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1.
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.  相似文献   

2.
The effect of feeding scheme and prey density on survival and development of Eriocheir sinensis zoea larvae was studied in three experiments. Different combinations and densities of rotifers (Brachionus rotundiformis) and newly hatched Artemia nauplii were fed to zoea larvae. Average survival at each stage, larval development (larval stage index, LSI), duration of zoeal stage and individual megalopa dry weight were compared among treatments. This study revealed that, under the experimental conditions, rotifers should be replaced with Artemia between the zoea 3 (Z3) and the zoea 4 (Z4) stage. The optimal rotifer feeding densities for zoea 1 (Z1) and zoea 2 (Z2) were 15 and 20 mL?1 respectively, while the optimal Artemia feeding density for Z3, Z4 and zoea 5 (Z5) was 3, 5 and 8 mL?1 respectively. Further trials in production scale are recommended.  相似文献   

3.
不同饵料对中华绒螯蟹幼体发育和存活的影响   总被引:15,自引:1,他引:15  
江洪波 《水产学报》2000,24(5):442-447
采用高度不饱和脂肪酸(HUFA)营养强化的轮虫、轮虫与卤虫组织投喂中华绒螯蟹幼体,以各项幼体的存活率为评判指标,对不同饵料及其组合的投喂效果进行了探讨。研究结果表明:轮虫是中华绒螯解早期幼体(Ⅰ、Ⅱ期)的适口饵料,幼体存活率随轮虫密度的增加而逐渐上升,但当轮虫数量超过最适密度时,幼体存活率反而有所下降。其中,未强化的轮虫达投喂密度为60ind.mL^-1,强化轮虫最适密度为40ind.mL^-1。Zao状Ⅰ、Ⅱ期投喂40ind.mL^-1轮虫,从Ⅲ期开始投喂10ing.mL^-1卤虫无节幼体,能较好地满足中华绒螯蟹幼体发育的营养需求,提高大眼幼体的存活率。表明强化幼体饵料HUFA特别是EPA和DHA能有效地促进幼体的发育与存活和脱壳率。  相似文献   

4.
First feeding success is critical to larval marine finfish and optimization of live feed densities is important for larval performance and the economics of commercial hatchery production. This study investigated various rotifer feeding regimes on the prey consumption, growth and survival of yellowtail kingfish Seriola lalandi larvae over the first 12 days post hatch (dph). The common practice of maintaining high densities of rotifers (10–30 ind. mL?1) in the rearing tank was compared to a low density feeding technique, where 5–8 ind. mL?1 of rotifers were offered. A ‘hybrid’ feeding regime offered rotifers at the high density treatment until 5 dph and the lower feeding densities thereafter. There was no significant difference in larval survival (hybrid: 28.9 ± 7%, low density: 17.3 ± 5% and high density: 17.2 ± 9%) or growth (hybrid: 6.12 ± 0.18 mm, low density: 6.03 ± 0.10 mm and high density: 6.11 ± 0.23 mm) between treatments. Rotifer ingestion was independent of rotifer density throughout the trial and increased with larval age, with larvae at 4 dph ingesting 22 ± 1.5 rotifers larvae?1 h?1 and by 11 dph ingesting 59 ± 1.6 rotifers larvae?1 h?1. These data demonstrate that from first feeding, yellowtail kingfish larvae are efficient at capturing prey at the densities presented here and consequently significant savings in rotifer production costs as well as other potential benefits such as facilitation of early weaning and improved rotifer nutritional value may be obtained by utilizing lower density rotifer feeding regimes.  相似文献   

5.
The effects of culture parameters of tank color and feeding regimes were examined on larval white bass Morone chrysops during 1994–1995. Under high surface illumination (998 lux), dark tank walls were essential for effective prey capture. Larvae reared in clear glass aquaria did not grow and had died by day 6 of the study. In contrast, 48.7% of the larvae reared in black-walled tanks were alive on day 24 and had grown to 17.2 mm total length (TL). In another study, larvae were fed rotifers Brachionus plicatilis and Artemia nauplii in different feeding protocols. In one treatment only rotifers (10/mL) were fed day 1 (4 d post-hatch), rotifers and Artemia (3/mL) were fed days 2–4, and Artemia fed days 5–15. This protocol produced similar growth (mean size 11.7 mm TL) and survival (mean 30.3%) as slower weaning times from rotifers to Artemia . Juveniles (27-day-old, 17.2 mm TL) were converted to a dry crumble diet over a 14-d period by slow transfer from a combination diet consisting of live Artemia nauplii, frozen adult Artemia , plankton flakes and dry crumbles. Survival offish weaned to the dry diet was 64.5%. Most of the mortalities during the weaning period were fish with uninflated swim bladders which were cannibalized by larger fish. Using the above tank culture techniques, white bass were reared to a mean size of 73.2 mm TL (mean weight 5.8 g) over a 73-d period. This essentially closes the life cycle of white bass.  相似文献   

