Nutritional Value of Preserved Microalgae for Subadult Mytilus galloprovincialis

Abstract.— Subadult (4–5 cm) Mytilus galloprovincialis were fed for 31 d with equal daily rations, equivalent to 6% of their body weight on a dry weight basis, of Chaetoceros sp. and Phaeodactylum tricornutum fresh, or preserved by air-drying, freeze-drying, and by freezing. At the end, increases in size, in dry weight, and in condition index with preserved diets were significantly lower than those of the mussels fed with live algae. In general, the frozen diets were better than the air- and freeze-dried ones. Increases with live Chaetoceros sp. were greater than with live P. tricornutum ; however, with preserved diets the latter was better than Chaetoceros sp .     

The effects of temperature and food ration on metabolite concentrations in newly settled king scallop (Pecten maximus) spat

Juvenile king scallop (Pecten maximus L.) between 0.2 and 1.5 g wet shell weight per individual, reared at 10, 14 and 17 °C, were fed either a full ration equivalent to 0.5 g (ash-free dry weight of algae) g^− 1 (live weight of spat) week^− 1 or a restricted algal ration of 0.07 g (ash-free dry weight of algae) g^− 1 (live weight of spat) week^− 1. The algal food was a mixture of two microalgal species: Chaetoceros ceratosporum (Droop) Green and Pavlova lutheri Ostenfeld. Measurements were made of tissue concentrations of adenylate tri-, di- and mono-phosphate, lactate, succinate, acetate, pyruvate and l-alanine. The metabolite measurements were used as indicators of viability in animals exposed to a matrix of temperature and food supply conditions. It was found that the variations in metabolic responses could be correlated with those observed in a previous study that measured body condition in relation to the same set of variables. It was also found that the data from the present study were most strongly influenced by temperature-related effects and that there was an optimal temperature range between 10 and 14 °C. The metabolic responses, measured in terms of metabolite concentrations, would seem to confirm the existence of a bi-stable physiology in P. maximus in which there is a switch in state between 10 and 14 °C.     

皱纹盘鲍与盘鲍杂交效果分析

从杂种优势的角度对皱纹盘鲍♀与盘鲍♂杂交子一代的经济性状进行分析。结果表明,4月龄杂交鲍子一代(F1)活体重比皱纹盘鲍增加36.87%,软体部干重增加33.21%,总干重增加29.20%,其它性状也显著优于皱纹盘鲍。杂交鲍F1的壳长、壳宽、活体重、软体部干重和总干重等主要性状的变异系数为12.94%~44.51%,其中软体部干重的变异系数最大,壳长的变异系数最小;且杂交鲍各性状的变异系数均大于皱纹盘鲍。杂交鲍子一代的变异有助于定向选择,提高杂交育种的效果。     

The effect of intertidal exposure on the growth and survival of hatchery-reared Pacific oysters (Crassostrea gigas Thunberg) kept in trays during their first ongrowing season

In a number of trials during 1971 and 1972 small populations of hatchery-reared Pacific oyster spat (Crassostrea gigas Thunberg) 0.07–4.1 g mean live weight, were grown intertidally in trays to measure the effect of exposure to air on growth and survival. In the Menai Straits, N. Wales, and at Paglesham Pool, R. Roach, Essex, several stations were selected above low water of spring tides (LWST) to cover the range of 0–30% exposure to air. Live weight, dry meat weight and dry shell weight were reduced with increased exposure to air, but the ratio of dry meat weight to dry shell weight (shell condition index), the gross biochemical composition, and survival were not affected. By extrapolation the point of no growth was found to be at 36 and 47% exposure to air at the sites in the Menai Straits and R. Roach, respectively.     

A preliminary study on growth of Crassostrea gigas larvae and spat in relation to dietary protein

Diets of Chaetoceros calcitrans (Paulsen) Takano and Tetraselmis suecica (Kylin) Butch containing high or low levels of protein were fed to Crassostrea gigas Thunberg larvae and spat. The 4-day increment in D-larvae shell length was not related to differences in the ash-free dry weight or protein content of the diets at cell concentrations of 75–125 Chaetoceros μl⁻¹. At concentrations of 2–100 Chaetoceros μl⁻¹ the largest growth increment was found when 0.267 μg ash-free dry weight larva⁻¹ d⁻¹ (equivalent to 3.35 Joules · 10⁻³ larva⁻¹ d⁻¹) was filtered at a temperature of 28.1°C.Percentage settlement of C. gigas increased as protein in Chaetoceros, fed at 75–125 cells μl⁻¹ (P < 0.001), and in Tetraselmis, fed at 5–15 cells μl⁻¹ (P < 0.05), increased. Growth of spat during the 14 days immediately after settlement was better on a low-protein than a high-protein Tetraselmis diet (P < 0.001) but differences between Chaetoceros diets were not significant.     

