Environmental quality improvement of a mariculture plant after its conversion into a multi-trophic system.

Integrated Multitrophic Aquaculture (IMTA) seems to be one of the best solutions for sustainable aquaculture. Within the Remedia LIFE Project, an experimental IMTA plant was put in place in the Mar Grande of Taranto (Mediterranean Sea, Southern Italy). The polyculture of several bioremediating organisms, such as mussels, tubeworms, sponges, and seaweeds, was combined with a coastal cage fish farm, in order to remove organic and inorganic wastes coming from the fish's metabolism. To verify the effectiveness of the system, the ex ante measurement of chemical-physical variables, trophic status, microbial contamination, and zoobenthos community health was compared with the results of the same measurement performed one year and two years after the implementation of the experimental IMTA plant. The results were encouraging, since a reduction in total nitrogen concentration in the seawater (from 43.4 ± 8.9 to 5.6 ± 3.7 µM/l), a reduction in microbial pollution indicators in the seawater (total coliforms: from 280 ± 18 MPN/100 mL to 0; E. coli: from 33 ± 1.3 MPN/100 mL to 0) and in the sediments (total coliforms: from 230 ± 6.2 MPN/100 g to 170 ± 9; E. coli: from 40 ± 9.4 MPN/100 g to 0), an enhancement of the trophic status (TRIX: from 4.45 ± 1.29 to 3.84 ± 0.18), and an increase in the zoobenthic quality indices and biodiversity were recorded (AMBI: from 4.8 to 2.4; M-AMBI: from 0.14 to 0.7). These results prove that the Remedia LIFE project's purpose was achieved. The selected bioremediators worked synergistically, improving water and sediments quality within the fish farm area. Moreover, bioremediating organisms increased their weight as a result of wastes uptake, producing, as co-products, large amounts of additional biomass. This could be commercially exploited, thus being an added value of the IMTA plant. Based on our findings, the promotion of eco-friendly practices to ameliorate ecosystem health should be encouraged.

Life-cycle traits in the demosponge Hymeniacidon perlevis in a land-based fish farm.

Background: The demosponge Hymeniacidon perlevis is characterized by wide geographic distribution and great adaptability to numerous and highly variable climatic and hydrological conditions. Indeed, the species can colonize many different environments, including several unusual ones, such as concrete drainage conduits of a marine land-based fish farm plant. This research aimed to enhance existing knowledge on the reproductive cycle and growth performance of H. perlevis while also evaluating the impact of a controlled supply of trophic resources, wastewater flow and constant water temperature on these biological traits. Methods: Specimens included in this one-year study inhabited drainage conduits of a land-based fish farm. The approach included measurements of sponge biomass and occurrence and abundance of reproductive elements across different seasons and environmental parameters, such as fish biomass, trophic resources, and wastewater flow. Sponge growth and reproductive elements, including oocytes, spermatic cysts, and embryos, were measured monthly in sponges positioned in the drainage conduit, thus with different trophic resources but with constant water temperature. Finally, we used generalized additive models to describe variables that contribute the most to the growth of sponges. Results: Growth performance showed marked variations during the study period. The highest increase in sponge volume was observed from August/September to January/March. The volume of sponges was principally determined by the reduction of reared fish biomass and the increase of pellet amount and wastewater flow. Sponge specimens exhibited an active state during the entire study, as proven by the occurrence of recruits. However, sexual elements were only sporadically observed, thus not permitting the recognition of a true sexual cycle. Discussion: The results of the present study confirmed that H. perlevis exhibits high flexibility and adaptability to the differential, and somewhat extreme, environmental conditions. Indeed, this species can live, grow and reproduce in the drainage conduits of the fish farm, where the species face constant darkness, water temperature and continuous nutritional supply. In such conditions, H. perlevis display an active state during the entire year, while avoiding stages of decline and long dormancy usually observed in wild populations. It seems plausible that stable environmental conditions induce an almost continuous sexual phase, probably under the control of endogenous factors. No asexual elements were detected, although it was impossible to exclude the contribution of asexual reproduction in the origin of the newly settled sponges, which were repeatedly detected throughout the study. The growth performance seemed linked to the fish farm conditions, thus providing useful indications on the best maintenance conditions for H. perlevis in land-based integrated multitrophic systems, where the species could be used for wastewater treatment.

Alien and native species in Italian marine and transitional waters.