6.
A feeding protocol was developed for red drum larvae based on combining a commercial microparticulate diet (Kyowa Fry Feed) with live prey (rotifers) in a closed, water reuse system. In five trials, growth and survival were measured on larvae reared on a combination of live and microdiet for 1–5 d and then microdiet alone. Results in each trial were compared to control larvae reared on live rotifers Brachionus plicatilis and brine shrimp nauplii Artemia salinas. The most satisfactory combination was feeding live food and microdiet together for the first five days and then completely discontinuing live prey, eliminating the need to feed brine shrimp to the larvae. Growth rates of larvae fed progressively larger sizes of the microdiet were as good as larvae reared on live prey. Both groups metamorphosed to the juvenile stage at less than one month. Survival rates on the five day live food and microdiet combination were a remarkable 60% from egg to the juvenile stage. The successful weaning of red drum to microdiets paves the way to produce a semipurified diet to test nutrient requirements of larval fish.  相似文献   

7.
ABSTRACT:   It has been reported that the larvae of willow shiner Gnathopogon elongatus caerulescens have many free neuromasts on their body surface. This study examined the ability of the willow shiner larvae to feed on zooplankton by mechanoreception by the free neuromasts. Feeding experiments using untreated larvae and larvae treated with streptomycin, which impairs free neuromast function, were conducted under light and completely dark conditions. The larvae were put into Petri dishes, then nauplii of Artemia salina were introduced. The average number of Artemia eaten by the larvae was expressed as the average ingestion rate of Artemia /10 min. The ingestion rate of Artemia for untreated larvae was 12.3 under light conditions and 10.6 Artemia /10 min. even in complete darkness. The ingestion rate in the larvae treated with streptomycin was 11 under light conditions and only 0.8 Artemia /10 min under dark conditions. The low rate in the treated larvae under dark conditions must be due to impairment by the streptomycin. Therefore, the high ingestion rate for the untreated larvae under dark conditions would be surely dependent on mechanoreception. The results indicate that larval willow shiner is able to feed on zooplankton under limited light conditions.  相似文献   

8.
The growth, survival, food selection and consumption of pompano larvae under different rotifer densities as well as their colour preference during the rotifer feeding stage were examined in this study. Growth and survival of fish larvae were not significantly affected when rotifer density was between 10 and 20 mL?1. Fish larvae grew slower at 1 and 40 rotifers mL?1 than at 10 and 20 rotifers mL?1, and higher fish survival was achieved when fish larvae were exposed to 10 and 20 rotifers mL?1. The rotifer density of 1 mL?1 not only reduced food ingestion during the early stage, but also delayed diet switch from rotifer to copepod nauplii. On 5 days post hatching (DPH), larval pompano ingested more rotifers in dark‐coloured tanks and ingested more rotifers when prey colour was green. Based on the results obtained in the present study, the culture of larval pompano larvae is recommended using dark wall tanks with a feeding density of 10–20 rotifers mL?1 during the initial feeding stage. This study proposes a management protocol to use appropriate type and quantity of live food to feed pompano larvae in a hatchery rearing condition, which could be applicable to the culture of fish larvae in other marine fish species.  相似文献   

9.
A laboratory study was conducted to examine the effects of food level and water temperature on the ingestion rate in the larvae of the peppermint shrimp Lysmata wurdemanni , a popular aquarium spe cies. Artemia nauplii were used as the food item. Number of newly hatched Artemia nauplii consumed by the larvae (from zoea II to zoea VII, zoea I can metamorphose to zoea II without exogenous nutrition in about one day) was measured daily at four food concentrations (2, 5, 10 and 20 Artemia nauplii/mL) and two temperature levels (25 C and 28 C). The experiment was conducted in 500-mL beakers with three replicates for each treatment. The results show that the shrimp consumed significantly more food at 28 C than at 25 C (P < 0.01). Ingestion rate increased with increasing food concentration in all larval stages and with larval development except for the lowest food level ( 2 Artemia nauplii/mL) where insufficient food supply limited the ingestion rate to around 35 Artemia nauplii/ larva per d after zoea IV stage. The larval development rate was significantly lower (P < 0.05) in the shrimp subjected to the two lowest food concentrations (2 and 5 Artemia nauplii/mL) in the 500-mL beakers. But in a separate experiment conducted in the 1,400-mL beakers, the results were reversed: both survivorship and development rate were significantly lower at the two higher food levels (6 and 12 nauplii/mL) than those at 3 nauplii/mL level. During molting period, ingestion rate decreased significantly, followed by a sharp rise to the normal rate the following day.  相似文献   

