Addition of bacteria bioencapsulated in Artemia metanauplii to a rearing system for halibut larvae

Theaim of this study was to determine whether it is possible to influence thespecies composition of the gut microflora in 70-days old halibut larvae(Hippoglossus hippoglossus L.) by addition of bacteriabioencapsulated in Artemia franciscana in two shortpulses.Two Vibrio strains, PB 1-11 and PB 6-1 were used. Twotreatments received each strain alone, a third treatment received the twobacterial strains in mixture, whereas in a control treatment no bacteria wereadded. Five fish tanks were included in each treatment. The bacteria werebioencapsulated in Artemia franciscana metanauplii duringashort-term incubation in bacterial suspensions of the specific strains, andwereadded in two pulses, on day 1 and day 10 of the experiment. Addition ofbacteriadid not increase the total number of colony-forming units (CFU) in the larvalgut. The total CFU in the water was lower in tanks added bioencapsulatedbacteria than in the control treatment (p < 0.05). Animmunocolony blot assay was used to measure the numbers of the specificbacteriaadded in samples of water, A. franciscana, and fishlarvae.At the end of the experiment on day 13, the strain PB 1-11 reached on average10% of the total CFU when added alone and 25% when added in mixture with PB6-1.Strain PB 6-1 reached at the end of the experiment 26.8% of the total CFU whenadded alone and 24.2% when added in mixture with PB 1-11, whereas thepercentages of PB 1-11 and PB 6-1 in the control fish were 12.7% and 10.8% ofthe total CFU, respectively. However, the differences between the experimentaltreatments compared with the control group were not significant(p > 0.05). The addition of bioencapsulated bacteria intwo pulses within a ten days period was therefore not sufficient to influencethe species composition of the microflora of the halibut larvae.     

Microbially matured water: a technique for selection of a non-opportunistic bacterial flora in water that may improve performance of marine larvae

Before transfer to larval incubators, water was membrane filtered to remove >95% of the bacteria and then transiently maintained in a biofilter that promoted recolonization of the water by non-opportunistic bacteria. The process is termed microbial maturation of the water. Hypothetically the bacterial flora in the matured water should protect the marine larvae from colonization and proliferation by opportunistic bacteria. Testing of the hypothesis demonstrated 76% higher survival of yolk sac larvae of Atlantic halibut (Hippoglossus hippoglossus) in matured than in membrane filtered water. Proliferation of opportunistic bacteria was observed in the rearing water after hatching of turbot eggs (Scophthalmus maximus), but to a less extent in the microbially matured water. In the early phase of first feeding of turbot larvae, the matured water induced qualitative differences in the gut microflora. Significantly higher initial growth rate of the turbot larvae in the matured water affected 51% higher average weight of 13 days old larvae than in membrane filtered water. Algal addition to the matured water enhanced the larval growth further. The experiments conducted supported the proposed hypothesis that microbial maturation selects for non-opportunistic bacteria, which protects the marine larvae from proliferation of detrimental opportunistic bacteria.     

Lipolytic activities in developing turbot larvae as influenced by diet

The development of neutral lipase and phospholipase activities was studied in larval turbot fed live prey. Activities of neutral lipase and phospholipase (activity larva⁻¹) increased significantly between days 6 and 24 after hatching in turbot larvae. The specific activities of both enzymes (activity μg protein⁻¹) decreased in older larvae. Feeding of a microdiet for 3 days (days 10–13) affected the lipolytic activity of neutral lipase and phospholipase negatively, compared to the larvae fed on rotifers. Since neutral lipase activities in whole larval homogenates and in the gut were significantly lower, it suggests a reduced synthesis rate and a reduced secretion of the enzyme in larvae fed the microdiet. A correlation between neutral lipase and phospholipase activities was found in larvae fed rotifers, but not in larvae fed the microdiet. This may indicate different regulating and stimulating mechanisms for these enzymes. The contribution of exogenous enzymes from ingested live prey to the total larval enzyme activity was about 6% for neutral lipase and 10% for phospholipase on day 6. The exogenous prey enzymes accounted for only 2% of the total activities in 12-day-old turbot larvae, suggesting that enzymes from prey did not contribute considerably to the digestion of lipids. This revised version was published online in August 2006 with corrections to the Cover Date.     

