Ingestion of Brachionus plicatilis and Artemia salina nauplii by mud crab Scylla serrata larvae

Two feeding experiments were conducted to determine if Brachionus plicatilis and Artemia salina nauplii were ingested by mud crab Scylla serrata larvae. In the first experiment, larvae were fed with increasing densities of Artemia nauplii with or without Brachionus to determine consumption with increasing densities of Artemia and with increasing zoeal stage. This experiment also aimed to determine if the presence of Brachionus as an alternative prey influenced the intake of Artemia by the crab larvae. There was generally an increase in intake with increasing densities of Artemia and increased consumption of Artemia as the larvae grew. Consumption of Brachionus was consistently high in all zoeal stages. There was a significant reduction in the intake of Brachionus with increasing consumption of Artemia in the early zoeal stages (Z1, Z2, Z3), but at later stages (Z4, Z5) the intake of Artemia was no longer affected by the presence of Brachionus. In the second experiment, daily ingestion within instar of zoeal stages and megalopa were compared. There was an increased consumption of Artemia nauplii on the day before molting and increased ingestion of Brachionus on the day after larvae had molted, except at Z3. Megalopae exhibited a decline in Artemia nauplii intake on the days before metamorphosis to crablet.     

褶皱臂尾轮虫室内培养及在牙鲆育苗中的应用

研究了褶皱臂尾轮虫在不同的接种密度下的生长情况,以及轮虫强化在牙鲆早苗培育中的作用。结果表明:较高的轮虫接种密度可产生高增值数,最高培育密度2380个/ml;是否添加小球藻对轮虫生长具有明显作用;在牙鲆早苗培育中,轮虫投喂前须用乳化油强化,投喂未强化轮虫组白化率达78%,成活率仅12%。     

Optimum Feeding Rate of the Rotifer Brachionus plicatilis on the Marine Alga Nannochloropsis sp.

The optimum feeding rate of the rotifer Bruchionus plicutilis was investigated to determine the best conditions for growth of the rotifer, and also in order to maintain good water quality of the culture. Fifty rotifers of a large size strain were cultured individually at five food density levels of Nannoehloropsis sp. (0.5 ± 10⁶, 1.5 ± 10⁶, 3 ± 10⁶, 5 ± 10⁶, and 8 ± 10⁶ cells/ml). At each level, daily survival and offspring production were recorded until the death of the final individual. The data obtained were analyzed by the life table method. The maximum value of three growth indices (the net reproduction rate, mean life expectancy at age 0, and intrinsic rate of increase) was obtdned at the food density of 1.5 ± 10⁶ cells/ml. The ration size was calculated to be 325% (dry weight)/ day, which is equivalent to about 70% of the saturated feeding rate. It was suggested that the feeding rate should be controlled to lower than the saturated value for an efficient mass culture.     

Production and Nutritional Quality of Two Small-Sized Strains of the Rotifer Brachionus plicatilis1

The rotifer Brachionus glicatilis, strain-S (from Japan) and strain-S1 (Pozuelo 1975) were mass cultured using Chlorella and bakers' yeast. Under the same feed regime, a significant increase (P < 0.001) in rotifer strain-S production (44.19 ± 8.50 individuals/mL/d) was observed compared with strain-S1 (29.64 ± 9.38 individuals/mL/d). The population growth rate was significantly higher (P> 0.001), and doubling time was significantly lower (P> 0.0001) in rotifer strain-S than in strain-S1. There was a significant decline (P> 0.001) in birth rate of strain-S rotifers in the culture system compared with strain-S1, suggesting short longevity and deterioration of the culture system while using strain-S. In general, no significant difference (P< 0.05) in the presence of ω3 polyunsaturated fatty acids (ω3 PUFA) in different strains of rotifers was observed.     

酵母及藻类对褶皱臂尾轮虫培养效果的比较研究

采用种群累积培养法研究了两种酵母、两种藻类对褶皱臂尾轮虫的最适投喂密度。结果表明 ,这四种饵料对褶皱臂尾轮虫的最适投喂密度 (× 10 6cell·ml-1)分别是 :干酵母 ,15 ;鲜酵母 ,5 ;微绿球藻 ,4 5 ;三角褐指藻 ,2 0。同时 ,在最适密度下比较了这四种饵料对轮虫的培养效果。结果表明 ,四种饵料对轮虫的培养效果以微绿球藻为最优 ,其它依次为三角褐指藻 ,鲜酵母 ,干酵母。实验结果显示 ,褶皱臂尾轮虫批量培养及至工厂化培养的首选饵料是微绿球藻和三角褐指藻     