10.
This investigation examined the effects of temperature, density and early weaning on the survival and growth of Palaemonetes varians larvae. Survival of larvae raised at 17.5 °C was not significantly different (average + standard deviation) (94 ± 5%) from the survival of those raised at 19.5 °C (95 ± 5%) and at 21.5 °C (94 ± 4%). However, the duration of the larval stage was significantly longer for shrimp reared at 17.5 °C (17.3 ± 0.8 days) compared with shrimp reared at 19.5 °C (14.3 ± 0.7 days) and at 21.5 °C (11.3 ± 0.6 days). No significant differences ( P >0.05) were found in the survival rate, final weight and length of larvae reared at the densities of 5, 10, 20 and 50 larvae L−1. The survival of P. varians larvae fed solely on Artemia was significantly higher ( P <0.05) than larvae weaned with an artificial practical diet from Zoea II stage (94 ± 4% and 82 ± 1%, respectively, for Artemia and artificial diet-fed larvae), but no significant differences ( P >0.05) were observed in the final larval weight or length between these two treatments. The survival and growth of the larvae fed with the practical diet tested is a promising step ahead in the development of the culture of this species as it eliminates both the need for Artemia throughout all larval stages, and the need for more expensive artificial diets.  相似文献   

11.
This study investigated the protective effect of poly-β-hydroxybutyrate (PHB) on Chinese mitten crab, Eriocheir sinensis, zoea larvae challenged with pathogenic Vibrio anguillarum. PHB was delivered to the crab larvae through rotifer and Artemia bioencapsulation. Zoea 3 larvae were challenged with V. anguillarum at a final concentration of 10(5) CFU mL(-1). PHB-enriched rotifers and Artemia nauplii were added to the culture water 24 h prior to, upon and 24 h after challenge. The results confirmed that PHB could enhance the survival and growth of unexposed E. sinensis larvae. Moreover, PHB protected larvae from the pathogen as the larvae fed PHB-enriched live food showed the highest survival and development rate in all challenged groups (P < 0.05). Furthermore, larval performance was the best when PHB was delivered to the larvae 24 h before challenge (P < 0.05). In conclusion, our results indicate that PHB can be used as part of an effective strategy to protect E. sinensis larvae from V. anguillarum resulting in higher survival and better growth, especially when applied before the challenge.  相似文献   

12.
Rotifers and Artemia salina nauplii are the most widely used live prey for newly hatched larvae, but they do not always promote optimal survival and growth. Alternative food sources such as copepods, which bypass these inadequacies and promote adequate growth, are needed and they are viewed with considerable interest by the scientific community. The aim of the present study was to test two different diets [rotifers and A. salina nauplii (group A) and a mixture (group B) of rotifers/Tisbe spp. copepods and A. salina nauplii/copepods] during the larval rearing of the striped blenny Meiacanthus grammistes. The analysis of the survival rate, size (total length and wet weight) and metamorphosis time during the larval phase of this species showed that Tisbe spp. administration can significantly improve larval survival and growth and also reduce the metamorphosis time. The results obtained are related to the fatty acid content of the live prey used and are essential in order to improve the captive production of M. grammistes through a closed system and, in turn, to preserve natural stocks.  相似文献   

13.
Abstract To improve survival of cultured juvenile fishes, it is important to understand prey preferences and predation behaviour of fish larvae. In this study, the feeding behaviour and prey preference of Allotoca dugesi (Bean), a small fish species endemic to Mexico and currently threatened with extinction are presented. Three zooplanktonic prey, viz. Brachionus calyciflorus (Pallas) , Moina macrocopa (Goulden) and Daphnia pulex (Leydig) were tested. The mean size (standard length ± SE, mm) of the larvae ranged from 9.0 ± 0.1 mm at week 1 to 18 ± 2 mm at the end of the experimental period (8 weeks). The gape size (mean ± SE) increased from 0.125 ± 0.002 mm at the first week to 2.300 ± 0.361 mm by the eighth week. Capture success (capture/attack) ranged from 0.80 to 0.98 with Brachionus , 0.72–0.94 with Moina and 0.17–0.46 with Daphnia . Prey preference experiments were conducted using B. calyciflorus, M. macrocopa and D. pulex at a fixed ratio of 5 : 2 : 2 ind. mL−1, respectively, and revealed a positive selection for rotifers and Moina , but avoidance of Daphnia . The results are discussed with reference to conservation efforts for Allotoca dugesi .  相似文献   

