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Achieving efficient metamorphosis and settlement of larvae is a major bottleneck in the culture of sea urchins; therefore, in order for culture operations to be economically viable, it is urgent to optimize this crucial step under captive conditions. This study aimed to investigate how various parameters, including temperature, salinity, light cycle, and inducer type, affect the settlement of competent P. lividus larvae. Three different salinities (35, 30, 25‰), three temperatures (25, 20, 15 °C), four light conditions (16/8, 12/12, 24/0 and 0/24) and five types of biofilms (three of "natural" origin and the other two from monospecific collection cultures) were tested. The results suggest a relationship between low salinity and decreased survival and settlement rates. Conversely, the photoperiod appears not to have significant influence over survival and settlement rates. It appears that specific temperatures did not affect rates of survival and settlement, rather it was the deviation from initial culture temperature that is responsible for these rates. Finally, the multispecific inoculum of benthic diatoms showed a higher survival and settlement rate and lower mortality rate compared to monospecific inoculum. • The total survival and settlement percentage are higher in multi-species biofilms that monospecific. • The biofilms with the best results in terms of survival and settlement are those whose origin is natural. • The photoperiod has not clear influences on the total survival and settlement percentage. • Low salinity has a negative influence on the total survival and settlement percentage. • Temperature has a variable effect on the % of total survival and % of settlement of P.lividu s larvae. [ABSTRACT FROM AUTHOR]

Chromatographic fractions of a rough extract of echinoid spawn (REES) is demonstrated to efficiently induce oocyte maturation in aspidochirote holothuroids. The method is so efficient that it is currently used in holothuriculture to obtain fertilised eggs even outside the reproductive period of the aquacultivated species. In the present study, we isolated and identified from echinoid spawns the molecule responsible for the induction of the oocyte maturation in the Mediterranean holothuroid Holothuria tubulosa and the Indo-Pacific Holothuria scabra. The use of proteinase K and dialysing membranes suggests that the active molecule is a protein with a molecular weight superior to 12,000 kDa. The active molecule has been isolated on G-100 Sephadex chromatography column. Active chromatographic fractions include seven proteins identified with nanoLC-MS/MS technique. One of them, identified as a thioredoxin-2 and to which the name Trx-REES was given, gave levels of maturation similar to those obtained with the REES and with a commercial thioredoxin extracted from Escherichia coli. Occurrence of thioredoxin in REES was confirmed by immunoblot analysis, and the maturation-inducing properties of thioredoxin were positively checked using anti-thioredoxin antibodies. A peptide of 6 AAs corresponding to the active site of Trx-REES , composed of WCNPCK, was synthesised and its efficiency in holothuroid oocyte maturation was tested. At some concentrations, the isolated peptide was 1.2 times more active than the REES. This short peptide may be used as an effective tool for artificial induction of oocyte maturation in the sea cucumber aquaculture context. • Identification of a thioredoxin, from sea urchin spawns, that induces oocyte maturation in holothuroids. • The catalytic site of Thioredoxin (hexapeptide), alone, induces oocyte maturation in holothuroids. • In an aquaculture context, this study opens new perspectives for in vitro fertilisation within sea cucumber hatchery. [ABSTRACT FROM AUTHOR]

The Mediterranean sea urchin Paracentrotus lividus Lamark, 1816 is a resource as food and model organism for scientific research. Increasing market demand, commercial fisheries and destructing harvesting methods produced a dramatic reduction of natural stocks along the Mediterranean coasts. The techniques for in vitro fertilization and growth of larvae and adults are well known but various bottlenecks still hinder the industrial maturity of its aquaculture. In particular, the transition from planktonic larvae to benthic juveniles, as well as their correct development and survival, still represent critical phases, since larval and post-larval experiences are the primary determinant of juvenile fitness. Thus, techniques improving survival and settlement rates in the first two months after fertilization could considerably improve the effectiveness of echinoculture practices. This study was conducted to determine, for the first time, the effect of strictly benthic diatoms on P. lividus post-larval performances, as compared to other micro- and macro-algae. In addition, three larval dietary treatments were applied, to confirm previous findings on the efficacy of algae and formulated diets. In particular, survival and ability to produce competent larvae for settlement were tested in groups subjected to three algal diets ( Isochrisis galbana , Rhodomonas baltica and Dunaliella tertiolecta ), all integrated with a formulated food. Furthermore, six post-larval feeding regimes, i.e., the benthic diatoms Cocconeis scutellum parva , Diploneis sp., Navicula incerta , Cylindrotheca closterium and Nanofrustulum shiloi , compared with Ulva rigida along with a negative control (absence of food), were tested on larvae deriving from the most effective treatment. Our results confirmed the efficacy of Dunaliella tertiolecta integrated with a formulated food, consistently producing about 60% survival. Furthermore, the most adhesive benthic diatom, Cocconeis scutellum parva , sustained settlement (about 63%) and good survival in the first two months of life of sea urchins. [ABSTRACT FROM AUTHOR]

This study evaluated the growth of the purple sea urchin Paracentrotus lividus , fed with two diets, in sea- and land-based systems compared to wild populations. The experiments investigated the effects of the feeding regimes on gonad yield, nutritional traits and overall quality. Sea-based trials were performed by the CNR of Taranto (Trial S), whereas land-based trials were performed in the facilities of the University of Cagliari (Trial L). Urchins fed with a laboratory prepared pelletized diet (P), and a mix diet PU (50% of P-Diet and 50% of fresh Ulva sp.) were compared to wild urchins (W). In both trials the experimental diets supported a gonad growth when compared to wild population ( p  < .05). Sensory characteristics, assessed by 6 panel experts for each trial, highlighted significant differences in gonad colour and taste in both trials, while only in Trial S for texture (p < .05). The changes in the biochemical composition of sea urchins' gonads caused significant variations in the nutritional profile. Sea urchins fed with the experimental diets contained higher levels of total protein and lipids and PUFAs than wild sea urchins, although EPA, DHA and n-3/n-6 ratio, were lower in urchins fed with artificial diets. In Trial L, total free amino acids showed an increase respect to W gonads ( p  < .05), whereas in Trial S, total free amino acids showed a decrease only in sea urchin fed with P-Diet (p < .05). The results presented in this study provide evidence of the good performance of the formulated diet assuming its application for the development of Mediterranean echinoculture. [ABSTRACT FROM AUTHOR]

As a result of the increase in demand for sea urchin gonads, which are considered a gourmet food, the sea urchin aquaculture industry has gradually expanded in some South American and Asian countries. This study investigated the growth, metamorphosis and MYP gene expression of larvae of two species of sea urchin ( Strongylocentrotus intermedius and Strongylocentrotus nudus ) fed with four microalgal diets: Chaetoceros muelleri , Dunaliella tertiolecta , Isochrysis galbana , and a mixture of the three. The larvae fed the C. muelleri and mixture diets were successfully raised to competence for metamorphosis and showed better stomach growth, development rates and metamorphosis rates than the larvae that were fed D. tertiolecta or I. galbana . The results also suggest that the larvae could accumulate long-chain polyunsaturated fatty acids (LC-PUFAs), such as docosahexaenoate (DHA; 22:6n-3), eicosapentaenoate (EPA; 20:5n-3) and arachidonate (ARA; 20:4n-6), either by the assimilation and retention of dietary fatty acids or by synthesis from α-linolenic acid (18:3n-3) and linoleic acid (18:2n-6). Moreover, an accumulation of n-6 and n-3 LC-PUFAs and higher ARA/EPA ratios in the larvae appeared to be associated with improved larval performance. The results also showed that the MYP gene expression levels in the larvae fed the C. muelleri and mixed diets were significantly higher than in the D. tertiolecta and I. galbana groups. In addition, the trend of the MYP gene expression in the different stages was 6-arm stage > 8-arm stage > 4-arm stage > fertilized eggs > prismatic stage. These results provide suggestions for diet selection for sea urchin larvae and the fatty acid composition of diets for urchin larvae, and they provide a reference for further study of the effects of diets on the gene expression of MYP in larvae. [ABSTRACT FROM AUTHOR]

