An Innovative IMTA System: Polychaetes, Sponges and Macroalgae Co-Cultured in a Southern Italian In-Shore Mariculture Plant (Ionian Sea)

Seasonal occurrence and distribution of microplastics in four different benthic suspension feeders from an Integrated Multi-Trophic Aquaculture (IMTA) facility: A bioremediation perspective

Microplastics (MPs) are dangerous and ubiquitous in the environment. The urgency to contrast plastic pollution is prompting the scientific community to offer new proposals. Recently, bioremediation using filter feeders is gaining consent as a nature-based solution. Herein four filter feeders (Mytilus galloprovincialis Lamarck, 1819, Sabella spallanzanii Gmelin, 1791, Phallusia mammillata Cuvier, 1815, Paraleucilla magna Klautau, Monteiro & Borojevic, 2004), studied in a previous laboratory experiment as MPs bioremediators, are evaluated in field conditions within 1-year. These organisms are part of an established fouling community growing on eco-friendly ropes in an Integrated Multi-Trophic Aquaculture (IMTA) in the Mar Grande of Taranto. After digesting the animal tissue, the MPs content was quantified by optical microscopy and spectroscopically characterized in the four seasons: highest values were measured in Autumn and lowest in Spring. M. galloprovincialis and P. mammillata were the most contaminated, but S. spallanzanii removed more MPs, due to its high density on the ropes. The whole community removed 3.15 × 107 MPs/season, with the amount of microfibers corresponding to a bottle cap/season.

The seaweed Chaetomorpha linum cultivated in an integrated multitrophic aquaculture system: A new tool for microplastic bioremediation?

Microplastics (MPs) are emerging pollutants with detrimental impacts on ecosystems and human health. Due to their adverse effects, new strategies to mitigate MP pollution in the marine environment need to be developed urgently. In this context, the capability of the seaweed Chaetomorpha linum (Chlorophyta, Cladophorales) to trap MPs, as well as the effectiveness of a simple washing procedure to clean up the harvested seaweed biomass, were investigated. This algal species was grown in an integrated multitrophic aquaculture system (IMTA), where bioremediator organisms such as macroalgae, polychaetes, sponges and mussels were farmed in the vicinity of the fish cages. MPs trapped in C. linum were classified based on shape and size, and representative samples of each shape were analysed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to evaluate their chemical composition. Fibre MPs were the most abundant (97.3 %), while the size ranged from 0.025 to 2.00 mm, with most samples being in the size range 0.80-1.00 mm. MPs were composed mainly of polypropylene, polystyrene, and polyethylene. They were efficiently removed from the cultured seaweeds by a simple density separation procedure, consisting of three extractions with hypersaline solutions of sodium chloride. These results suggest that C. linum cultivated in an IMTA system can be proposed as a bioremediator to capture MPs from the surrounding environment. At the same time, harvested and cleaned green seaweeds may be considered a co-product of the bioremediation process and can find application in several biotechnological fields, including the use as a food source for human consumption.

Transfer and bioaccumulation of chemical and biological contaminants in the marine polychaete Hediste diversicolor (OF müller 1776) when reared on salmon aquaculture sludge

Side streams from aquaculture production such as fish sludge poses ample opportunities for biological upcycling, as the sludge contains high amounts of nutrients, energy and valuable biochemicals, making it an ideal food for extractive species. Sludge has been proposed as a feed stock for polychaete production, which in turn can be utilized live in shrimp aquaculture or as an aquafeed ingredient. However, the biosafety of such value chains has not yet been addressed. We conducted an experiment exposing the polychaete Hediste diversicolor to aquaculture sludge spiked with four different fish pathogens (Mycobacterium salmoniphilum, Yersinia ruckeri, Infectious Pancreatic Necrosis (IPN) and Infectious Salmon Anaemia (ISA)) known to cause diseases in Atlantic salmon (Salmo salar L.). Moreover, we assessed whether heavy metals and other potentially hazardous elements present in fish sludge bioaccumulates in the polychaetes. Neither of the bacteria nor viruses could be detected in the polychaetes after 14 days of continuous exposure. Seven of the 15 elements we analysed showed bioaccumulation factors significantly below one, meaning biodilution, while the other eight did not differ from one, meaning no bioaccumulation. None of the elements showed a significant bioaccumulation. Further on, none of the heavy metals found in the polychaetes at the end of our experiment exceeded the EU regulatory maximum levels for fish feed ingredients. The current results suggest that a H. diversicolor can reared on aquaculture sludge, and aquaculture sludge may serve as feed stock for polychaete production without the product exceeding EU regulations for contaminants in animal feed.

