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1.
Abstract. Rainbow trout, Oncorhynchus mykiss (Walbaum), eggs were exposed to [methane-14C] malachite green chloride on day 0 and on every third day thereafter through day 24, with a final treatment administered to fry on day 31. Eggs or fry were sampled before each treatment, and at selected times from day 31 to day 59. Malachite green equivalence in eggs and fry was determined by sample oxidation and liquid scintillation counting. Total malachite green residues increased throughout the exposure period to 0.271 ± 0.042 μg g−1 (± SD) on day 31. Residues declined to 0.055 ± 0.011 μg g−1 on day 59. The depuration phase declined monoexponentially with a half-life of 13.3 days for the absolute amount (μg sample−1) and a half-life of 9.7 days for the concentration of malachite green residues (μg g−1). Growth dilution accounted for the 25% increase in the elimination (9.7 days) of malachite green residues. Extracts from treated eggs and fry were analysed by reversed-phase liquid chromatography. Three peaks were resolved in treated eggs: chromatic malachite green, leuco malachite green and an unknown polar metabolite. Only two peaks were resolved in the fry: leuco malachite green and the unknown polar metabolite. The most prominent residue in all samples was leuco malachite green.  相似文献   

2.
Abstract— Two bacterial strains, rich in either eicosapentaenoic acid [EPA, 20:5(n-3)] ( Shewanella gel-idimarina ACAM 456) or docosahexaenoic acid [DHA, 22:6(n-3)] ( Colwellia psychroeryrhrus ACAM 605) were tested for their ability to enrich rotifers Erachionus plicatilis in these polyunsaturated fatty acids. Rotifers were exposed for 24 h to each bacterial strain and to a mixture of the two strains. They were then harvested and their fatty acid compositions were analysed and compared to those of rotifers that had been either starved or fed yeast Saccharomyces cerevisiae or microalgae Tetraselmis suecica in 2-L glass flasks. Exposure to 1.4 × 109 cells/ml of the EPA-producing bacterium only resulted in rotifer EPA levels increasing from 0.1% to 1.2% of total dry weight (%dw). Similarly, following exposure to 1.0 × 109 cells/mL of the DHA-producing bacterium only, rotifer DHA levels increased from below detection to 0.1% dw. When exposed to a mixture of the two bacterial strains, containing 7.0 × 108 celldml of the EPA producer and 5.0 × 108 cells/mL of the DHA producer, the rotifers'final EPA and DHA levels were 0.5% dw and 0.3% dw respectively. Although feeding strategies need refining, these results show, for the first time, that rotifers can be enriched with DHA from bacteria, and that rotifers can be enriched simultaneously with both DHA and EPA from different bacterial strains.  相似文献   

3.
The aim of this study was to evaluate the dynamics of the blood plasma parameters and the content of microcystins in the tissues of common carp ( Cyprinus carpio L.) in relation to the toxic cyanobacterial water bloom. Fish (average body mass 2176±697 g) in the hypertrophic pond were exposed to natural water bloom (dominated by Planktothrix agardhii, Pseudanabaena limnetica and Limnothrix redekei ), which contained microcystins (concentration in biomass 20–181 μg g−1 dry wt, concentration in water 0.3–9.5 μg L−1). Biochemical parameters in fish blood plasma were analysed in 89 fish at 14-day intervals during the whole season (nine sampling periods). Our results demonstrated high variability and fluctuations in the investigated parameters. The content of microcystins and density of cyanobacterial cells correlated with some haematological indices as lipase, alanine–aminotransferase, albumin, magnesium and chlorides. The concentrations of microcystins in the muscle and liver of the fish (determined by high-performance liquid chromatography with mass spectrometer) were below the limit of detection during the monitored period [0.31 ng g−1 fresh weight (f.w.) for the liver and 0.13 ng g−1 f.w. for muscle]. Our study demonstrates that although known cyanobacterial toxin microcystins were not detected in the fish tissues, several biochemical parameters important for the fish physiology were modulated by natural cyanobacterial bloom.  相似文献   