Optimum time for weaning South African <Emphasis Type="Italic">Scylla serrata</Emphasis> (Forskål) larvae from rotifers to <Emphasis Type="Italic">Artemia</Emphasis>

To determine the optimum time at which to wean Scylla serrata larvae from rotifers onto Artemia two experiments were conducted, approximately 1 month apart, using larvae from two different female crabs. In the first experiment, the larvae in three treatment groups, with nine replicates each, were fed rotifers for the first 8 days after hatching. Artemia were introduced on days after hatch (DAH) 0 – during the first zoeal instar (treatment R + A); on DAH 4 – during the second zoeal instar (treatment R4A); on DAH 8 – during the third zoeal instar (treatment R8A). In a control (ROT) larvae were fed with rotifers exclusively for 18 days until the completion of metamorphosis to megalopa. In the second experiment, the same four feeding schedules as in experiment 1 were used with an additional group of larvae (treatment AC) that were fed only on Artemia throughout the rearing period. Similar results were recorded in the two experiments. Larvae in treatments R + A and R4A performed significantly better than those in treatments R8A, ROT and AC. This was particularly evident when examining the proportion of zoeae which successfully completed metamorphosis to megalopa. Poor performance of larvae in treatments AC and ROT implied that rotifers are needed as a first food, but that rotifers alone do not fill the nutritional requirements of S. serrata larvae. Poor performance of larvae in treatment R8A suggested that the diet should be supplemented with Artemia before the end of the zoea 3 stage.     

Optimal first feed organism for South African mud crab <Emphasis Type="Italic">Scylla serrata</Emphasis> (Forskål) larvae

It is not known whether rotifers or Artemia nauplii are the best first food for South African mud crab Scylla serrata larvae. In order to test this, larvae were fed with five different test diets. These were rotifers for the first 8 days and newly hatched EG^® type Artemia nauplii (San Francisco Bay) from day 6 onwards (treatment R6A); newly hatched EG^® type Artemia nauplii throughout the rearing period (treatment EG); newly hatched Vinh-Chau strain (Vietnam) Artemia nauplii throughout the rearing period (treatment VC); decapsulated cysts of EG^® type Artemia throughout the rearing period (treatment DECAP); or decapsulated cysts supplemented with low densities of Artemia EG type Artemia nauplii (treatment MIX). Two experiments were conducted approximately 1 month apart using larvae from two different female crabs. Although results showed it is possible to rear S. serrata larvae through metamorphosis on Artemia nauplii exclusively, larval performance (development, survival and successful metamorphosis) was enhanced by the inclusion of rotifers as a first feed.No significant difference in performance was recorded between larvae fed on the two strains of Artemia nauplii. Larvae fed on decapsulated cysts in treatments DECAP and MIX performed poorly, but there were indications that decapsulated cysts and other inert diets may have potential as supplements to live food in the rearing of S. serrata larvae.     

Effect of an immunostimulating alginate on protein turnover of turbot (Scophthalmus maximus L.) larvae

High densities of marine larvae are often associated with microbial problems, mostly caused by opportunistic pathogens, resulting in poor growth and mass mortalities. The early life stages of fish have a very limited immune defence system. Therefore stimulation of non-specific immune mechanisms in fish larvae might be a very interesting tool. The present study evaluates the effects of a known immunostimulant on protein turnover in larval turbot (Scophthalmus maximus). Protein turnover and food intake was determined at day 13 using a time course after feeding the larvae with ¹⁵N-labelled rotifers. Turbot larvae fed with rotifers enriched with the immunostimulant FMI at first feeding had significantly higher fractional rates of protein synthesis when compared to a control group. This resulted in three-fold higher protein turnover in the larvae given the immunostimulant compared to the control group. Food intake, larval size and survival at the end of the experiment were similar in the two treatments. The effect of FMI in increasing protein turnover probably imply a higher larval viability and survival in case of environmental/disease stress. However, protein turnover is costly, and this may cause a trade-off between fast growth and stress-resistance/survival in fish larvae.     

