The Effect of Maturation Diets on the Reproductive Output of the White‐striped Cleaner Shrimp,Lysmata amboinensis

Aquaculture production of the cleaner shrimp Lysmata amboinensis, a high‐valued marine ornamental, has been problematic because of prolonged larval development punctuated by periods of mortality. Broodstock maturation diets have been shown to affect fecundity and offspring quality and early survival. The common practice in shrimp culture is the use of fresh frozen foods supplemented with artificial diets. The objective of the study was to identify a suitable maturation diet (natural or artificial) for L. amboinensis. Six diets, comprised of squid, mussel, adult Artemia, a commercial feed, and combinations of the aforementioned, were fed to L. amboinensis for four reproductive cycles. Broodstock fed the squid–mussel diet lost a large proportion of the eggs during incubation, with decreased larval production (P < 0.05). In contrast, broodstock fed Artemia retained the highest proportion of the egg mass; however, hatchability was poor, resulting in low larval numbers per hatch. The Artemia and squid–mussel diets produced significantly fewer larvae than the combination or commercial diets (P < 0.05). In L. amboinensis, a maturation diet consisting of natural feeds alone resulted in poor reproductive performance and partial or complete replacement with an artificial diet was feasible.     

Successful rearing of whiteleg shrimp Litopenaeus vannamei larvae fed a desiccation‐tolerant nematode to replace Artemia

The nematode Panagrolaimus sp. was tested as live feed to replace Artemia nauplii during first larval stages of whiteleg shrimp Litopenaeus vannamei. In Trial 1, shrimp larvae were fed one of four diets from Zoea 2 to Postlarva 1 (PL1): (A) Artemia nauplii, control treatment; (NC) nematodes enriched in docosahexaenoic acid (DHA) provided by the dinoflagellate Crypthecodinium cohnii; (N) non‐enriched nematodes; and (Algae) a mixture of microalgae supplemented in C. cohnii cells. In Trial 2, shrimp were fed (A), (NC) and a different treatment (NS) with nematodes enriched in polyunsaturated fatty acids (PUFAs) provided by the commercial product S.presso^®, until Postlarva 6 (PL6). Mysis 1 larvae fed nematodes of the three dietary treatments were 300 μm longer (3.2 ± 0.3 mm) than control larvae. At PL1, control shrimp were 300 μm longer (4.5 ± 0.3 mm) than those fed DHA‐enriched or PUFAs‐enriched nematodes. No differences were observed in length and survival at PL6 between control larvae and those fed DHA‐enriched nematodes (5.1 ± 0.5 mm; 33.1%–44.4%). Shrimp fed microalgae showed a delay in development at PL1. This work is the first demonstration of Panagrolaimus sp. suitability as a complete substitute for Artemia in rearing shrimp from Zoea 2 to PL6.     

Differences in fatty acid composition of egg capsules from broodstock spotted babylon, <Emphasis Type="Italic">Babylonia areolata</Emphasis>, fed a local trash fish and formulated diet under hatchery conditions

This study is the first attempt to condition broodstock Babylonia areolata using formulated diets under hatchery conditions. Samples of spotted babylon egg capsules from broodstock fed either a formulated diet or a local trash fish, carangid fish (Seleroides leptolepis) for 120 days were analyzed for proximate composition and fatty acid composition. The formulated diet contained significantly higher levels of arachidonic acid (20:4n − 6; ARA), eicosapentaenoic acid (20:5n − 3; EPA) and docosahexaenoic acid (22:6n − 3; DHA) than those of the local trash fish. The formulated diet also had significantly higher ratios of DHA/EPA and (n − 3)/(n − 6) PUFA than those of local trash fish but not for the ARA/EPA ratio. The compositions of egg capsules produced from broodstock fed formulated diet contained significantly more ARA, EPA and DHA compared to broodstock fed the local trash fish. The ARA/EPA and DHA/EPA ratios in egg capsules were significantly higher in the trash fish—fed group compared to those fed the formulated diet. However, (n − 3)/(n − 6) PUFA ratios in egg capsules produced from broodstock fed the formulated diet did not differ significantly compared to those from broodstock fed the local trash fish. The relatively low DHA/EPA, ARA/EPA and (n − 3)/(n − 6) ratios in the egg capsules produced from the formulated diet—fed broodstock B. areolata suggested that this diet is inferior, when compared to the traditional food of trash fish.     