4.
This study tested the effect of the level of dietary phosphatidylcholine (PC) and its constituent medium-chain fatty acids on microdiet ingestion (μg diet larva−1 h−1) and the absorption rate of the free fatty acid [14C]16:0 (pmole larva−1 h−1) in 15, 20, 21, 25, 26, 30 and 31-day-old gilthead sea bream, Sparus auratus L., larvae. Fish were fed four microdiets (A, B, C and D): microdiet A contained no phospholipid (PL), while microdiet B included 10 g kg−1 Artemia nauplii PL (3.7 g kg−1 PC). Microdiets C and D contained 10 g kg−1 purified saturated PC dimyristoyl (C14:0) and polyunsaturated PC dilinoleoyl (C18:2[cis]−9,12), respectively.
Larvae from one or both of the PC microdiets demonstrated significantly higher ( P < 0.05) ingestion rates (μg diet larva−1 h−1) than the non-PL microdiet control in 15, 21, 22, 25 and 26-day-old larvae and the Artemia PL microdiet in 15, 22 and 26-day-old larvae. However, microdiet ingestion and fatty acid absorption rate appeared to be independent of the associated medium carbon chain saturated or polyunsaturated fatty acid moiety of the PC diets. Apparent absorption, as measured by the retention of radio-labelled [14C]16:0 following 8 h of non-labelled microdiet feeding, was possibly related to feeding.  相似文献   

5.
The rotifer Brachionus plicatilis requires vitamin B12. Freshwater Chlorella , which is produced by traditional culture, cannot support rotifer growth under bacteria-free conditions. However, Chlorella enriched with vitamin B12 can support rotifer growth. To attain stable mass production of Brachionus , it is desirable to develop a food that can completely support growth of the rotifers. The authors cultured rotifers at experimental and mass culture scale with concentrated Chlorella vulgaris suspension enriched with vitamin B12 in their cells.
Chlorella suspensions were prepared containing different amounts of vitamin B12 in their cells, and rotifers were then cultured in 20 ml of the prepared suspensions. The highest rotifer yield was obtained from the group cultured with Chlorella containing more vitamin B12 in their cells. The suitable content of vitamin B12 in the concentrated Chlorella suspension commercially available for mass culture of the rotifer is considered to be 200 μg per 100 g dry matter of Chlorella . The amount of vitamin B12 necessary to produce one individual rotifer is calculated at 0.32 pg.
The authors conducted mass production of the rotifer with baker's yeast and refrigerated concentrated Chlorella containing vitamin B12 Rotifer culture with vitamin B12 was more stable and showed 1.3 times higher production than with normal Chlorella .  相似文献   

6.
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.  相似文献   

7.
Herpesviral haematopoietic necrosis is a disease of goldfish, Carassius auratus , caused by Cyprinid herpesvirus-2 (CyHV-2) infection. Quantitative PCR was carried out on tissue homogenates from healthy goldfish fingerlings, broodfish, eggs and fry directly sampled from commercial farms, from moribund fish submitted to our laboratory for disease diagnosis, and on naturally-infected CyHV-2 carriers subjected to experimental stress treatments. Healthy fish from 14 of 18 farms were positive with copy numbers ranging from tens to 107 copies μg−1 DNA extracted from infected fish. Of 118 pools of broodfish tested, 42 were positive. The CyHV-2 was detected in one lot of fry produced from disinfected eggs. Testing of moribund goldfish, in which we could not detect any other pathogens, produced 12 of 30 cases with 106–108 copies of CyHV-2 μg−1 DNA extracted. Subjecting healthy CyHV-2 carriers to cold shock (22–10 °C) but not heat, ammonia or high pH, increased viral copy numbers from mean copy number (±SE) of 7.3 ± 11 to 394 ± 55 μg−1 DNA extracted after 24 h. CyHV-2 is widespread on commercial goldfish farms and outbreaks apparently occur when healthy carriers are subjected to a sharp temperature drop followed by holding at the permissive temperature for the disease.  相似文献   

