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- The effects of stocking density on physiological traits in Holothuria forskali broodstockPublication . Sousa, João; Félix, Pedro M.; Brito, Ana C.; Venâncio, Eliana; Silva, Francisco Azevedo e; Simões, Tomás; Raposo, Andreia; Neves, Marta; Narciso, Luís; Melo, Ricardo; Pombo, AnaThe high demand of sea cucumbers in international markets, mostly based in Asia, has left a deep impact on the natural stock of many species, leading to an investment in aquaculture techniques in order to mitigate these impacts. This study aimed to determine the effects of stock density in rearing broodstock of Holothuria (Panningoturia) forskali Delle Chiaje, 1823, a common species in the Mediterranean Sea and eastern Atlantic with commercial value. To do so, two different density treatments were selected: 1 kg/m2 and 2 kg/m2. The trial took place over five months and individuals were fed a mixture of frozen microalgae (Tetraselmis sp. and Phaeodactylum tricornutum). At the end of the trial, the effects of stock density on the individuals’ condition were assessed by analysing different variables, namely their fresh and gutted weight, evisceration and mortality rates, gonadosomatic index and oocyte size and even biochemical content, such as protein and lipid content in muscle bands. No significant differences were found between density treatments regarding any of the parameters assessed, aside from mean oocyte diameter. Individuals from the lower-density treatment presented a smaller mean oocyte diameter, supplied with fewer oocytes, than individuals in both the higher-density treatment and the baseline group. Regardless of this one difference, all trial individuals were able to maintain their elevated gonadal developmental stage for a full period of five months past their reproductive peak, with female holothurians subjected to the higher-density treatment showing signs of increasing vitellogenic reserves, a considerable advantage in aquaculture broodstock rearing.
- The biotechnological and seafood potential of Stichopus regalisPublication . Santos, Rita; Dias, Simaura; Pinteus, Susete; Silva, Joana; Alves, Celso; Tecelão, Carla; Pombo, Ana; Pedrosa, RuiSea cucumbers are highly used not only for the production of the bêche-de-mer, but also recent studies have been showing the high potential of these marine invertebrates on the pharmaceutical industry, as they are rich in bioactive compounds with important functions. Stichopus regalis extracts (1 mg∙mL−1) were used in antioxidant, antimicrobial and antitumor assays. The lipid profile was also evaluated. No significant antioxidant activity was detected in both methanolic and dichloromethane extracts. The methanolic fraction showed the highest antimicrobial potential against Candida albicans with an IC50 of 475.4 μg∙mL−1. In the antitumor assays, the dichloromethane fraction showed a high potential for both cell lines, as revealed by the MTT method. The total fat content was 3.63% ± 0.11% and the fatty acid profile revealed the highest amount in C16:0 (9.43% ± 0.77%), C18:0 (12.43% ± 0.83%), C18:1 ω7 (5.63% ± 0.33%), EPA (12.49% ± 0.15%), DHA (7.35% ± 0.02%), ARA (19.29% ± 0.14%) and a ω3/ω6 ratio of 1.078. These findings led us to suggest the potential use of S. regalis as a new source of bioactive compounds with pharmacological potential and its nutritional benefits for human health.