Bacterial nutrition of great scallop larvae

Bacterial nutrition of great scallop, Pecten moximus, larvae was investigated using the radioactive tracer technique. The bacterial labelling was studied initially to obtain a high and stable specific radioactivity (¹⁴C) of bacterial cells. A higher bacterial specific ¹⁴C activity was obtained when the tracer (amino acid) was introduced in the culture medium at the beginning of the exponential growth phase. After a 12 h labelling period in a rich nutritive medium, the bacteria were depurated in seawater for 5 h (chase) to prevent further ¹⁴C excretion and then added to larval rearing vessels. The larval labelling was followed for 12 h and then larvae were placed in new vessels without radioactive bacteria. The depuration of larvae was followed for 3 days. Data obtained on ingestion and assimilation efficiency show that bivalve larvae are able to ingest and digest bacteria.     

Development of digestive enzyme activity in larvae of spotted sand bass <Emphasis Type="Italic">Paralabrax maculatofasciatus</Emphasis>. 1. Biochemical analysis

Spotted sand bass Paralabrax maculatofasciatus is a potential aquaculture species in Northwest Mexico. In the last few years it has been possible to close its life cycle and to develop larviculture technology at on pilot scale using live food, however survival values are low (11%) and improvements in growth and survival requires the study of the morpho-physiological development during the initial ontogeny. In this research digestive activity of several enzymes were evaluated in larvae, from hatching to 30 days after hatching (dah), and in live prey (rotifers and Artemia), by use of biochemical and electrophoretic techniques. This paper, is the first of two parts, and covers only the biochemical analysis. All digestive enzyme activities were detected from mouth opening; however the, maximum activities varied among different digestive enzymes. For alkaline protease and trypsin the maximum activities were detected from 12 to 18 dah. Acid protease activity was observed from day 12 onwards. The other digestive enzymes appear between days 4 and 18 after hatching, with marked fluctuations. These activities indicate the beginning of the juvenile stage and the maturation of the digestive system, in agreement with changes that occur during morpho-physiological development and food changes from rotifers to Artemia. All enzymatic activities were detected in rotifers and Artemia, and their contribution to enhancement the digestion capacity of the larvae appears to be low, but cannot be minimised. We concluded that the enzymatic equipment of P. maculatofasciatus larvae is similar to that of other marine fish species, that it becomes complete between days 12 and 18 after hatching, and that it is totally efficient up to 25 dah.     

添加外源益生菌对大菱鲆育苗生物饵料菌群结构的影响

为评价在大菱鲆育苗生产中添加外源益生菌对生物饵料轮虫和卤虫微生物菌群结构的影响,运用基于illumina HiSeq平台的高通量测序技术对添加益生菌和按照生产流程正常强化的轮虫、卤虫进行了菌群结构的分析和对比。添加外源益生菌的实验组轮虫和卤虫中的菌群物种多样性均明显高于对照组。在轮虫强化过程中,不同时期的对照组样品中菌群结构差异较明显,优势细菌种类变化较大。而添加外源益生菌后的各时期实验组轮虫菌群结构很相似,优势菌群的种类更为丰富,Lactococcus sp.、Pseudoalteromonas sp.和Alteromonas sp.等一直是各实验组中的优势细菌。在卤虫强化过程中,各对照组样品的菌群结构高度相似,优势细菌Cobetia sp.的相对丰度高达54%~65.2%。而在添加益生菌后,各实验组中的菌群结构仍高度相似,但Cobetia sp.的比例下降至4.3%~25.3%,最优势的细菌为Pseudoalteromonas sp.和Alteromonas sp.等几种,菌群结构中的物种均匀度更好。研究表明,在轮虫和卤虫强化过程中添加外源益生菌,能够改变生物饵料的菌群结构,使生物饵料中的细菌种类均匀度更好,并使菌群结构趋于稳定。     

Partial decontamination of rotifers with ultraviolet radiation: the effect of changes in the bacterial load and flora of rotifers on mortalities in start-feeding larval turbot

