of farmed seabream to assess similarities and differences among microbial assemblages associated to different tissues and compare them with those in the surrounding environment. Seabream had distinct associated microbiomes according to the tissue and compared to the marine environment. The gut hosted the most diverse microbiome; different sets of dominant ASVs characterized the environmental and fish samples. The similarity between fish and environmental microbiomes was higher in seawater than sediment (up to 7.8 times), and the highest similarity (3.9%) was observed between gill and seawater, suggesting that gills are more closely interacting with the environment. We finally analyzed the potential connections occurring among microbiomes. These connections were relatively low among the host's tissues and, in particular, between the gut and the others fish-related microbiomes; other tissues, including skin and gills, were found to be the most connected microbiomes. Our results suggest that, in mariculture, seabream microbiomes reflect only partially those in their surrounding environment and that the host is the primary driver shaping the seabream microbiome. These data provide a step forward to understand the role of the microbiome in farmed fish and farming environments, useful to enhance disease control, fish health, and environmental sustainability

Sperimentazione in mesocosmo per la valutazione degli effetti di sostanze nutraceutiche sul bioaccumulo di mercurio in esemplari di Sparus aurata

CIRCLES “Controlling mIcRobiomes CircuLations for bEtter food Systems” è un progetto Europeo che nasce con l’obiettivo generale di fornire le conoscenze scientifiche necessarie a sfruttare i microbiomi naturali per la produzione sostenibile di alimenti di alta qualità, con l'obiettivo finale di fornire applicazioni alimentari nuove e più sane. Valutare gli effetti del microbioma sul bioaccumulo di sostanze tossiche nei tessuti di specie ittiche commerciali potrebbe rappresentare una strategia innovativa per produrre “cibo” sicuro, sostenibile e di qualità superiore. Nello specifico, le attività sperimentali di seguito descritte sono state eseguite allo scopo di determinare gli effetti di mangimi innovativi arricchiti con sostanze nutraceutiche nel contrastare/modulare il bioaccumulo di mercurio (Hg) nei tessuti della specie commerciale Sparus aurata

Oocyte development of captive <i>Seriola dumerilii V Micale</i> et al<i>.</i>

A study of the reproductive biology of the amberjack, Seriola dumerilii, held in captivity was carried out, describing oogenesis as well as the different stages of the ovarian cycle. Seven stages of oocyte development, as well as oogonia, were distinguished. Cortical alveoli were hardly detectable within the oocyte, as they were small, sparse and contained few mucopolysaccharides. It is suggested that their role in the fertilization process might be less important than in other teleost species. Fish aged 3 and 4 years were found to be sexually immature, with ovaries containing only previtellogenic oocytes. Vitellogenesis started in December in fish aged 4 + years. Late-developing ovaries showing deposition of yolk protein granules were found at the end of the 5th year of life (May) in specimens measuring 80.0 6 3.5 cm standard length. This should be regarded as the minimum size at which sexual maturity is reached in S. dumerilii. Final vitellogenesis and oocyte maturation were, however, inhibited in captivity, and extensive follicular atresia took place as the natural spawning season approached. It is suggested that insufficient gonadotrophic stimulation because of confinement stress may be the cause of failed maturation and spawning in this species under culture conditions

Lab experimental setting for analysis of Mytilus galloprovincialis’ behaviour after wave-generated sounds exposure