Effect of Artemia enrichment on the growth and survival of Pacific bluefin tuna Thunnus orientalis (Temminck & Schlegel) larvae

This study was carried out to investigate the suitability of Artemia enriched with docosahexaenoic acid (DHA) and choline as live food on the growth and survival rate of the Pacific bluefin tuna (PBT; Thunnus orientalis) larvae. The PBT larvae were fed either Artemia enriched with oleic acid (Diet 1), DHA (Diet 2), DHA+choline 1.0 mg L^?1 (Diet 3) and DHA+choline 2.0 mg L^?1 (Diet 4) or striped knifejaw larvae (Diet 5, reference diet), in duplicate for 12 days. Enrichment of Artemia with DHA significantly increased the DHA levels to 13.9, 13.8 and 12.5 mg g^?1 on a dry matter basis in Diets 2, 3 and 4 respectively; however, the levels were significantly lower than the reference diet (26.9 mg g^?1 dry matter basis; Diet 5). Although growth and survival rate were significantly improved by the enrichment of Artemia with DHA and choline, the improvement was negligible compared with the enhanced growth and survival rate of the fish larvae‐fed group (P<0.05). The results demonstrated that enriched Artemia does not seem to be the right choice to feed the PBT larvae perhaps because of the difficulties in achieving the correct balance of fatty acid with higher DHA/EPA from Artemia nauplii.     

Effect of different enrichment products rich in docosahexaenoic acid on growth and survival of meagre,Argyrosomus regius (Asso, 1801)

Live prey used in aquaculture to feed marine larval fish – rotifer and Artemia nauplii – lack the necessary levels of n‐3 polyunsaturated fatty acids (n‐3 PUFA) which are considered essential for the development of fish larvae. Due to the high voracity, visual feeding in conditions of relatively high luminosity, and cannibalism observed in meagre larvae, a study of its nutritional requirements is needed. In this study, the effect of different enrichment products with different docosahexaenoic acid (DHA) concentrations used to enrich rotifers and Artemia metanauplii have been tested on growth, survival, and lipid composition of the larvae of meagre. The larvae fed live prey enriched with Algamac 3050 (AG) showed a significantly higher growth than the rest of the groups at the end of the larval rearing, while the larvae fed preys enriched with Multigain (MG) had a higher survival rate. DHA levels in larvae fed prey enriched with MG were significantly higher than in those fed AG‐enriched prey. High levels of DHA in Artemia metanauplii must be used to achieve optimal growth and survival of meagre larvae.     

Delivery of HUFA, probionts and biomedicine through bioencapsulated Artemia as a means to enhance the growth and survival and reduce the pathogenesity in shrimp Penaeus monodon postlarvae