Exposure of the rotifer Brachionus plicatilis to ultraviolet radiation in 1 mm deep liquid layers at an energy intensity of 38 mW cm⁻² reduced the rotifer bacterial load by >90% within 2 min. Such radiation doses had no significant effect upon rotifer viability, fatty acid composition, swimming or feeding activity. The surviving bacterial flora of irradiated rotifers was similar to that of un-irradiated rotifers and there was no evidence of major differences in sensitivity to ultraviolet radiation between different bacteria. For irradiation of large numbers of rotifers, a flow-through cell was used, operated with rotifer densities of 200 ml⁻¹ and a flow rate of 1.5 l min⁻¹. In two separate field trials involving groups of 34,000 turbot larvae per group, higher survival was found in groups receiving ultraviolet-irradiated rotifers in which the bacterial load was reduced by 88%. This was attributed to the slower rate of colonisation of the larval gut by bacteria, as a consequence of the lower bacterial load on the rotifers. Attempts to introduce specified bacteria into the larval turbot gut in significant numbers by colonisation of either normal or irradiated rotifers with particular bacteria were unsuccessful.     

Vitamin requirements in great scallop larvae

Vitamins were analysed in food (microalgae) and larvae of great scallop, Pecten maximus, during larval development. Microalgae used to feed larvae in hatcheries show great variability in their vitamin composition depending on both the species and culture condition (phase of growth). The microalgae used to feed Pecten maximus larvae were rich in vitamins; their content compared with diets used in fish culture appeared sufficient, with the possible exceptions of pyridoxine, biotin and pantothenic acid. Vitamins in bacteria, isolated from the larval rearing tank were also analysed, as they can also contribute to the diet. Vitamin B₁₂, -tocopherol and -carotene were detected in very low concentration in bacteria; however, some bacterial strains were rich in pantothenic acid, and the pattern of other vitamins was similar to that from microalgae. The presence of bacteria can complement the diet in panthothenic acid, as it has been demonstrated that bacteria are ingested by larvae. The vitamin content of Pecten maximus larvae was analysed from the second day after hatching to just before metamorphosis. The content of some vitamins, ascorbic acid (C), -tocopherol and -carotene, increased during larval development, suggesting that their requirement was satisfied. However, thiamin and riboflavin decreased during larval development and further studies, possibly using microencapsulated vitamins supplements, are needed to determine whether these vitamins are limiting during larval development.     

Bacterial colonization of winter flounder Pseudopleuronectes americanus fed live feed enriched with three different commercial diets

The proliferation of bacteria in intensive aquaculture systems may be responsible for poor growth and mass mortality of marine fish larvae. Essential fatty acids provided in the diet could protect larvae by modulation of the immune response via arachidonic acid (AA) and eicosapentaenoic acid (EPA). Winter flounder Pseudopleuronectes americanus larvae were fed rotifers Brachionus plicatilis enriched with three commercial diets containing different fatty acid profiles. Bacterial colonization on the gills and skin and in the intestinal lumen was evaluated at the end of the rotifer feeding period (day 26), and growth was surveyed until metamorphosis. At 26 days post hatching, larvae fed rotifers containing the higher AA content and with a higher docosahexaenoic acid (DHA) to EPA ratio showed better growth and the lowest bacterial colonization of the intestinal lumen compared to larvae fed rotifers with the lowest AA and DHA : EPA levels. AA had been selectively incorporated into the polar lipids of larvae fed the rotifers enriched with the three diets. This is the first study in winter flounder larvae to report a link between different commercial rotifer enrichments and bacterial density in intestinal lumen.     

Mortality control of scallop larvae in the hatchery

Larval mortalities occurring in molluscan hatcheries have often been associated with bacterial contamination, and more specifically with vibrios. Although batches of oyster and clam larvae have been routinely reared in the hatchery of Argenton (North Brittany, France) without antibiotics, high larval mortalities have been recorded with the great scallop, Pecten maximus, under similar conditions. For this species, an addition of antibiotics was found necessary and chloramphenicol was used at a concentration of 8 mg l^–1. However, this chemical has now been banned in Europe, making either substitution products or an improvement in the rearing procedures essential. Studies carried out have shown that neither a decrease in larval density (to 1 larva ml^–1) nor an increase in seawater change frequency (to one per day) had any positive effects. Furthermore, elective substances such as sugars were not suitable and the use of another antibiotic, erythromycin, led to inconsistent results. The only positive effects were obtained with lower levels of chloramphenicol, which does not resolve the problem. Because no alternative solutions have as yet been found, further research needs to be undertaken.     

