A population of sea urchins, Paracentrotus lividus, from the central west coast of Portugal was studied to characterise their reproductive biology and possible relationships with environmental factors. An annual gametogenic cycle was found, with a broad spawning season, from May to November, according to a relatively synchronous gamete maturation process. Depending on the environmental factors (temperature, photoperiod), two separate periods could be distinguished, with more individuals maturing and spawning at the same time. When this happened, the first event evolved when temperature rose to a critical point, and the second occurred afterwards, when temperature decreased significantly. Notwithstanding, it was found that individuals matured later than previously described for other populations (e.g., north of Portugal), mostly in late spring, with a higher gonadosomatic index in May. A new classification scale was proposed for identifying the stages of P. lividus gametogenic cycle, based on new findings. It contributed to its simplification and easier comprehension. This study provides useful information for a differentiated sustainable management of P. lividus, according to local conditions. Establishing a closed harvesting season might be considered, based on the differences observed between Portuguese populations and other European ones.

Paracentrotus lividus (Lamarck, 1816) is a sea urchin species that appears on hard substrata in shallow subtidal habitats of the Atlantic coast of Portugal. P. lividus is opportunistic, able to exploit a number of food sources, although brown macroalgae and seagrasses constitute the main feeding resource. It has been reported that the quality and quantity of food affect the reproductive maturation and growth of sea urchins roe and that may also modify the biochemical composition of gonads. Fatty acids (FA) are also important for sea urchin reproduction and during gametogenesis where they can be used as a source of energy. Sea urchin spermatozoa obtain energy for swimming through the oxidation of FA derived either from phosphatidylcholine or from triacylglycerols. Besides this, triacylglycerols play an important role in larval development and survival. Sea urchins, as many other marine animals, are able to synthesize most FA required for a proper development. However, some FA must be provided by the diet, the so called essential FA, namely linoleic (18:2n-6), linolenic (18:3n-3) and other important long-chain polyunsaturated fatty acids such as arachidonic (20:4n-6) and eicosapentaenoic (20:5n-3) acids. Thus, tissue FA composition must be considered as the result of endogenous synthesis and exogenous supply. This study aims to evaluate the effect of different diets on the gonad fatty acid profile of P. lividus fed with those diets. The reared sea urchins were fed with three artificial diets (A - green macroalgae Codium sp., B – solid mix diet, with macroalgae Codium sp., carrot and cabbage and C - maize and spinach). Recirculating aquaculture systems (RAS), with 60 L aquaria, at 20 ± 1°C were used in triplicate. For each individual, one gonad was removed and used for the analysis of fatty acid methyl esters by gas chromatography. Fatty acid profile of the three diets was also analysed. The most abundant FA in the three diets were palmitic (C16:0) and stearic (C18:0) acids and diet C revealed the highest content in polyunsaturated fatty acids (PUFA), namely linoleic and linolenic FA. Concerning gonad fatty acid composition, palmitic and stearic were the most prevalent FA regardless of the diet used. The highest content of PUFA was obtained in the individuals fed with diet C, being linoleic and linolenic the most prevalent FA. This results suggest that changes observed in gonad fatty acid composition may be related to differences in the diet of P. lividus.

The sea urchin gonads have been considered one of the most cherished delicacies, not only by the Asians, but also in some European countries. In Europe, Paracentrotus lividus is much appreciated due to its reddish-orange gonads, quality and high nutritional content. P. lividus fishery is common in some Portuguese regions. The sea urchin populations have been dramatically exploited in the intertidal and shallow subtidal rocky reefs, reaching a complete disappearance from areas where they were formerly abundant. There is a general concern to produce P. lividus in aquaculture, in order to avoid the depletion of its natural stocks. Accordingly, the development of new techniques to increase the gonadal quality of reared edible sea urchins is a keystone issue to be addressed in aquaculture research. In this study, adults of P. lividus (n=90), with test diameter ranging from 37 to 41 mm, were collected in the intertidal rocky pools, from the coast of Peniche (western central coast of Portugal), in November of 2015. The sea urchins were starved for a month, in order to promote the re-absorption of the gonads. After this period, the sea urchins were subject to 3 different diets to evaluate their specific breeding conditions. Three artificial diets (A - green macoalgae Codium sp., B – solid mix diet, with macroalgae Codium sp., carrot and cabbage and C - maize and spinach) were used during 80 days, to ensure a rapid gonadal growth and promote the maturation of P. lividus’ gametes. Three recirculating aquaculture systems (RAS) were maintained at 20 ± 1°C. All systems consisted in three aquaria of 60 L, one for each diet. Every single aquaria contained 30 sea urchins. Diets were administered ad libitum throughout the experiment. In order to evaluate the effectiveness of the different diets, biological data were analyzed: gonads weight (GW), gonadal index (GI) and histological examination of gonadal tissue with measurements of the oocytes diameter. The gonads were larger in sea urchins reared with the diet C (3.04 ± 0.74 g), regarding the gonadal weight referred to diet A (1.55 ± 0.21g) or diet B (1.81 ± 0.20 g). The GI was higher in sea urchins fed with diet C (11.22 ± 2.28), in relation to those fed with diet A (5.63 ± 1.03) and with diet B (5.71 ± 0.24). The histological analysis showed that the maize and spinach (diet C), combined with a temperature of 20 ± 1°C, led to a gonad maturation in P. lividus within 80 days. P. lividus specimens were found in different active gametogenesis phases (stages II–V) within all the diets. Nevertheless, the oocyte diameter was similar in sea urchins fed with the three diets. In this study, all the diets resulted to be effective in stimulating P. lividus gametogenesis, but the diet C was the most adequate to guarantee the best results in terms of GW, GI values and gonad size.

Holothuria tubulosa (Gmelin, 1788) is a marine invertebrate, belonging to the group Echinodermata, usually known as sea cucumber. Its geographical distribution extends from the Atlantic Ocean to the Mediterranean Sea and it is frequently associated to sandy and rocky areas, as well as sea meadows. Generally, they occur at depths less than 100 m. The sea cucumbers are very sensitive and in conditions of stress they can easily eviscerate, which may lead to the death of the organisms. This study aimed to evaluate the stress induced by the catch, transport and triage of H. tubulosa. One hundred specimens were captured in the Sado Estuary (Setúbal, Portugal) resorting to diving and acclimated in thermic containers (46 L) with seawater and constant aeration, with around 15 animals per container. Acclimation, including transport to MARE-IPLeiria, had the duration of 3 hours. At the facilities, sea cucumbers were weighed, measured and distributed randomly in 3 tanks of 400 L and kept in densities of 20.3 kg m-3. The quality of water was monitored daily, with a measured temperature of 15.1 ±1.1 °C, dissolved oxygen of 6.9 ±0.5 mg L-1, salinity of 34 ±1 and pH of 8.3 ±0.1. The maximum value to the concentration of ammonia, nitrites and nitrates were controlled and was established as 1 mg.L-1. H. tubulosa presented a mean weight of 264.46 ±78.19 g and a submersed mean length of 27.30 ±3.77 cm. Although there were no registered mortalities throughout the trial, evisceration occurred in 3.33% of the individuals. The results suggest H. tubulosa is resistant to catch, transport and handling, representing an advantage for its use in laboratorial trials, with scientific purposes or on a commercial level. Considering the high demand of sea cucumbers worldwide and H. tubulosa 's high tolerance to stress and relatively large size, these organisms present strong advantages for aquaculture.