The present paper proposes an experimental lab setting and an innovative method in order to evaluate the behavioural reactions of Mediterranean mussels (Mytilus galloprovincialis) exposed to different acoustic stimuli. Ninety mussels were exposed for 30 minutes to one of five acoustic tones repeated in continuous or to the control condition. The tones lasted 1 s and differed in frequency band: Low frequencies-sweep (L, 0.1 - 5 kHz); Mid-Low frequencies-sweep (ML, 5 - 10 kHz); Mid frequencies-sweep (M, 10 - 20 kHz); Mid-High frequencies-sweep (MH, 20 - 40 kHz); High frequencies-sweep (H, 40 - 60 kHz). Experimental test sweeps were produced using a signal generator connected to underwater loudspeakers and a calibrated hydrophone was used to obtain acoustic recordings of sweeps and experimental tank background noise. An underwater camera, placed overhead the animals, recorded the mussels’ behaviours. A continuous visual sampling procedure, performed by an observatory, was adopted to detect the mussel gape rate and the outpouching of the muscular foot while an automatic analysis was performed using EthoVision XT 9.0 software. The behavioural parameters assessed automatically included changes in mobility status, movement, velocity and turn angle that are usually estimated in vertebrates and higher invertebrates

Measuring the effects of temperature rise on Mediterranean shellfish aquaculture

Shellfish aquaculture represents a worldwide valuable segment of the aquaculture market, spreading along the Mediterranean coasts, and is sensitive to the still unforeseen, poorly-known effects of climate change. Threats due to temperature rise can threaten the deployment and development of this sector, up until now recognised as the best candidate to mitigate the effects of fishery overexploitation. Here, we investigate the effects of temperature increase on the model species, Mytilus galloprovincialis, measuring outcomes from valve fragility (thickness) and condition index. Evidence of a reduction in the thickness of valves and the modulation condition of the mussels along with temperature increase have been gathered from simulations of a natural temperature gradient changing along latitude (the Italian Peninsula) and temperature risen (mesocosm trial). The obtained results offer a baseline to help the next generation of managers and stakeholders when assessing the reliability and feasibility of shellfish culture in a changing sea that can generate undetected and underestimated impacts on the sector

Influence of Hermetia illucens Larvae Meal Dietary Inclusion on Growth Performance, Gut Histological Traits and Stress Parameters in Sparus aurata

This study provided new data and knowledge on the potential use of Hermetia illucens meal (HIM) as a new sustainable ingredient for Sparus aurata diet. The effect of HIM dietary inclusion on fish growth performance, stress indicators and gut histology was studied. For 131 days, 312 fish were fed a basal diet containing fishmeal as animal protein source, and three diets containing 25%, 35% and 50% HIM as a partial replacement for fishmeal. The main findings indicated that fishmeal can be replaced by HIM up to 110 g/kg of substitution (35% of inclusion in diet) without negative effects on growth performance, stress parameters or histological traits of the posterior gut tract, and with positive effects (p &lt; 0.05) on the histological and morphometric characteristics of the anterior gut tract. At the same time, the results showed that the effect of Hermetia illucens meal at 50% inclusion level caused morphometric and histopathological alterations in the anterior gut tract of seabream. In conclusion, this preliminary study suggested that the dietary inclusion level of HIM35 was the most tolerated by fish showing the best gut morphometric parameters and histological conditions, with fewer signs of inflammation, as well as good nutritional and health status

Dietary inclusion of Tenebrio molitor larvae meal: Effects on growth performance and final quality treats of blackspot sea bream ( Pagellus bogaraveo )