Microplastics determination and quantification in two benthic filter feeders Sabella spallanzanii, Polychaeta and Paraleucilla magna, Porifera

Plastic pollution is a worldwide problem especially in the marine environment. Plastic items once fragmented into microplastics (MPs), can be captured by different marine species. Benthic filter feeders like sponges and polychaetas, due to their trophic strategy, are highly exposed to MPs pollution. Herein a simple but effective method to digest the fan worm Sabella spallanzanii and the calcareous sponge Paraleucilla magna is presented: a solution with KOH and H2O2 was able to remove quantitatively (more than 98 %) the organic matter in 3 h while an acid treatment dissolved most of spicules and chaetes in less than 30 min. MPs were easily identified both microscopically and spectroscopically on filters. Quantification in animals collected from the same environment showed that, on average, sponges accumulate fewer MPs than polychaetes (66 ± 31 and 117 ± 46 particles/g dry weight, respectively). The plastic recovery of the method was validated using three different approaches (spiking of standard PS microspheres, of common-use plastic objects, and of microplastics already weathered in marine environment). This procedure can make it easier and cost-effective to process biota in monitoring studies, providing information about bioindicator/bioremediation species.

Identification of Marine Biotechnology Value Chains with High Potential in the Northern Mediterranean Region

Marine (blue) biotechnology is an emerging field enabling the valorization of new products and processes with massive potential for innovation and economic growth. In the Mediterranean region, this innovation potential is not exploited as well as in other European regions due to a lack of a clear identification of the different value chains and the high fragmentation of business innovation initiatives. As a result, several opportunities to create an innovative society are being missed. To address this problem, eight Northern Mediterranean countries (Croatia, France, Greece, Italy, Montenegro, Portugal, Slovenia and Spain) established five national blue biotechnology hubs to identify and address the bottlenecks that prevent the development of marine biotechnology in the region. Following a three-step approach (1. Analysis: setting the scene; 2. Transfer: identification of promising value chains; 3. Capitalization: community creation), we identified the three value chains that are most promising for the Northern Mediterranean region: algae production for added-value compounds, integrated multi-trophic aquaculture (IMTA) and valorization aquaculture/fisheries/processing by-products, unavoidable/unwanted catches and discards. The potential for the development and the technical and non-technical skills that are necessary to advance in this exciting field were identified through several stakeholder events which provided valuable insight and feedback that should be addressed for marine biotechnology in the Northern Mediterranean region to reach its full potential.

Particle uptake by filter-feeding macrofoulers from the Mar Grande of Taranto (Mediterranean Sea, Italy): potential as microplastic pollution bioremediators

Microplastics (MPs) are a serious threat to the marine environment affecting ecosystem functioning and biodiversity. There is a vast literature about the uptake of MPs at different trophic levels, mainly focused on ecotoxicological effects in commercially relevant species. Little is still known about possible strategies to face MP pollution. Bioremediation is recently gaining attention in this framework. The clearance rate and particle retention of Sabella spallanzanii, Mytilus galloprovincialis, Phallusia mammillata, Paraleucilla magna at three MP concentrations (C1: 1.4 · 10¹ p/L; C2: 1.4 · 10² p/L; C3: 1.4 · 10³ p/L) were investigated to test their potential as MP remover. Digestion protocol removed 98 % of tissues simplifying the MP quantification. P. magna clearance rate decreased with increasing concentration while P. mammillata showed no significant variations. S. spallanzanii and M. galloprovincialis instead exhibited the highest values of clearance rate. Yet, unlike mussels, S. spallanzanii can inhibit particle return to the surrounding water storing them in the tube, resulting to be the best candidate for bioremediation purposes.