14.
This study aimed to evaluate the effect of enriching Artemia nauplii with vitamin C (ascorbyl-6 palmitate) or vitamin E (α-tocopherol acetate), 20% w/w, together with a mixture of concentrated eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) on the growth, survival, and stress resistance of fresh water walleye Stizostedion vitreum larvae. Either cod liver oil (CLO) or EPA/DHA ethyl esters concentrate was used as lipid sources in the Artemia enrichment. Walleye larvae were fed ad libitum for 40 days. At day 40, submersion in salt water (25 g L−1) was performed to evaluate larvae resistance to stress. EPA and DHA levels in walleye juveniles fed EPA/DHA-enriched Artemia increased significantly, by an average of 650% compared with fish fed non-enriched Artemia . A significant increase was found for vitamins C (71.8 ± 1.0 and 42.7 ± 1.2 μg g−1 wet weight (WW)) and E (17.0 ± 3.7 and 6.5 ± 0.9 μg g−1WW) concentrations in fish fed enriched and unenriched Artemia , respectively. Growth was comparable throughout treatments, whereas survival was significantly higher in fish fed CLO-enriched Artemia nauplii compared with fish fed Artemia nauplii enriched with EPA/DHA concentrate. The addition of vitamin C increased fish survival by 1.4-fold compared with fish fed Artemia enriched with only EPA/DHA concentrate. The survival of the latter was similar to control fish ( Artemia without enrichment). The supplementation of vitamin E did not affect fish survival significantly. Stress tests revealed that the resistance of walleye larvae to salinity changes increased when Artemia enrichment was supplemented with vitamin C. However, walleye larvae fed CLO-enriched Artemia had the best performances in the stress test.  相似文献   

15.
Identification of alkaline proteases produced during larval stages of gilthead sea bream, Sparus aurata was achieved using SDS-PAGE and specific inhibitors. Such techniques were also applied to determine proteases existing in rotifers, Brachionus plicatilis, and Artemia nauplii, which are used as live food for these larvae, as well as proteases of adult fish. The results show a great prominence of trypsin-like proteases during the 4 weeks after hatching, but the number of enzyme species was reduced in adult fish. Alkaline proteases present in the rotifers and Artemia showed clear differences when compared with those of the larvae and were not detected in extracts obtained from fed larvae. The results obtained provide information about the role of exogenous enzymes in larval feeding of sea bream.  相似文献   

16.
Lipid Nutrition and Feeding of Cobia Rachycentron canadum Larvae   总被引:3,自引:0,他引:3  
This study examined the fatty acid composition of cobia Rachycentron canadum eggs and yolksac larvae, as well as the ovaries of wild caught females as an initial guide to lipid nutritional requirements. A 2-wk feeding study also was conducted to investigate the effectiveness of four dietary treatments on the growth and survival of cobia larvae. Cobia eggs in the tailbud stage contained 31.4 ± 1.3 μg lipid/egg. After hatching, the amount of lipid decreased significantly (P < 0.05) from 28.3 ± 0.3 to 23.2 ± 0.1 μg lipid/larvae during the yolksac larval stage (days 1 to 3 after hatching). Ovaries from wild caught adults and captive spawned eggs and yolksac larvae contained high levels of PUFAs with docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA) accounting for approximately 80% of the total suggesting that cobia larvae may have a high dietary requirement for these fatty acids. For the feeding study, larvae were fed: 1) Artemia only; 2) enriched rotifers for 1 d only + microparticulate diet (day 313); 3) enriched rotifers for 3 d (day 3–5) + Artemia (day 3–13); and 4) enriched rotifers for 6 d (day 3–8) + Artemia (day 3–13). Cobia larvae began feeding on rotifers 3 d after hatching and on newly hatched Artemia nauplii by the fifth day following the onset of exogenous feeding (day 7). On day 7, no differences in larval growth were found among larvae fed rotifers for 3 versus 6 d, whereas larvae fed only Artemia or rotifers for I d followed by microparticulate diet were significantly smaller (P < 0.05) and did not survive beyond day 9 and 13, respectively. The results of the feeding study indicate that cobia larvae require rotifers for a minimum of 4 d following the onset of exogenous feeding.  相似文献   

