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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 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.
- Motivation and preferences of Portuguese consumers’ towards sea urchin roePublication . Lourenço, Sílvia; Mendes, Susana; Raposo, Andreia; Santos, Pedro M.; Gomes, Ana S.; Ganhão, Rui; Costa, José L.; Gil, Maria M.; Pombo, AnaSea urchin roe is a gastronomic delicacy appreciated worldwide and Portugal is the third largest consumer nation of seafood. However, sea urchin roe is recognized as a seafood by few members of the national coastal communities. Motivated by an increasing interest of gastronomic and aquaculture sectors in producing this seafood, a survey was conducted among the participants of gastronomic festivals aiming to characterize the motivations and preferences regarding sea urchin roe. The results showed that a high percentage of consumers would be willing to eat sea urchin roe in a restaurant, and approximately half of these were not motivated to buy it in the supermarket. The consumers willing to buy sea urchins in the supermarket, would buy it as the whole urchin or the chilled/frozen roe. In conclusion, sea urchin roe can be characterized as a high valued shellfish to be consumed in restaurants.
- Somatic growth and gonadal development of Paracentrotus lividus (Lamarck, 1816) fed with diets of different ingredient sourcesPublication . Lourenço, Sílvia; Cunha, Beatriz; Raposo, Andreia; Neves, Marta; Santos, Pedro M.; Gomes, Ana S.; Tecelão, Carla; Ferreira, Susana M. F.; Baptista, Teresa; Gonçalves, Sílvia C.; Pombo, AnaSea urchins’ gonads are a delicacy highly appreciated worldwide. In Europe, Paracentrotus lividus is one of the most valuable edible sea urchin species and a desired target for aquaculture. One of the challenges of echinoculture is to increase the sea urchins’ growth rate during the on-growing phase and reducing the production cycle required to obtain sea urchins of commercial size (test diameter ≈ 50 mm). The present study aimed to evaluate the growth and gonad development of P. lividus urchins fed with three dry diets for 15 weeks. The diets were formulated with ingredients of three different sources: an algae-based, a fishmeal-based and a cereals-based diet. The somatic growth was assessed by biometric indicators like the linear and specific growth rates. The gonadal development was assessed by the gonadal somatic index (GSI), gametogenesis level, proximate composition and fatty acids profile. The results obtained showed high growth rates in all the three diets tested (0.44% per day). The sea urchins fed with the cereals diet presented the highest GSI (8.22%) with higher proportion of gonads in growing and premature stages. The proximate composition of the sea urchins’ gonads was significantly affected by diet and sea urchins’ sex, particularly the lipid content. Concomitantly, fatty acids (FA) profile of the gonads was influenced by both diet and sea urchins’ sex with saturated and polyunsaturated FA playing an important role in this differentiation.
- Effects of single and mixed-diatom diets on growth, condition, and survival of larvae of the sea urchin Paracentrotus lividus (Lamarck, 1816)Publication . Gomes, Ana; Lourenço, Sílvia; Santos, Pedro M.; Raposo, Andreia; Mendes, Susana; Gonçalves, Sílvia C.; Ferreira, Susana M. F.; Pombo, AnaThe development of rearing protocols promoting the larval development, pre and postmetamorphosis are key for echinoculture. Mixed diets combining diatom with other microalgae have been used with success and Rhodomonas sp. (Rho)-based diets showed promising results in larval survival. This study was aimed to evaluate the rearing success of Paracentrotus lividus larvae fed with mixed diets combining Rho with two diatoms, Phaedactylum tricornutum (Phae) and Chaetoceros calcitrans (Chae) in two experiments. In experiment I, the effect of the mixed diet of Rho and Phae (Mix I) was compared with monospecific diets of both species, while in experiment II, Rho was combined with Chae (Mix II) and compared with both monospecific diets. In experiment I, larvae fed with Rho I and Mix I diets grew faster than larvae fed with Phae I diet, attained the competence earlier with survival rates of 15-16%. In experiment II, the larvae fed with Rho were larger and the larvae fed with Mix II attained the highest survival rate (32.22%). The analysis of the larval biometric models showed that the larger larvae, with bigger stomachs, and shorter post-oral arm attained the age-at-competence earlier with higher survival rates. In conclusion, the larvae fed with a combination of Rho with the selected diatoms showed identical growth performance and condition to larvae fed with Rho monospecific diet but obtained higher survival rate. These results indicate that mixed-diatoms diets may be more suitable for P. lividus larval rearing.
