Enriched Artemia Research Articles

Captive Breeding and Hatchery Production of Mouth Brooding Jewel Cardinal Perch, Pterapogon Kauderni, (Koumanns, 1933) Using Brackish Water: The Role of Live Prey and Green Water Enrichment in Juvenile Production

An attempt was made to study the captive breeding and larval rearing of the Cardinal fish Pterapogon kauderni using brackish water for the first time in India. P. kauderni, a mouth brooder fish was procured from the traders at the size range of 4-6 cm and acclimatized under captive conditions. Suitable water quality parameters were maintained and standardized. The fish was fed with boiled clam meat, octopus, oyster, squid and trash fish thrice a day. Spawning took place after two months of rearing, in between 10:45-13:00 hrs and hatch out occurred after the sunset. Incubation was in the male’s mouth, which was extended up to 21-23 days and after hatch out, juveniles were separated from the parental tank. The tanks were maintained with optimal physico-chemical conditions as in the parent tanks. Different light intensities and diets were provided for the successful of juveniles rearing. Good survival (58%) was achieved by adopting the photoperiod 24L/0D. the results illustrated that the photoperiod and different diets given to the juveniles influences the physiological performance of the juveniles. SGR, FCR and AGR of juveniles of P. kauderni increased significantly with the increase of the photoperiod (P<0.05). Babies looked like their parents at birth and within a week, they obtained parental coloration. Comparatively higher growth rate was observed, when they were fed with algal enriched artemia than the Poly Unsaturated Fatty Acid (PUFA). Babies reached the marketable size within 45 days. This study deliberately reveals that, breeding and rearing of the marine fish P. kauderni using the estuarine water and also reveals the physiological response of juveniles of P. kauderni to the change of photoperiod and substantiated that photoperiod and different diets influences the juvenile growth, survival and feeding.

Storage and utilization of lipid classes and fatty acids during the early ontogeny of blue king crab, Paralithodes platypus

Stock enhancement, through the release of cultured juveniles, has been suggested as a possible recovery tool for depleted red (Paralithodes camtschaticus) and blue (Paralithodes platypus) king crab populations in Alaska, USA. Considerable progress has been made in the past decade in red king crab culture technology, but similar technologies are less developed for blue king crabs. We examined changes in organic content, lipid classes, and fatty acids (FAs) during the larval (zoeae), post-larval (glaucothoe), and first juvenile stages to understand energetics, nutritional requirements, and potential dietary deficiencies of this new aquaculture species. Total lipids increased throughout the larval stages and then showed a decrease in both total lipids and neutral storage lipids (triacylglycerols) during the non-feeding glaucothoe phase. The proportions of C18 polyunsaturated FAs (PUFAs) dramatically increased from the first zoeal (Z1) to the second zoeal stage (Z2), reflecting the uptake of enriched Artemia FAs. Both the selective retention of C20 & 22 PUFAs relative to their diet and the proportional increase in these PUFAs during the non-feeding glaucothoe stage suggest that they are essential for early growth and survival. Analytical measures of total lipids were highly correlated with a hatchery-based visual assessment of maximum lipid droplet size, an index of relative nutritional health. Formulated hatchery larval diets containing high levels of C20 & 22 PUFAs may optimize nutrition in early ontogeny for blue king crabs, but future research should refine specific ratios and absolute amounts.

Performance and skeletal abnormality of striped trumpeter Latris lineata larvae and post larvae fed vitamin A enriched Artemia