The Controlled Semi-Solid Fermentation of Seaweeds as a Strategy for Their Stabilization and New Food Applications

For centuries, macroalgae, or seaweeds, have been a significant part of East Asian diets. In Europe, seaweeds are not considered traditional foods, even though they are increasingly popular in Western diets in human food applications. In this study, a biological processing method based on semi-solid fermentation was optimized for the treatment of the seaweed Gracilaria gracilis. For the first time, selected lactic acid bacteria and non-conventional coagulase-negative staphylococci were used as starter preparations for driving a bio-processing and bio-stabilization of raw macroalga material to obtain new seaweed-based food prototypes for human consumption. Definite food safety and process hygiene criteria were identified and successfully applied. The obtained fermented products did not show any presence of pathogenic or spoilage microorganisms, thereby indicating safety and good shelf life. Lactobacillus acidophilus-treated seaweeds revealed higher α-amylase, protease, lipase, endo-cellulase, and endo-xylanase activity than in the untreated sample. This fermented sample showed a balanced n-6/n-3 fatty acid ratio. SBM-11 (Lactobacillus sakei, Staphylococcus carnosus and Staphylococcus xylosus) and PROMIX 1 (Staphylococcus xylosus) treated samples showed fatty acid compositions that were considered of good nutritional quality and contained relevant amounts of isoprenoids (vitamin E and A). All the starters improved the nutritional value of the seaweeds by significantly reducing the insoluble indigestible fractions. Preliminary data were obtained on the cytocompatibility of G. gracilis fermented products by in vitro tests. This approach served as a valid strategy for the easy bio-stabilization of this valuable but perishable food resource and could boost its employment for newly designed seaweed-based food products.

Integrated multitrophic aquaculture (IMTA) as an environmentally friendly system for sustainable aquaculture: functionality, species, and application of biofloc technology (BFT)

Aquaculture is one of the fastest-growing industries in the world, and its prominent role has been proven in supplying food for the growing world population. The expected growth of aquaculture requires the development of responsible and sustainable approaches, technologies, culture systems, and practices. The integrated multitrophic aquaculture (IMTA) system has been developed over the past decades. This system is based on the use of all food levels for simultaneous production of some aquaculturally species in a way that contributes to environmental sustainability (biocontrol), economic stability (product diversity and risk reduction), and social acceptance (better management operations). In IMTA, selecting suitable culture species and considering their appropriate population size is absolutely necessary to achieve an optimal biological and chemical process, improving the ecosystem health and sustainability of the industry. Biofloc technology (BFT) is closely related to the IMTA system, where the IMTA potential can be used to control suspended solids in aquaculture systems with limited water exchange. This study reviews the significance of IMTA systems, potential target species for cultivation, the relationship between BFT and IMTA, total suspended solids control, the economics of IMTA farming, and the recent findings in these fields.

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.

Restoration of Marine Sponges—What Can We Learn from over a Century of Experimental Cultivation?

Marine sponges are the driver of many critical biological processes throughout various ecosystems. But anthropogenic and environmental pressures are rapidly compromising the diversity and abundance of Porifera worldwide. In our study, we reviewed the main experiences made on their cultivation to provide a roadmap of the best methodologies that could be applied to restore coastal sponge populations. We synthesized the results of experimental trials between 1950 and today to facilitate information on promising methods and materials. We detected a strong geographical imbalance between different ecoregions, as well as a shift of scientific effort from the investigation of “bath sponge” mariculture towards the rearing of bioactive compounds from sponges. Although sponge cultivation is arguably highly species-dependent, we further found that skeletal consistency in combination with taxonomy may be used to decide on appropriate techniques for future restoration initiatives.