One of the major problems in the shrimp culture industry is the difficulty in producing high-quality shrimp larvae. In larviculture, quality feeds containing a high content of highly unsaturated fatty acids (HUFA) and ingredients that stimulate stress and disease resistance are essential to produce healthy shrimp larvae. In the present study, Penaeus monodon postlarvae (PL15) were fed for 25 days on an unenriched Artemia diet (control; A) or on a diet of Artemia enriched with either HUFA-rich liver oil of the trash fish Odonus niger (B), probionts [Lactobacillus acidophilus (C1) or yeast-Saccharomyces cerevisiae (C2)] or biomedicinal herbal products (D) that have anti-stress, growth-promoting and anti-microbial characteristics. P. monodon postlarvae fed unenriched Artemia exhibited the lowest weight gain (227.9 ± 8.30 mg) and specific growth rate (9.95 ± 0.05%), while those fed the HUFA-enriched Artemia (B) exhibited the highest weight gain and specific growth rate (362.34 ± 12.56 mg and 11.77 ± 0.08%, respectively). At the end of the 25-day rearing experiment, the shrimp postlarvae (PL40) were subjected to a salinity stress study. At both low and high (0 and 50‰) salinities, the group fed the control diet (A) experienced the highest cumulative mortality indices (CMI) 935.7 ± 2.1 and 1270.7 ± 3.1, respectively. Those fed diet D showed the lowest stress-induced mortality, and CMI were reduced by 31.1 and 32.3% under conditions of low and high salinity stress, respectively. A 10-day disease challenge test was conducted with the P. monodon postlarvae (PL40–PL50) by inoculating the shrimp with the pathogen Vibrio harveyi at the rate of 10⁵–10⁷ CFU/ml in all rearing tanks. P. monodon postlarvae fed probiont-encapsulated Artemia diets (C1 and C2) exhibited the highest survival (94.3 and 82.3%, respectively) and lowest pathogen load (V. harveyi) in hepatopancreas (5.2 × 10² ± 9.0 × 10 and 4.6 × 10² ± 9.0 × 10 CFU g⁻¹, respectively) and muscle (2.0 × 10² ± 6 × 10 and 1.7 × 10² ± 8.6 × 10 CFU g⁻¹, respectively) tissues. The shrimp that were fed the unenriched Artemia (Control; A) showed the lowest survival (26.33%) and highest bacterial load in the hepatopancreas (1.0 × 10⁵ ± 5 × 10³ CFU g⁻¹) and muscle (3.6 × 10⁴ ± 6 × 10² CFU g⁻¹). The shrimp fed the herbal product (D)-enriched Artemia also exhibited enhanced survival and reduced V. harveyi load in the tissues tested compared to the control diet (A) group. The results are discussed in terms of developing a quality larval feed to produce healthy shrimp larvae.     

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.     

Iodine enrichment of Artemia and enhanced levels of iodine in Atlantic halibut larvae (Hippoglossus hippoglossus L.) fed the enriched Artemia

Flatfish metamorphosis is initiated by the actions of thyroid hormones (TH) and iodine is an essential part of these hormones. Hence, an iodine deficiency may lead to insufficient levels of TH and incomplete metamorphosis. In this study, different iodine sources for enrichment of Artemia were evaluated and the levels of iodine obtained in Artemia were within the range of 60–350 μg g^?1 found in copepods. Larval Atlantic halibut was fed Artemia enriched with either normal DC‐DHA Selco or DC‐DHA Selco (commercial enrichments) supplemented with iodine from days 9 to 60 postfirst feeding. There was no significant difference in growth, mortality or metamorphic development between the groups. The analyses showed that we were able to enrich Artemia with iodine. Further, the larvae‐fed iodine‐enriched Artemia had higher whole body iodine concentration compared to larvae‐fed Artemia without iodine enrichment.     

The effect of docosahexaenoic and eicosapentaenoic acids in live food on the development of abnormal morphology in hatchery-reared brown sole Pseudopleuronectes herzensteini

We examined the effect of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on the rates of abnormal morphology in juvenile brown sole Pseudopleuronectes herzensteini. Larvae during the D–E stages (15–24 days post hatching) were fed live food containing various amounts of DHA and/or EPA prepared using emulsified oils (DHA ethyl ester, EPA ethyl ester, and corn oil). Larvae during the F–I stages were fed Artemia enriched with a commercial diet supplement. We found that DHA and EPA promoted larval development and improved the incidence of morphological abnormalities in brown sole juveniles to a similar extent. However, DHA was more effective than EPA in preventing the appearance of morphological abnormalities in brown sole. The incidence of normal morphology was clearly improved by an increase of the DHA content in brown sole larvae at 25 days post-hatching. These results suggest that it is important to promote larval development and feed larvae with live food containing high levels of DHA during the D–E stages to prevent morphological abnormalities in brown sole juveniles.     

A Comparison of Growth,Survival, and Fatty Acid Composition of the Lined Seahorse,Hippocampus erectus,Juveniles Fed Enriched Artemia and a Calanoid Copepod,Schmackeria dubia