- Effect of three diets on the growth and fatty acid profile of the common ragworm Hediste diversicolor (O.F. Müller, 1776)Publication . Santos, António; Granada, Luana; Baptista, Teresa; Anjos, Catarina; Simões, Tiago; Tecelão, Carla; Fidalgo e Costa, Pedro; Costa, José Lino; Pombo, AnaThe polychaete Hediste diversicolor has a high physiological tolerance to extreme environmental factors, being easily farmed and reproduced in different types of conditions. Both in the field and under laboratory conditions, this worm can feed on different types of food. In order to highlight the potential of H. diversicolor for aquaculture, specific growth rate (SGR), daily growth rate (DGR), survival rate and fatty acid profile of juvenile worms, fed with three different diets, were assessed. The experiments were conducted using juvenile polychaete from a controlled reproduction with wild adults. H. diversicolor individuals were fed with two commercial diets, seabream dry feed (Aquagold) and semi-wet pellets for reared sole (Moist Sole), and with a non-processed diet consisting on mackerel's fillets (Trachurus trachurus). Juveniles fed with Aquagold had the highest final individual weight (0.89 ± 0.10 g). The SGR was higher in H. diversicolor fed with Aquagold and Moist Sole, (6.49 ± 0.30% d−1 and 6.54 ± 0.06% d−1 , respectively. The highest DGR was observed for juveniles fed with Aquagold (0.146 ± 0.02 g d−1 ). The survival rate of ragworms under different treatments ranged from 96 to 100%. Regarding the protein content, the Moist Sole diet provided the highest percentage of protein in the reared worms (8.87%). Results showed that the total fat content of the diets was reflected in the fat content of the reared worms. The Moist Sole diet treatment had the highest fat content (2.25%) and individuals fed with seabream dry feed showed similar results (2.18%), while the lowest percentage was observed for the mackerel diet (0.85%). According to the fatty acid profile, the major fatty acids found in the juveniles fed with the three different diets were palmitic (C 16:0), with a higher value in the individuals fed with mackerel's fillets. Oleic (C 18:1 n9), eicosapentaenoic (C 20:5 n3), docosahexaenoic (C 22:6 n3) and stearic (C 18:0) acids presented high values in H. diversicolor fed with all the experimental diets. Statement of Relevance: The common ragworm Hediste diversicolor is a potential high quality fatty acids source for reared fish and shrimp. Previous studies suggested that diet could be a relevant factor affecting the fatty acid composition of this polychaete (Luis and Passos, 1995). This study aimed to assess the effect of different diets on growth and survival of common ragworms juveniles (H. diversicolor), as well as the fatty acid profile and protein content in their tissues, aiming to find an appropriate diet to be used in commercial aquaculture.
- High dietary protein, n − 3/n − 6 ratio and β-carotene enhances Paracentrotus lividus (Lamarck, 1816) larval developmentPublication . Gomes, Ana S.; Lourenço, Sílvia; Santos, Pedro M.; Neves, Marta; Adão, Pedro; Tecelão, Carla; Pombo, AnaThe nutritional characteristics of microalgae affect the growth, survival and fatty acid composition of sea urchin larvae. This study aimed to evaluate the influence of nutritive characteristics of single microalgal diets in Paracentrotus lividus (Lamarck, 1816) larval development, growth, and condition. Larvae of P. lividus were fed with three monospecific microalgal diets, Rhodomonas sp. (Rho), Dunaliella tertiolecta (Duna) and the diatom Chaetoceros calcitrans (Chae), and their development and growth were analysed until competence. Additionally, the fatty acid (FA) profile of larvae was analysed at competence and compared with the FA profile of the correspondent diet. The three groups of larvae attained competence simultaneously with differences in growth performance. The larvae fed with Chae attained the largest stomach and the shortest post-oral arm. The larvae were able to accumulate long-chain polyunsaturated fatty acids (PUFA), such as docosahexaenoic (DHA, C22:6n − 3), eicosapentaenoic (EPA, C20:5n − 3) and arachidonic (ARA, C20:4n − 6) acids, either by assimilation and retention of dietary FA or by the synthesis from α-linolenic acid (ALA, C18:3n − 3) and linoleic acid (LA, C18:2n − 6). Furthermore, the low DHA/EPA ratio and high EPA/ARA and n − 3/n − 6 ratios of Rho and Chae and the high levels of the β-carotene present in Chae improved larval growth and development. In conclusion, the results indicated that of the three microalgal diets tested, C. calcitrans provided important nutritional characteristics, especially in terms of FA composition and carotenoids, improving P. lividus larval growth and condition.