Nutritional Properties of the Marine Rotifer Brachionus plicatilis Fed the Freshwater Microalgae Selenastrum capricornutum

This study examined the effects of storage time on the fatty acid composition of freshwater Selenastrum capricornutum algal paste under 4 C refrigeration, the fatty acid composition of rotifers fed the fresh and stored algal paste, and the toxicological properties of the algal paste. Microalgae were produced in a hydraulically integrated serial turbidostat algal reactor (HIS-TAR), harvested as a paste, refrigerated and analyzed every 2 wk. Fresh Selenastrum capricornutum paste had almost three times greater concentration of unsaturated fatty acids than saturated fatty acids. Over 50% of the unsaturated fatty acids were made up of n-3 and n-6 fatty acids. Total unsaturated, n-3 group and n-6 group fatty acids decreased ( P 0.05) during storage, including the nutritionally important fatty acids (C20:4n6, C20:5n3, C22: 6n3). Rotifers fed 2– and 4-wk-old algal paste had a significantly lower ( P 0.05) total unsaturated fatty acid percentage and significantly greater ( P 0.05) total saturated fatty acids than those fed fresh algae. There were no significant changes in the n-6 group fatty acid level in the 4-wk-old paste feeding study or for the n-3 or n-6 groups in the 2-wk-old paste feeding study as compared to fresh algae. The levels of the three nutritionally important fatty acids (C20:4n6, C20:5n3, C22:6n3) did not differ between rotifers fed fresh and stored algae. Stored algae did not present toxicity to rotifers and Daphnia at the normal feeding concentration. These results indicated that the use of refrigerated freshwater algal paste for production of rotifers results in live feed with adequate nutritional properties for marine larviculture. This could eliminate the costs associated with production of marine algae, which could be replaced with freshwater algae, and may provide an alternative to cryopreservation.     

营养强化的轮虫、卤虫对牙鲆仔鱼的成活、生长及体脂肪酸组成的影响

用3种营养强化剂强化的轮虫和卤虫无节幼体投喂牙鲆仔鱼,研究牙鲆仔鱼的生长、成活、体脂肪酸的组成。结果表明:用强化的轮虫和卤虫无节幼体投喂牙鲆仔鱼,成活率、增重均显著高于对照组(p<0 01),其中V号强化剂的效果最好,成活率为29 34%,比对照组提高100%;增重倍数为217 90,比对照组提高68 61%;这是由于V号强化剂强化的卤虫无节幼体体内含有较多的AA的缘故,饵料中AA含量的提高,可以提高牙鲆仔鱼的成活率、促进其生长。牙鲆摄食强化过的轮虫、卤虫无节幼体后,其EPA、DHA、n-3HUFA、PUFA的含量随着饵料中含量的升高而升高,这也是牙鲆仔鱼生长速度和成活率提高的重要因素之一。     

Bioencapsulation and pharmacokinetic study of oxolinic acid in rotifers (Brachionus plicatilis), Artemia franciscana nauplii and metanauplii

The uptake of oxolinic acid by the rotifer Brachionus plicatilis, Artemia franciscana nauplii and metanauplii was studied as a function of its concentration in the enrichment medium and the duration of the enrichment period. An emulsion containing 5, 10, 20 or 30% (w/w) oxolinic acid was administered and the enrichment period lasted 4, 8, 12 or 36 h. Highest incorporation of oxolinic acid was achieved using a 20% emulsion and a 12 h enrichment for rotifers (205.05 ± 17.1 μg g^?1 dry weight), a 24 h enrichment for nauplii (2528.8 ± 254.6 μg g^?1 dry weight), and an 8 h enrichment for metanauplii (1236.58 ± 22.9 μg g^?1 dry weight). Higher concentrations of oxolinic acid in the enrichment emulsion or longer enrichment times resulted in decreased survival. Two hours post enrichment the contents of the drug appeared significantly decreased. The concentration data of oxolinic acid were best fit to a two phase exponential elimination model, the first phase elimination half‐life (t_1/2α) being 1.86, 1.08 and 1.74 and the terminal phase elimination half‐life (t_1/2β) 26.83, 29.67 and 17.48 in rotifers, nauplii and metanauplii correspondingly. Enrichment with an emulsion containing 20% oxolinic acid is recommended employing a duration of 12, 24, or 8 h enrichment for rotifers, nauplii and metanauplii respectively, while enriched carriers should be used shortly after enrichment.     