8.
The culture quality of rotifers, Brachionus plicatilis, was compared for yeast and algal-based cultivation diets. The rotifer quality was evaluated based on factors which may affect survival and growth of marine fish larvae, including individual length and biomass, nutritional value, bacterial content, and rotifer viability. The diets used were monocultures of Tetraselmis sp., Isochrysis galbana, Pavlova lutheri, and baker's yeast plus capelin oil.Rotifers grown to early stationary phase with equal food rations exhibited equal length distribution, but the rotifer individual biomass was 10–25% higher for yeast-grown rotifers than for algal-grown rotifers.All diets gave equal protein content of individual rotifers. The lipid content was slightly higher and the ratio of protein to lipid was slightly lower with yeast plus capelin oil than with algae. The fatty acid composition of the rotifers was closely related to that of their dietary lipids and the 3 fatty acid content was not systematically different for the two types of diets.Use of yeast plus capelin oil resulted in considerably higher numbers of both suspended and rotifer-associated bacteria than with use of algal diets. No differences were found for the algal species involved. The viability of the rotifers in a temperature and salinity test was far better in groups fed algae than in groups fed yeast plus capelin oil.The results indicated an overall better quality of rotifers cultivated with algae than for rotifers cultivated with yeast and oil. Questions related to proteins and the microflora of rotifers should be further emphasized in future research.  相似文献   

9.
Microparticles (< 40 μm diameter) composed of 600 mg g−1 tripalmitin/400 mg g−1 fish oil were used to encapsulate the low-molecular-weight (mol. wt 460) antibiotic oxytetracycline in the form of either oxytetracycline hydrochloride (OTC.HCl) or oxytetracycline hemicalcium salt (OTC.HEM). Dry, finely ground particles of core material were encapsulated in spray beads. Dissolved core material was encapsulated in lipid-walled microcapsules.
Oxytetracycline (OTC) was most efficiently delivered (≈ 46.5 mg g−1 lipid after 24 h suspension in seawater) as a hemicalcium salt in spray beads. Lipid-walled microcapsules were most efficient for delivering OTC (≈ 8.7 mg g−1 lipid) as OTC.HCl dissolved in 0.2  M HCl at a concentration of 300 mg mL−1.
Spray beads containing OTC.HEM were very stable over 1 month in storage. Lipid-walled microcapsules containing aqueous OTC.HCl lost ≈ 30% of their core material during storage. Freeze-drying of both microparticle types did not improve storage of spray beads, but showed promise for reducing leakage from lipid-walled microcapsules during storage and delivery to suspension feeders.  相似文献   

10.
Abstract. The production potential of any shellfish hatchery depends on the capacity of its algal system. The hypothesis that microalgal cultures grown under 12:12h light:dark photoperiod may produce the same cell densities as those using constant light is tested.
Two species of marine microalgae used in shellfish hatcheries. Chaetoceros gracilis Schütt and Isochrysis galbana clone T-iso, were grown in cultures at 18°C, under continuous light (1.43 × 107μ-2day-1) and 12:12h light:dark cycles (2.87 × 107μE m-2 day-1). Both light regimes provided equal amounts of light per day. In the continuous light cultures the mean doublings per day for exponentially growing cells were 1.37 and 1.49 for C. gracilis and I. galbana respectively and for the 12:12h light:dark cycles were 1.47 and 1.56 respectively. After 14 days of growth, the numbers of cells per unit of volume showed no significant differences between the two light regimes. The results are discussed in terms of a review of other authors' findings and in terms of the usefulness of the continuous light method in producing algae to be used in shellfish hatcheries.  相似文献   