Sea urchin larvae have developed metamorphosis and settlement stages as an adaptation serving to increase their distribution and find more suitable habitats; for aquaculture farmers, these stages represent a bottleneck, as the cost-effective production of large numbers of metamorphosed larvae in confined conditions remains a major constraint. The aim of this study was the development of a reliable metamorphosis cue for Paracentrotus lividus larvae that is widely available and easy to prepare and use even at the hatchery scale. For this purpose, substrates of environmental origin (GUS - ground Ulva spp. solution) and chemical origin (histamine) were tested for their effectiveness, evaluating the metamorphosis rates of competent P. lividus larvae after 24-h exposure. In addition, differences in metamorphosis rates following exposure to scaled concentrations of both fresh and frozen-thawed GUS were evaluated, with a view to the latter's routine adoption as a metamorphic cue. The metamorphosis rates obtained in the presence of GUS were always around 80%, using both fresh and thawed solutions. Decreasing GUS concentrations resulted in significantly lower percentages of metamorphosed larvae. No metamorphosis occurred after exposure to histamine solutions. GUS proved to be an effective metamorphic cue and to have several other strengths. Indeed, Ulva spp. are widely available and easy to collect in the field as well as being currently cultivated, in some cases in integrated multi-trophic systems. Ulva spp. represent a common food source for natural populations of juvenile and adult P. lividus , and GUS can therefore be used in the formulation of a settlement substrate that also serves as food in the initial post-metamorphosis period. Finally, GUS is prepared by grinding fragments of Ulva spp. with FSW in a mortar and then filtering the solution, with no need for time-consuming or expensive methods. It can thus be easily produced on a commercial scale and then stored or delivered after being frozen. In conclusion, the formulation of GUS represents a promising advance in the development of protocols for echiniculture, meeting the need for tailored metamorphosis and settlement methods that support successful and cost-effective production of sea urchin juveniles. Moreover, it could represent an additional valuable method for obtaining marketable products from harvested Ulva grown in integrated multi-trophic aquaculture systems. [ABSTRACT FROM AUTHOR]

A 28-day feeding experiment was performed to investigate the effects of soya lecithin (SL) addition on the growth, gonad development, fatty acid composition, transcription of genes related with fatty acid synthesis and inflammation between sexes of sea urchin Strongylocentrotus intermedius (A. Agassiz, 1864). Three experimental diets were prepared with increasing levels of SL (0%, 1.6%, and 4%). Each diet was randomly assigned to eight male and eight female sea urchins individually cultured in floating cages. The results showed that SL addition significantly decreased the weight gain rate of male sea urchins but had no significant effects on that of female individuals. The gametogenesis of male S. intermedius was markedly accelerated by SL addition at a moderate level (1.6%), reflected by more spermatozoa and fewer nutritive phagocytes in the testis. By comparison, the gametogenesis of female individuals was only slightly promoted by 1.6% and 4% SL addition, with no oocytes observed in the ovary. The contents of arachidonic acid (ARA) in the digestive tract and gonads, and eicosapentaenoic acid (EPA) in the gonads of male and female S. intermedius were increased by SL addition at a moderate level, although their contents were still lower than the initial values. Similarly, the transcription of most fatty acid synthesis-related genes was significantly increased by 1.6% SL addition in both sexes of S. intermedius. The transcription of almost all inflammation-related genes increased with the increase of SL addition in both male and female S. intermedius. Notably, male S. intermedius showed higher ARA contents and transcription of most fatty acid synthesis and inflammation related genes than their female counterparts, especially in the SL1.6 and/or SL4 groups. In summary, SL addition showed no beneficial or negative effects on growth performance but markedly promoted gonad development and ARA and EPA accumulation in S. intermedius , especially at a moderate level (1.6%). Males showed faster gametogenesis than females possibly due to relatively higher ARA synthesis and cyclooxygenase-2 mediated eicosanoid production. The retarded growth and gametogenesis of male S. intermedius fed diets with the addition of 4% SL could be due to excessive inflammation. These results could be helpful for understanding the dosage-dependent and sex-related physiological effects of SL on growth and gonad development of S. intermedius. • SL showed no beneficial effects on the growth, but markedly promoted gonad yield and gametogenesis of S. intermediu s. • A moderate SL (1.6%) significantly increased the ARA and EPA contents and fatty acid synthesis related gene expression. • Excessive SL-induced inflammation could be responsible for their negative effects on growth, gonad yield and gametogenesis. • Males showed more active fatty acid synthesis and inflammation reaction than females in response to the same level of SL. [ABSTRACT FROM AUTHOR]

The effect of different treatments on the settlement success, survival and growth of sea urchin juveniles has been evaluated. Two experiments were performed for assessing the ability of substrates or seawater to induce settlement. In the first test 500 competent larvae were inoculated in transparent plastic containers conditioned for ten days with: Tetraselmis marina , Cyilindrotheca closterium , Nitzschia sp., Maërl beds, 100 μm filtered natural seawater and 1 μm filtered and UV disinfected seawater. Maximum settlement values were obtained with C . closterium , Nitzschia sp. films and UV treated seawater; and significant differences were only detected between T . marina films and the other treatments. In the second test the following treatments were performed in order to investigate the effects of filtered seawater on settlement: 0.22 μm filtered and autoclaved seawater (negative control), 1 μm filtered and UV treated seawater and C . closterium (positive control). Settlement success was significantly higher for C . closterium than for autoclaved seawater. Survival and growth of juveniles were monitored for 32 days on these treatments: T . marina , C . closterium , Nitzschia sp., Maërl beds and 100 μm filtered natural seawater. Growth of juveniles could be adequately described by linear fitting and maximum growth rate was found for C . closterium film. There were no significant differences between treatments in terms of mortality at days 21 or 32. In general, the results showed that C . closterium biofilms provide good settlement, growth and survival of sea urchin juveniles which would allow improving general performance of these phases of culture compared to the other diets tested. [ABSTRACT FROM AUTHOR]

In this study, we present the results of two experiments; in the first one we evaluated the effects of four larval dietary treatments on the survival and growth of the sea urchin Paracentrotus lividus , larvae and post-larvae. In the second experiment we have measured the effects of two different settlement substrates, combined with the presence of conspecifics, on metamorphosis, survival and growth of post-larvae. The microalgae dietary treatments consisted in: Dunaliella tertiolecta (Duna); 50% mixture of Isochrysis galbana and D. tertiolecta (ID); 50% mixture of Chaetoceros gracilis and D. tertiolecta (CD); 33% mixture of I. galbana , C. gracilis and D. tertiolecta (ICD). Although all dietary treatments resulted in a good survival at competence, significant difference in post-larval survival was observed between treatments, and indeed, only larvae fed Duna and CD survived to 180 days post settlement (DPS). In the second experiment, the settlement substrates consisted in a film of cultured Ulvella lens or a naturally developing biofilm of diatoms, and the employed rearing water was either natural seawater or seawater previously exposed to P. lividus adults. At 10 DPS, larger ( p < 0.05) post-larvae were observed in the natural biofilm treatment, whilst the presence of conspecifics significantly increased larval settlement in both substrates ( p < 0.01). These results indicate that it is important to consider the survival of post-larvae and juveniles to establish the efficiency of the dietary treatment on the hatchery production of P. lividus . Furthermore, it suggests that improved settlement protocols, such as the use of conspecifics, could contribute to increase hatchery outputs. Finally, it confirms the suitability of U. lens as settlement cue but also highlights that further research is required to establish its effectiveness for post-larvae first feeding. Statement of relevance Our work contributes to improving hatchery rearing methods of larvae and post-larvae of the sea urchin Paracentrotus lividus . [ABSTRACT FROM AUTHOR]