17.
Larvae of Uca pugilator (Bosc) were reared in the laboratory from hatching to the megalopa stage on three different diets: (1) newly hatched Artemia salina nauplii (diet A), (2) the rotifer Brachionus plicatilis (O.F. Müller) and a ciliate Euplotes sp. (diet RC), and (3) a combination of the above two diets (diet ARC). The survival rate of zoeae fed diet A (90.0%) and diet ARC (93.8%) was much higher than that of the larvae fed diet RC (22.5%). The duration of the zoeal stages was significantly shorter for the larvae fed diet ARC than for those fed diets A and RC. The survival rate of megalopa larvae (reared on diets A and ARC in the zoeal stages) was high (above 90%) for megalopa fed Artemia nauplii only, as well as for those fed a combination of Artemia nauplii and shrimp. No significant differences in duration of the megalopa stage were found between the latter diet groups.  相似文献   

18.
Live adult brine shrimp, Artemia franciscana (Latreille), were enriched with erythromycin to determine if Artemia could accumulate therapeutic levels for subsequent feeding to young fish. Three trials were conducted to determine the erythromycin incorporation and survival rates of enriched Artemia when fed either liposomes containing erythromycin or various erythromycin suspensions. Erythromycin concentration in Artemia fed a liposome suspension was low (∼ 5 μg mL−1) relative to Artemia fed the direct suspension (> 100 μg mL−1) over the same time period. When enriched with suspensions up to 1 g erythromycin L−1 sea water for 14 h, Artemia survival was not significantly affected ( P > 0.05) relative to controls. Using a suspension of 1 g L−1, tissue erythromycin concentrations of 109 ± 16 μg erythromycin mL−1  Artemia homogenate (mean ± SEM) were achieved after 12 h. Concentrations above 170 μg mL−1 were obtained using suspensions of 2–5 g L−1, but Artemia survival significantly ( P < 0.05) decreased.  相似文献   

19.
The effect of varying levels of dietary n-3 highly unsaturated fatty acid (HUFA) and docosahexaenoic acid/eicosapentaenoic acid (DHA/EPA) ratios on growth, survival and osmotic stress tolerance of Eriocheir sinensis zoea larvae was studied in two separate experiments. In experiment I, larvae were fed rotifers and Artemia enriched with ICES emulsions with 0, 30 and 50% total n-3 HUFA levels but with the same DHA/EPA ratio of 0.6. In experiment II, larvae were fed different combinations of enriched rotifers and Artemia, in which, rotifers were enriched with emulsions containing 30% total n-3 HUFA, but different DHA/EPA ratio of 0.6, 2 and 4; while Artemia were enriched with the same emulsions, but DHA/EPA ratio of 0.6 and 4. In both experiments, un-enriched rotifers cultured on baker's yeast and newly-hatched Artemia nauplii were used as control diets. Larvae were fed rotifers at zoea 1 and zoea 2 stages; upon reaching zoea 3 stage, Artemia was introduced.Experiment I revealed no significant effect of prey enrichment on the survival of megalopa among treatments, but higher total n-3 HUFA levels significantly enhanced larval development (larval stage index, LSI) and resulted in higher individual dry body weight of megalopa. Furthermore higher dietary n-3 HUFA levels also resulted in better tolerance to salinity stress. Experiment II indicated that at the same total n-3 HUFA level, larvae continuously receiving a low dietary DHA/EPA ratio had significantly lower survival at the megalopa stage and inferior individual body weight at the megalopa stage, but no negative effect was observed on larval development (LSI). The ability to endure salinity stress of zoea 3, zoea 5 and megalopa fed diets with higher DHA/EPA ratio was also improved.  相似文献   

20.
ABSTRACT:   Larvae of the Japanese nephropid lobster Metanephrops japonicus hatched in the laboratory were reared at 15°C, and the development and feeding were observed. All larvae hatched at the 'prezoea stage' with no natatory setae on the exopodite of the pereiopods. Without feeding, 50% of prezoea molted into the megalopa stage, having small buds as the exopodite, within 1 h and all molted within 22 h. The megalopa fed with Artemia nauplii, shrimp meat and pelleted food molted into the first juvenile stage with no exopodite after approximately 17 days. The average carapace lengths of prezoea, megalopa and the first juvenile stage were 3.2, 3.6 and 4.4 mm, respectively. The survival rate from hatching to the first juvenile stage was high (90–100%). This lobster may be the only known nephropid species with no zoeal stage.  相似文献   

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