The purpose of this study was to evaluate the effect of varying dietary levels of highly unsaturated fatty acids (HUFAs) in live prey (Artemia nauplii and a calanoid copepod, Schmackeria dubia) on the growth performance, survival, and fatty acid composition of the lined seahorse, Hippocampus erectus, juveniles. Artemia nauplii were enriched with a commercial product (SS^? 50DE‐microcapsule as HUFA source, 2/3 DHA, 1/3 EPA. Shengsuo Fishery Feed Research Center of Shandong Province, Qingdao, China) at four concentrations of 0.0, 14.0, 28.0, and 56.0. Newly hatched juveniles were cultured for 35 days. The content of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and n‐3 HUFAs in the Artemia nauplii was positively related to the enrichment concentration. At the end of the trials, growth performance of the juveniles was positively related to the enrichment concentration as well. However, the juveniles fed prey enriched with the highest concentration of enrichment (56.0 μL/L) had the significantly lower (P < 0.05) survival rate. The juveniles fed the copepod had the best growth performance and the highest survival rate, suggesting that the copepod, S. dubia, is suitable for feeding the seahorse juveniles. The comparisons between the growth, survival, and fatty acid profiles of the juveniles fed Artemia and copepods indicate that the seahorse juveniles require dietary levels of DHA beyond those achieved by enriching prey with the HUFA enrichment. Surplus EPA resulted from an imbalance between DHA and EPA in the enriched Artemia nauplii probably caused an adverse effect on the seahorse juveniles. This study suggests that DHA and EPA requirement of the lined seahorse juveniles is roughly 32% of total fatty acid, and the optimal DHA/EPA ratio for the species is circa 4:1. To avoid an adverse effect resulting from excessive EPA, maximum proportion of EPA in enriched Artemia nauplii should not exceed 13% of total fatty acid, and a recommended minimum DHA/EPA ratio in the enriched Artemia nauplii is 1.46. Arachidonic acid (20:4n‐6) might not be an essential fatty acid for the seahorse juveniles.     

Survival and Growth Improvement of Palm Ruff,Seriolella violacea,Larvae Fed Artemia Nauplii Enriched with an Experimental Emulsion

The palm ruff, Seriolella violacea (Cojinoba), is a potential new species for Chilean aquaculture. To approach Cojinoba larviculture, an experimental Artemia enrichment emulsion, containing docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) = 2.5, supplemented with vitamin E, astaxanthin, and β‐glucan, was evaluated in both Artemia and Cojinoba larvae, 30–50 d.a.h. This study tested an experimental enrichment emulsion versus a commercial emulsion, with an integral approach of multicompound emulsions. After 23 h enrichment, experimental emulsion (EE)‐enriched nauplii reached DHA and EPA concentrations of 23.8 and 18.7 mg/g dry weight (dwt), respectively, while in Cojinoba larvae they were 18.4 and 19.7 mg/g dwt. Control emulsion (CE)‐enriched nauplii exhibited lower DHA and EPA (6.1 and 7.7 mg/g dwt), while only DHA decreased in the control larvae (12.6 mg/g dwt). Vitamin E was higher in EE‐enriched nauplii (29.2 mg/100 g dwt) than in the control (8.4 mg/100 g dwt). Larvae fed EE‐enriched Artemia exhibited 8% increase in survival and 19% in growth compared with the control. Astaxanthin was detected only in larvae fed EE‐enriched nauplii. The tumor necrosis factor‐α concentration was not significantly different between larvae fed EE‐ and CE‐enriched nauplii. EE looks promising as an Artemia enrichment and experimental diet to assess palm ruff larval requirements, and has a positive impact on fish larvae performance.     

The effect of PUFA enriched Artemia on growth, survival and lipid composition of western rock lobster, Panulirus cygnus, phyllosoma