New research is currently underway to explore the potential of macroalgae for the production of biofuels. Marine biofuels in general and macroalgae in particular, offer a number of advantages over terrestrial biofuels including reduced competition for freshwater resources and for land use. Sugars can be extracted from macroalgae and processed into biofuels by anaerobic digestion and fermentation. This process generates significant waste biomass, which, if used, could improve the economic sustainability of the biorefinery sector. Bivalves' aquaculture relies heavily on the production of unicellular algae to feed juvenile individuals and this can represent a bottleneck for the bivalve industry especially in locations where sunlight is limited. Previous research explored the use of macroalgae derived digestate as alternative or integrative feed for juvenile bivalves, exploiting the notion that organic particulate matter (detritus) is an integral part of this animal class natural diet. The prospect of using waste products from the emerging biorefinery industry to solve a bottleneck for aquaculture businesses and, by so doing, improving profitability of both, is an exciting one. In this paper we describe the main nutritional profiles (Protein, Lipid, Carbohydrates and Fatty acids) of the tested diets and investigate the potential for the use of a biorefinery a by-product as replacement option for bivalves' production, by benchmarking it against aquaculture industry standards (live microalgae and commercially available algae paste) and natural detritus constituted by farmed sea urchin digesta. Both the digestate and the natural detritus supported the survival and growth of bivalve spat, especially when used at 50% inclusion rate, over the course of 4-week preliminary trials. Data suggest that a synergistic effect of the nutritional profiles of the diets employed may underpin the observed results. Statement of relevance With this study we compare the biochemical composition and suitability as oyster feed of the Single Cell Detritus produced by S. latissima enzymatic saccharification and natural detritus produced by sea urchin digestive action, with live microalgae as well as commercial algae paste. A comparison between biochemical composition and suitability as aquaculture feed between biorefinery by-products and natural detritus was, to our knowledge, lacking. Results indicate that both the digestate and the natural detritus supported the survival and growth of oyster spat, especially when used at 50% inclusion rate, over the course of 4-weeks trial. [ABSTRACT FROM AUTHOR]

Juvenile Lytechinus variegatus (ca. 3.95 ± 0.54 g) were fed one of 10 formulated diets with different protein (ranging from 11 to 43%) and carbohydrate (12 or 18%; brackets determined from previous studies) levels. Urchins ( n = 16 per treatment) were fed a daily sub-satiation ration equivalent to 2.0% of average body weight for 10 weeks. Our objective was (1) to create predictive models of growth, production and efficiency outcomes and (2) to generate economic analysis models in relation to these dietary outcomes for juvenile L. variegatus held in culture. At dietary protein levels below ca. 30%, models for most growth and production outcomes predicted increased rates of growth and production among urchins fed diets containing 18% dietary carbohydrate levels as compared to urchins fed diets containing 12% dietary carbohydrate. For most outcomes, growth and production was predicted to increase with increasing level of dietary protein up to ca. 30%, after which, no further increase in growth and production were predicted. Likewise, dry matter production efficiency was predicted to increase with increasing protein level up to ca. 30%, with urchins fed diets with 18% carbohydrate exhibiting greater efficiency than those fed diets with 12% carbohydrate. The energetic cost of dry matter production was optimal at protein levels less than those required for maximal weight gain and gonad production, suggesting an increased energetic cost (decreased energy efficiency) is required to increase gonad production relative to somatic growth. Economic analysis models predict when cost of feed ingredients are low, the lowest cost per gram of wet weight gain will occur at 18% dietary carbohydrate and ca. 25–30% dietary protein. In contrast, lowest cost per gram of wet weight gain will occur at 12% dietary carbohydrate and ca. 35–40% dietary protein when feed ingredient costs are high or average. For both 18 and 12% levels of dietary carbohydrate, cost per gram of wet weight gain is predicted to be maximized at low dietary protein levels, regardless of feed ingredient costs. These models will compare dietary requirements and growth outcomes in relation to economic costs and provide insight for future commercialization of sea urchin aquaculture. Statement of relevance This paper uses general linear modeling to predict growth, production and efficiency in cultured L. variegatus within an optimal range of dietary carbohydrate levels (12 or18%) at different levels of dietary protein. Data were used to generate economic analysis models for high, medium and low feed ingredient prices. We believe that these data are the first to provide any information regarding the economic viability of sea urchin aquaculture. Further economic analysis will be required to estimate costs of labor and culture systems. However, these data may prove to be useful and informative in predicting feed costs for urchins held in culture. [ABSTRACT FROM AUTHOR]

The standardization of procedures for the post-collection management of semen samples is a prerequisite for the development of husbandry techniques, as well as for the use of semen in laboratory research. Despite the relevance of the sea urchin Sphaerechinus granularis as a laboratory model, the basics related to sperm collection and storage have received little attention. The aim of this research was to optimize procedures for the management of S. granularis semen , focusing on the post-collection storage of samples. Specifically, the effects of post-collection storage conditions on sperm motility parameters were evaluated; motility was assessed by computer-assisted analysis (CASA-mot) upon activation (t0), and 15 min, 30 min and 60 min after dilution in freshly collected semen, and in chilled and cryopreserved samples. Motility parameters remained unchanged for up to 60 min after activation in both fresh and chilled semen. In cryopreserved samples, sperm motility upon activation was significantly lower than in fresh semen; however, no differences with respect to t0 values were recorded when thawed semen was cold- incubated for up to 60 min post activation, thus meeting standards required by germplasm cryobanks. Post-activation longevity showed by both fresh and stored S. granularis semen, as well as its resistance to cryopreservation, are positive spermatological features that will allow the running of easy management procedures, encouraging a wider use of S. granularis in hatchery practices, as well as in laboratory activities. • The production of model species for research activities is a strategic issue in aquaculture. • Sperm handling and storage conditions are crucial for the development of husbandry techniques. • The effects of the storage conditions on the sea urchin S. granularis sperm motility were evaluated. • Sperm motility can be well-maintained during chilled storage (undiluted, 4 °C) for up to 24 h. • Motility on thawing of cryopreserved sperm meets the standards required by semen cryobanks. [ABSTRACT FROM AUTHOR]

The long spined sea urchin Diadema antillarum was an abundant grazer on Caribbean coral reefs, until 1983–1984, when densities were reduced by ∼98% during a region wide die-off. Since then, there has been very little natural recovery of the species and interest is growing in applying aquaculture as a tool for population enhancement. In this study we optimized a new shaker bottle cultivation method for D. antillarum. The method was tested in a series of experiments by culturing D. antillarum from egg to juvenile in the Netherlands as well as the USA. Larvae were cultured in standard 1-L glass reagent bottles, suspended by gentle constant movement on an orbital shaking table and fed with either the microalgae Rhodomonas lens or Rhodomonas salina. Effects on larval growth and survival were evaluated for different microalgal feeding concentrations, larval densities, and culture temperatures. Larval density and growth were measured twice a week over a period of up to 56 days. Larvae grew significantly faster on a higher feeding concentration up to 90,000 Rhodomonas sp. cells mL−1, twice weekly, compared to 30,000 and 60,000 cells mL−1. A density of 1 larvae mL−1 resulted in the highest body size and survival compared to densities of 2 or 4 larvae mL−1. Overall survival from larva to settled juvenile urchin increased from 8 to 10% settlement to 32–33% when the initial density was lowered further from 1.2 to 0.4 larvae mL−1. Growth, survival, competency and settlement did not differ between larval cultures kept at 25 °C or 28 °C. We believe that this novel method for culturing D. antillarum larvae, once scaled-up and validated to pilot scale, could provide juveniles for restocking of urchin-depleted reefs that suffer from algae overgrowth. • Diadema antillarum can be cultured with a new shaker bottle method. • High larval survival and settlement was achieved using this new method. • Scale-up and validation of this method could support mass juvenile production. [ABSTRACT FROM AUTHOR]

