Holothuria tubulosa (Gmelin, 1788) has recently shown an increased demand in Asian markets, becoming one of the intensively exploited holothurian species in the Mediterranean Sea. A risk is that over-harvesting is likely affecting both the species' natural stocks and the benthic communities. In this scenario, sea ranching and restocking through aquaculture could assist in mitigating its overexploitation. This study is the first to demonstrate the successful artificial breeding and rearing of H. tubulosa, and its consequent potential as a new species for the Mediterranean aquaculture industry. Here we describe the spawning induction, larval development and early juvenile growth in hatchery cultures, aimed at developing a spawning and rearing protocol for this species. The trials were conducted from July to October in both 2014 and 2015. Holothuria tubulosa was induced to spawn by testing four different methods. Thermal stimulation plus thermal shock emerged as the most efficient method to obtain active and healthy gametes. Larval development in H. tubulosa progressed through five stages, reaching the juvenile stage in 27 days. Two different microalgal feeding regimens were tested for larval breeding. Under the best feeding conditions, 7% of the larvae metamorphosed into settled juveniles, adhering to artificial substrates previously conditioned with benthic biofilm. Our results indicate that H. tubulosa shows good performance in hatchery rearing during the larval phases, indicating that this species could be a new candidate for aquaculture in the Mediterranean region, both for production and restocking proposes.

Echinoderms play a crucial role in the functioning of marine ecosystems and due to their extensive distribution, rapid response, and the high sensitivity of their planktonic larvae to a large range of stressors, some species are widely used as biological indicators. In addition to sea urchins, sea cucumbers have recently been implemented in embryotoxicity bioassays showing high potential in ecotoxicological studies. However, the use of this species is still hindered by a lack of knowledge regarding their comparative responsiveness. The present study aimed to investigate the responsiveness of different echinoderm species to environmental pollution in order to develop their integration in batteries of ecotoxicological bioassays. To this end, the embryos of two sea urchins (Paracentrotus lividus and Arbacia lixula) and two sea cucumbers (Holothuria polii and Holothuria tubulosa) were incubated with inorganic and organic toxicants (cadmium, copper, mercury, lead, sodium dodecyl sulphate and 4-n-Nonhyphenol) and elutriates from contaminated marine sediments, chosen as a case study model. The results obtained, expressed through the percentage of abnormal embryos and Integrative Toxicity Indices (ITI), indicated species-specific sensitivities to pollutants, with comparable and correlated responsiveness between sea urchins and sea cucumbers. More specifically, sea cucumber larvae exposed to elutriates appear to be more sensitive than sea urchins, especially when incubated with samples containing trace metals, PCB and TBT. These results indicate that toxic responses in embryos exposed to environmental matrices are probably modulated by interactions between different variables, including additive, synergistic and antagonistic effects. These findings suggest that performing a larval test using different echinoderm classes can integrate the interactive effects of bioavailable fraction of contaminants on various levels, providing sensitive, representative and all year-round batteries of bioassays to apply in ecotoxicological studies.

Filter-feeding mussels blend suspended particles into faeces and pseudo-faeces enhancing organic matter flows between the water column and the bottom, and strengthening benthic-pelagic coupling. Inside operating farms, high bivalve densities in relatively confined areas result in an elevated rate of organic sinking to the seabed, which may cause a localized impact in the immediate surrounding. Deposit-feeding sea cucumbers are potentially optimal candidates to bioremediate mussel organic waste, due to their ability to process organic-enriched sediments impacted by aquaculture waste. However, although the feasibility of this polyculture has been investigated for a few Indo-Pacific species, little is known about Atlanto-Mediterranean species. Hence, for the first time, in the present study, we conducted a comparative investigation on the suitability of different Mediterranean sea cucumber species, to be reared in Integrated Multitrophic Aquaculture (IMTA) with mussels. A pilot-scale experiment was accomplished operating within a mussel farm where two sea cucumbers species,Holothuria tubulosaandHolothuria polii, were caged beneath the long-line mussel farm ofMytilus galloprovincialis. After four months,H. tubulosashowed high survivorship (94%) and positive somatic growth (6.07%); converselyH. poliishowed negative growth (− 25.37%), although 92% of specimens survived. Furthermore, sea cucumber growth was size-dependent. In fact, smaller individuals, independently from the species, grew significantly faster than larger ones. These results evidenced a clear difference in the suitability of the two sea cucumber species for IMTA withM. galloprovincialis, probably due to their different trophic ecology (feeding specialization on different microhabitats, i.e. different sediment layers). Specifically,H. tubulosaseems to be an optimal candidate as extractive species both for polycultures production and waste bioremediation inM. galloprovincialisoperating farms.