光照、pH及盐度对褶皱臂尾轮虫培养效果的影响

研究了在不同光照周期,pH和盐度突变条件下褶皱臂尾轮虫的存活和增殖率.试验结果表明,光照对褶皱臂尾轮虫种群增殖的促进作用明显,持续光照条件下轮虫种群增殖率为持续黑暗状态的3.5倍;pH存活上限9.5,下限5.5;种群增殖最适pH为7.5～8.5;种群繁殖的最适盐度为30～35,存活的下限为15,上限为40.研究结果显示,光照对于褶皱臂尾轮虫的增殖是必要的;pH的不同对褶皱臂尾轮虫带卵量、孵化率和孵化时间均有影响.盐度突变盐差越大,褶皱臂尾轮虫的适应能力(适应所需时间和存活率)越弱.     

Encapsulated Spirulina Powder Feed for the Nutritional Enrichment of Adult Brine Shrimp (Artemia salina)

Abstract

Liposomes were prepared in the laboratory with lipids obtained from chicken egg yolk to encapsulate Spirulina powder. Artemia napulii were hatched and fed with lipid-encapsulated Spirulina or Spirulina powder. After 20 days of rearing, the experimental A. salina were harvested and measured for total body length and total content of protein and carbohydrates. Total body length was 45% higher, protein content was 49% higher, and carbohydrate was 35% higher in Artemia fed with liposomes as compared with those fed only Spirulina powder.     

Reproductive performance,survival and development of nauplii and copepodites,sex ratio and adult life expectancy of the harpacticoid copepod,Euterpina acutifrons,fed different microalgal diets

A series of laboratory experiments were conducted on the harpacticoid copepod, Euterpina acutifrons, to assess the influence of 10 different microalgal diets (four monoalgal and six mixed algal diets) on several parameters related to its productivity in culture. The four monoalgal diets were the Tahitian strain of Isochrysis sp. (T‐Iso), Pavlova salina (Pav), Tetraselmis chuii (Tet) and the diatom Chaetoceros muelleri (Chaet), the five binary diets were T‐Iso+Tet, Pav+Tet, T‐Iso+Pav, Tet+Chaet and Pav+Chaet, while the tri‐algal diet was T‐Iso+Tet+Pav. All diets were fed to copepods at 1500 μ gC L^?1 and in the case of binary or trialgal diets, carbon concentration was divided equally between the two or three algae offered. Among monoalgal diets, the diatom Chaet was excellent for E. acutifrons. Out of the 10 diets tested, the binary diet Tet+Chaet, which contained the diatom Chaet, was the best for naupliar production of single pair E. acutifrons (19.5±1.7 nauplii female^?1 day^?1), significantly (P<0.05) higher than all other treatments except for the Chaet treatment (P>0.05). Similarly, in the group naupliar production trial (50 adult E. acutifrons per replicate), Tet+Chaet produced a significantly higher number of nauplii (405.8±18.6 nauplii day^?1) than the other treatments (P<0.05). Tet+Chaet further supported the highest naupliar survival (82.0±2.8%) and copepodite survival (89.0±2.8%), while the mono‐algal diet Chaet produced the second highest naupliar (76.7±2.6%) and copepodite survival (83.5±2.6%). In contrast, Pav produced the lowest overall survival at the naupliar stage (30.0±2.9%), significantly lower than all other treatments (P<0.05). While development from newly hatched nauplii to copepodites was not significantly affected by diets, mean development time from nauplius to adult was significantly different among treatments. Mean development time from hatching (naupliar I stage; NI) to the adult stage was the fastest with Tet+Chaet and Chaet (6.8±0.0 days for both treatments), which was significantly faster than that of Pav, T‐Iso Pav+Tet and T‐Iso+Pav+Te treatment (P<0.05). E. acutifrons sex ratio was significantly affected by diets, and always skewed in favour of males. Feeding on Pav resulted in the lowest proportion of females (23.7±1.2%), significantly lower than for six of the other treatments (P<0.05). Adult females had longer average life expectancy than males for all treatments, and were the longest when fed Tet+Chaet (9.5±0.4 days), which was more than twice as long as the shortest lifespan recorded for the Pav treatment (4.2±0.6 days) (P<0.05). In summary, among 10 diets tested, the binary diet Tet+Chaet appeared to support the highest culture productivity of E. acutifrons while the diatom Chaet also performed well as a monoalgal diet.     

观赏鱼和水族生态神仙鱼的饲养和繁殖

一、神仙鱼的命名 神仙鱼的英文名为Angelfish(天使鱼),隶属于丽鱼科神仙鱼属,原产于南美洲亚马逊河流域,在圭亚那的鲁普努尼诺河和埃塞奎博河亦有分布.1911年被正式引进欧洲.1823年,Liech-tenstein首次将其命名为Zeus scalaris,后正式定名为Pterophyllum scalare,其同物异名为Pterophyllum eimekei .     

