The Effect of Vitamins on Weight Gain and Organ Production in the Sea Urchin,Lytechinus variegatus (Echinodermata: Echinoidea)

We investigated the requirements for a commercial vitamin premix in diets of Lytechinus variegatus. Small L. variegatus (ca. 28 mm diameter) were collected from Saint Joseph Bay, Florida, and acclimated to laboratory conditions (32 ppt salinity, 22 C, 12:12 photoperiod) for 3 wk, then placed individually into plastic mesh cages (n = 16 per treatment). Sixteen urchins were dissected to obtain initial weights of organs (gut, gonad, test). Each treatment was fed one of five semipurified diets supplemented with levels of a commercial shrimp vitamin premix ranging from 0 to 0.9% dry weight. At 4‐wk intervals, wet weights and test diameters were measured. At 16 wk, urchins were dissected and organs weighed. Significant weight gain and 100% survival was observed with all diets. At 16 wk, urchins fed 0% vitamin premix exhibited no noticeable pathology but had significantly less weight gain than those fed the 0.6% vitamin premix. Those fed the 0.6% vitamin premix had significantly greater weight gain than all other diets (P < 0.0001). Gonad weights increased in all treatments, but did not vary significantly. Under the conditions of this study, L. variegatusexhibited a satisfactory nutritional response. Experiments are planned to determine specific dietary vitamin requirements for L. variegatus.     

Evaluation of Direct and Indirect Techniques for Measuring Absorption Efficiencies of Sea Urchins (Echinodermata: Echinoidea) Using Prepared Feeds

Measurement of absorption efficiencies is essential for evaluating feeds for the culture of marine invertebrates. There are currently several direct and indirect techuiques that may be used for measuring absorption efficiencies in sea urchins. Three of these methods were evaluated and compared. Based on this evaluation, the conditions under which each technique should be used are reviewed. Direct measures require complete fecal collection and should not be used for estimating absorption efficiency. Ash can be used as a marker to estimate absorption efficiencies under most circumstances, but absorption efficiencies tend to be overestimated as the inorganic fraction decreases slightly with passage through the gut. Chromic oxide can only be used as a marker for estimating absorption efficiencies when complete fecal collection is made, as it may pass through the gut at a different rate than the rest of the egesta.     

Mass production of competent larvae of the sea urchin <Emphasis Type="Italic">Lytechinus variegatus</Emphasis> (Echinodermata: Echinoidea)

We evaluated the mass production of competent larvae of the sea urchin Lytechinus variegatus cultured at three initial densities (0.25, 0.5, and 1 larvae per ml) and fed Chaetoceros muelleri. Survival, length, dry weight of larvae, and larval stage index (LSI) were estimated in each treatment as a function of the density. Density decreased during the experiment due to mortality, but the percentage was similar in all three treatments (68.5, 66.7, and 76.0%). The experiment was stopped at 13 days after fertilization, when most of the larvae were competent and had settled. There were no significant differences in survival (exceeded 65% in all treatments), length and larval stage index among treatments. However, larvae weight in the two low density treatments (1.1 ± 0.11 mg and 1.2 ± 0.05 mg, respectively) was greater than the high density treatment (0.59±0.376 mg). This study demonstrates that competent larvae of Lytechinus variegatus can be produced with less than 25% mortality in 13 days when cultures are started at densities of 0.25–1 larvae/ml. Culturing at higher densities (0.5–1 larvae/ml) had no apparent disadvantages and would reduce the cost of production.     

Cultivation of Paracentrotus lividus (Echinodermata: Echinoidea) on extruded feeds: digestive efficiency, somatic and gonadal growth

This study assessed the use of extruded feeds, in the form of pellets, for the growing of echinoid Paracentrotus lividus within a closed-culture system. Two feed types, one with soya-bean protein, the other with both soya-bean and fish protein were compared with dried Lessonia sp. and fresh Laminaria sp. as food sources. Pellets present a very high conversion efficiency (about 80%) against about 50% for Laminaria and 35% for Lessonia . However, as pellets are less absorbed, somatic growth (SG) is statistically equivalent for the sea urchins fed with pellets and Laminaria between 2 and 2.2% g soma day^–1. Sea urchins fed with pellets produced significantly more gonadal tissue in a shorter time, resulting in a gonadal index (GI) twice higher (6.5%) than Laminaria (3%) in the second month of the experiment. Dry Lessonia does not promote gonadal growth (GG). This study shows that extruded feeds are well assimilated by P. lividus and promote both SG and production of gonadal tissue.     