- The effect of temperature on somatic and gonadal development of the sea urchin Paracentrotus lividus (Lamarck, 1816)Publication . Santos, Pedro M.; Albano, Pedro; Raposo, Andreia; Ferreira, Susana M. F.; Costa, José L.; Pombo, AnaThe common sea urchin Paracentrotus lividus (Lamarck, 1816) is the most consumed echinoid in Europe. It is considered a seafood delicacy, given its high-valued gonads. In sea urchins, temperature probably represents the most important abiotic factor affecting several physiological processes and it is essential to better establish optimal reference conditions for aquaculture. In this study, four rearing temperatures (18 °C, 20 °C, 22 °C and 24 °C) were tested in wild-caught adult P. lividus, from the west coast of Portugal. The animals were fed an agarbased artificial diet, over a period of 90 days. The effect of temperature was tested in terms of test diameter and total wet weight, feed intake, gonadosomatic index (GI) and reproductive development. Thus, linear growth rate (mm month−1), daily growth rate (% day−1), total wet weight gain (mg ind.−1 day−1) and total feed intake (g day−1 ind.−1) of sea urchins were calculated at the end of the trial. Although feed intake was relatively similar between groups, the results showed a consistent response for biometric parameters regarding the different temperatures regimes. The rearing temperature of 22 °C promoted the highest test diameter (.53 mm month−1) and total wet weight (47 mg ind.−1 day−1) growth. Sea urchins from the same group (22 °C) presented the highest final GI of 9.3%, a 163.5% increase in comparison to the initial value, after the fasting period (3.5%). This temperature also promoted the highest gonad maturation levels, both in males and females. Although increasing temperatures (until 22 °C) generally produced favourable rearing results, the 24 °C regime led to lower somatic and gonadal growth, plus slower gonad maturation results. Overall, P. lividus fed with a formulated diet and reared at 20–22 °C, showed considerable somatic and gonadal growth, as well as a significant sexual maturation, which will allow to obtain developed gonads and gametes all year round. On the other hand, 18 °C promoted a slower progression in the gametogenic cycle, which may contribute to produce gonads with better organoleptic properties for human consumption.
- Morphometric approach to the development of Paracentrotus lividus larvae fed with different microalgae dietsPublication . Lourenço, Sílvia; Gomes, Ana Sofia; Santos, Pedro M.; Raposo, Andreia; Ferreira, Susana; Pombo, Ana
- A morphometric approach to the development of Paracentrotus lividus larvae fed with different microalgae dietsPublication . Lourenço, S.; Gomes, A.S.; Santos, Pedro Castelo Filipe Moreira dos; Raposo, A.; Ferreira, S.M.F.; Pombo, AnaParacentrotus lividus is the most valuable sea urchin species in the European roe markets. Its economic value has been driving an intense exploration of wild populations leading to their over-exploitation in several areas of the Mediterranean and eastern Atlantic coast. The full production of P. lividus in aquaculture can potentially supply the European market for sea urchin roe reducing the impact over the wild populations. However, the low survival rates of sea urchin planktonic stages represent a critical bottleneck for the full cycle production for commercial purposes. Together with the zootechnical challenges, the selection of a suitable microalgal diet is fundamental to overcome this challenge. In the present study, we conducted two larvae rearing experiments testing the effect of five microalgae diets in the larvae development, age at competence and survival. The experimental diets tested were: Rhodomonas baltica (rho); Phaedactylum tricornutum (phae); Chaetoceros calcitrans (chae); a mix diet of rho and phae (1:1); and a mixed diet of rho and chae (1:1). The larvae were reared in closed system in triplicate tanks (50 L) at a density of 4 larvae/mL with seawater temperature ranging between 18.5 and 20°C. The daily feed concentration was adapted to the larval stage of development and standardized to the ratio between microalgae biovolume. Larvae samples were regularly collected to measure larvae body length, body width, post-oral arm length and the rudiment length. Linear models were fitted to the larval measurements and the model residuals were analyzed as an indication of larvae body condition. The larval survival was assessed volumetrically every two days. The results showed that the larvae fed with rho attained age at competence (at 18 days post fecundation, DPF, in experiment I and at 16 DPF at experiment II) earlier than larvae fed with phae, chae or with the mixed diets. On the other hand, the larvae fed with the rho and chae mixed diet presented higher survival rate (32 %). Moreover, the preliminary analysis of the linear model residuals showed that the mixed diet promoted the development of larvae with better condition. These results indicated that the rho diet promoted a reduction of the planktonic phase albeit with costs in terms of larval condition and survival rate.