Western rock lobster, Panulirus cygnus, phyllosoma were grown from hatching to stage IV. Larvae were fed with Artemia enriched with a (i) base enrichment (Base) containing 520 g kg^?1 squid oil or tailor made enrichments in which oils high in polyunsaturated fatty acid (PUFA) have been added at the expense of squid oil. These treatments were (ii) base enrichment supplemented with docosahexaenoic acid (DHA) rich oil, (iii) base enrichment supplemented with arachidonic acid (AA) rich oil, or (iv) base enrichment supplemented with DHA and AA (D + A) rich oils. Total survival of phyllosoma to stage IV was high, with no significant difference between treatments (range 12.3–17.5%). By stage IV, the larvae fed the DHA or AA enriched Artemia were significantly larger (3.33 mm length) than larvae fed the Base or D + A enriched Artemia (3.18–3.24 mm length). Phyllosoma were sampled at stages II and III for biochemical analysis. The major lipid class (LC) in all phyllosoma was polar lipid (PL) (88.9–92.4%), followed by sterol (ST) (6.2–9.7%). Triacylglycerol (TAG), free fatty acid (FFA) and hydrocarbon/wax ester were minor components (≤1%) in all phyllosoma samples. In contrast, the major LC in all enrichments and enriched Artemia was TAG (76.3–85.1% and 53.4–60.2%, respectively), followed by PL (11.4–14.8% and 30.6–38.1% respectively). The main fatty acids (FA) in phyllosoma were 16:0, 18:1n‐9, 18:1n‐7, 18:0, AA, eicosapentaenoic acid (EPA) and DHA. Addition of AA, and to a lesser extent DHA, to enrichments resulted in increased levels of those FA in Artemia and phyllosoma compared with the Base enrichment. This was particularly evident for stage III larvae. Comparatively, elevated growth for phyllosoma to stage IV was achieved with DHA and AA enriched diets. Our findings highlight the importance of lipids and in particular essential long‐chain PUFA, as nutritional components for phyllosoma diets.     

Effect of hot water extracts of brown seaweeds Sargassum spp. on growth and resistance to white spot syndrome virus in shrimp Penaeus monodon postlarvae

An experiment was conducted to evaluate the effect of a hot water extract of brown seaweeds Sargassum duplicatum and Sargassum wightii on the growth and white spot syndrome virus (WSSV) resistance in shrimp Penaeus monodon postlarvae (PL). Artemia nauplii (instar II) were enriched with both seaweed extracts at various concentrations (250, 500 and 750 mg L^?1) and fed to the respective P. monodon (PL15–35) group for 20 days. A control group was also maintained without seaweed extract supplementation. The weight gain of the experimental groups was significantly higher (0.274–0.323 g) than the control group (0.261 g). Similarly, the specific growth rate was also significantly higher (16.27–17.06%) in the experimental groups than in the control group (16.03%). After 20 days of the feeding experiment, the shrimp PL were challenged with WSSV for 21 days. During the challenge test, the control shrimp displayed 100% mortality within 8 days. In contrast, the mortality percentage of the highest concentration (750 mg L^?1) of seaweed extract enriched Artemia nauplii fed shrimp was 54–79%. Comparatively, low mortality was observed in S. wightii extract‐enriched Artemia nauplii fed shrimp. The polymerase chain reaction analysis indicated the concentration‐dependent infection of WSSV in P. monodon PL.     

Lipid enrichment for Senegalese sole (Solea senegalensis) larvae: effect on larval growth, survival and fatty acid profile

Results from three larval Senegalese sole (Solea senegalensis) feeding trials using non-enriched Artemia and Artemia enriched with Super HUFA®, Arasco®, sunflower oil and microalgae are presented and the effects on larval survival, growth and fatty acid (FA) composition are reported. The FA profile of Senegalese sole eggs was analysed to gather information about the nutritional requirements of the early larval stages and a quite high DHA/EPA ratio (4.3) was found. However, there was no evidence of a high dietary demand for DHA or EPA, given that no relationship was found between dietary HUFA concentration and larval growth and survival. When larvae were fed non-enriched Artemia a significantly better growth and comparable survival were obtained than with Artemia enriched with Super HUFA® (containing the highest HUFA level and DHA/EPA ratio). The FA profiles of the larvae generally reflected those of their diets. DHA was an exception, as it was present in high proportions, even in larvae fed DHA-deficient prey. Total FAME concentration decreased during larval development, with SFA, MUFA and PUFA being equally consumed; HUFA appeared to be less used, with its relative concentration being either kept constant (particularly EPA and ARA) or increased (DHA). A specific requirement for ARA in the first larval stages could not be confirmed but it was always present in considerable amounts, even in larvae fed an ARA poor diet.     