文蛤浮游期发病幼虫细菌群落分析和致病菌的分离鉴定

为研究文蛤育苗过程中幼虫病害及其主要致病菌,实验通过构建细菌16S rDNA克隆文库、病原菌分离纯化、人工感染和药敏实验等方法对育苗场发病的浮游期文蛤壳顶幼虫样品进行了系统分析。结果显示,发病的文蛤壳顶幼虫细菌群落多样性低,地中海弧菌占比高达75%以上,推断其可能为引发此次幼虫发病的主要致病菌。从发病幼虫的匀浆组织中分离获得该优势菌株,测序及系统发育鉴定为地中海弧菌。人工感染实验确定了其致病性,菌株US2-01在1.0×10⁶ CFU/mL的菌液浓度下浸泡感染文蛤浮游幼虫,96 h累计死亡率为84%。药敏实验表明,地中海弧菌菌株US2-01在12种抗生素的测试中对常用的青霉素、氨苄西林、红霉素等抗生素具有一定的耐药性,对四环素和多西环素中度敏感,对头孢他啶、庆大霉素、卡那霉素等其余7种抗生素呈现高度敏感。本研究首次报道了地中海弧菌为文蛤浮游期幼虫致病的一种潜在病原,研究结果可为文蛤幼虫疾病研究及贝类苗种培育过程中的病害防控提供科学依据。     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.     

Lactobacillus spp. bacteria as probiotics in gilthead sea bream (Sparus aurata, L.) larvae: Effects on growth performance and digestive enzyme activities

In this study, the influence of commercial probiotic, Lactobacillus spp., supplementation was investigated on growth parameters and digestive enzyme activities in gilthead sea bream, Sparus aurata, during larval development. All experiments were triplicated and designed in three different administrations of probiotic from 3 days after hatching (DAH) concurrently with starting of exogenous feeding. In the first group, probiotic was added to live food (rotifer and Artemia). In the second group, probiotic was supplemented directly to both live food and water. In the third group, probiotic was added directly to water. Also, no probiotic treatment was maintained in control group. Total bacterial counts among probiotic probiotic-supplemented groups were significantly different from total bacterial counts in controls in water and digestive tract of larvae (p < 0.05). The mean of total bacterial counts in control was approximately 4 × 10⁴-fold increased from the experimental groups in the sea water (p < 0.05). Besides, mean digestive enzyme activities of all probiotics treatment groups were significantly different (p < 0.05) with that of the control. Except probiotic water supplementation group, in all treatments, the specific activities of pancreatic and intestinal enzymes were significantly higher (p < 0.05) in larvae to which probiotic had been supplemented by live food and live food with water. Also, S. aurata larvae that had probiotic administered by live food with water demonstrated significant (p < 0.05) increases in both survival (13–105% higher) and specific growth rate (2–9% higher) as compared to controls. As a result, supplementation of probiotic to directly tank water could not significantly increase growth parameters and digestive enzyme activities and therefore, administration of probiotics by this method would not be effective in terms of husbandry parameters and nutritional condition.     

Addition of bacteria bioencapsulated in Artemia metanauplii to a rearing system for halibut larvae

Theaim of this study was to determine whether it is possible to influence thespecies composition of the gut microflora in 70-days old halibut larvae(Hippoglossus hippoglossus L.) by addition of bacteriabioencapsulated in Artemia franciscana in two shortpulses.Two Vibrio strains, PB 1-11 and PB 6-1 were used. Twotreatments received each strain alone, a third treatment received the twobacterial strains in mixture, whereas in a control treatment no bacteria wereadded. Five fish tanks were included in each treatment. The bacteria werebioencapsulated in Artemia franciscana metanauplii duringashort-term incubation in bacterial suspensions of the specific strains, andwereadded in two pulses, on day 1 and day 10 of the experiment. Addition ofbacteriadid not increase the total number of colony-forming units (CFU) in the larvalgut. The total CFU in the water was lower in tanks added bioencapsulatedbacteria than in the control treatment (p < 0.05). Animmunocolony blot assay was used to measure the numbers of the specificbacteriaadded in samples of water, A. franciscana, and fishlarvae.At the end of the experiment on day 13, the strain PB 1-11 reached on average10% of the total CFU when added alone and 25% when added in mixture with PB6-1.Strain PB 6-1 reached at the end of the experiment 26.8% of the total CFU whenadded alone and 24.2% when added in mixture with PB 1-11, whereas thepercentages of PB 1-11 and PB 6-1 in the control fish were 12.7% and 10.8% ofthe total CFU, respectively. However, the differences between the experimentaltreatments compared with the control group were not significant(p > 0.05). The addition of bioencapsulated bacteria intwo pulses within a ten days period was therefore not sufficient to influencethe species composition of the microflora of the halibut larvae.     