A comparison of three land-based containment systems for use in culturing green sea urchins, Strongylocentrotus droebachiensis (Müller) (Echinodermata: Echinoidea)

Worldwide, most sea‐urchin populations are in decline. Future market demands will likely be met through aquaculture, which may consist of gonad enhancement of wild‐caught sea urchins. In this context, we examined three land‐based containment systems for suitability in maintaining commercial‐size green sea urchins (Strongylocentrotus droebachiensis). Mortality rate, gonad quantity, gonad quality (colour, brightness, firmness, texture) and cleaning efficiency associated with each containment system were the criteria for comparing the effectiveness of the systems (large raceways, small raceways and washtub tanks). After 6 weeks, urchins maintained in large raceways displayed significantly higher mortality rates than urchins maintained in either the small raceways or washtub tanks (mean±SD: 24.3±10.4%, 8.0±3.5% and 4.3±1.5% respectively). Significant differences in cleaning time were detected among the three systems with washtub tanks requiring significantly more cleaning time (0.11±0.02 min urchin^?1) than the other two systems and large raceways requiring significantly less cleaning time (0.06±0.02 min urchin^?1) than the other two systems. No significant differences in gonad characteristics were detected among the three containment systems. Because of the higher mortality rate in the large raceways and the increased cleaning time required for the washtub tanks, the small raceways were considered to be the best of the three systems tested.     

Fertilization and Development of Eggs of the Sea Urchin Lytechinus variegatus Maintained on an Extruded Feed

Sea urchin eggs are used extensively as models for studies in developmental and molecular biology. Developing aquaculture techniques and facilities for sea urchins would facilitate their use for this purpose and for production of young sea urchins for stock enhancement. A basic requirement for the aqua-culture of sea urchins is the availability of a feed that predictably produces eggs of a consistent, high quality. We tested an extruded feed with Lyrechinus variegatus for this purpose. Lytechinus variegatus (mean horizontal diameter 55 mm, 75 g wet weight) were collected in April 1998. Nine individuals were maintained in each of four aquaria with closed, recirculating filtered sea water. They were fed approximately 1 g extruded feedindividual per week. All feed was consumed. The mean weight of the sea urchins changed little with this feeding regime. The sea urchins spawned spontaneously on a monthly basis during water changes. Four females in February and one in March were spawned by injection with potassium chloride. Fertilization was 99–100% successful in each case. Egg diameters from these spawnings and a spontaneous spawning in April ranged from 102 × 6 to 128 × 1 μm. Gastrulation occurred in <20 h and metamorphosis after 22 to 37 d. Newly metamorphosed juveniles ranged in size from 435 × 38 to 473 × 56 μm. Egg size, larval size, the chronology of embryonic and larval development, and size of newly metamorphosed juveniles are similar to those obtained from field individuals reported in the literature. These results indicate that a predictable production of high quality eggs by sea urchins under controlled conditions in the laboratory with a prepared feed is feasible.     