Several nutritional studies have found that excess or reduced dietary vitamin A (VA) causes skeletal malformations in marine fish larvae. Feeding VA enriched rotifers to striped trumpeter (Latris lineata) from 6 to 18 days post hatch (dph) has been shown to affect vertebral column malformations but not jaw malformation. Our study examined the effect of dietary VA during the later Artemia feeding period on the prevalence of malformations. Larvae were initially reared in a 3000 l tank and fed a diet of Algamac-3050 enriched rotifers from 2 to 16 dph. At 16 dph, larvae were transferred to 24 × 300 l tanks and fed Artemia enriched with one of six doses of retinyl palmitate (VA) four times per day from 19 to 44 dph. Enrichment with emulsions containing 0 (control), 795, 1558, 3174, 4911 and 10,518 ng retinyl palmitate mg− 1 emulsion resulted in an average VA in Artemia of 0, 6, 7, 27, 30 and 55 ng retinyl palmitate mg− 1 dry weight (DW). The retinoid content of L. lineata at 44 dph was positively correlated with the enriched Artemia they fed on. Growth in length (15.91 ± 0.31 mm, mean ± SD) and dry weight (5.08 ± 0.32 mg), and survival (26.1 ± 2.9%), were not significantly affected at 44 dph by increasing dietary doses of retinyl palmitate. Retinyl palmitate enrichment in Artemia did not affect jaw malformation in L. lineata, which is contrary to other studies on a range of marine fish species treated with increased doses of dietary VA. By the end of the study, 54 ± 10% and 18 ± 6% of the post larvae across treatments had short lower and open jaws, respectively. Severe jaw malformations affected 50 ± 11% of the post larvae. Early culture of larvae in a larger tank was likely to reduce overall prevalence of jaw malformations compared to previous studies as interaction with tank walls was reduced. The prevalence of vertebral column malformations in 44 dph post larvae (58 ± 4%) were also not affected by dietary VA. The study suggests that the window of influence for dietary VA is during earlier development of bone structures in L. lineata.

Ontogenetic patterns of growth and lipid composition changes of blue swimmer crab larvae: insights into larval biology and lipid nutrition

Blue swimmer crab, Portunus pelagicus, is a commercially important crab throughout the Indo-Pacific region, that plays an important role in the food chains of coastal ecosystems. P. pelagicus undergoes four pelagic zoeal stages and a post-larval megalopal stage before settling as benthic juvenile; however, very limited information is available on larval biology and lipid nutrition of this species. The present comprehensive study investigated survival, growth and ontogenetic changes in lipid composition of P. pelagicus larvae under laboratory conditions. Larvae were fed rotifers (zoea I), rotifers and Artemia (zoea II) and enriched Artemia (zoea III – megalopa), consecutively. Among five larval stages of P. pelagicus, zoea I and II had the shortest durations (2.2–2.3 days), whereas megalopa had the longest duration (4.7 days). As larvae developed, their wet weight, dry weight and carapace length increased exponentially. Lower mortality occurred during zoea II (12.5%) and zoea III (14.3%), coincidental with the lower percentage increments in dry weight and specific growth rate of dry weight during these two stages. Generally, fatty acid composition of larvae can reflect that of their diets. However, increases in mono-unsaturated fatty acids, 20 : 4n-6 and 22 : 6n-3 in megalopa and the first crab compared with zoea IV might suggest that the later larvae were still deficient in essential fatty acids, and that 20 : 4n-6 and 22 : 6n-3 were preferentially accumulated. Therefore, measures of ontogenetic patterns of growth and lipid composition will provide valuable insights for better understanding of larval biology and lipid nutrition of P. pelagicus.

Efficacy of fish oil- and linseed oil-enriched Artemia nauplii on growth performance and stress resistance of tiger barb larvae (Puntius tetrazona)

Fish oil is the important fat source in fish nutrition. High demand for fish oil and low global supply arise a need of alternative oils in fish culture. Plant oils are a good candidate in this case. The aim of the present study was to compare the efficacy of fish oil and linseed oil on growth and stress resistance of tiger barb ( Puntius tetrazona ) larvae. Artemia nauplii were enriched by 2.5, 5 and 7.5 of each oil. The enriched nauplii were offered to larvae for 14 d. thereafter, fish were fed non-enriched nauplii for another 14 d. At the end of the trial, larvae were subjected to osmotic stress and their survival was recorded. There was no significant difference in final weight, SGR and weight gain among the treatments at day 14. However, oil type and oil levels significantly affected these parameters after 28 d. Fish of 2.5-LO and 5-FO groups showed the best and worst performance, respectively. There was no significant difference in survival rate among the treatments, after 14 and 28 d; however, oil type significantly affected survival of the larvae after osmotic stress. Survival of larvae fed on linseed oil-enriched nauplii was significantly higher than that of those fed on fish oil-enriched nauplii. Linseed oil showed significantly better results in growth performance and stress resistance compared to fish oil. It is concluded that linseed oil is more suitable than fish oil for Artemia enrichment to feed tiger barb larvae. The potential reasons for the better performance of larvae fed on linseed oil-enriched Artemia were discussed.

