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Sea cucumbers are highly marketable as a food product due to their nutritional value. Also, it has been suggested that sea cucumbers possess a wide range of bioactive compounds that can be used in the pharmaceutical industry. In this study, the reproductive biology of Holothuria forskali was performed by evaluating the gonadosomatic index (GI) and histological analyses of the gonadal tubules. The biotechnological potential was assessed through the evaluation of the antioxidant, antimicrobial and antitumor potential. Finally, the fatty acid profile was also evaluated. These three subjects were chosen to increase the interest and to focus the economic potential of this species rearing, predicting that it can be sold in Europe or export to Asia to be used for human consumption or for the pharmaceutical industry. The GI and the histological analysis of the gonadal tubules revealed that the range from February to March corresponds to the peak of gonads maturation. Furthermore, the methanolic fraction revealed the highest antimicrobial potential against Candida albicans with an IC 50 of 233.2 mg mL À1 . Also, this fraction presented the highest cytotoxic and anti-proliferative activities through the method for measuring cell proliferation method in both cell lines, with an IC 50 of 238.2 and 396.0 mg mL À1 for MCF-7 cells respectively and 260.3 and 218.7 mg mL À1 for HepG-2 cells respectively. Regarding the fatty acid profile, the total fat content was 4.83% and the highest values were obtained for palmitic acid (9.96%), stearic acid (11.23%), eicosapentaenoic acid (10.49%) and arachidonic acid (20.36%).

There is an increasing demand for sea cucumbers, for human consumption, mainly from Asian markets and, as a consequence, NE-Atlantic species are now new targets for exploitation and exportation. Holothuria mammata is one of the most valuable species in Europe. However, the lack of historical economic interest in this species in most European countries has also led to a lack of studies concerning biological and ecological aspects on wild populations and this is a major issue for stock management. This study aims to determine the temporal and spatial patterns of distribution of H. mammata, considering its abundance and demographic structure in a NE-Atlantic area, SW Portugal, as a function of environmental conditions. For that, a population from a marine protected area was followed for 1 year at 1.5-month intervals. Throughout the coastal area, six sites were selected and at each sampling campaign three random transects per site and substrate (rock and sand) in which all H. mammata individuals were counted and measured. For each site and survey several environmental parameters of interest, from the water column, the sediment and substrate cover, were also measured. Generalized Linear Models were used to model the spatial and temporal distribution of the species according to environmental conditions, to determine the species’ habitat preferences. The distribution models indicate that abiotic and biotic parameters of the water column are not the main drivers shaping the distribution of H. mammata. The species has a patchy distribution, and its habitat preferences depend on environmental stability, the presence of shelter and habitat complexity, which is more important for smaller, more vulnerable, individuals, while bigger size classes tend to venture more into less stable environments in an opportunistic fashion. The knowledge of these population traits is determinant to develop stock management measures, which are now urgent to prevent the depletion of commercial sea cucumber populations in the NE-Atlantic. Sustainable fisheries policies should be developed and start by considering to delimit fishing areas and periods, considering the species spatial and temporal distribution patterns.

Polychaetes are marine annelid worms that can contribute to aquaculture diversification. Its culture has been viable, and commercially attempted, but intensive production has progressed only in few countries around the world. In the countries with no production, marine polychaetes are imported or harvested. A strong and sustained research investment provided to a better understanding of the nutritional requirements and reproduction of some species. Recent studies showed new technical improvements, which can lead to an important progress in productivity and give a new impetus to the polychaete production. Some marine worm species were identified as good candidates for integrated multitrophic aquaculture. The development of cost‐effective aquaculture techniques for marine annelid worms is essential to ensure a balance between commercial interests and the preservation of ecosystems. The influence of polychaete aquaculture on the environment and vice versa raise important concerns related to ecological security and sustainability of this activity. This review focus on the main technical improvements and advances that have been made in areas as diverse as: aquaculture potential of polychaetes, reared species, main species used worldwide, and highlights biological and ecological concerns, important challenges and recommendations.

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