Growth and lipid composition of Atlantic cod (Gadus morhua) larvae in response to differently enriched Artemia franciscana

Considerable progress has been achieved in the intensive culture of Atlantic cod (Gadus morhua). However, there is little information concerning optimum live-feed enrichments for cod larvae, since many of the techniques used during the larviculture have been borrowed from other fish species and adapted for the production of Atlantic cod. The present study compared four different protocols for the enrichment of Artemia to be used as live feed for cod larvae. The protocols tested were: (1) AlgaMac 2000, (2) AquaGrow Advantage, (3) Pavlova sp. + AlgaMac 2000, and (4) DC DHA Selco + AlgaMac 2000. Larvae were fed differently enriched Artemia between 37 and 59 days post hatch. At the end of the experiment, larvae from treatment 1 [specific growth rate (SGR) = 10.4 ± 0.4% day⁻¹] grew faster than larvae from treatments 3 (SGR = 6.9 ± 0.2% day⁻¹) and 4 (SGR = 4.9 ± 0.4% day⁻¹, P < 0.0001). However, treatments 3 and 4 resulted in better larval survival at the end of the experimental period, estimated to be 3 on a scale from 1 to 5, whereas the survival estimates for the two other groups were 2. The treatments affected the fatty-acid composition of Artemia and of cod larvae. Larvae from treatment 1 had a higher percentage of AA (20:4ω6, P < 0.0001) and ω6DPA (22:5ω6, P < 0.0001) than the other larvae. Levels of DHA (22:6ω3) were similar in larvae from treatments 1 and 4, and higher than in the other larvae (P < 0.0001). Our results suggest that Artemia containing a DHA/EPA/AA ratio of 7/2/1 result in good larval performance. Joseph A. Brown—Deceased September 2005.     

Effects of supplementation of decapod zoea to Artemia basal diet on fatty acid composition and digestive gland histology in common octopus (Octopus vulgaris) paralarvae

The present study aimed to evaluate the effect of the supplementation of different crab zoeas to enriched Artemia basal diet for Octopus vulgaris paralarvae during the first month of life. Paralarvae were fed using enriched Artemia nauplii alone and Artemia co‐fed either first zoea stages of Grapsus adscensionis or Plagusia depressa. The experiment was carried out over a period of 28 days, in 0.12 m³ tanks with a flow‐through rearing system. Growth in dry weight as well as mantle length and width were assessed weekly. Additionally, prey and paralarvae fatty acid composition and digestive gland (DG) histology were evaluated. Addition of low amounts of crab zoeas (approx. 100 indv. L^?1 day^?1) provided during critical life stages of O. vulgaris proved to be good enough to improve paralarvae growth and survival in comparison with those fed exclusively on enriched Artemia. These results were supported by the finding of a higher number of glycoprotein absorption vacuoles in the DG from paralarvae co‐fed crab zoeas, suggesting a higher feeding activity. In addition, fatty acid analysis of crab zoea showed that these are good sources of dietary arachidonic and eicosapentaenoic acids during the octopus planktonic life stage, whereas the low docosahexaenoic (DHA) content suggests the use of additional DHA sources or higher zoea densities to meet paralarvae nutritional demand to carry out a successful metamorphosis to benthic life.     

A comparison of the fatty acid profiles of adult tissues,and newly hatched,fed and starved Lysmata amboinensis larvae

This study evaluated the lipid content and fatty acid (FA) profile of the hepatopancreas, ovaries and tail muscle of Lysmata amboinensis broodstock, as well as newly hatched larvae subjected to a period of starvation or feed from hatch to Zoea 2. The hepatopancreas had a high lipid content, confirming its role as a process and storage organ in L. amboinensis. Lipids were also a major component of ovarian dry weight, in agreement with reports on other crustaceans during maturation. The tail muscle, being a functional rather than a storage organ, contained low total lipids and was the tissue that closely resembled the FA profile of the newly hatched larvae. Saturated fatty acids (SFAs) and highly unsaturated fatty acids (HUFAs) were the most abundant components of the lipid profiles in broodstock and larvae. The HUFAs docosahexaenoic and eicosapentaenoic were preferentially retained during nutritional stress, confirming their importance for marine cleaner shrimp during early larval development. It appeared polyunsaturated fatty acid and HUFA requirements were met through the larval diet. The SFAs stearic and palmitic were abundant in adult tissues and larvae, whereas monounsaturated fatty acids may have been preferentially catabolized to meet energetic and metabolic larval requirements.     