Advantage of Species Diversification to Facilitate Sustainable Development of Aquaculture Sector

Intensified agrochemical-based monoculture systems worldwide are under adoption to meet the challenge of human population growth and the ever-growing global demand for food. However, this path has been opposed and criticized because it involves overexploitation of land, monoculture of few species, excessive input of agrochemicals, and adverse impacts on human health and the environment. The wide diversity among polyculture systems practiced across the globe has created confusion over the priority of a single strategy towards sustainable aquaculture development and safer products. Herein, we highlight the significance of polyculture and integrated aquaculture practices in conveying the successful transition of the aquaculture industry towards sustainable development. So far, the established thought is that the precise selection of aquatic species and a focus on compatible and complementary species combinations are supposed to facilitate rapid progress in food production with more profitability and sustainability. Therefore, the advantages of species diversification are discussed from an ecological perspective to enforce aquaculture expansion. This account asserts that a diverse range of aquaculture practices can promote synergies among farmed species, enhance system resilience, enable conservation, decrease ecological footprints, and provide social benefits such as diversified income and local food security.

Volatile Organic Compounds, Indole, and Biogenic Amines Assessment in Two Mediterranean Irciniidae (Porifera, Demospongiae)

Solid phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was employed for the headspace determination of the volatile organic fraction emitted by two of the most common Mediterranean demosponges, Ircinia variabilis and Sarcotragus spinosulus, and of indole and some biogenic amines released by sponges in an aqueous medium. A total of 50/30 µm divinylbenzene/carboxen/polydimethylsiloxane and 75 µm carboxen/polydimethylsiloxane fibers were used for the headspace extraction of low molecular weight sulfur compounds from a hermetically sealed vial containing sponge fragments, while the direct immersion determination of indole and biogenic amines was performed. The biogenic amines were extracted after in-solution derivatization with isobutyl chloroformate. All analytical parameters (linearity, limits of detection, and quantification, precision, and recovery) were evaluated for indole and biogenic amines. SPME-GC-MS proved to be a reliable means of highlighting the differences between molecules released by different sponges, principally responsible for their smell. The combined approaches allowed the identification of several volatile compounds in the headspace and other molecules released by the sponges in an aqueous medium, including indole and the BAs cadaverine, histamine, isobutylamine, isopentylamine, propylamine, 2-phenylethylamine, putrescine and tryptamine. The results obtained represent a further contribution to the picture of odoriferous molecules secreted by sponges.

Anti-fouling activity and toxicity of the Mediterranean alien sponge Paraleucilla magna Klautau, Monteiro & Borojevic, 2004 (Porifera, Calcarea)

Poriferans, as sessile organisms without rigid external covering, use secondary metabolites for protection from predators and fouling organisms. The present study tested the antifouling activity of ethanolic extract of the Mediterranean alien calcareous sponge Paraleucilla magna towards juvenile mussels Mytilus galloprovincialis. Furthermore, toxicity tests on nauplii of brine shrimp Artemia salina and two microalgae strains, Nannochloropsis sp. and Tetraselmis suecica, were also conducted. A total attachment inhibition of M. galloprovincialis was achieved at a concentration of 400 µg/mL of sponge extract. The 50% mortality of A. salina nauplii was recorded at a concentration of 500 µg/mL of ethanolic extract. The growth inhibitory effect on both marine microalgae strains has been registered at a concentration of 300 µg/mL. Our results suggest promising natural antifouling activity and low toxicity of the ethanolic extract of P. magna that could be used as antifouling compound.

Screening for Health-Promoting Fatty Acids in Ascidians and Seaweeds Grown under the Influence of Fish Farming Activities

The present study aimed to contrast the fatty acid (FA) profile of ascidians (Ascidiacea) and seaweeds (sea lettuce, Ulva spp. and bladderwrack, Fucus sp.) occurring in a coastal lagoon with versus without the influence of organic-rich effluents from fish farming activities. Our results revealed that ascidians and seaweeds from these contrasting environments displayed significant differences in their FA profiles. The n-3/n-6 ratio of Ascidiacea was lower under the influence of fish farming conditions, likely a consequence of the growing level of terrestrial-based ingredients rich on n-6 FA used in the formulation of aquafeeds. Unsurprisingly, these specimens also displayed significantly higher levels of 18:1(n-7+n-9) and 18:2n-6, as these combined accounted for more than 50% of the total pool of FAs present in formulated aquafeeds. The dissimilarities recorded in the FAs of seaweeds from these different environments were less marked (≈5%), with these being more pronounced in the FA classes of the brown seaweed Fucus sp. (namely PUFA). Overall, even under the influence of organic-rich effluents from fish farming activities, ascidians and seaweeds are a valuable source of health-promoting FAs, which confirms their potential for sustainable farming practices, such as integrated multi-trophic aquaculture.