Background: Biological invasions are one of the major threats to the ecosystem structure and functioning. After the initial introduction, frequently mediated by human activities, alien species can overcome different biogeographical and ecological barriers and determine severe impacts on native biodiversity and socio-economic activities. The Italian peninsula is located at the intersection of large trade routes within the Mediterranean Sea. Such position, along with the intense commercial activity and the high population density of the Italian coast, are considered important drivers of alien species in Italian marine and transitional ecosystems. The Italian peninsula, however, is also one of the regions with the highest native species richness within the Mediterranean Sea and, therefore, it is crucial to account for both alien and native species diversity when estimating the impact of biological invasion. Yet, such comprehensive information is frequently scattered across several biodiversity information systems and databases. New information: Here, two datasets with alien and native species records in Italian marine and transitional waters are described. These datasets, created for the LifeWatch Italy case study on alien species, are the result of a large-scale collaboration involving experts working across the whole range of taxonomic diversity. The marine dataset includes a total of 12,219 records belonging to 3,772 species gathered from 91 investigated sites and seven EUNIS habitats. The dataset on transitional waters biodiversity includes 3,838 records belonging to 2,019 species found in 23 locations and four EUNIS habitats. Alien species were recorded in both marine and transitional waters, accounting respectively for 140 and 171 biological records belonging to 59 and 97 species. These occurrence data can be used for further research studies or management purposes, including the evaluation of the invasion risk and the formulation of alien species control and management plans. Furthermore, these compiled datasets can be used as input data for the Biotope vulnerability case study of LifeWatch ERIC, which offers a number of ICT services for the calculation of the incidence and of the impact of alien species on European biotopes.

An Integrated Monitoring Approach to the Evaluation of the Environmental Impact of an Inshore Mariculture Plant (Mar Grande of Taranto, Ionian Sea).

The results of an ex-ante survey aiming to assess the impact of a fish farm in the Mar Grande of Taranto (southern Italy, Mediterranean Sea) on the surrounding environment are reported. There, the implementation of an innovative IMTA plant was planned, with the goals of environment bioremediation and commercially exploitable biomass production. Analyses were conducted in February and July 2018. Both seawater and sediments were sampled at the four corners of the fish farm to detect the existing biological and physico-chemical features. The investigation was performed to identify the best area of the farming plant for positioning the bioremediating system, but also to obtain a data baseline, to compare to the environmental status after the bioremediating action. Data were also analyzed by canonical analysis of principal coordinates (CAP). All the measurements, in particular, microbiology and macrobenthic community characterization using AZTI's Marine Biotic Index (AMBI) and the Multivariate-AMBI (M-AMBI) indices, suggest that the effect of fish farm waste was concentrated and limited to a small portion of the investigated area in relation to the direction of the main current. A site named A3, which was found to be the most impacted by the aquaculture activities, especially during the summer season, was chosen to place the bioremediation system.

Large-Scale Distribution of the European Seahorses (Hippocampus Rafinesque, 1810): A Systematic Review.

Human pressures on marine ecosystems have caused extensive degradation of marine habitats and several local extinctions. Overexploitation and destructive fishing practices are responsible for biodiversity loss in many coastal ecosystems. The definition of conservation programs in marine fish requires comprehensive knowledge on large-scale geographical distribution, while considering distribution/abundance patterns in relation to key environmental variables. Due to their life-cycle traits, the two European seahorses (Hippocampus guttulatus and H. hippocampus), as with other congeneric species, are particularly sensitive to the effects of anthropogenic activities and habitat changes. However, information on the ecological distribution of these two species is scattered, patchy, and mainly focused on small-scale studies. In this paper, we followed an international standard protocol for systematic reviews (the PRISMA protocol) to provide a detailed assessment of the two species' geographical distribution in relation to the environmental characteristics. According to the 134 analyzed studies, Hippocampus guttulatus is more common in confined areas, while H. hippocampus is found in marine shelf waters. With several interspecific differences, seagrasses were the most used holdfasts of both species. The EUNIS codes (European nature information system) referring to a specific and unique habitat were discussed as a potential tool for defining the ecological distribution of the two species. The obtained results and their future implementation could help plan conservation actions.

Evaluating the Efficiency of DNA Metabarcoding to Analyze the Diet of Hippocampus guttulatus (Teleostea: Syngnathidae).

Seahorses are considered a flagship species for conservation efforts and due to their conservation status, improving knowledge on their dietary composition while applying a non-invasive approach, could be useful. Using Hippocampus guttulatus as a case study, the present study represents pioneering research into investigating the diet of seahorses by NGS-based DNA metabarcoding of fecal samples. The study developed and tested the protocol for fecal DNA metabarcoding during the feeding trials where captive seahorses were fed on a diet of known composition; the process was subsequently applied on fecal samples collected from wild individuals. The analysis of samples collected during the feeding trials indicated the reliability of the applied molecular approach by allowing the characterization of the effectively ingested prey. In the field study, among detected prey species, results revealed that the majority of the seahorse samples contained taxa such as Amphipoda, Decapoda, Isopoda, and Calanoida, while less common prey taxa were Gastropoda and Polyplacophora. As only a small amount of starting fecal material is needed and the sampling procedure is neither invasive nor lethal. The present study indicates DNA metabarcoding as useful for investigating seahorse diet and could help define management and conservation actions.

Massive bioconstructions built by Neopycnodonte cochlear (Mollusca, Bivalvia) in a mesophotic environment in the central Mediterranean Sea.