This study evaluated the effects of diets containing Tenebrio molitor (TM) larvae meal in partial substitution of fishmeal (FM) on growth performances, marketable, physical and chemical traits of wild-caught blackspot sea bream, a valuable finfish species potentially candidate for Mediterranean aquaculture. One hundred thirty fish were randomly divided into three groups with three replicates each. Fish were fed three diets presenting increasing levels of TM in FM substitution for 131 days: TM0, TM25 and TM50 with 0%, 25% and 50% of fishmeal replacement, respectively. Daily intake ratio, feed conversion ratio and specific growth rate were not affected by different diets, like slaughter traits and carcass yield. No significant differences were detected for some fillet quality parameters, such as water holding capacity and texture characteristics (hardness, cohesiveness, resilience, gumminess and adhesiveness), whilst pH value was found lower in TM50 than in TM0 and TM25 specimens. Different diets did not affect the colour of the skin dorsal region, unlike the skin ventral region where significant variations in colour were observed, as lower lightness and hue while higher redness in TM50 group than in the other two groups. Regarding colour of fillet epaxial region, yellowness and chroma were higher when TM was added in the diets; instead hue resulted higher in fish fed diet containing FM as exclusive source of protein. In the fillet hypaxial region, the colour presented yellowness and chroma values lower in TM0 and TM25 groups than in TM50 group; whilst this last showed the lowest value for hue. Fillet proximate composition was not affected by the diet, unlike the fatty acids profile. Σn3FA, especially EPA, was higher in fish fed TM0 diet. On the contrary Σn6, especially linoleic acid, significantly increased with TM inclusion in the diets. The Σn3/Σn6 FA ratio was linearly (TM0 > TM25 > TM50) reduced by TM inclusion in the diet and TM50 specimens had the highest (i.e. the worst) values for Atherogenicity and Thrombogenicity Indexes. Since no detrimental effects on growth performance were found, the use of Tenebrio molitor meal as alternative protein source in blackspot sea bream diet seems to be encouraging, but the effects on fillet quality should be considered

Intestinal alterations in European sea bass Dicentrarchus labrax (Linnaeus, 1758) exposed to microplastics: Preliminary results

This study investigates, for the first time, the intestinal responses of European sea bass Dicentrarchus labrax chronically exposed to microplastics through ingestion. Fish (n = 162) were fed with 3 different treatment diets for 90 days: control, native polyvinyl chloride (PVC) and polluted polyvinyl chloride (PVC) pellets. Intestines were fixed and processed for histological analysis using standard techniques. Histopathological alterations were examined using a score value (from 0 to 4). The distal part of intestine in all samples proved to be the most affected by pathological alterations, showing a gradual change varying from moderate to severe related to exposure times. The histological picture that characterizes both groups especially after 90 days of exposure, suggests that the intestinal functions can be in some cases totally compromised. The worst condition is increasingly evident in the distal intestine of fish fed with polluted PVC pellets respect to control groups (p &lt; 0.05) to different exposure times. These first results underline the need to assess the impact of increasing microplastics pollution on the marine trophic web

La duna artificiale di Parco Italia (Rosario, Argentina) | Parco Italia and the artificial dune (Rosario, Argentina)

L’idea di Parco Italia - il parco espositivo delle eccellenze italiane in Argentina - nasce sin dalla seconda metà del primo decennio 2000 come occasione per mettere in luce in termini di eccellenza la consistenza della offerta italiana rivolta al Paese sud-americano. Si tratta di una idea condivisa che coglie istanze di diversa provenienza: l’interesse della comunità italiana di Rosario, terza città in Argentina e prima per dimensione dell’immigrazione dall’Italia, la rappresentanza scientifica dell’Ambasciata italiana a Buenos Aires, imprenditori vicini all’Italia e all’Argentina e ai loro differenziati ma complementari mercati. In quel periodo Gabriele Paparo, allora addetto scientifico dell’Ambasciata d’Italia, ha il merito non solo di mettere a punto il primo organigramma funzionale di quattro padiglioni a cui ricondurre l’insieme delle “eccellenze” da esporre ma anche di tessere intorno al progetto una trama di attenzioni sia a livello istituzionale che operativo capace di portare l’idea all’attenzione generale.The idea of Parco Italia - the exhibition park of the Italian excellences in Argentina - was born from the second half of the first decade of 2000 as an opportunity to highlight the consistency of the Italian offer addressed to the South American country in terms of excellence. Gabriele Paparo, in that time Italian scientific attaché in Buenos Aires, remains with tenacity protagonist of the project over the following years, together with the new Italian scientific attaché José Kenny, bringing the project to the attention of CONICET, the National Research Council of Argentina, and to the attention of the Italian University Consortium for Argentina (CUIA) in Italy