Incidence of systemic granulomatosis is modulated by the feeding sequence and type of enrichment in meagre (Argyrosomus regius) larvae

Systemic granulomatosis is the most frequent disease in juvenile and adult meagre, but studies regarding the first appearance of granulomas in larvae do not exist. In order to evaluate this, meagre larvae were fed four different feeding regimes as follows: RS and RO (rotifer enriched with Easy DHA Selco or Ori‐Green from 3 to 30 dph respectively), RAS and RAO (rotifer enriched with Easy DHA Selco or Ori‐Green from 3 to 21 dph and Artemia enriched with Easy DHA Selco or Ori‐Green from 12 to 30 dph respectively). All treatments were also fed with commercial microdiet from 20 to 30 dph. At 30 dph weight, length, specific growth rate and survival were significantly higher in Artemia‐fed larvae, regardless of the enrichment. Microscopic first appearance of granulomas was observed in 20 dph larvae fed RS and RO. At 30 dph granulomas and thiobarbituric acid reactive substances (TBARS), values were significantly higher in RS and RO‐fed larvae than in RAS and RAO‐fed larvae. The results showed that granulomas first appeared in meagre larvae at 20 dph when fed rotifers only. Conversely, a reduced appearance of granulomas and lipid peroxidation occurs when Artemia is included in the feeding sequence reinforcing the hypothesis of a nutritional origin of the systemic granulomatosis.     

Effects of dietary docosahexaenoic acid (22:6n‐3) and arachidonic acid (20:4n‐6) on the growth,survival, stress resistance and fatty acid composition in black sea bass Centropristis striata (Linnaeus 1758) larvae

The objectives of this study were to determine the effects of the dietary docosahexaenoic acid (DHA) to arachidonic acid (ARA) ratio on the survival, growth, hypersaline stress resistance and tissue composition of black sea bass larvae raised from first feeding to metamorphic stages. Larvae were fed enriched rotifers Brachionus rotundiformis and Artemia nauplii containing two levels of DHA (0% and 10% total fatty acids=TFA) in conjunction with three levels of ARA (0%, 3% and 6% TFA). On d24ph, larvae fed the 10:6 (DHA:ARA) treatment showed significantly (P<0.05) higher survival (62.3%) than larvae fed 0:0 (DHA:ARA) (27.4%). Notochord length and dry weight were also significantly (P<0.05) greater in the 10:6 (DHA:ARA) treatment (8.65 mm, 2.14 mg) than in the 0:0 (DHA:ARA) (7.7 mm, 1.65 mg) treatment. During hypersaline (65 g L⁻¹) challenge, no significant differences (P>0.05) were observed in the median survival time (ST50) between larvae fed 10% DHA (ST50=25.6 min) and larvae fed 0% DHA (ST50=18.2 min). The results suggested that black sea bass larvae fed prey containing 10% DHA with increasing ARA within the range of 0–6% showed improved growth and survival from first feeding through metamorphic stages.     

Effects of early weaning strategies on growth,survival and digestive enzyme activities in cobia (<Emphasis Type="Italic">Rachycentron canadum</Emphasis> L.) larvae

The effects of weaning strategies of cobia (Rachycentron canadum L.) larvae to commercial microdiets, either from rotifers or from Artemia, on growth, survival and enzymatic digestive capacity, were investigated. In the first experiment, cobia larvae were weaned from rotifers by co-feeding with a microdiet (Otohime) from 8, 13 or 20 days post-hatching (dph). The larvae in the control treatment were fed rotifers (2–12 dph), Artemia nauplii from 7 dph, and co-fed with the microdiet from 20 dph. In the second experiment, the larvae were weaned from Artemia, which was fed to the larvae from 7 dph, by co-feeding with a microdiet (NRD) from 8, 13 or 18 dph. The larvae in control treatment were fed rotifers, then Artemia to the end of the experiment (28 dph). Weaning of cobia larvae onto a microdiet directly from rotifers significantly reduced growth, survival and digestive capacity of the larvae and did not lead to larval acceptance of the microdiet, compared to those weaned from Artemia in the first experiment. Early weaning of cobia larvae onto NRD microdiet (on 8 or 13 dph) from Artemia in the second experiment also reduced growth, survival rate and gut maturation index, compared to those fed live feed. With available microdiets, weaning of cobia larvae could start from Artemia at around 18 dph in order to obtain comparable growth, survival and gut maturation to larvae fed live feed.