Reliable methods of tracing the geographical origin of sea urchin are urgently needed for food safety and consumer health. To the best of our knowledge, the present study was the first attempt to trace the geographic origins of sea urchin by using stable isotope techniques. The δ 13C, δ 15N and δ 18O values from the gonad and spine of sea urchins collected from five locations were analyzed. From the gonad samples, the δ 13C values ranged from −22.07‰ to −18.37‰, the δ 15N values ranged from 6.59‰ to 9.99‰, and the δ 18O values ranged from 17.64‰ to 27.19‰. From the spine samples, the δ 13C values ranged from −5.43‰ to −3.57‰, the δ 15N values ranged from 7.95‰ to 13.66‰, and the δ 1 8O values ranged from 33.99‰ to 40.15‰. The δ 13C and δ 15N values from the gonads differed significantly among samples from different geographic origins, but the δ 1 8O values did not differ. The δ 15N and δ 18O values from the spines differed significantly among samples from different geographic origins, but the δ 13C values did not differ. Both quadratic discriminant analysis (QDA) and the k-nearest neighbor (KNN) methods yielded low recognition of the δ 13C, δ 15N, and δ 18O values from the gonad samples. However, higher accuracy was obtained using the stable isotope values from the spine samples combined with QDA or KNN methods. Moreover, the KNN methods gave more satisfactory accuracy, the initial, cross-validated, and predictive classification rates were 97.1%, 97.1%, and 93.3%, respectively. The C, N, and O stable isotope analysis of spine samples may be used to verify the geographic origin of sea urchins. • The δ13C, δ15N, and δ18O values in the gonad and spine of sea urchin were analyzed. • The δ13C and δ15N values in gonads were different among geographic origins. • The δ15N and δ18O values in spines were different among geographic origins. • Stable isotopes in gonads gave low recognition in the discrimination models. • Stable isotopes in spines gave satisfactory results in the discrimination models. [ABSTRACT FROM AUTHOR]

Little experimental evidence of multiple generations of inbreeding depression is available for marine invertebrates. Here, we report that two generations of inbreeding significantly reduced larval growth and metamorphosis, but did not significantly impact fertilization and hatching in the sea urchin Strongylocentrotus intermedius . A higher inbreeding coefficient had significantly more negative impacts on some traits of S. intermedius larvae (for example, larval length) but not all. Maternal effects of inbreeding depression probably appear in the eight-arm stage and metamorphosis of S. intermedius . The present study provides convincing evidence of inbreeding depression on larval growth and metamorphosis in S. intermedius and highlights the importance of avoiding multiple generations of inbreeding in sea urchin aquaculture. Statement of relevance Multiple inbreeding dramatically impacts aquaculture of marine species. Here, we investigated effects of second generation of inbreeding on fertilization, hatching, larval growth and metamorphosis in sea urchins. The present study provides the convincing evidence on the inbreeding depression of larval growth and metamorphosis in sea urchins and highlights the importance of avoiding multiple generation of inbreeding in sea urchin aquaculture. [ABSTRACT FROM AUTHOR]

Among aquatic organisms, nutritional requirements are historically assessed by evaluating formulated diets with changes in a single nutrient profile. These studies provide organisms with the option of regulating the total feed intake but do not enable individuals to regulate intake of specific nutrient ratios. An alternate experimental approach, known as the geometric framework (GF) for nutrition, tests whether organisms held under specific conditions have optimal target intake levels for particular nutrients and whether, when provided with diet choices, they will self-regulate nutrient intake to reach these specific targets. In this study, we used the GF to assess intake levels of dietary protein and carbohydrate in cultured adults of the sea urchin Lytechinus variegatus provided choices between diets varying in both dry matter and specific macronutrient concentrations. Adult urchins (ca. 120 g) held previously on formulated diets were offered moist gel-based diets in pairwise combinations. Diets varied in levels of fish meal isolate (as a protein source) and wheat starch (as a carbohydrate source) and in nutrient concentration (5 or 10% dry matter). Regardless of diet combination, individuals maintained an average dietary protein intake of ca. 0.047–0.061 g day − 1 . Dietary carbohydrate intake was not regulated to a specific level and ranged from 0.042–.0136 g day − 1 . These data suggest that large adult L. variegatus held in culture have a tightly regulated intake target for dietary protein but not carbohydrate. Regardless of nutrient ratios or macronutrient concentration, individuals adjusted intake patterns to defend this target. We suggest that the GF will be an important tool in evaluating macronutrient requirements in cultured sea urchins and other aquatic species. [ABSTRACT FROM AUTHOR]

Abstract: The ability of the green sea urchin (Strongylocentrotus droebachiensis) to consume and subsequently reduce the organic content of sablefish (Anoplopoma fimbria) culture waste was assessed and properties influencing the dispersal of fecal pellets egested by the sea urchins were quantified in laboratory trials. Ingestion rate, absorption efficiency, and oxygen uptake in sea urchins and the shape, size, and settling velocity of fecal pellets were determined for individuals fed sablefish waste or a natural control diet (giant kelp, Macrocystis pyrifera). Results showed that S. droebachiensis consumes sablefish waste at a dry weight ingestion rate of 0.43±0.039gindividual−1 d−1 and absorbs 40±4.84% (mean±SE) of the organic material ingested, with no significant (P <0.05) differences between the diets tested. Oxygen consumption was significantly (P <0.05) higher in sea urchins fed sablefish waste than in those fed kelp at 0 and 2d after feeding. The fecal pellets egested by sea urchins fed sablefish waste were significantly rounder and smaller and had a higher settling velocity than those from individuals fed kelp. This study demonstrates that green sea urchins actively ingest and absorb organic material from the waste produced by sablefish culture. Further research is recommended to determine the effect of the sablefish-waste diet on sea urchin survivorship, growth, and gonad quality. Culture of S. droebachiensis integrated with sablefish is warranted on an experimental scale. [Copyright &y& Elsevier]

Abstract: Fouling organisms on scallop cultivation nets and shells are costly to remove and can reduce scallop growth. In the present study, we investigated the biological control efficiency of using the sea urchin Hemicentrotus pulcherrimus as a means of preventing fouling in suspended scallop cultivation of Chlamys farreri and Patinopecten yessoensis in Sanggou Bay, Northern China. Tests were carried out from June to September 2009, during the period of the heaviest fouling. The scallops were co-cultured in scallop lantern nets for 3months. At the end of the experiment, all sea urchins were alive and the survival rates of scallops were very high. Scallop shell length and soft tissue growth were not significantly affected by sea urchins, but a greater growth in scallop soft tissue was associated with the presence of the sea urchin. Sea urchin had a minimal effect on the shell fouling of C. farreri, but noticeably reduced the weight of fouling on scallop nets and efficiently reduced fouling on the shell of P. yessoensis. Results suggest that the sea urchin was an effective biological control organism, especially for the shell fouling of P. yessoensis. This experiment indicated that biological control, using sea urchin, of fouling in suspended scallop cultivation has the potential to become an efficient and environmentally-sound method for addressing the problem of fouling in scallop cultivation. [Copyright &y& Elsevier]