11.
Juvenile rainbow trout Oncorhynchus mykiss (Walbaum) were fed six low-phosphorus (P) diets supplemented with two different sizes of ground fish bone-meals (fine, 68 μm or less; coarse, 250–425 μm) and a coarse bone-meal diet containing four levels of citric acid (0, 4, 8 or 16 g kg−1 diet) to investigate the effects of pH and bone particle size on P bioavailability. The basal diet provided 3.4 g P   kg−1 and bone-meal increased P contents to 5.4–6.0 g P   kg−1. Coarse bone-meal diets supplemented with 0, 4, 8 or 16 g kg−1 of citric acid had pH values of 6.0, 5.7, 5.4 and 5.0, respectively. Weight gain and whole-body water, protein and lipid contents were not influenced by bone-meal supplementation. Supplementing the basal diet with both coarse and fine bone-meal significantly increased whole-body ash content. Fish fed no bone-meal were hypophosphataemic compared with fish fed with either fine or coarse bone-meals. Phosphorus in fine bone-meal had higher availability than P in coarse bone-meal. Bone-meal supplementation significantly decreased whole-body manganese content from 8.9 μg g−1 in fish fed no bone-meal to 2.3 and 4.5 μg g−1 in fish fed with fine and coarse bone-meals, respectively. The concentration of magnesium increased but zinc concentration was not affected by bone-meal supplements. Citric acid increased whole-body ash content but the influence of citric acid on the body P content was not significant ( P  = 0.07). Dietary acidification by citric acid significantly increased whole-body iron in a linear fashion. The bioavailability of dietary P can be improved by fine grinding the bone in fish meals.  相似文献   

12.
We describe the development and evaluation of a new microparticle for delivering low-molecular weight, water-soluble materials to suspension feeders. Spray beads successfully incorporated materials dissolved in an aqueous phase or as dry particulate, within a triacylglyceride bead composed of tripalmitin, 600 mg g−1 tripalmitin/400 mg g−1 triolein, or 600 mg g−1 tripalmitin/400 mg g−1 fish oil.
Riboflavin was successfully incorporated (up to 44 mg g−1 lipid) and retained (up to 98% over 24 h in seawater) as dry particles in all three mixtures of lipid. Aqueous oxytetracycline hydrochloride or polymeric dye were incorporated (45.6 mg g−1 lipid and 18.1 mg g−1 lipid, respectively) and retained best (99% and 94%, respectively) in spray beads composed of tripalmitin. The addition of triolein or fish oil to the lipid bead reduced incorporation and retention efficiencies for aqueous core materials by up to 75%.
Manila clam seed readily ingested and digested lipid microparticles, spray beads and lipid-walled microcapsules. Microparticles composed of tripalmitin were excreted with their payloads intact. Intact microparticles composed of 600 mg g−1 tripalmitin/400 mg g−1 fish oil were largely absent in faecal strands suggesting successful release and delivery of microparticle contents to clams.
Spray beads composed of tripalmitin softened with 400 mg g−1 fish oil represent an effective microparticle type for delivering low-molecular weight, water-soluble materials to aquatic suspension feeders.  相似文献   

13.
Two trials were conducted to determine the effects of dietary enrichments with the microalga Parietochloris incisa , rich in arachidonic acid (ARA), on stress resistance in guppies Poecilia reticulata . The microalga was added to commercial diets as a neutral lipid (NL) extract and its fractions or as broken cells. Experimental diets were applied for a period of 14 days. In trial 1, commercial diets were supplemented with NL (containing 25 mg ARA and 0.11 mg β-carotene g−1 feed), its triacylglycerol (TAG) fraction (containing 25 mg ARA g−1 feed and no β-carotene) and the β-carotene fraction (containing 0.11 mg carotenoid g−1 feed and minute amounts of ARA). Neutral lipid-fed fish demonstrated the highest resistance ( P <0.05) to osmotic stress (32-ppt NaCl), followed by fish fed with diets supplemented with TAG and β-carotene alone, which were more resistant than control ( P <0.05). In trial 2, fish fed diets supplemented with higher levels of broken alga (26.1 mg ARA g−1 feed) were more resistant ( P <0.05) to stress as compared with fish fed lower ARA (16.3 mg g g−1) or an unsupplemented control diet. We suggest a dietary supplementation with broken P. incisa cells to enhance stress resistance in guppies before a stressful event.  相似文献   