Comparison of Three Culture Methods for the Intensive Culture of Northern Quahog Seed, Mercenaria mercenaria

A number of approaches have been utilized for growing bivalve hatchery seed (1 mm) to a size suitable for field planting (< 8 mm) but few have been directly compared. This study evaluated the growth and survival of northern quahog seed in three different culture systems and two different stocking densities. The three systems were: 1) a stacked-tray unit with downward water flow; 2) traditional upweller culture units with water flowing upward without seed bed expansion; and 3) upweller culture units with water flowing upward at fluidization velocities to provide seed bed expansion. The two stocking densities were 1.0 and 3.0 g whole wet weight clam/cm² respectively. During each trial period the seed clams were fed a 1% daily ration (% dry weight algae per wet weight clam per day) of the cultured diatom Chaetoceros muelleri . After 14 d of culture at the 1.0 g whole wet weight/cm² stocking density, seed clams (4.4 ± 0.6 mm initial shell length) under fluidized-flow condition exhibited better growth (0.54/d), and a greater final shell length (5.9 ± 1.0 mm). At the high density stocking conditions, after 28 d of culture, seed clams (4.2 ± 0.6 mm initial shell length) in the fluidized-flow culture conditions again exhibited better growth rate (0.031/d) and a greater final shell length (6.0 ± 1.0 mm). The preliminary evaluation of fluidized-flow for seed clam culture in land-based nurseries indicates its potential as a suitable alternative to raceway, downwelling, or traditional forced-flow culture methods.     

Suspension feeding of the ark shell <Emphasis Type="Italic">Scapharca subcrenata</Emphasis> as a function of environmental and biological variables

ABSTRACT:   To assess the roles of the ark shell Scapharca subcrenata in material cycling in the northern part of Ariake Sound (Mae-no-umi), Japan, filtration of the ark shell fed on small diatoms was examined as a function of environmental and biological variables. The clearance rate ( CR ) specific to the soft-body dry weight ( w ) of the animals (shell length, 8–26 mm) followed a power function of w with an exponent of −0.35. Over the range of 10–20°C, CR increased 2.7 times, and filtration did not occur below a salinity of 14 practical salinity unit. Neither food concentration (10–40 µg/L of chlorophyll- a ) nor weight-specific daily ration (0.5–6%/day in terms of ash-free dry weight) notably affected CR . Using this information on CR as well as data regarding abundance and size distribution, the population filtration rate was calculated to be 1.6 m³/m² per day in the ark-shell culturing ground of Mae-no-umi (mean water depth, ∼3 m), corresponding to the potential to locally process a volume of water equivalent to the water column within 2 days. Because the culturing ground accounts for 12% of Mae-no-umi (mean water depth, ∼8 m), the ark shell seems to play an important role in its material cycling.     

Influence of hatchery diets on early grow-out of the Cortez oyster Crassostrea corteziensis in Sinaloa, Mexico

We measured the growth and physiological condition of juveniles of the Cortez oyster Crassostrea corteziensis during the early grow-out phase in Sinaloa (Mexico) after using three experimental diets during the hatchery period: (1) 1:1 blend of the microalgae Isochrysis galbana and Chaetoceros muelleri as the control group; (2) mix of the same microalgae replaced by 50% of its wet weight with cornstarch; and (3) mix of the two microalgae replaced by 50% its wet weight with wheat flour. Specimens were cultivated under suspension conditions for 60 days and monitored weekly for growth (shell height and wet and dry weight) and the first 15 days for physiological response (condition index, digestive gland index and muscle index). Juveniles fed exclusively on microalgae attained larger sizes and had higher digestive gland and muscle indices, while those fed microalgae with cornstarch gained more biomass (wet and dry weight) and reached a better condition. The lowest values of these indicators occurred in oysters fed microalgae with wheat flour. Statistical data revealed that differences in the growth and condition of specimens between treatments were slight, confirming that mixed diets (particularly microalgae/cornstarch) have potential application for reducing hatchery-operating costs without affecting the performance of planted juveniles in the field.     