Abstract: Adult Lytechinus variegatus were fed eight formulated diets with different protein (ranging from 12 to 36%) and carbohydrate (ranging from 21 to 39%) levels. Each sea urchin (n=8 per treatment) was fed a daily sub-satiation ration of 1.5% of average body weight for 9weeks. Akaike information criterion analysis was used to compare six different hypothesized dietary composition models across eight growth measurements. Dietary protein level and protein: energy ratio were the best models for prediction of total weight gain. Diets with the highest (≥68.6mgPkcal−1) protein:energy ratios produced the most wet weight gain after 9weeks. Dietary carbohydrate level was a poor predictor for most growth parameters examined in this study. However, the model containing a protein×carbohydrate interaction effect was the best model for protein efficiency ratio (PER). PER decreased with increasing dietary protein level, more so at higher carbohydrate levels. Food conversion ratio (FCR) was best modeled by total dietary energy levels: Higher energy diets produced lower FCRs. Dietary protein level was the best model of gonad wet weight gain. These data suggest that variations in dietary nutrients and energy differentially affect organismal growth and growth of body components. [Copyright &y& Elsevier]

Abstract: The digestive enzymatic profile (amylase, lipase, proteases, trypsin, chymotrypsin and cellulases) was studied in three species of Mediterranean regular sea urchin: Arbacia lixula, Sphaerechinus granularis and Paracentrotus lívidus collected from the natural environment. A different enzymatic profile was manifested in the three studied species. A higher amylase capacity in S. granularis would support a preferential use of feed rich in vegetable sources. The marked cellulolytic potential in P. lividus would qualify this specie to feed on cellulose rich vegetable sources. Finally A. lixula would be the species with a higher total digestive capacity (greater lipase, proteases and trypsin activity) that would enable it to feed on a wide variety of foods, including of animal origin, and to get more energy from nutrients. Further investigation related to these aspects could explain and complete the current knowledge about feeding habits of these species extrapolating results to improve feed formulation for sea urchins culture and their possible application as digestive enzymes source for biotechnological applications. [Copyright &y& Elsevier]

Abstract: This study investigated the growth, survival and fatty acid composition of sea urchin Paracentrotus lividus larvae fed four microalgal diets: Cricosphaera elongata, Pleurochrysis carterae, Tetraselmis suecica and Dunaliella tertiolecta (control). Larvae were successfully raised to competence for metamorphosis when fed C. elongata, P. carterae and D. tertiolecta diets but significant differences were found in survival rate and development. Larvae fed C. elongata showed 3 times higher survival and 20% faster development than larvae fed the other two microalgae diets that supported development. In contrast, T. suecica failed to fully support development and larvae stalled at the four arms stage for more than 30days. The urchin larvae could accumulate long-chain polyunsaturated fatty acids (LC-PUFA) such as docosahexaenoate (DHA; 22:6n-3), eicosapentaenoate (EPA; 20:5n-3) and arachidonate (ARA; 20:4n-6), either by assimilation and retention of dietary fatty acids, and/or synthesis from α-linolenic acid 18:3n-3 and linoleic acid 18:2n-6. Moreover, an accumulation of n-3 LC-PUFA and higher EPA/DHA and EPA/ARA ratios appeared to be associated with improved larval performance. The results indicate that live microalgae species, with appropriate fatty acid profiles are able to improve P. lividus larval performance, ultimately increasing hatchery profitability. [Copyright &y& Elsevier]

Abstract: This study evaluated the effect of diet and ration on the growth and survival of larvae of the purple sea urchin, Strongylocentrotus purpuratus. Larval total length, mid-line body length, body width, post-oral arm length, time to reach metamorphic competency, and survival rate were assessed during the experimental period (28days). In the first experiment, seven algal diets [i.e. Dunaliella tertiolecta, Chaetoceros muelleri, Isochrysis sp. (Tahitian strain) and all possible binary and tertiary combinations] were assessed, along with a control treatment of no food. Larvae reared on the bi-algal diet of D. tertiolecta/Isochrysis sp. and the uni-algal diet of D. tertiolecta provided significantly better growth than all other treatments. Larvae were successfully raised to metamorphic competency with both the binary combination of D. tertiolecta/Isochrysis sp. and the single species D. tertiolecta within 28days of culture, whereas larvae in all other dietary treatments failed to reach competence within 28days. In the second experiment, a bi-algal diet (D. tertiolecta and Isochrysis sp. at equal biovolumes) was evaluated using five rations: (1) low ration: 1.25×103 cellsml−1; (2) normal ration: 2.5×103 cellsml−1; (3) standardized ration: 2.5×103 to 10.0×103 cellsml−1, with increasing ration according to developmental stage; (4) medium ration: 5.0×103 cellsml−1; and (5) high ration: 10.0×103 cellsml−1. Typical echinoid larval development in all body dimensions was only achieved for larvae offered the standardized ration. Larvae reared on this ration attained metamorphic competency within 28days, whereas larvae fed the fixed rations (lower or higher concentrations) failed to attain competency by the end of the experiment. In general, in comparison to larvae fed the standardized ration, larvae on the low ration showed longer post-oral arm length and narrower body width whereas larvae on the high ration showed shorter post-oral arm length and body width in relation to their total length. Overall survival (from prism stage to metamorphic competency) for the best treatments in both experiments was 44.4±2.9 and 53.3±1.9% (mean±SE) for the binary diet of D. tertiolecta/Isochrysis sp. and standardized ration treatments, respectively. Based on these results, larvae fed a binary combination of D. tertiolecta and Isochrysis sp. or D. tertiolecta alone with a ration increasing with developmental stage is recommended for hatchery production of S. purpuratus. [Copyright &y& Elsevier]

Abstract: During two 12week trials, groups of edible sea urchins, Psammechinus miliaris, were fed artificial diets containing carotenoid pigments. The aim was to improve both the biomass and the colour of the sea urchin gonad in terms of its acceptability as a human food-stuff in the European market place. The pigmented artificial diets, based on the formula used by , increased gonad index (GI), pigment deposition and improved gonad colour from that of the initial samples. In Trial I gonad β-carotene levels increased >2 fold, echinenone and total carotenoid >7 fold. Trial II showed greater increases. Diets containing high levels of β-carotene (500mg per kg dry weight of diet) gave rise to the highest percentages of marketable gonad colours (61–73%), and GI of 17.87–19.81%, (Trial I and II respectively). There was some variation in the results for this particular diet treatment across the two trials presumably reflecting individual urchins varying capacity to ingest, deposit or express the carotenoids in their diet. Providing additional lipids in the diets gave no improvement to gonad colour (56% acceptable) or GI (15.95%) suggesting the lipid content of the basic formulation is adequate. Utilizing an esterified form of lutein and zeaxanthin as a pigment source gave no significant improvement in gonad colour (30–63% acceptable) suggesting that this form of xanthophyll cannot be assimilated by P. miliaris. Female urchins had acceptable gonad colouration more often than males. The dominant carotenoid in the successful diets was β-carotene and this was successfully metabolized into echinenone, the dominant carotenoid in all gonad samples. Total levels of echinenone positively correlated with acceptable gonad colour scores. This study demonstrates that 12weeks is sufficient to effect the desired change in gonad biomass and colour in cultivated P. miliaris. [Copyright &y& Elsevier]

Abstract: Here we provide methods for generating triploid green sea urchin embryos (Strongylocentrotus droebachiensis). These are the first triploid sea urchins of any species that have been produced at any life stage and represent an initial step in a larger effort to yield triploid adult green sea urchins for large-scale land-based and near-shore commercial aquaculture ventures. Following fertilization, triploid mollusks and fish result by preventing release of the second polar body. Adult triploids in all of these organisms are sterile and may be larger than diploids based on accelerated growth of somatic tissues. Similar methods are impossible for sea urchins since haploid (1n) ova are released from the ovary after completion of both meiotic divisions. We have produced triploid green sea urchin embryos (3n=63) by fusing two 1n ova (each n=21) and fertilizing the diploid products of these fusions with highly diluted spermatozoa (n=21). Mechanical, proteolytic and acidic treatments were employed to remove the jelly coat and vitelline membrane prior to fusion. Results indicate that acidic removal of the extracellular structures, subsequent fusion with poly(Arg) in 1.5ml microcentrifuge tubes and fertilization with highly diluted sperm yield 60.64±1.39% triploid embryos that reach prism pluteus stage (with spicules). Triploidy was verified at all developmental stages by counting chromosomes. We discuss scaling up our laboratory methods for embryos to the hatchery environment and also issues unique to the reproductive biology of sea urchins that will be vital for commercial aquaculture ventures to consider if triploid adult green sea urchins can ultimately be produced. [Copyright &y& Elsevier]