14.
The feasibility of obtaining a similar growth response from juvenile pink abalone Haliotis corrugata at a research laboratory and a hatchery, when using natural feeds was evaluated. Four macroalgae, Egregia menziesii , Eisenia arborea , Macrocystis pyrifera , Gracilaria sp., and the surfgrass Phyllospadix torreyi were used as feeds. Response patterns of abalone were very similar at both facilities in terms of final length, weight, and survival, varying from 13.0 to 15.50 mm, 0.31 to 0.52 g, and 60.0% to 78.6%, respectively. Better growth was obtained when E. menziesii , M. pyrifera , and Gracilaria sp. were offered. Poor results were obtained with surfgrass. The feed conversion ratio was determined at the laboratory and did not vary significantly, ranging from 42.3 to 199.0; although a significant inverse correlation was observed with growth rate. Growth in length and weight and survival rates varied within 1.6–20.2 μm day−1, 0.123–1.664 mgday−1, 0.4–0.64%day−1, respectively. Mean growth rate in length (14.7μm day−1) and weight (1.18 mg day−1) at the hatchery were significantly higher than that obtained at the laboratory (9.4 μm day−1 and 0.77 mg day−1), which is most likely a consequence of more suitable water temperature at the hatchery. Mean survival rate was significantly higher at the laboratory (53.1%day−1) than at the hatchery (46.1%day−1).  相似文献   

15.
Juvenile northern Chilean scallops of 937±55 μm shell height were exposed to five different concentrations of chloramphenicol (CHL) (5, 10, 25, 50 and 100 μg mL−1), plus a control without antibiotics. To determine the effect of CHL on the accompanying microflora, the number of colony-forming units (CFU) that grew on TGE culture medium was counted in the seawater of containers with juveniles, and in containers with microalgae used as food. Both were exposed to the same concentrations of CHL. The growth rates of juveniles treated with CHL and the control without antibiotic showed highly significant differences ( P =0.0001). The growth rate was inversely proportional to the CHL concentration. The control sample presented the highest growth rate (84.4±14.3 μm day−1), followed by the sample treated with 5 μg mL−1 (64.2±14.3 μm day−1). The survival in the control and in the treated samples with 5–50 μg mL−1 was rather high, with a mean value of 95%. Only the sample treated with 100 μg mL−1 had a low survival (36.7%). The CFU count was larger in the containers with juveniles, when compared with the ones with food. The CFU count tended to decrease with increasing CHL concentration in the juveniles.  相似文献   

16.
The effects of several feeding levels (1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4% and 4.5% of body weight per day, BW day−1) on the growth, feed efficiency and body composition of juvenile Lutjanus argentimaculatus (body weight 27.1 g) were examined. Fish were fed a test diet (40% protein, 18.4% lipid and 13.4 kJ g−1) for 75 days in three equal meals. Weight gain and specific growth rate increased with increasing feeding level up to 2.5% BW day−1, after which no significant improvement in growth was observed. The feed efficiency, protein efficiency ratio, retention of protein and digestibility of nutrients did not differ for fish fed 1–2.5% BW day−1, but decreased significantly when feeding levels were increased above 3% BW day−1. The chemical compositions of whole fish or body organs were significantly affected by the feeding level. The condition factor, mesenteric fat, hepato- and viscerosomatic indices were higher in fish fed 2.5–4.5% BW day−1. The cholesterol, triglycerides and haematocrit values were similar among treatments, except that high levels of plasma lipids were recorded in fish fed at 2.5% BW day−1. Taking into consideration the growth, feed efficiency and body composition data attained in this study, a feeding level of 2.5% BW day−1 is recommended for juvenile L. argentimaculatus weighing between 27 and 140 g.  相似文献   