Growth and Survival of Larval Sandfish,Holothuria scabra (Echinodermata: Holothuroidea), Fed Different Microalgae

This study assessed the nutritional value of four species of microalgae for larval sandfish, Holothuria scabra (Echinodermata: Holothuroidea). Two‐day‐old larvae were fed either a single diatom (Chaetoceros muelleri, Chaetoceros calcitrans), flagellate (Isochrysis aff. galbana (T‐ISO), Pavlova salina), or a ternary microalgal diet (TMD) comprised of 40% C. muelleri, 40% T‐ISO, and 20% P. salina for 12 d. On Days 4, 6, and 8 length of larvae fed either C. muelleri, C. calcitrans, or the TMD was significantly greater than in T‐ISO and P. salina fed larvae as well as the unfed control larvae. T‐ISO fed larvae had a significantly greater length compared to unfed larvae on Days 4, 6, and 8; however, larvae fed P. salina had a significantly greater length compared to unfed larvae on Days 6 and 8 only. Survival of larvae fed either C. muelleri or the TMD was significantly better than the flagellate fed and unfed larvae on Days 4, 8, and 12. There was no significant difference between survival of unfed larvae and larvae fed either T‐ISO or P. salina during the 12‐d larval culture period. On Day 12, larvae fed either a diatom or the TMD developed in excess of 84% competent doliolariae. Larvae fed C. muelleri had a significantly higher percentage competent doliolariae than larvae from all other treatments except the TMD. Neither larvae fed either T‐ISO or P. salina nor unfed larvae developed any competent doliolariae. In conclusion, this study showed C. muelleri to be the most effective of the four microalgae tested as a single microalgal diet for larval H. scabra and, as such, C. muelleri will be used as a reference diet in future studies.     

Protein content and amino acid composition of eggs and endotrophic larvae from wild and captive fed sea urchin Paracentrotus lividus (Echinodermata: Echinoidea)

Knowledge on the biochemistry of proteins and amino acids (AA) of eggs and larvae of echinoids is scarce and the possibility to modify their profiles by diet manipulations is unknown. The protein content of eggs, prisms and pre‐plutei and the amino acid composition of eggs of Paracentrotus lividus from captive broodstock fed prepared diets were analysed and compared with the ones obtained from wild broodstock. Diets differed on protein source (fish or soy meals) and on protein content (10–40% dry weight – DW). Total and soluble protein content of both eggs and larvae was higher than 400 g kg^?1 DW and 200 g kg^?1 DW respectively. Glycine was the most abundant free AA. Very few differences were found among P. lividus eggs and larvae biochemical parameters, suggesting that their AA composition can hardly be changed by broodstock diet manipulations.     

The Effect of Dietary Carotenoids on Gonad Production and Carotenoid Profiles in the Sea Urchin Lytechinus variegatus

Although dietary carotenoids are generally considered important in sea urchin aquaculture only for their effect on gonad color, they also have important biological roles. The effects of dietary carotenoids on gonad production and organ carotenoid profiles of Lytechinus variegatus were examined. Individuals were collected in January 1999 and fed a replete diet with a level of 0.60 mg carotenoids/kg for 4 wk, followed by one of four prepared diets for 8 wk: one without supplemental carotenoids, one with β‐carotene (16.92 mg carotenoids/kg feed), and two carotenoid mixtures, one high in zeaxanthin (5.28 mg carotenoids/kg feed) and another high in capsanthin (9.63 mg carotenoids/kg feed). The carotenoid profiles of the body compartments differed. The primary carotenoid in gonads of males and females was echi‐nenone. The carotenoid profile of the test was similar to that of the gonad. The carotenoid profile of the gut varied with diet, but was not identical to composition of the diet. The gut profiles included echinenone but at lower concentrations than in the gonad and test. The carotenoid profile in the gut probably results from the presence of the carotenoids absorbed and those metabolized. The results suggest that several pathways exist to metabolize dietary carotenoids and that some of them are in the gut. The concentration of carotenoids in the gut (g wet weight) was higher than that of the gonad, which was higher than that of the test. The gonads increased significantly in size regardless of diet, indicating carotenoids are not required for gonad production under the conditions of this experiment. Although the concentration of carotenoids in the gonad decreased over time, the absolute amount of carotenoids increased with the increase in gonad size. Either gonad growth was more rapid than carotenoid deposition or differential deposition in nutritive cells and gametogenic cells occurred, or the amount of carotenoids used in the diets was too low to have an effect.     