Abstract: Sea-urchin ingestion rate, absorption, gonad yield, and gonad quality can be influenced by a variety of factors, including food quantity, food quality, and various environmental conditions. We examined the combined effects of two factors (diet and temperature) on ingestion rate, absorption, assimilation efficiency, and gonad enhancement of the purple sea urchin, Strongylocentrotus purpuratus, over a 12-week period. Four diets [three kelp species (Macrocystis integrifolia, Nereocystis luetkeana, and Saccharina latissima) and one prepared feed] and three temperatures (8.0±0.4, 12.3±0.3, and 16.2±0.4°C: mean±SD) were tested in a completely crossed factorial design. Ingestion rate, gravimetric absorption, and assimilation efficiency of urchins fed the various diets were calculated at weeks 6 and 12. In addition, a number of gonad attributes were quantified at the beginning and end of the experiment including wet weight, percent water content, gonad index, texture, firmness, colour, and flavour. Ingestion rate, gravimetric absorption, and assimilation efficiency were generally significantly affected by both temperature and diet. Wet-weight ingestion rates were significantly higher with the three kelp treatments than with the prepared diet at both weeks 6 and 12. This particular dietary difference was not apparent, however, when ingestion rates were expressed on a dry-weight basis. The highest ingestion rates were recorded for animals held at 12°C at week 6 and at 16°C at week 12. Absorption rates and assimilation efficiencies were significantly higher at 16°C than at 8°C at week 6 and significantly higher at 16°C than at the other two temperatures at week 12. Final gonad weight and gonad index were significantly greater in urchins fed the prepared diet than in those fed any of the three kelp species, with little difference among the kelp treatments. Final gonad weight was significantly affected by temperature, but this effect was dependent on diet; temperature had little impact on gonad weight (and index) in the three kelp treatments, but 12 and 16°C produced significantly heavier gonads than 8°C for urchins fed the prepared diet. Gonads of urchins fed kelps had more (significantly more in the case of M. integrifolia and N. luetkeana) water than those fed the prepared diet. Gonad colour, texture, and firmness were generally not significantly affected by temperature, diet, or the interaction of these two factors. Gonad flavour was generally (sometimes significantly) better in urchins fed the prepared diet than in those fed the three kelp species. Taking all the measured variables into consideration, we recommend that culture operations utilise a prepared diet at 12°C to optimise gonad production of S. purpuratus. [Copyright &y& Elsevier]

Abstract: Sea urchins (Evechinus chloroticus) were held in sea cages and fed either one of two manufactured diets, or seaweed. Physical (gonad index, maturity index and colour L*a*b*), biochemical (lipids, glycogen, soluble protein, moisture and free amino acids) and sensory characteristics of the gonads from caged and wild sea urchins were measured at the end of a 13- week trial. The gonad index of sea urchins fed the manufactured diet which was highest in protein, was approximately double that of wild sea urchins, and significantly (p ≤0.05) higher than sea urchins fed seaweed. Gonads from sea urchins fed the manufactured diet highest in protein had significantly (p ≤0.05) higher glycogen and total free amino acid concentration, and a lower triglyceride concentration than gonads from sea urchins fed seaweed or collected from the wild. Ovaries had a significantly (p <0.01) higher soluble protein concentration than testes, and there were significant (p ≤0.05) differences in the concentration of individual free amino acids between genders and diet. Descriptive analysis carried out using a trained sensory panel reported differences in gonad sensory quality. Ovaries from wild sea urchins were significantly higher for sweet and umami taste, than ovaries from sea urchins fed the manufactured diets, which had a higher rating for bitter taste. Testes from wild sea urchins had a significantly harder texture than testes from sea urchins fed manufactured diets or seaweed. Sweet taste was significantly (p ≤0.05) positively correlated to glycine concentration in testes but not ovaries, while bitter taste was positively correlated to valine, leucine, and isoleucine concentration in both testes and ovaries. This study demonstrated that diet had a significant influence on the physical, biochemical and sensory characteristics of E. chloroticus gonads, and highlighted the importance of analysing E. chloroticus testes and ovaries separately. [Copyright &y& Elsevier]

Abstract: The natural spawning of Strongylocentrotus droebachiensis is limited to late winter into early spring. In order to reduce the cost of urchin production, out-of-season gamete production is necessary. This study attempted to condition broodstock for out-of-season gamete production through the use of two different photoperiod and temperature regimes: a Constant Spring and an Advanced year; hypothesized to induce maturation through suspension or advancement of the gametogenic cycle, respectively. Viable gametes were successfully produced out-of-season with fertilization and hatch rates equal to or surpassing the levels recorded for wild urchin''s in-season. In addition, specific fecundity was significantly higher in out-of-season conditioned urchins compared to the in-season wild urchins. Histological techniques proved that gametogenesis was both suspended and advanced through manipulation of the photoperiod and temperature. In addition, several important observations were made regarding reproductive physiology in the green sea urchin, the implications of which are important to the economic development of the green sea urchin aquaculture industry and management of wild stocks. [Copyright &y& Elsevier]

Abstract: To facilitate sea urchin aquaculture, nutritionally-complete feeds are being developed for a number of species. In this study, the effects of dietary phospholipids from soy lecithin on weight gain and production were investigated to ascertain a potential dietary requirement for small juvenile sea urchins, Lytechinus variegatus. Laboratory-produced juvenile L. variegatus (n = 16 per treatment, average 0.091 g±0.01 SE wet weight and 5.80 mm±0.09 SE diameter) were fed semi-purified formulated diets supplemented with 1, 2.5, 4, 5.2, 6.4, 7.6, or 8.8% phospholipids (as fed) from soy lecithin for 12 weeks. Under the conditions of this study, a negative correlation between dietary phospholipid level and weight gain was observed. By 6 wk and continuing through 12 wk, sea urchins fed the 1 to 6.4% supplemented phospholipid diet (SPLD) had significantly higher total wet weight than sea urchins fed either the 7.6 or 8.8% SPLD (final wet weight ranged from 10.53±0.41 g to 7.42±0.65 g, for the 1 and 8.8% treatments, respectively, P <0.05). Feed intake and apparent dry matter digestibility coefficients were similar among the 1, 5.2, and 8.8% SPLD treatments. A requirement for greater than 1% dietary phospholipid derived from soy lecithin could not be determined. Gonad production was observed at 12 wk. No significant differences were observed for ovary wet or dry weight; however, testis wet weight was higher for males fed the 1% SPLD than males fed the 8.8% SPLD (ANOVA, P <0.05). In the gut, nonpolar lipid levels were highest for individuals fed the 8.8% SPLD (4.6, 5.4, and 10.6% for 1, 5.2, and 8.8% SPLD, respectively), indicating conversion of phospholipid to nonpolar lipid, presumed to be stored as triacyglycerols. In the ovary and testis, polar lipid levels were similar among the three treatments tested (ovary, 9.2, 10.9, 10.3% and testis, 8.1, 9, and 7.6% for 1, 5.2, and 8.8% SPLD, respectively), but nonpolar lipid levels were highest for females and males fed the 8.8% SPLD (ovary, 9.4, 12, and 16.6% and testis, 3.7, 9.4, and 12.7%, respectively). These data suggest that dietary phospholipids are, in part, being metabolized and stored as neutral lipid in the gut and gonad. [Copyright &y& Elsevier]