17.
ABSTRACT:   Tropical minute rotifer strains (SS-type) induce mixis at 30–35°C but sexual reproduction and resting egg formation do not proceed well due to rapid environmental change. The present study examined the effect of temperature regulation on rotifer Brachionus rotundiformis (Langkawi strain, SS-type) resting egg formation in small (500 mL in culture volume)- and large-scale (500 L in culture volume) experiments. Rotifers were cultured at 30°C in 15–17 p.p.t. seawater with an initial density of 1 individual (ind.)/mL. After 4 days, when cultures were in exponential growth stage with active mixis induction, the culture temperature of the experimental rotifers was changed to 25°C. Control rotifers were cultured at 30°C throughout the experiment. Fresh or frozen Nannochloropsis oculata and condensed freshwater Chlorella vulgaris were used as the rotifer diets in the small- and large-scale experiments, respectively. Significantly higher resting egg production was observed with the experimental rotifers (30→ 25°C) versus the control rotifers. In the large-scale trial, experimental rotifers produced 2.6 × 106 resting eggs during a 9-day experiment, which was 1.6-fold more than the control rotifers. Moreover, the efficiency of resting egg formation was found to increase by a factor of 1.8. The present study indicates that decreasing culture temperature from 30 to 25°C after active mixis increased resting egg formation in B. rotundiformis (SS-type).  相似文献   

18.
The rotifer Brachionus plicatilis is an important component of aquaculture as a larval feed. Its taxonomic status has been recently re-defined as a species complex, consisting of at least 14 new species/lineages. This study deals with the lineage Brachionus 'Nevada', which has been shown to occur in European hatcheries. A strain of B . 'Nevada' was mass cultured using two commonly applied feeding regimes and analysed in terms of its morphometry. A new formula was proposed for the calculation of volume, which can be used as an index of adequacy of rotifers as feed for fish larvae. The results were related to life cycle parameters. The pre-reproductive and reproductive phases were divided into distinct size groups. Differences were also found between the two diets in morphometry and demography. Rotifers of a larger size (yeast-based diet) showed a lower growth rate and a longer reproductive period, lifespan and mean generation time compared with smaller-sized rotifers (Culture Selco®-based diet). In terms of lorica length, the present study's strain of B . 'Nevada' (238.5 μm) was intermediate between values reported for Brachionus ibericus (193.5 μm) and B. plicatilis sensu stricto (299 μm).  相似文献   

19.
A study was conducted to test the performance of a high‐density (>3000 individuals/mL) continuous recirculating system for rotifers (B. rotundiformis) fed nonviable Nannochloropsis oculata and using sodium hydroxymethanesulfonate to neutralize ammonia. Three different microalgae feed rates (g of N. oculata [68 × 109 cells/mL] per million rotifers/d) were tested in successive trials. In Trial 1 (feed rate = 1.5), during a 30‐d period, rotifers were harvested daily to 3000 individuals/mL, for an average yield of 178 million/d. Feed efficiency (million rotifers/g/d) was 0.33. In Trial 2 (feed rate = 1.1), during a 32‐d period, an average of 106 million rotifers were harvested daily, and feed efficiency was 0.26. In Trial 3 (feed rate = 1.3), during a 30‐d period, an average of 107 million rotifers was harvested daily, and feed efficiency was 0.23. An economic analysis based on a feed rate of 1.5 showed that production cost was 40% lower than the traditional batch culture method (US$ 0.29 vs. 0.46 per million rotifers/d). The continuous culture system tested reliably produced large quantities of rotifers on a daily basis without the use of a biofilter and with a lower production cost than a batch culture system.  相似文献   

20.
We evaluated the effects of maturation-stimulating hormones on the post-thaw motility of land-locked form ayu ( Plecoglossus altivelis ) spermatozoa. Male ayu were administered three intraperitoneal injections of either salmon pituitary extract (SPE; 0.2 or 0.6 mg g−1 BW day−1) or of 17, 20β-dihydroxy-4-pregnen-3-one (DHP; 2 or 10 μg g−1 BW day−1), the maturation-inducing steroid (MIS) in ayu. Before cryopreservation, the motility of spermatozoa of the SPE- and DHP-treated groups was significantly higher than that of the control group. Similarly, the comparative post-thaw motility (presented as a percentage of the motility obtained before cryopreservation) was significantly higher in the SPE group than in the control; however, there was no significant difference between the DHP group and the control. The effect of SPE and DHP on pre- and post-cryopreservation motility was not dose dependent. Our results suggest that the hormone(s) present in salmon pituitary are effective in enhancing the tolerance of ayu sperm cells to cryopreservation and that the MIS (DHP) is not involved in this process.  相似文献   

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