不同地理群体菲律宾蛤仔壳形态对体重性状的影响研究

采集我国南北沿海9个地理群体的菲律宾蛤仔(Ruditapes philippinarum),利用通径分析等方法评估各群体形态性状对活体重和软体重的影响。结果显示,各群体壳长、壳高、壳宽和壳厚4 个形态性状对菲律宾蛤仔活体重和软体重的影响存在显著差异。除壳厚外,其他形态性状与活体重和软体重呈显著相关(P < 0.05)。通径分析和决定系数分析显示,大多数群体的壳宽对活体重和软体重的直接作用最大。2个形态比例参数(壳宽/壳长和壳高/壳长)最大值出现在山东莱州群体(0.49和0.74),而最小值出现在大连东港群体(0.42和0.67)。壳厚的变异系数最大(22.74),而壳高的变异系数最小(9.47)。通过检验偏回归系数的显著性,建立了各群体形态性状对软体重的最优回归方程。聚类分析表明,菲律宾蛤仔不同群体未出现明显的地域分布特征,而呈现出不规律的南北交替聚类现象。本研究查明了不同地理群体菲律宾蛤仔壳形态性状对体重性状的影响,为菲律宾蛤仔地理群体的形态判别、种质资源分析和遗传育种研究等提供了重要科学依据。     

Physical properties of soft shell clams, Mya arenaria

Soft shell clams, Mya arenaria, are found from Canada to North Carolina on the U.S. Atlantic Coast and from Canada to California on the U.S. West Coast. They are also found in several other parts of the world including Europe. The primary market for these clams on the U.S. East Coast is in New England. Clams are sold whole live or in one of the several cooked forms. Commercial soft clam shucking and processing is primarily by manual methods. However, physical properties data for these clams is lacking and is a constraint on the automation of processing. Several properties of soft shell clams harvested from five different harvest locations in the Chesapeake Bay are detailed in this paper and relationships between the components of the clam are defined mathematically through regression equations. The live weight and the clam length are related to shell weight, siphon weight, meat weight, total solids and free water in the clams. Meat yields under both standard processing methods and for clams steamed and consumed with only the shell removed are detailed. The effect of harvest area on the clam parts is also defined. Soft shell clams shucked manually result in a meat yield of approximately 29% of the live weight. If steamed and eaten the meat yield may be as high as 43% of the live weight, primarily because the siphon is often consumed in steamed clams.     

Effects of selected mixed‐algal diets on growth and survival of early postset juveniles of the Pacific geoduck clam,Panopea generosa (Gould, 1850)

Four microalgal species [Dunaliella tertiolecta, Phaeodactylum tricornutum, Tetraselmis suecica, Thalassiosira pseudonana], previously identified as poor single‐algal diets for juvenile geoduck clams, Panopea generosa, were selected to mix with two comparatively better food‐value microalgae [Isochrysis sp. (TISO), Chaetoceros muelleri (CM)] to estimate synergistic or non‐additive effects of mixed microalgae on the growth/survival of young juveniles of P. generosa. In addition, the effects of different TISO/CM proportions [75/25, 50/50, 25/75; ash‐free dry weight (AFDW) basis] on growth/survival were assessed. Shell length, wet weight, dry weight, AFDW and organic matter content were significantly increased when using mixed TISO diets compared with TISO alone. In contrast, there were no significant differences with these variables when comparing mixed CM diets with CM alone. Ultimately, the best diet in terms of length and weight enhancement was a previously identified optimal one of TISO/CM (50/50). Survival on day 23 (60.7–79.3%) was not significantly different among any of the 11 diets tested. There were no significant differences in shell length, wet weight, dry weight, AFDW and organic matter content among the three TISO/CM ratios tested, but these diets gave superior results to TISO and CM fed alone. Survival (60.7–74.7%) on day 23 in the three TISO/CM ratios tested did not vary significantly.     

A continuous culture apparatus for the mass production of algae

A multi-stage, continuous culture apparatus has been designed and tested for the production of algae for larval molluscs and crustacea. A single-line system produced a maximum of 2.4 × 10¹¹ cells/day, or 5 g ash-free dry weight of Monochrysis lutheri. Multiple-line systems are recommended for hatcheries. The flow rate affected algal cell density, yield, biomass, protein level, and residual nitrate.Maximal cell yield occurred at 10 I flow per day, a dilution rate of 63% of the volume of the first growth carboy, or 30% of the volume of the total system. The system is also adaptable to growth of larger planktonic algae or mixed cultures of algae and protozoa and/or rotifers.     