Effect of unionized ammonia, viscosity and protozoan contamination on the enzyme activity of the rotifer Brachionus plicatilis

Substrates that are cleaved to yield fluorescent products can be used to quickly quantify enzyme activity in vivo with image analysis or in vitro with fluorometry. This study was carried out to determine whether enzyme activity in rotifers is useful for assessing the physiological condition of rotifers. Neonates of Brachionus plicatilis Müller hatched from cysts were exposed to a concentration series of unionized ammonia ranging from 0 to 9.8 p.p.m., increasing seawater viscosity relative to 1.17 to control sea water by the addition of methyl cellulose and the addition of the protozoan Euplotes sp. to a density of 40 mL^?1. Rotifer glucosidase and esterase activities decreased with increasing unionized ammonia and viscosity respectively. Activities of glucosidase and phospholipase decreased with increasing protozoan contamination. There was a significant relationship between enzyme activities and rotifer population growth. In vivo activities of certain rotifer enzymes can therefore serve as biomarkers for the rapid assessment of environmental stressors in rotifer mass cultures.     

Elimination of the associated microbial community and bioencapsulation of bacteria in the rotifer Brachionus plicatilis

The bioencapsulation of live bacteria in the rotifer Brachionus plicatilis was determined under monoxenic conditions. The first objective was to evaluate the microbiota of the rotifer during intensive production and to obtain sterile rotifer cultures starting from adult females or amictic eggs using PVP-Iodine, Hydrogen peroxide or antibiotic mixtures. In the rotifers, the proportion of vibrios increased significantly during the mass production, displacing other unidentified marine bacteria. Rotifers, in the absence of culturable bacteria were obtained starting from amictic eggs and using Trimetroprim-sulfametoxasole (Bactrim Roche®) at 10 ml l^–1. The effect of members of Vibrionaceae on the survival and growth rate of rotifers was determined under monoxenic conditions. The survival of rotifers was not affected in the presence of different isolates, while amictic egg formation occurred and the populations increased when the strains Vibrio proteolyticus C279 and Aeromonas media C226 were tested. All isolates were successfully incorporated in the rotifers, since there was no significant difference between the numbers of bioencapsulated cells of different strains of isolates. The results show that it is possible to replace the microbial community in rotifer cultures, started from disinfected amictic eggs, with selected bacterial strains. This could be used as a tool for future studies to reveal the role of specific bacteria on first larval stages of marine fish species.     

Growth, filtration and ingestion rate of the rotifer Brachionus plicatilis fed with large (Asteromonas gracilis) and small (Chlorella sp.) celled algal species

The rotifer Brachionus plicatilis was fed in experimental conditions with a small celled (2–5 μm) Chlorella sp. and a large celled (16–22 μm) Asteromonas gracilis algae. The specific growth rate (SGR) of rotifers fed Asteromonas (maximum 0.79) was statistically higher than that for rotifers fed Chlorella (maximium 0.61). The filtration and ingestion rates using different rotifer and algal densities exhibited certain maxima depending on the species, the cell density and the condition of the rotifers. The filtration rate was higher with Asteromonas and, although ingestion rate was lower than with Chlorella, the ingestion in terms of cell volume was 10‐fold higher. It seems that B. plicatilis ingests the larger cell diameter algal species more efficiently than the smaller species that is usually used for its mass culture.     

The enrichment of rotifers (Brachionus plicatilis) and Artemia franciscana with taurine liposomes and their subsequent effects on the larval development of California yellowtail (Seriola lalandi)

Taurine is an essential or conditionally essential nutrient for many species of marine fish, especially during early development. There is growing evidence that marine fish larvae benefit from taurine‐enriched rotifers; however, it is unknown if larvae benefit from taurine‐enriched Artemia. We investigated the effects of taurine‐enriched rotifers (Brachionus plicatilis) and Artemia franciscana on the growth and whole‐body taurine concentrations of California yellowtail (Seriola lalandi; CYT) larvae. The approach used in this study was to encapsulate taurine within microparticles (liposomes), which were then fed to rotifers and Artemia. We found that feeding taurine liposomes to rotifers and Artemia resulted in taurine concentrations in these prey species that were similar to or above those previously reported in copepods. At the end of the rotifer phase, CYT larvae fed taurine‐enriched rotifers showed increased growth (final dry weights; DW) and had higher whole body taurine concentrations when compared to larvae fed unenriched rotifers. At the end of the Artemia phase, CYT whole body taurine concentrations varied among dietary treatments. Larval lengths and DWs were not significantly different among treatments at the end of the Artemia phase, suggesting that the taurine concentrations of unenriched Artemia were sufficient to support the growth of CYT larvae.     