Effects of docosahexaenoic acid on growth,survival and swim bladder inflation of larval amberjack ( Seriola dumerili, Risso)

The effect of docosahexaenoic acid (DHA) on the growth performance, survival and swim bladder inflation of larval Seriola dumerili during the rotifer feeding period was investigated in two feeding experiments. Amberjack larvae at 3 day post hatching were fed rotifers enriched with (1) freshwater C hlorella (Chlo), (2) a mixture (2:1, v/v) of Chlo and DHA‐enriched C hlorella (DHA‐Chlo), (3) DHA‐Chlo and (4) DHA‐Chlo and commercial DHA emulsion, in triplicate for 7 days. The average DHA contents of the rotifers were 0.0, 0.4, 1.0 and 1.9 mg g^?1 DM respectively. The survival rate was improved by the enrichment of rotifers with DHA‐Chlo alone, and DHA‐Chlo and emulsion. Growth and swim bladder inflation of fish fed rotifers enriched with DHA‐Chlo were significantly (P < 0.05) improved, however, with increased levels of DHA further improvement was not found. DHA content in the larval whole body proportionally increased with the DHA level in the rotifers. These results suggest that DHA enrichment of rotifers is effective to improve the growth, survival rate and swim bladder inflation of amberjack larvae. The DHA requirement of amberjack larvae is estimated to be 1.5 mg g^?1 on a dry matter basis of rotifers.     

Three different lipid sources in formulated start-feeds for turbot (Scophthalmus maximus, L.) larvae – effect on growth and mitochondrial alteration in enterocytes

Turbot, Scophthalmus maximus, larvae were start‐fed with formulated feeds containing soya phospholipids (SP), marine phospholipids (MP) or triacylglycerol (TAG). The levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were the same in the MP and TAG feeds. The control group was given rotifers (R). The larvae were offered feed from day 4 post‐hatch. Larvae fed formulated feed with added MP showed good initial growth and there were no significant differences in weight on day 6 between this group and the group given rotifers. Using feed with added TAG enriched with EPA and DHA gave no growth at all. Using SP as the lipid source in the feed resulted in reduced initial growth. Electron microscopical examination of enterocytes was performed on larval intestines on day 6. Larvae fed MP, TAG or rotifers had normal looking enterocytes with numerous normal looking mitochondria. In the enterocytes of larvae fed SP the mitochondria appeared swollen with a translucent matrix and fragmented cristae. Thus, SP or TAG appear not to be suitable as the sole source of lipids and/or phospholipids in start‐feed for turbot larvae and the effects of MP are not solely caused by high levels of EPA and DHA.     

Waste‐grown phototrophic bacterium supports culture of the rotifer,Brachionus rotundiformis

The present and commonly used batch culture system (BCS) as adopted by many small‐scale tropical hatcheries is beset by poor rotifer production and sudden crashes. This study aimed to produce nutritive rotifers and evaluate their performance based on the BCS by using phototrophic bacteria (PB) that can be easily and cheaply cultured from palm oil mill effluent (POME), an agro‐industrial byproduct usually discarded as waste. Brachionus rotundiformis given a sole diet of POME‐grown PB (Rhodovulum sulfidophilum) grew as well as on the commercially produced microalgae, Nannochloropsis. Production, growth rate and fecundity of rotifers fed condensed bacterial cells (bPB) and culture broth of bacteria grown in POME (cPB) were evaluated. The best performance in terms of the stated parameters was obtained for rotifers fed 200 mL of cPB in 3 L of culture water; this media sustained a mean rotifer density of 600–900 individuals mL^?1 after 3–6 days of culture. The biochemical composition of rotifers fed PB was comparable to those fed microalgae, except that the former contained more polyunsaturated fatty acids.