The development of clean and renewable energy sources is currently one of the most important challenges facing the world. Although research interests in algae-based energy have been increasing in the last decade, only a small percentage of the bewildering diversity exhibited by microalgae has been investigated for biodiesel production. In this work, seven strains of green microalgae belonging to the genera Scenedesmus, Tetradesmus and Desmodesmus were grown in liquid medium with or without a nitrogen (N) source—at two different irradiances (120 ± 20 and 200 ± 20 μmol photons m⁻² s⁻¹)—to evaluate biomass production and FAME (fatty acid methyl esters) content for biodiesel production. The strains of Tetradesmus obliquus and Desmodesmus abundans grown in N-deprived medium showed the highest FAME content (22.0% and 34.6%, respectively); lipid profile characterization highlighted the abundance of saturated FAME (as C16:0 and C18:0) that favors better viscosity (flow properties) and applicability of biodiesel at low temperatures. Light microscopy and confocal laser scanning microscopy observations were employed as a fast method to monitor the vital status of cells and lipid droplet accumulation after Nile red staining in different culture conditions.

Sea cucumbers are considered a traditional food delicacy in Asian countries. In last decades high market demand, uncontrolled exploitation and inadequate management have led to stock overexploitation, driving commercial interest in new target species and new areas. In recent years, Mediterranean and North-East Atlantic sea cucumbers have become fishing targets, and, due to overfishing, a significant decline of wild populations have been observed, with detrimental effects on benthic communities and ecosystems. Indeed, in addition to being an important economic resource, sea cucumbers play a key ecological role in benthic dynamics where they are involved as ecosystem engineers in the processing of organic matter in the detrital food web pathway. In this context, aquaculture can play a crucial role in supporting the conservation of natural stocks by reducing harvesting pressure on wild populations and enabling restoration programmes for depleted stocks. Commercial sea cucumber farming is already an established reality in the Indo-Pacific region, where it has become one of the most profitable sectors of aquaculture production. In Europe, on the other hand, sea cucumber aquaculture is still an emerging sector, whose development is hampered by poor and fragmented information on the farming requirements of native species. In this context, this systematic review was carried out with the aim of providing a comprehensive summary of the state of the art of farming practices of the European sea cucumbers considered as a target of commercial fisheries. A total of 34 original articles were included in this review, after title, abstract and full-text screening. The results highlighted a sharp increase in the number of studies over the last six years. Portugal, Turkey and Italy are the countries where most research has been carried out. Among the selected species, Holothuria tubulosa was the most studied, while only one article was found on Parastichopus regalis. The main aims of this review were i) to gather all available literature on the farming practices of North-East Atlantic and Mediterranean sea cucumber species, ii) to outline the most common farming practices, iii) to identify gaps and future directions in this emerging aquaculture sector.

Sustainable mussel farming practices are critical for maintaining production and enhancing growth of the low trophic aquaculture sector. The concept of Integrated Multi‐Trophic Aquaculture (IMTA) and incorporating mussels as extractive species, holds promise for enhancing overall system efficiency, nutrient cycling, and environmental sustainability. This review delves into innovative aquaculture techniques emphasizing the synergistic relationships between Mytilus galloprovincialis and other species such as seaweeds and deposit feeders that prioritize environmental stewardship by absorbing excess nutrients, processing organic waste, and including best management practices for waste mitigation. Marine spatial planning (MSP) through IMTA development can support optimal capacity building scenarios, incorporating ecosystem services and social benefits. This review explores the different aspects of mussel biology, ecology, aquaculture, sustainability, and future perspectives on the basis of literature data, with a context of capacity building in the Atlanto‐Mediterranean area. The literature data were analyzed in order to explain interactions between primary species and mussels as extractive species. We developed conceptual models at three different scales—small, medium, and large—to define the optimal growth performance of mussels in relation to their distance from the aquaculture nutrient source. The consistent trend favoring medium‐scale conditions has led us to conclude that mussels predominantly extract nutrients indirectly, primarily through the phytoplankton blooms resulting from fertilization. On this basis, we recommend that the marine spatial integration of mussels must be designed according to these models to optimize production while mitigating the side effects of fish cage aquaculture.