四角蛤蜊形态性状对重量性状的影响效果分析

以随机选取的123只野生四角蛤蜊为材料,对其形态性状(壳长X₁、壳高X₂、壳宽X₃)和重量性状(活体质量Y、软体质量Z)进行了测量,然后运用相关分析、通径分析和回归分析等分析方法研究形态性状对重量性状的影响。结果表明,5个数量性状间的相关系数均达到极显著水平(P<0.01)。形态性状对活体质量和软体质量的直接影响依次为壳宽>壳长>壳高。壳宽是影响活体质量和软体质量的主要因素,其决定系数分别为0.302 5和0.224 7。多元回归分析建立了估计活体质量、软体质量的最优回归方程:Y=-19.537+0.244X₁+0.266X₂+0.732X₃、Z=-2.456+0.035X₁+0.035X₂+0.089X₃。     

The food and feeding of marine finfish in floating net cages at the National Seafarming Development Centre, Lampung, Indonesia: rabbitfish, Siganus canaliculatus (Park)

Abstract. A 100-day cage feeding trial was conducted with juvenile pearl spotted rabbitfish, Siganus canaliculatus (Park), so as to test eight different dietary feeding regimes, namely: no exogenous feeding (NF), frozen fish Leiognathus splendens (Cuvier; FF), live seaweed Eucheuma cottoni (EC), live seaweed Gracilaria lichenoides (GL), commercial broiler starter crumble (BS), commercial carp starter pellet (CP), in-house prepared dry pellét RDl (RDl) and in-house prepared dry pellet RD2 (RD2). The best growth and feed efficiency was observed for rabbitfish fed a dry in-house crumble containing 31% crude protein (diet RDl), followed by fish fed FF, CP, BS, and RD2. By contrast, all fish fed live seaweed displayed a negative growth response over the 100-day trial period. Interestingly, all rabbitfish fed formulated rations displayed marked sexual activity by the end of the feeding trial; 62-93% of the fish (50-100g in weight) yielding milt or eggs on hand stripping. The results are analysed from an economic viewpoint and discussed on the basis of other published studies.     

Nutritional Depletion of the Aquaculture Feed Organisms Euterpina acutifrons, Artemia sp. and Brachionus plicatilis During Starvation

The nutritional quality of the harpacticoid copepod Euterpina acutifrons , freshly-hatched Artemita nauplii, juvenile and adult Artemia , and the rotifer Brachionus plictatilis , in fed and starved conditions, was evaluated through the use of ratios of dry weight to wet weight (DW/WW), ash-free dry weight to dry weight (AFDW/DW), calories per mg ash-free dry weight (cal/mg AFDW), and carbon to nitrogen by weight (C/N). E. acutifrons had in nearly all cases the highest values of DW/WW, AFDW/DW, and cal/mg AFDW. Calculated losses in caloric content per unit of wet weight (cal/mg WW) during one day's starvation were similar among species, ranging from 3 to 52 percent. C/N ratios were less variable, but also reflected starvation-related changes indicating depletion of C relative to N, which is consistent With depletion of lipids and carbohydrates relative to protein.
Because little or no change in caloric density of organic material (cal/mg AFDW) was observed in any species under either condition, decreases in caloric content of wet weight or of individuals were due to decreases in DW/WW and AFDW/DW. Caloric content and carbon content were related by the factor 11.3 cal/mg C. Starvation-related losses in the nutritional value of forage organisms can be important in larval rearing systems.     

Interactive effects of temperature and diet on the growth and biochemical composition of juveniles of the pearl oyster Pinctada mazatlanica

The combined effects of temperature and diet on the growth and biochemical composition of juveniles of the pearl oyster Pinctada mazatlanica at the hatchery were investigated. Specimens were subjected to a combination of four temperatures (20, 23, 26 and 29 °C) and five microalgal diets ( Isochrysis galbana alone, I. galbana + Pavlova salina, I. galbana + Chaetoceros muelleri, C. muelleri + P. salina and I. galbana + P. salina + C. muelleri ). An increase in shell height occurred in a linear pattern, while wet weight gain fitted a power law. Temperature, more than diet, exerted a stronger influence on the growth and condition of the specimens. The combination of 29 °C with P. salina+C. muelleri led to the fastest growth in shell height, while the combination of 29 °C with I. galbana + C. muelleri led to the highest wet and dry weight biomass. In contrast, specimens grew significantly less in shell height and wet weight at 20 °C, regardless of the diet. At all temperatures, the monoalgal diet of I. galbana led to the slowest growth of specimens, but in turn favoured the highest levels of protein, carbohydrate and lipid reserves as a possible strategy to store more energy reserves under stressful events.     