Aquaculture and Restoration: Perspectives from Mediterranean Sea Experiences

In this paper, the different possibilities and innovations related to sustainable aquaculture in the Mediterranean area are discussed, while different maricultural methods, and the role of Integrated Multi-Trophic Aquaculture (IMTA) in supporting the exploitation of the ocean’s resources, are also reviewed. IMTA, and mariculture in general, when carefully planned, can be suitable for environmental restoration and conservation purposes. Aquaculture, especially mariculture, is a sector that is progressively increasing in parallel with the increase in human needs; however, several problems still affect its development, mainly in relation to the choice of suitable sites, fodder production, and the impact on the surrounding environment. A current challenge that requires suitable solutions is the implementation of IMTA. Unfortunately, some criticisms still affect this approach, mostly concerning the commercialization of new products such as invertebrates and seaweeds, notwithstanding their environmentally friendly character. Regarding the location of a suitable site, mariculture plans are currently displaced from inshore to offshore, with the aim of reducing the competition for space with other human activities carried out within coastal waters. Moreover, in open water, waste loading does not appear to be a problem, but high-energy waters increase maintenance costs. Some suggestions are given for developing sustainable mariculture in the Mediterranean area, where IMTA is in its infancy and where the scarce nutrients that characterize offshore waters are not suitable for the farming of both filter feeder invertebrates and macroalgae. From the perspective of coupling mariculture activity with restoration ecology, the practices suggested in this review concern the implementation of inshore IMTA, creating artificially controlled gardens, as well as offshore mussel farming coupled with artificial reefs, while also hypothesizing the possibility of the use of artificially eutrophized areas.

Fanworms: Yesterday, Today and Tomorrow

Sabellida Levinsen, 1883 is a large morphologically uniform group of sedentary annelids commonly known as fanworms. These annelids live in tubes made either of calcareous carbonate or mucus with agglutinated sediment. They share the presence of an anterior crown consisting of radioles and the division of the body into thorax and abdomen marked by a chaetal and fecal groove inversion. This study synthesises the current state of knowledge about the diversity of fanworms in the broad sense (morphological, ecological, species richness), the species occurrences in the different biogeographic regions, highlights latest surveys, provides guidelines for identification of members of each group, and describe novel methodologies for species delimitation. As some members of this group are well-known introduced pests, we address information about these species and their current invasive status. In addition, an overview of the current evolutionary hypothesis and history of the classification of members of Sabellida is presented. The main aim of this review is to highlight the knowledge gaps to stimulate research in those directions.

Filtering Activity and Nutrient Release by the Keratose Sponge Sarcotragus spinosulus Schmidt, 1862 (Porifera, Demospongiae) at the Laboratory Scale

Sponges are an important constituent of filter-feeder benthic communities, characterized by high ecological plasticity and abundance. Free bacteria constitute an important quota of their diet, making them excellent candidates in aquaculture microbial bioremediation, where bacteria can be a serious problem. Although there are studies on this topic, certain promising species are still under investigation. Here we report applied microbiological research on the filtering activity of Sarcotragus spinosulus on two different concentrations of the pathogenic bacterium Vibrio parahaemolyticus in a laboratory experiment. To evaluate the effects of the filtration on the surrounding nutrient load, the release of ammonium, nitrate, and phosphate was also measured. The results obtained showed the efficient filtration capability of S. spinosulus as able to reduce the Vibrio load with a maximum retention efficiency of 99.72% and 99.35% at higher and lower Vibrio concentrations, respectively, and remarkable values of clearance rates (average maximum value 45.0 ± 4.1 mL h−1 g DW−1) at the highest Vibrio concentration tested. The nutrient release measured showed low values for each considered nutrient category at less than 1 mg L−1 for ammonium and phosphate and less than 5 mg L−1 for nitrate. The filtering activity and nutrient release by S. spinosulus suggest that this species represents a promising candidate in microbial bioremediation, showing an efficient capability in removing V. parahaemolyticus from seawater with a contribution to the nutrient load.