Mixis in rotifers of the lineage 'Nevada', belonging to the Brachionus plicatilis species complex, under different feeding regimes

A strain of Brachionus‘Nevada’, which belongs to the Brachionus plicatilis species complex, and is commonly found in European hatcheries, was investigated in terms of its mixis potential. Two feeding regimes used for mass culturing were employed. Rotifer populations were fed on phytoplankton (Tetraselmis suecica) and either baker's yeast, Saccharomyces cerevisiae (treatments A) or Culture Selco^® (treatments B). In order to promote mixis, the salinity of the culture medium was reduced from 40 to 20 g L⁻¹. Indeed, the rotifer populations of lower salinity (A 20, B 20) showed a twofold increase in mixis rates compared with those of higher salinity (A 40, B 40). In addition, treatment A 20 showed significantly higher levels of mixis (22.59±2.07%) compared with B 20 (16.56±1.46%). The opposite trend was observed for the parthenogenetic growth rates (A 20: 0.46±0.01; B 20: 0.62±0.01). It is thus concluded that Culture Selco leads to a higher abundance of amictic ovigerous females, whereas yeast supports a higher abundance of males and mictic females carrying resting eggs. The two types of feeding regimes can be used for different purposes in a hatchery.     

Nutritional Enhancement of n-3 and n-6 Fatty Acids in Rotifers and Artemia Nauplii by Feeding Spray-dried Schizochytrium sp.

A docosahexaenoic acid (DHA), 22:6(n-3), rich strain of Schizochytrium sp. was used in a spray-dried form to evaluate the enhancement of highly unsaturated fatty acids (HUFAs) in Artemia franciscana nauplii (Utah biotype) and the rotifer Brachionus plicatilis . This heterotrophic microalga was selected because of its high concentration of the longest chain HUFAs in the n-3 and n-6 series, DHA and docosapentaenoic acid (DPA), 22:5(n-6), respectively. When 24-h-old Artemia nauplii were fed 400 mg/L of the algae for 24 h, the DHA content of the nauplii went from undetectable levels to 0.8% of dry weight and the omega-3 HUFA eicosapentaenoic acid (EPA), 20:5n-3, content went from 0.1% to 0.5% of dry weight in the nauplii. Similarly, 22:5(n-6) increased in the nauplii from undetectable levels to 0.4% of dry weight, with a concomitant increase in arachidonic acid, (20:4n-6), from trace to 0.3% of dry weight even though there was no arachidonic acid in the algal biomass. Similar enrichment patterns were observed in rotifers. The results suggest that spray-dried cells of Schizochytrium sp. are effective in enriching Artemia naupli and rotifers in both n-3 and n-6 HUFAs. The results also suggest that Artemia nauplii and rotifers are capable of readily retroconverting 22:6(n-3) to 20:5(n-3) and 22:5(n-6) to 20:4(n-6) through the process of β-oxidation, a well-known process in mammals.     

Lutein enrichment of the rotifer Brachionus sp. using freeze‐dried Muriellopsis sp. cells

Rotifers, used in aquaculture as feed for early larval stages, are poor in carotenoids compared with copepods, the natural most common prey item of marine fish larvae. A minimal sufficient level of carotenoids in fish larvae may be essential for a correct development. The freshwater microalga Muriellopsis sp. has been identified as a potential source of the carotenoid lutein with possible application in aquaculture. Lutein is a potent antioxidant, with potentially beneficial effects as a carotenoid for fish larvae. This study describes the lutein enrichment of the rotifer Brachionus sp. when incubated with homogeneously dispersed suspensions of freeze‐dried, lutein‐rich Muriellopsis sp. in seawater. A short enrichment time (2 or 2.5 h) resulted in a higher lutein content of the rotifers than a long enrichment time (13.5 or 24 h). Although the concentration of lutein in enriched rotifers, 0.06–0.16 mg (g dry weight)^?1 was low compared with its content in Muriellopsis sp. [about 3 mg (g dry weight)^?1], it was in the range reported for natural copepod populations. Therefore, we conclude that freeze‐dried biomass of Muriellopsis sp. can be used to enrich rotifers with lutein, providing an adequate level of this carotenoid for marine fish larvae.