Comparison of spawning induction techniques on <Emphasis Type="Italic">Paracentrotus lividus</Emphasis> (Echinodermata: Echinoidea) broodstock

The performance of different and expedite spawning induction methods was compared on samples of both mature wild and captive Paracentrotus lividus sea urchin populations. Thermal, saline and mechanical shocks, emersion during different periods of time, addition of con-specific gametes and different KCl concentrations were tested. Percentage of spawned sea urchins, mean number of released eggs, percentage of males that released more than 200 million spermatozoa, and survival after 5 days were the variables analysed. Results indicate that both thermal and saline shocks were ineffective methods to trigger spawning. Mechanical shock and addition of con-specific gametes were able to promote spawning but with a reduced number of released gametes. Emersion for a period of 3 h induced spawning with 100% broodstock survival but longer periods up to 12 h, although increasing the number of spawners can cause significant broodstock mortality. An injection of 1-mL intra-peristomial KCl was an expedite method to obtain P. lividus gametes, but high mortalities were always recorded and was related with excessive KCl concentrations. When there is need for a small number of gametes, the mechanical shock technique can be considered since led to 100% survival. When large spawnings are required, the emersion procedure can be a viable method, but further investigation must be carried out to assess the best time period to obtain broodstock full survival.     

摄食不同饲料的黄鳝肌肉营养成分比较研究

野生黄鳝和分别投喂配合饲料、蚯蚓、鲢肉的黄鳝的肌肉营养成分差别主要在粗脂肪，野生黄鳝的粗脂肪含量最低，摄取鲢肉的黄鳝粗脂肪含量最高，蛋白质及其它成分的差异不大。氨基酸组成差异不大，但鲜味氨基酸(谷氨酸、丙氨酸、天冬氨酸、甘氨酸)的总量以摄食蚯蚓的较高，而以摄食配合饲料的较低。     

Effects of Reduced Carbonate Saturation State on Early Development in the Common Edible Sea Urchin Lytechinus variegatus: Implications for Land-Based Aquaculture

Land-based aquaculture facilities often utilize additional bicarbonate sources such as commercial sea salts that are designed to boost alkalinity in order to buffer seawater against reductions in pH. Despite these preventative measures, many facilities are likely to face occasional reductions in pH and corresponding reductions in carbonate saturation states due to the accumulation of metabolic waste products. We investigated the impact of reduced carbonate saturation states (Ω_Ca, Ω_Ar) on embryonic developmental rates, larval developmental rates, and echinoplutei skeletal morphometrics in the common edible sea urchin Lytechinus variegatus under high alkalinity conditions. Commercial artificial seawater was bubbled with a mixture of air and CO₂ gas to reduce the carbonate saturation state. Rates of embryonic and larval development were significantly delayed in both the low and extreme low carbonate saturation state groups relative to the control at a given time. Although symmetry of overall skeletal body lengths was not affected, allometric relationships were significantly different between treatment groups. Larvae reared under ambient conditions had significantly greater postoral arm and overall body lengths relative to body lengths than larvae grown under extreme low carbonate saturation state conditions, indicating that extreme changes in the carbonate system affected not only developmental rates but also larval skeletal shape. Reduced rates of embryonic development and delayed and altered larval skeletal growth are likely to negatively impact larval culturing of L. variegatus in land-based, intensive culture situations where calcite and aragonite saturation states are lowered by the accumulation of metabolic waste products.     

Feeding time,frequency and ration affect growth and energy allocation in young adults of the sea urchin Lytechinus variegatus

In a 62‐day growth trial, wild caught Lytechinus variegatus (ca. 18 g, 35 ± 2 mm dia.) were fed as follows: (i) ration equivalent to 3% of average body weight proffered once daily in the morning (AM treatment); (ii) ration equivalent to 3% of average body weight proffered once daily in the evening (PM treatment); (iii) ration equivalent to 1.5% of average body weight proffered twice daily (every 12 h, AM/PM treatment); (iv) ration equivalent to 3% of average body weight proffered in the evening on alternate days (EODSR/PM); or (v) ration equivalent to 6% of average body weight proffered in the evening on alternate days (EODDR/PM). At 30 and 62 days, wet weight gain among urchins fed daily was significantly higher than that of urchins fed on alternate days, regardless of ration size. At 62 days, reduced gonad dry matter production and gonad index were observed among individuals fed on alternate days, regardless of ration size. At 30 and 62 days, feed conversion ratio was optimized among individuals fed daily and in the EODSR/PM treatment. These data suggest that, for culture of L. variegatus, daily feeding will optimize growth, gonad production and feed efficiency regardless of ration size or time of feeding.     