Controlled propagation of the African catfish,Clarias lazera (C. & V.): III. Feeding and growth of fry

The suitability of some common, natural and artificial feedstuffs for the rearing of fry of Clarias lazera (C. & V.) was investigated in 2 experiments.It was found that a dry trout starter, an experimental dry feed and dried inactive yeast were not suitable feeds for rearing C. lazera fry. Neither could ground Clarias fingerlings or frozen zooplankton be used. By contrast, frozen Artemia and especially live Artemia and live zooplankton gave good results. After 4 weeks the fish thus fed had attained an average weight of 0.3 to 1 g and survival ranged from 50 to 96%.Feeding in excess of satiation and feeding 24 h/day gave the fastest growth, although the differences in comparison with feeding Artemia or live zooplankton to satiation 4 times per day were not significant. The specific growth rate (% body weight) of these fish decreased from 68% at the start of the experiment to 9% after 28 days.     

Dietary leucine requirement of fingerling Indian major carp, Labeo rohita (Hamilton)

An 8-week feeding experiment was conducted to evaluate the dietary leucine requirement of fingerling Indian major carp, Labeo rohita (3.50±0.04 cm; 0.40±0.02 g) using amino acid test diets (40% crude protein; 17.90 kJ g⁻¹ gross energy) containing casein and gelatin as intact protein sources and l -crystalline amino acids. Growth performance and biochemical parameters were assessed by feeding six amino acid test diets supplemented with graded concentrations of leucine (0.75, 1.0, 1.25, 1.50, 1.75 and 2.0 g per 100 g) to triplicate groups of fingerlings to apparent satiation divided over two feedings at 07:00 and 17:30 hours. Performance of the fish was evaluated on the basis of live weight gain, feed conversion ratio (FCR), protein efficiency ratio (PER) and body protein deposition (BPD) data. Maximum live weight gain (315%), best FCR (1.35), highest PER (1.86) and BPD (33.9) were recorded at 1.50 g per 100 g dietary leucine. Statistical analysis of live weight gain, FCR, PER and BPD data reflected significant differences (P<0.05) among treatments. Live weight gain, FCR, PER and BPD data were also analysed using second-degree polynomial regression analysis to obtain more accurate leucine requirement estimate which was found to be at 1.57, 1.55, 1.52 and 1.50 g per 100 g of dry diet, corresponding to 3.92, 3.87, 3.80 and 3.75 g per 100 g of dietary protein respectively. Based on the quadratic regression analysis of the live weight gain, FCR, PER and BPD data, the optimum requirement of fingerling L. rohita for leucine is estimated to be in the range of 1.50–1.57 g per 100 g of the dry diet, corresponding to 3.75–3.92 g per 100 g of dietary protein.     

虾夷马粪海胆壳性状对活体质量的影响效果分析

选择66只13月龄虾夷马粪海胆,测定其体积、壳径、壳高、活体质量,计算相关系数,用通径分析方法计算其他性状对活体质量作为依变量的通径系数、决定系数以及相关指数。试验结果表明,虾夷马粪海胆体积、壳径、壳高、活体质量的相关系数均达到极显著水平(P<0.01),壳径对活体质量的直接影响(0.778)最大,是影响活体质量的主要因素;体积与活体质量的相关程度很大,但是对活体质量的直接影响最小(0.098)。通径系数分析后剔除不显著自变量(体积)后,计算壳径、壳高对活体质量的复相关指数为R2=0.8978,多元回归分析建立了壳径、壳高估计活体质量的回归方程:y=-21.78+1.035x1+0.188x2     

Hatchery cultivation of Pacific oyster juveniles using algae produced in outdoor bloom-tanks

Algae were bloomed as batch cultures by adding fertilizers to natural seawater in 500 l outdoor tanks, from mid-June to mid-August, over a period of 2 y. In the first year of experiments the bloomed algae were fed to Pacific oyster (Crassostrea gigas Thunberg) juveniles at a range of rations from 0.06 to 1.63 g (organic weight of algae) g–1 (live weight of spat) week–1. At rations of 0.5 g g–1 week–1 or higher, growth rates of juveniles were similar (mean, 97%) to those fed a control diet of intensively cultured algae (Tetraselmis suecica Kylin) Butch and Chaetoceros calcitrans (Paulsen) Takano at a ration of 0.3 g g–1 week–1). In the second year, the bloomed algae were fed at a ration of 0.5 g g–1 week–1 throughout all the experiments, and gave growth rates of 70–98% (mean, 85.6%), compared with the control diet. The proportion (by weight) of the diet consumed by the juveniles was about 70% for the control diet and 78% for the bloomed algae. Total lipid and essential fatty acid content of the bloomed algae were similar and total carbohydrate content was lower, when compared with typical published values for intensively cultured algae food species. © Rapid Science Ltd. 1998