The present paper provides a multidisciplinary fine-scale description of a Mediterranean mesophotic new habitat dominated by the bivalve Neopycnodonte cochlear (Poli, 1795), building large and thick pinnacles on vertical cliffs at two study areas along the southern Italian coast. The pinnacles, constituted by a multilayered aggregation of living and dead specimens of N. cochlear, were interconnected with each other to form a framework of high structural complexity, never observed before for this species. The bioconstruction, considerably extended, resulted very complex and diversified in the associated community of structuring organisms. This latter included 165 taxa attributable to different ecological groups occurring in different microhabitats of the bioconstruction. Among the secondary structuring taxa there were scleractinians, serpulids and bryozoans, all contributing to the deposition of calcium carbonate, and poriferans, helping to bind shells together or eroding carbonate by boring species. In comparison with coralligenous sensu stricto and the recently described Mediterranean mesophotic coral reef, the Neopycnodonte bioconstruction showed peculiar features, since it lacked the major contribution of encrusting coralline algae and scleractinians as reef builders, respectively.

Data on the diet composition of Hippocampus guttulatus cuvier, 1829: Different prey preferences among habitats.

The data presented here support research article entitled 'Trophic flexibility and prey selection of the wild long-snouted seahorse Hippocampus guttulatus Cuvier, 1829 in three coastal habitats'' Ape et al., 2019. Determinations of the dietary composition, differences in prey selection and potential prey abundance and availability among three habitats at Taranto Mar Piccolo were based on the analysis of gut contents of seahorses and sediment samples. Both highly (Corallina elongata and Cladophora prolifera) and low complex (sandy bottom) habitats were investigated. Prey items were divided into two size classes: <1 mm and >1mm. Data about the total abundance of each prey size class in gut contents and sediments in three different habitats and PERMANOVA comparisons are given.

A Mediterranean mesophotic coral reef built by non-symbiotic scleractinians.

This is the first description of a Mediterranean mesophotic coral reef. The bioconstruction extended for 2.5 km along the Italian Adriatic coast in the bathymetric range -30/-55 m. It appeared as a framework of coral blocks mostly built by two scleractinians, Phyllangia americana mouchezii (Lacaze-Duthiers, 1897) and Polycyathus muellerae (Abel, 1959), which were able to edify a secondary substrate with high structural complexity. Scleractinian corallites were cemented by calcified polychaete tubes and organized into an interlocking meshwork that provided the reef stiffness. Aggregates of several individuals of the bivalve Neopycnodonte cochlear (Poli, 1795) contributed to the compactness of the structure. The species composition of the benthic community showed a marked similarity with those described for Mediterranean coralligenous communities and it appeared to be dominated by invertebrates, while calcareous algae, which are usually considered the main coralligenous reef-builders, were poorly represented. Overall, the studied reef can be considered a unique environment, to be included in the wide and diversified category of Mediterranean bioconstructions. The main reef-building scleractinians lacked algal symbionts, suggesting that heterotrophy had a major role in the metabolic processes that supported the production of calcium carbonate. The large amount of available suspended organic matter in the area could be the main nutritional source for these species, as already suggested in the literature referred to Mediterranean cold-water corals.

The co-occurrence of the demosponge Hymeniacidon perlevis and the edible mussel Mytilus galloprovincialis as a new tool for bacterial load mitigation in aquaculture.

Pollutants in marine coastal areas are mainly a consequence of anthropogenic inputs, and microorganisms often play a major role in determining the extent of this pollution. Thus, practical and eco-friendly techniques are urgently required in order to control or minimise the pathogenic bacterial problem. The bacterial accumulation of Mytilus galloprovincialis (Lamarck 1919) in the presence or absence of another filter feeder, the demosponge Hymeniacidon perlevis (Montagu 1818) on sewage flowing into the Northern Ionian Sea has been estimated in a laboratory study. On account of the interesting results obtained, we also evaluated the bioremediation capability of the sponges when reared in co-culture with mussels. Specimens of M. galloprovincialis and H. perlevis were collected from the Mar Grande and from the Second Inlet of the Mar Piccolo of Taranto (Northern Ionian Sea, Italy), respectively. In the laboratory, we detected the bacterial abundances in the sewage, in sponge homogenates (both sponges alone and sponges that have been added to sewage with mussels) and in mussel homogenates (both mussels alone and mussels that have been added to sewage with sponges). In the field, we estimated the bacterial concentration in both the seawater within the mussels culture and the seawater collected where mussels were reared in co-culture with sponges. The bacteriological analyses were performed analysing the following parameters: the density of culturable heterotrophic bacteria by spread plate on marine agar, total culturable bacteria at 37 °C on plate count agar and vibrios on thiosulphate-citrate-bile-sucrose-salt (TCBS) agar. Total coliforms, Escherichia coli and intestinal streptococci concentrations were detected by the MPN method. The study demonstrates a higher efficiency of the sponges in removing all the considered bacterial groups compared to the mussels. Due to the conspicuous bacterial accumulation by the sponge, we can conclude that the co-occurrence of the filter-feeder H. perlevis with M. galloprovincialis is a powerful tool in reducing the bacterial load in shellfish culture areas thus playing a role in mitigating the health hazard related to the consumption of edible mussels.