豆油替代鱼油对圆斑星鲽幼鱼生长和肌肉脂肪酸的影响

本实验旨在研究饲料中豆油替代鱼油对圆斑星鲽(Verasper variegatus)幼鱼生长和肌肉脂肪酸组成的影响。用豆油分别替代0、25%、50%和75%的鱼油,配制4组等氮、等脂肪的饲料。选择初始体重为(65.47±1.57)g的圆斑星鲽幼鱼360尾,随机分为4组,每组3个重复,每个重复30尾鱼,养殖56 d。结果显示,(1)随着豆油替代水平的升高,增重率(WGR)呈现降低的趋势(P0.05),饲料系数(FCR)呈现升高的趋势(P0.05),25%替代组的WGR高于鱼油组(P0.05)。(2)豆油替代鱼油对圆斑星鲽肌肉的粗蛋白、粗脂肪、灰分和水分含量无显著性影响(P0.05),对肝体比(HSI)、脏体比(VSI)和肥满度(CF)无显著性影响(P0.05),豆油替代组肝脏的脂肪含量显著高于鱼油组(P0.05)。(3)随着饲料中豆油水平的增加,圆斑星鲽幼鱼肌肉亚油酸(C18:2n-6)和亚麻酸(C18:3n-3)显著升高(P0.05),而二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)则显著降低(P0.05)。研究结果表明,在该实验条件下,饲料中高比例的豆油替代鱼油会降低鱼体的生长性能和肌肉脂肪酸营养品质。     

Enhancement of Gonad Production in the Sea Urchin Loxechinus albus in Chile Fed Extruded Feeds

Loxechinus albus were fed algae ( Macrocystis pyrifera and Ulva sp.) and two feeds prepared by extrusion (one containing kelp). Results were the same for individuals maintained in suspended cages in the sea and in aquaria on land. Gonads increased in size in individuals fed extruded feeds and decreased in individuals fed algae during the spawning season. Gonads increased ca. four-fold in size in individuals fed the extruded feeds during the post-spawning season, much greater than those fed algae. Individuals fed extruded feeds had a lower feeding rate than individuals fed algae on a wet-weight but not on a dry-weight basis. The extruded feed supports gonadal growth more than natural food and has potential for use for aquaculture of sea urchins.     

Induction of Spawning in the Sea Cucumber Holothuria scabra (Echinodermata: Holothuroidea)

With the advent of sea cucumber aquaculture in the South Pacific region, a reliable method is needed to induce large numbers of animals to spawn in captivity. Broodstock of the sea cucumber Holothuria scabra , collected from Stradbroke Island, Moreton Bay (27°90'N, 153°24'E) Australia, during the reproductive season from October to January, were used in spawning trials. During the 1997–1998 summer between one to five weeks of captivity, 100% of animals were induced to spawn in four trials at dusk on or close to a new or full moon, using nine males and nine females contained in a Reln tank and 30 cm of filtered sea water, using a 3–5 C temperature shock. H. scabra was induced to spawn in small numbers during the 1996–1997 summer despite a marked degree of weight loss, and all animals spawned during 1997–1998 with minimal loss of weight. The difference in the number of spawned eggs between animals of similar size and mean numbers of spawned eggs in consecutive trials decreased the longer animals were held in captivity before spawning. The hatch rate of eggs was reduced significantly for broodstock held for more than one month. Hatch rate and numbers of spawned eggs are important indicators of egg viability of broodstock maintained in captivity for an extended period.     

