Distribution of non-native Pacific oyster Magallana gigas (Thunberg, 1793) along the eastern Adriatic coast

Non-native Pacific oyster Magallana gigas (Thunberg, 1793) was introduced to the Mediterranean Sea for aquaculture purposes in the 1960s. Although this species was not introduced for aquaculture to the Croatian part of the Adriatic Sea, in the 1970s, it was reported in the Lim Bay, in the North-eastern Adriatic. Until recently, there has been no research on the species in the Croatian part of the Adriatic. The aim of this research was to summarize existing and novel data on the distribution of M. gigas in coastal areas of the Eastern Adriatic and to provide a baseline for the future monitoring and assessment programmes of the species. Distribution of M. gigas was determined by three different methods: (i) a visual census of the presence of M. gigas specimens in the medio-littoral zone ; (ii) DNA identification of M. gigas larvae in the water column ; and (iii) the presence of M. gigas in the subtidal zone at depth between 25 and 40 m. Magallana gigas has a well- established population in the medio-littoral zone of natural and anthropogenic habitats along the coast of the North-eastern Adriatic Sea (west coast of Istria peninsula), but it is not present in the deeper layers . In the Central-eastern and South-eastern Adriatic Sea, the species was either absent or sporadically recorded with no evidence of fully established populations. Considering the great invasion success of M. gigas worldwide and effects that this species could have on the invaded ecosystem (e.g. competition for food and space with native species), detailed future monitoring is needed for the Eastern Adriatic Sea

A plant-based diet supplemented with Hermetia illucens alone or in combination with poultry by-product meal: one step closer to sustainable aquafeeds for European seabass

Background: Increasing demand for high-value fish species and pressure on forage fish is challenging aquaculture to ensure sustainable growth by replacing protein sources in aquafeeds with plant and terrestrial animal proteins, without compromising the economic value and quality of the final fish product. In the present study, the effects of a plant protein-based diet (CV), two plant-based diets in which graded amounts of plan protein mixtures were replaced with Hermetia illucens meal alone (VH10) or in combination with poultry by-product meal (PBM) (VH10P30), a fishmeal (FM) diet (CF) and an FM diet supplemented with H. illucens (FH10) on growth performance, gut health and homeostasis of farmed subadult European seabass were tested and compared. Results: Fish fed the VH10 and VH10P30 diets showed the highest specific growth rates and lowest feed conversion ratios among the tested groups. Expectedly, the best preservation of PI morphology was observed in fish fed the CF or FH10 diets, while fish fed the CV diet exhibited significant degenerative changes in the proximal and distal intestines. However, PBM supplementation mitigated these effects and significantly improved all gut morphometric parameters in the VH10P30 group. Partial substitution of the plant mixture with insect meal alone or PBM also induced most BBM genes and activated BBM enzymes, suggesting a beneficial effect on intestinal digestive/absorption functions. Regarding intestinal microbiota, fish fed diets containing H. illucens meal (FH10, VH10, VH10P30) had the highest richness of bacterial communities and abundance of beneficial genera such as Lactobacillus and Bacillus. On the other hand, fish fed CV had the highest microbial diversity but lost a significant component of fish intestinal microbiota, the phylum Bacteroidetes. Finally, skin pigmentation most similar to that of farmed or even wild seabass was also observed in the fish groups fed CF, FH10 or VH10P30. Conclusion: Plant-based diets supplemented with PBM and H. illucens pupae meal have great potential as alternative diets for European seabass, without affecting growth performance, gut homeostasis, or overall fitness. This also highlights the importance of animal proteins in diets of European seabass, as the addition of a small amount of these alternative animal protein sources significantly improved all measured parameters

TOWARDS SUSTAINABLE ADRIATIC MARICULTURE USING NEW FEED FORMULATIONS: THE ADRIAQUANET PROJECT

The INTERREG project AdriAquaNet (https://www.italy-croatia.eu/web/adriaquanet), coordinated by Udine University, aims at enhancing the sustainable development of Adriatic mariculture and fostering cooperation between Italian and Croatian operators. In order to achieve these goals, the project is developing innovations concerning the whole seabass and seabream supply chain. In particular, the project focuses on: 1) farm management, fish nutrition and waste disposal; 2) fish health and welfare; 3) new added value products. The project also tests a comprehensive monitoring system, which integrates the real time monitoring of relevant environmental parameters, i.e. water temperature and dissolved oxygen, footage captured with high resolution video camera, which allows monitoring fish behaviour and simulation models. In this paper, preliminary results of fish growth performance using a novel feed formulation including insects and poultry PAP at lab scale and in at operational level, are also presented