The Integrated Multi-Trophic Aquaculture (IMTA) of sea cucumbers and sea urchins has high commercial values. The consumption of sea urchin feces by sea cucumbers is important but largely unknown. The present study aims to evaluate and subsequently improve the fecal consumption in sea cucumbers. Sea cucumbers ingested the feces of sea urchins at both 15 °C and 5 °C, suggesting that the feces of sea urchins has potential to be an appropriate diet for the aquaculture of A. japonicus. Because feces has a complex process after the egestion, the age and temperature significantly affected the fecal consumption by sea cucumbers. The optimal ageing time after egestion was 0–48 h at 15 °C, 0–72 h at 5 °C, respectively. Thus, we recommend aqua-farmers feed A. japonicus with feces at the optimal ageing hours and remove the feces in time. Further, light intensity significantly affected the fecal consumption by A. japonicus. Sea cucumbers had significantly more fecal consumption in low light intensity than that in high light intensity at both 5 and 15 °C. Further, sea cucumbers fed significantly more in low light intensity with shelters than those in low light intensity without shelter, suggesting that shelter provides extra benefits for the fecal consumption by sea cucumbers besides the low light intensity. In addition, significant feeding benefits were found in both low light intensity and shelter at low temperatures. This may solve the problem that sea cucumbers cease feeding at 5 °C in winter. Organizing IMTA in sheltered environment and low light intensity can improve fecal consumption at both 15 °C and 5 °C. The present study provides valuable information in evaluating and improving consumption of sea urchin feces by A. japonicus in the IMTA of sea cucumbers and sea urchins. • The feces of sea urchins have great potential in the IMTA with sea cucumbers. • We recommend feed A. japonicus with feces at optimal ageing hours in IMTA. • Low light intensity improve the fecal consumption of sea cucumbers. • Shelter provides extra benefits for the fecal consumption of sea cucumbers. [ABSTRACT FROM AUTHOR]

Abstract: An experiment testing the effects of elevated temperatures on roe enhancement of sea urchins Evechinus chloroticus collected from two widely separated sites in New Zealand was conducted over a 10 week period between September and December 2007. Groups of urchins from Central and Northern Populations were held at 18 °C, 20 °C, 22 °C and 24 °C and fed ad libitum a formulated moist feed. After 10 weeks there were no significant differences in GI between urchins held at 18 °C (15.32±0.47) and 20 °C (15.02±0.45) but the GI of urchins held at 22 °C were significantly lower (11.91±0.42) and those held at 24 °C were significantly lower again (8.69±0.33). The increase in GI from the initial GI followed the same pattern, with urchins held at 18 °C and 20 °C having a significantly greater increase than those held at 22 °C, which in turn had a significantly greater increase than those held at 24 °C. There was no significant difference in GI after 10 weeks between the urchins held at 24 °C and urchins that remained in the wild during the experimental period. Urchin survival was also significantly lower at higher temperatures and it was lower in the Central Population compared to the Northern Population, probably because the experimental temperatures exceeded the natural temperature range of the former. There were no significant differences between the increases in GI of the urchins collected from the two populations and held at each of the different experimental temperatures. The benefits from increasing the holding temperature for roe enhancement must be weighed against the increased cost of holding urchins at the higher temperatures. Roe enhancement of E. chloroticus should be carried out at temperatures less than 22 °C and the higher survivorship of urchins taken from populations with higher ambient seawater temperatures, compared with those collected from populations exposed to lower ambient seawater temperatures, must also be taken into consideration. [Copyright &y& Elsevier]

Abstract: A method for the objective assessment of sea urchin (Evechinus chloroticus) gonad characteristics was developed using descriptive analysis by a trained sensory panel. The influence of gender, diet, and storage under chilled conditions, on the sensory quality (appearance, odour, taste, flavour, texture, and aftertaste) of the gonads was investigated. Gender was found to be the major factor impacting on the sensory quality of E. chloroticus gonads. Testes had a sweet taste and dairy flavour, while ovaries had a bitter and sour taste, with an herbaceous and metallic flavour. Gonads obtained from sea urchins fed a diet high in the amino acids glutamate and glycine, were perceived as being sweeter than gonads obtained from urchins fed a diet high in valine and methionine, which had a marine and sulphur odour. Over 10 days of chilled storage, there was a significant decrease in fresh odour, sour taste, and dairy flavour of testes, while marine odour increased. Ovaries decreased in sour taste, and dairy, sulphur and metallic flavour, over storage time. The methodology and descriptive vocabulary of 35 terms developed from this study was successfully used to assess the sensory quality of E. chloroticus gonads, and could be adapted to other species of sea urchins. [Copyright &y& Elsevier]

Abstract: The carotenoid content and composition of the gonad and gut of the edible sea urchin Psammechinus miliaris were determined. The dominant carotenoid of the gut wall was fucoxanthinol, indicating the degradation of the main carotenoid found in the Phaeophycean algae. Also present in the gut wall was the carotenoid echinenone, a pigment absent from the diet of wild urchins. Its presence in the gut wall indicates that this is a site for metabolism of dietary, algal, β-carotene. Fucoxanthinol and related products are not found in the gonad and instead this organ was found to selectively accumulate echinenone and β-carotene together with a small number of related compounds. Both echinenone and β-carotene were found in two geometric forms, namely all-trans and 9′-cis or 9-cis respectively. Echinenone is predominantly deposited in the gonad as the 9′-cis form, whilst β-carotene is mainly found in the same form as that seen in the algae that, in part, make up its diet in the wild, i.e., all-trans. This indicates that isomerisation of dietary β-carotene occurs as part of the process of accumulating echinenone in the gonad. The colour and overall appearance of the gonads of this wild and food limited population were generally poor. No correlation between CIE L ⁎ a ⁎ b chromameter readings or a visual assessment of gonad colour with carotenoid content as determined by HPLC was observed. [Copyright &y& Elsevier]

Abstract: The current study describes the metabolic performance of adult green sea urchin Strongylocentrotus droebachiensis in terms of oxygen consumption, feed intake and gonad growth in relation to body weight and temperature. The experiments were conducted at six constant temperatures (4, 6, 8, 10, 12 and 14 °C), and with three body size groups, i.e. small (S, 40 g), medium (M, 65 g), and large (L, 100 g). Results show that 10–12 °C is the optimum temperature for gonad growth for 40–100-g green sea urchin during summer/autumn, and that there is an inverse relationship between optimum temperature and size. Contrary to gonad growth, both feed intake and oxygen consumption continued to increase throughout the entire temperature range (4–14 °C). The Q 10 values for oxygen consumption of fed animals were in the normal range (1.72–3.01), while the corresponding values for starved animals were low (1.17–1.36), indicating negligible effects of temperature on aerobic metabolism during starvation. The energetic analyses indicate a poorly developed regulation of energy intake in relation to energy expenditure. The oxygen consumption data from this study can, together with a still missing description of the relationship between oxygen saturation and somatic and gonad growth, be used to evaluate the water requirement of green sea urchin in aquaculture. [Copyright &y& Elsevier]