Opportunistic Predation of the Sea Urchin,Lytechinus variegatus,by the Amphipod,Elasmopus levis,in an Intensive Inland Culture System

Invasive and/or opportunistic organisms can negatively influence the success of sea urchin culture operations. To our knowledge, pests associated with sea urchin aquaculture have not been reported. In this study, we report the predatory association of the amphipod, Elasmopus levis (Amphipoda: Melitidae), with the sea urchin, Lytechinus variegatus (Echinodermata: Echinoidea), within an intensive inland culture system. Wild‐caught Ly. variegatus broodstock were placed in an intensive culture system, and within their canopy of spines or within transport seawater, populations of epifauna (including amphipods) and microfauna were most likely transferred into the culture system. A growing population of the amphipod developed over time. Associations of the amphipod with the sea urchin were observed to negatively affect the health of the sea urchin, and in some cases, epithelial tissue from the sea urchin test appeared to be consumed by the amphipod. An infestation of these amphipods in commercial sea urchin cultures could have the potential to be costly, and we recommend quarantine and/or water purification procedures be considered to prevent the introduction of pests to inland culture systems.     

Effect of Feed Protein and Carbohydrate Levels on Feed Intake,Growth, and Gonad Production of the Sea Urchin,Lytechinus variegatus

In this study, we evaluated protein and carbohydrate levels in cold‐extruded dry diets. Sea urchins (12.6 ± 0.12 SE g wet weight, 29.5 ± 0.11 SE mm diameter) were collected from St. Joseph Bay, Florida (30°N, 85.5°W), and transported to the Texas Agrilife Research Mariculture Laboratory in Port Aransas, Texas. Urchins were held individually in replicated enclosures within a recirculating seawater system (32 ± 2 ppt and 22 ± 2 C). Urchins (n = 16urchins) were fed diets that differed in protein : carbohydrate levels (31:33%, 25:39%, 21:44%, and 17:47% dry weight) for 12‐wk. Survival was 100% in all diet treatments. Urchins fed the 31:33% protein : carbohydrate diet consumed less feed, more dry protein, less dry carbohydrate, less energy, and had lower feed conversion ratios than urchins fed other diets. Urchins fed the 31:33% protein : carbohydrate diet had larger test diameters, total wet weights, production efficiencies, and gonad production efficiencies than urchins in the other diets. Weight gain varied directly and significantly with protein intake. Sufficient energy was available for maximum weight gain as protein was spared. Growth rates and production efficiencies for the urchins in this study were higher than in previous feeding studies with adult Lytechinus variegatus.     

方斑东风螺Babylonia areolata（Lamarck）工厂化人工育苗试验

报道了方斑东风螺工厂化人工育苗试验结果.试验结果表明,平均每只雌螺产卵量达6.7万多粒,受精卵孵化率达91.5%,稚螺育成率达16.12%,稚螺出苗量平均达1.3万个/m2.2007年育出壳长5.0～10.0 mm的优质方斑东风螺稚螺1 012.7万个,实现了可按计划的种苗规模化生产.     

Suspended Culture of Doughboy Scallops Mimachlamys asperrima (Lamarck)

To evaluate the effects of suspended culture on the wet meat weights, reproductive condition and fecundity of doughboy scallops Mimachlamys asperrima , scallops held either in suspended cages or collected from wild stocks on the sea bed were compared over a year. Changes in gonosomatic index (GSI) and macroscopic staging of gonads were similar in both populations; however, after one month, soft body, muscle and gonad weights were heavier in suspended scallops and, with the exception of gonad weight in early summer, remained heavier throughout the year. Fecundity following serotonin-induced spawning of suspended Mimachlamys asperrima was on average almost twice that of similar sized scallops grown on the sea bed (1.58 and 0.84 million eggs/female, respectively). Suspended scallops surpassed all previous maxima for tissue weights, GSI and fecundity recorded for wild Jervis Bay Mimachlamys asperrima . This indicated that farmers could obtain greater meat yields from suspended rather than reseeded or wild Mimachlamys asperrima and that broodstock to be used in hatcheries may be best obtained from suspended culture.