Combined Use of Morphological and Molecular Tools to Resolve Species Mis-Identifications in the Bivalvia The Case of Glycymeris glycymeris and G. pilosa

Morphological and molecular tools were combined to resolve the misidentification between Glycymeris glycymeris and Glycymeris pilosa from Atlantic and Mediterranean populations. The ambiguous literature on the taxonomic status of these species requires this confirmation as a baseline to studies on their ecology and sclerochronology. We used classical and landmark-based morphometric approaches and performed bivariate and multivariate analyses to test for shell character interactions at the individual and population level. Both approaches generated complementary information. The former showed the shell width to length ratio and the valve asymmetry to be the main discriminant characters between Atlantic and Mediterranean populations. Additionally, the external microsculpture of additional and finer secondary ribs in G. glycymeris discriminates it from G. pilosa. Likewise, landmark-based geometric morphometrics revealed a stronger opisthogyrate beak and prosodetic ligament in G. pilosa than G. glycymeris. Our Bayesian and maximum likelihood phylogenetic analyses based on COI and ITS2 genes identified that G. glycymeris and G. pilosa form two separate monophyletic clades with mean interspecific divergence of 11% and 0.9% for COI and ITS2, respectively. The congruent patterns of morphometric analysis together with mitochondrial and nuclear phylogenetic reconstructions indicated the separation of the two coexisting species. The intraspecific divergence occurred during the Eocene and accelerated during the late Pliocene and Pleistocene. Glycymeris pilosa showed a high level of genetic diversity, appearing as a more robust species whose tolerance of environmental conditions allowed its expansion throughout the Mediterranean

Two seas, two lineages: How genetic diversity is structured in Atlanticand Mediterranean greater amberjack Seriola dumerili Risso, 1810 (Perciformes, Carangidae)

The vastness of the ocean and our limited ability to observe and monitor the organisms therein makemolecular markers particularly useful tools in the investigation of the ecology and evolutionary biologyof fish. Nowadays, due to increased demand of fish foods, genetic researches are focused on new can-didate species for aquaculture, such as Seriola species. Here, the analyses of eight polymorphic nuclearmicrosatellites loci and three mitochondrial (mt) DNA genes (16S-rRNA, Cyt-b, and D-Loop) in the greateramberjack, Seriola dumerili, detected breakpoint between Atlantic and Mediterranean populations, pre-sumably arisen by the oceanographic features of the Almeria-Oran Front opposed to the gene flow of thespecies. Still, an absence of heterogeneity between the sampling locations within the Mediterranean Seawas noted, although an observed dichotomous structure of the phylogenetic mtDNA tree revealed twoclades, with no spatial division within the basin. The origin of these two clades likely predates the latePleistocene or Holocene colonization of the species from the Atlantic Ocean into the Mediterranean Sea.In addition, some preliminary genetic information are provided for Seriola rivoliana, the species that hasbeen recently recognized as an Atlantic migrant in the Mediterranean

Spillover of the Atlantic bluefin tuna offspring from cages in the Adriatic Sea : a multidisciplinary approach and assessment

During routine monitoring of commercial purse seine catches in 2011, 87 fingerling specimens of scombrids were collected in the southern Adriatic Sea. Sequencing of the mitochondrial DNA control region locus inferred that specimens belonged to the Atlantic bluefin tuna, Thunnus thynnus (Linnaeus, 1758) (N = 29), bullet tuna, Auxis rochei (Risso, 1810) (N = 30) and little tunny, Euthynnus alletteratus, Rafinesque, 1810 (N = 28). According to previously published growth parameters, the age of the collected specimens was estimated at approximately 30-40 days, suggesting they might have been spawned in the Adriatic Sea, contrary to the current knowledge. A coupled modelling system with hydrodynamic (ROMS) and individual based model (IBM-Ichthyop) was set up to determine the location of the spawning event. Numerical simulations with the IBM model, both backward and forward in time, indicate commercial tuna cages in the middle Adriatic coastal area as possible spawning location. The two other non-commercial species likely opportunistically use the positive environmental (abiotic and biotic) conditions to spawn in the same area