Abstract: The effects of different dietary lipids (hydrogenated coconut oil, corn oil, linseed oil, and mixtures of corn oil, linseed oil, menhaden oil, and/or soy lecithin) on the fatty acid composition of the sea urchin Strongylocentrotus droebachiensis were investigated. Dietary lipid compositions were reflected in the fatty acid profiles of sea urchin guts, gonads and shells. The shells had the highest level of 20:4n-6 and 20:5n-3, while the highest levels of monounsaturated fatty acids were seen in the guts. Tissue levels of 20:4n-6 and 20:5n-3 were influenced by the dietary levels of 18:2n-6 and 18:3n-3. The addition of soy lecithin to the diet (CLnML) enhanced the production and incorporation of 20:4n-6 in shell and gonad. Sea urchin also synthesized and incorporated 20 and 22 carbon non-methylene-interrupted dienoic fatty acids (NMIDs) in all tissue lipids. The NMID content varied among the different tissues and was influenced by the dietary lipid source. The hydrogenated coconut oil (HCO) diet resulted in the greatest NMID content, while the lowest levels were seen in sea urchins fed diets containing a mixture of corn oil, linseed oil, menhaden oil and lecithin (CLnML). The NMID content was lowest in gut and highest in the shell. Significant levels of mead acid (20:3n-9) were detected in the shells of sea urchins fed the EFA-deficient diet (HCO). The enzymatic capabilities of sea urchins to desaturate and elongate 18:2n-6 to 20:4n-6 and 18:3n-3 to 20:5n-3, as well as the capabilities to de novo synthesize NMID were hypothesized. Possible physiological roles and mechanisms for formation of NMID are discussed. [Copyright &y& Elsevier]

Abstract: For sea urchin aquaculture to be successful large numbers of juveniles need to be efficiently and cheaply produced. To do this, cues to induce settlement and metamorphosis need to be known. Potential settlement cues were tested in laboratory assays against larvae of the fast growing tropical/subtropical sea urchin Tripneustes gratilla. Preliminary experiments showed that T. gratilla larvae settle in response to marine biofilms, Dictyota dichotoma, Ulva lactuca, a non-geniculate coralline alga and adult conspecifics. In follow up experiments T. gratilla larvae settled in response to all of the 11 macroalgae tested including six brown macroalgae, two non-coralline red macroalgae, two geniculate coralline red macroalgae, a green alga and a marine biofilm. T. gratilla larvae settled in response to water conditioned with eight of the 11 macroalgae tested but only the crude ethyl alcohol extract of Zonaria angustata, induced settlement. When Sargassum linearifolium, Homeostrichus olsenii and Z. angustata were cleaned to reduce abundances of surface bacteria settlement in response to these algae was significantly reduced or inhibited totally indicating that T. gratilla larvae settle in response to bacterial biofilms on the surfaces of these macroalgae. T. gratilla larvae also settled at a significantly higher rate in the presence of live juveniles and their faeces compared to water and surfaces conditioned with juveniles and controls. This is the first report of a sea urchin settling in response to a conspecific. In all controls using filtered UV treated seawater there was no settlement of larvae, indicating that the need for a cue was obligatory. These results indicate that marine biofilms should provide an adequate cue to settle T. gratilla in culture however, the use of other cues may be possible. [Copyright &y& Elsevier]

Abstract: A key concern when developing artificial aquaculture diets is their palatability. This study investigated whether the palatability of artificial diets could be improved by incorporating a small quantity of highly preferred natural foods as feeding stimulants. The preference of Tripneustes gratilla for marine plants with which it co-occurs naturally in New South Wales, Australia, was assessed in a laboratory choice feeding experiment. T. gratilla displayed significant preference for the brown alga Ecklonia radiata over five other algae and one seagrass when they were offered simultaneously. Total protein or energy in the plants was not found to account for this preference. However, T. gratilla showed no preference among E. radiata, Sargassum linearifolium and Ulva lactuca when they were dried. Three artificial diets were made by incorporating one of each of these dried seaweeds at 5% dry weight. Although not statistically significant, T. gratilla ate more than twice as much the artificial diet containing S. linearifolium compared to the control diet containing no algae in a choice feeding experiment. In a no-choice feeding experiment, T. gratilla consumed significantly more of the Ecklonia and the Sargassum diets than the control diet despite each of the diets containing approximately the same protein and energy levels. T. gratilla consumed 49 and 43% more protein, and 37 and 44% more energy, respectively, when fed with the Ecklonia and the Sargassum diets compared to the control diet. Juvenile T. gratilla grew significantly faster on a wet weight basis on the Sargassum diet than the control diet at an average increase of 2.4% per day. These results indicate that the small amounts of palatable seaweed added to the artificial diets act as feeding stimulants, increasing the acceptability of artificial sea urchin diets, boosting the protein and energy consumption, and significantly increasing the growth of T. gratilla. Moreover, the fast growth of T. gratilla achieved in this study also indicates that this species would be a good candidate for commercial aquaculture. [Copyright &y& Elsevier]

Abstract: The elevated accumulation of certain essential long-chain polyunsaturated fatty acids (PUFA) during reproductive maturation can place a significant demand on lipid metabolism. As lipid metabolism is closely linked with protein metabolism, protein intake during maturation may significantly influence transport proteins and enzyme activity which is responsible for supplying the essential fatty acids for gamete development. The present study investigated the influence of increased protein intake on the accumulation of certain long-chain PUFA in two species of commercially valuable sea urchin, Paracentrotus lividus and Psammechinus miliaris during maturation. Sea urchins were fed three macroalgal diets over a 90-day period. These diets included the red alga Palmaria palmata, which had been grown in seawater enriched with two levels of ammonia-N, which produced a high protein content (41%) or low protein content (32%). The third diet (or reference diet) used the brown macroalga Laminaria saccharina with a 23% protein content. The fatty acid composition of the gonads was determined by GC. Feeding the high protein diet had no effect on the maturation and total lipid in the gonad compared with the low protein diet, however, it did significantly increase the levels of docosahexaenoic acid DHA 22:6n-3 in the mature gonad tissue in P. miliaris and P. lividus. In contrast, only P. miliaris exhibited higher levels of arachidonic acid ARA 20:4n-6 when fed the high protein diet. The present study suggests that elevated protein levels can promote the accumulation of DHA and ARA in gonadal tissue during maturation, although the extent of the influence is species-specific and highlights the importance of understanding the complexities and inter-connectivity between protein and lipid metabolism when producing commercially valuable species. [Copyright &y& Elsevier]

Abstract: Survivorship and performance was investigated for two size classes of the sea urchin Paracentrotus lividus grown adjacent to open-water Atlantic salmon (Salmo salar) cultivation on the north-west coast of Scotland. Juvenile P. lividus were maintained for 12 months at 0 m, 50 m and 2.5 km from the mariculture activity. The sea urchins at the 0 m station showed higher survivorship than at the 50 m and 2.5 km stations and had significantly greater test diameter than at the 50 m station. Only urchins at 0 m developed gonads and, although small, these were of acceptable or excellent colouration in terms of their marketability. Adult P. lividus were maintained for 3 months at 0 m and 15 m from the mariculture activity, either with or without additional macroalgae Laminaria spp. Sea urchins at the 0 m station and fed additional macroalgae showed higher gonadal growth than sea urchins at the 15 m station held without additional food. Gonad colouration in the adult urchins, irrespective of the treatment, was acceptable or excellent. The 0 m station also received significantly greater quantities of particulate organic matter (POM) than the other stations in both the juvenile and adult experiments. At the 0 m station, the presence of the fatty acid 22:1n-11 and elevated levels of the long chain n-3 fatty acid DHA 22:6n-3 in the gonadal tissue of the urchins confirmed the consumption of fish farm derived POM and highlighted the potential human health benefits from consuming sea urchin roe. The results show that P. lividus can thrive in the salmon culture environment and suggests that the integration of P. lividus with Atlantic salmon can provide a viable means to culture this species, even at this northerly latitude. Salmon-sea urchin co-culture would enable fish farms to diversify into producing a second highly valuable product and would reduce the increasing worldwide pressure of sea urchin fisheries on wild stocks. [Copyright &y& Elsevier]