- Chemical composition and omega 3 human health benefits of two sea cucumber species of North AtlanticPublication . Sales, Sabrina; Lourenço, Maria Helena; Pessoa, Maria Fernanda; Pombo, Ana; Félix, Pedro Miguel; Bandarra, Narcisa MariaThe main goal of this study was to investigate the seasonal chemical changes of two sea cucumber species caught from Portugal. The potential contribution to human health of lipids was also evaluated. For this, the chemical composition (protein, ash, and fat) and lipids composition of Holothuria arguinensis and Holothuria forskali was followed in summer and winter. Both species presented adequate levels of protein and ash and low content of total lipids, although their lipid profile showed a high proportion of polyunsaturated fatty acid (PUFA). Eicosapentaenoic acid (EPA) was abundant in all samples, and a favorable and similar n-3/n-6 ratio was found for both species. The atherogenic and thrombogenicity indices and ypocholesterolaemic/hypercholesterolaemic ratio suggests a high-quality for H. arguinensis and H. forskali. In general, significant differences were observed between species but not between summer and winter. Some significant variations were observed between summer and winter in the lipid profile of both species and in the chemical composition of H. forskali. Results indicate that these species have adequate nutritional quality for human consumption and may be suitable for the development of reliable fatty acid guides in sea cucumbers.
- Effect of rearing temperature in the growth of hatchery reared juveniles of the sea cucumber Holothuria arguinensis (Koehler & Vaney, 1906)Publication . Madruga, A.S.; Félix, P.M.; Sousa, J.; Silva, F. Azevedo e; Brito, A.C.; Mendes, S.; Pombo, A.Since the early 1980's there has been an increase in sea cucumber harvest and trade, mainly due to Asiatic market pressure. In the Indo-Pacific regions, the collapse of various stocks of these echinoderms has already occurred due to overfishing. In Europe, sea cucumber exportation depends exclusively on wild stock harvesting, which has demonstrated to be an unsustainable method to supply the markets, as these species are highly susceptible to overfishing. To enable a sustainable development of this emerging market in Europe the need to develop aquaculture techniques for these animals becomes of the utmost importance. At the current early stages of development, the viability of sea cucumber aquaculture for temperate species depends on the optimization of the rearing conditions. As ectotherms, temperature proves to be one of the most relevant parameters that affects the growth of sea cucumbers, as it influences metabolism and energy management and, in turn, future rearing methods and aquaculture sites. Therefore, this study aimed to determine the influence of temperature on the growth of H. arguinensis juveniles. A group of 168 juveniles (3.25 g ± 0.21; 3.81 cm ± 0.31) were placed under four different temperature treatments 18, 20, 22 and 24 ◦C for 4 months. The highest length (1.45 cm ± 0.16) and weight (2.79 g ± 0.14) gain were recorded at 20 ◦C. Similarly, the 20 ◦C treatment also produced the highest values for specific growth rate (0.50%/day) and the daily body length rate (0.30%cm/day). All allometric coefficients showed negative allometry (b < 3), a growth strategy that accentuates with increasing size. This lifehistory trait shows a higher distance from isometry the more distance the animals are from their optimum stocking temperature. Hence, metrics like the Fulton condition factor (K) show an inadequacy for the assessment of sea cucumber's condition, because a higher relative length decreases the value of K. A rearing temperature of 20 ◦C resulted in the best growth overall considering all increments in length and weight, pointing towards this as the best rearing temperature for the temperate species, H. arguinensis.
- Allometric relationships to assess ontogenetic adaptative changes in three NE Atlantic commercial sea cucumbers (Echinodermata, Holothuroidea)Publication . Silva, F. Azevedo e; Brito, A. C.; Simões, T.; Pombo, A.; Marques, T. A.; Rocha, C.; Sousa, J.; Venâncio, E.; Félix, P. M.Holothuria arguinensis, Holothuria mammata and Holothuria forskali are three common sea cucumber species found in the NE Atlantic, traded in international markets and susceptible to capture. Allometric relationships reveal if the scaling relationships between biometric characters are proportional with growth, being a useful tool to understand species growth strategies. Allometric relationships of the three species were estimated and compared between them and with populations from different regions. These allometric relationships revealed that the three species have negative allometric growth. However, they have different growth strategies between them and reveal different regional intra-specific growth strategies when compared to other populations, suggesting ontogenetic adaptation as a consequence of external factors.