- Temporal changes in sex-specific color attributes and carotenoid concentration in the gonads (roe) of the purple sea urchin (Paracentrotus lividus) provided dry feeds supplemented with β-carotenePublication . Lourenço, Sílvia; Raposo, Andreia; Cunha, Beatriz; Pinheiro, Joaquina; Santos, Pedro M.; Gomes, Ana; Ferreira, Susana; Gil, Maria Manuel; Costa, José L.; Pombo, AnaThe market value of sea urchin roe (female and male gonads) depends on several quality criteria, such as size, color, texture, and flavor. Sea urchins given dry pellet feed often produce large gonads, but the preferred bright orange color has been difficult to achieve without the inclusion of supplementary dietary carotenoids. Gonad color depends on carotenoid concentrations (CC), and is influenced by several factors, including diet and sea urchin sex. This study aimed to evaluate the impact of sea urchin sex, gonad size, and maturation level on gonad color and CC. Small Paracentrotus lividus urchins (18 mm test diameter) were fed every 48 h with three diets of similar proximate composition (protein: 31–33% dry matter DM, fat: 9–10% DM; carbohydrates: 45–46% DM). The diets were formulated with fishmeal, algae, and plant-based ingredients and supplemented with β-carotene (100 mg Kg−1). The nutritional trial was conducted in three recirculatory aquatic systems equipped with 40 L glass tanks guaranteeing triplicates by diet with an initial biomass of 5 g L−1. The gonadosomatic index (GSI), gonad maturity and color of 15 urchins per replica were analyzed at mid-trial (103 days, T1) and at the end of the trial (173 days, T2), and compare with initial condition (baseline). At each sampling event, the color of female (F) and male (M) gonads was analyzed using qualitative (four-level visual scale) and quantitative methods (Commission Internationale de l’ Eclairage CIE L*, a* and b* color parameters). Additionally, CC was determined by spectrophotometry in pooled samples freeze-dried gonads per replica and sex and compared with baseline. At T1, 59 females and 71 males were analyzed, and results showed that females presented larger (GSI = 7.50) gonads with higher CC (117.5 μg g−1 DM) than males (GSI = 5.16 and CC = 76 μg g−1). Female gonads also presented a more intense color (a* = 8.8, b* = 17.13) than males (a* = 5.1, b* = 12.49). At T2, 61 females and 62 males were analyzed and, except for a high percentage of female gonads classified as color grade I (57%), the differences on gonad color and CC between sexes identified in T1 became non-significant. In general, the gonad color tended to become lighter (L*, baseline: 34.8 and T2: 47.2) and yellower (b*, baseline: 12.5 and T2: 17.50), and CC decreased (baseline: 201.8 μg g−1 DM and T2: 31.6 μg g−1 DM) with increasing gonad weight (baseline: 0.16 g and T2: 0.77 g) and GSI (baseline: 3.0% and T2: 9.9%). In conclusion, this study shows that the carotenoid concentration and color attributes of sea urchin gonads are influenced by sea urchin sex and gonad size. The different diets and the carotene supplementation had little or no effect on the gonad CC and color attributes, indicating that the sources and concentrations of carotenoids in the diets were not sufficient to allow the accumulation of pigments in the gonads needed to enhance the color of P. lividus urchins.
- Can artificial diets be a feasible alternative for the gonadal growth and maturation of the sea urchin Paracentrotus lividus (Lamarck, 1816)?Publication . Santos, Pedro M.; Ferreira, Susana M. F.; Albano, Pedro; Raposo, Andreia; Costa, José L.; Pombo, AnaParacentrotus lividus (Lamarck 1816) has high-value reddishorange gonads that are regarded as a delicacy. In this study, three jellified diets have been tested for 90 days to assess the effect of different diets on P. lividus somatic and gonadal growth, gonad color, and reproductive state. All diets contained agar as a gelling agent and consisted of: maize and spinach (A); maize, spinach, and macroalga Laminaria digitata (B); and maize, spinach, and pumpkin Cucurbita maxima (C). Diet B was the most successful in promoting somatic growth with regard to test diameter (1.2 mm month−1) and total wet weight (79.9 mg ind−1 day−1). The individuals from Diet A presented a higher final gonadosomatic index (9.07 ± 2.39%) where all sea urchins initially presented with an index of 3.33 ± 0.02%. Diets A and C led to a marked advance (p < .05) in the gametogenic cycle (66.7% and 46.7% of the individuals with mature gametes, respectively), while Diet B resulted in less-developed gonadal stages, which are more appropriate for commercial purposes in terms of sensorial characteristics appreciated by the consumers. The gonad color analyses confirmed a redder roe in females and also the suitability of C. maxima as a potential gonad color enhancer for P. lividus.
- Effect of three diets on the gametogenic development and fatty acid profile of Paracentrotus lividus (Lamarck, 1816) gonadsPublication . Raposo, Andreia I.G.; Ferreira, Susana M. F.; Ramos, Rodolfo; Santos, Pedro M.; Anjos, Catarina; Baptista, Teresa; Tecelão, Carla; Costa, José L.; Pombo, AnaIn this study, the effects of three diets were investigated to enhance Paracentrotus lividus production for commercial purposes. P. lividus were fed ad libitum for 80 days with: diet A—fresh Codium tomentosum Stackhouse, 1797; diet B—formulated using a jellified mix of macroalgae and vegetables, including C. tomentosum (20%), Coralina sp. Linnaeus, 1758 (17%), cabbage Brassica oleracea var. capitata Linnaeus, 1753 (30%), carrot Daucus carota Linnaeus, 1753 (30%) and agar (3%) as a gelling agent. Diet C consisted of maize Zea mays Linnaeus, 1753 (56%) and New Zealand spinach Tetragonia tetragonoides (Pallas, 1781) Kuntze, 1891 (44%). Their effects on the gonadal and somatic growths, gonadosomatic index (GI) and gametogenesis were evaluated, as well as on the total lipid content and fatty acid composition of sea urchin's gonads. Diet A provided high values of eicosapentaenoic acid (EPA). Gonads of sea urchins fed with diet A were found mostly in growth and maturation stages of ametogenesis and showed the lowest lipid content. Sea urchins fed with diet B presented their gonads in the reabsorption stage and had the highest values of omega‐3 polyunsaturated fatty acids (PUFAs). Sea urchins fed with diet C were in the early stages of gametogenesis and had the highest values of lipid content, plus omega‐6 PUFAs. Once as an ingredient in a balanced mix with vegetables, C. tomentosum can be a key factor to the development of new promising high‐quality and low‐cost feed for P. lividus roe enhancement.