Effect of Temperature on Growth and Survival in Juvenile Opossum Pipefish, Microphis brachyurus : First Observations on the Species in Culture Conditions

In Mexico, natural populations of the opossum pipefish, Microphys brachyurus, are under pressure by anthropogenic alteration of their habitat and unregulated fishing as this species is traded as an aquarium fish, where its survival is low due to inadequate culture practices. The development of culturing techniques has been a successful strategy to protect many exploited species through providing an alternative source to wild exploitation. The aim of this study was to examine the effect on growth, condition, and survival of pipefish cultured for 6 wk at temperatures of 26, 28, and 30 C. Pipefish were fed enriched Artemia nauplii maintaining a ration rate of 14% body weight per day (dry weight Artemia : wet weight fish). The pipefish cultured at 26 and 28 C were longer, heavier, grew faster, and presented better condition than those at 30 C. The survival of pipefish cultured at 26 C was greater (83%) than at 30 C (30%) but not different than at 28 C (50%). This study is the first to report the acceptance of Artemia nauplii by juveniles of the species and that a temperature of 30 C is not suitable for juvenile M . brachyurus culture.

Therapeutic effect of Artemia enriched with Escherichia coli expressing double-stranded RNA in the black tiger shrimp Penaeus monodon

We exploited Artemia as a double-stranded (ds)RNA-delivery system to combat viral diseases in shrimp. First, the transformed Escherichia coli (E. coli) expressing red fluorescent protein (RFP) was tested in the Artemia enrichment process. RFP signals detectable in the gut of Artemia under confocal microscope were evident for the successful encapsulation. Second, the Artemia enrichment process was performed using E. coli producing Laem-Singh virus (LSNV)-specific dsRNA, which has been previously shown to inhibit the viral infection in the black tiger shrimp Penaeus monodon by intramuscular injection and oral administration. The enriched Artemia nauplii were confirmed to contain dsRNA-LSNV by RT-PCR, and were subjected to the feeding test with P. monodon postlarvae. Quantitative RT-PCR indicated that a number of LSNV copies in most of the treated shrimp were, at least, 1000-fold lower than the untreated controls. During 11–17weeks after feeding, average body weight of the treated group was markedly increased relative to the control group. A smaller differential growth rate of the treated group as compared to the control was also noticed. These results suggested that feeding shrimp with the dsRNA-enriched Artemia can eliminate LSNV infection, which is the cause of retarded growth in P. monodon. The present study reveals for the first time the therapeutic effect of dsRNA-enriched Artemia for shrimp disease control.

EnrichingArtemianauplii with a high DHA-containing lipid emulsion: search for an optimal protocol

This study aimed to investigate practical strategies to optimize the use of a high-docosahexaenoic acid (DHA) lipid emulsion (M70), a product with great potential in live prey enrichments for marine larviculture. Considering its particularly high content in DHA (22:6n-3), the adequate utilization of the emulsion for Artemia enrichments was evaluated in a series of six experiments. More specifically, the bioencapsulation efficiency of M70 into Artemia nauplii was tested under different experimental conditions of oxygen source, aeration flow, incubation temperature, concentration and dosage, as well as nauplial densities. Our results showed that an optimal utilization of M70 is achieved with incubation temperatures of 28°C, moderate aeration flows and nauplial densities of 300 ind per mL. In addition, the emulsion can be dispensed in the enrichment medium in one single dose of 0.8 g L−1, with no apparent detrimental effects on its oxidative stability and Artemia nauplii survival during enrichment.

Enriched on-grown Artemia metanauplii actively metabolise highly unsaturated fatty acid-rich phospholipids

On-grown (metanaupliar) stages of Artemia have been regarded as more adequate preys for early life-cycle stages of cephalopods, crustaceans, and a variety of fish species. In recent studies, we obtained successful enhancements of highly unsaturated fatty acids (HUFA) and polar lipids (PL) in enriched Artemia metanauplii using either a combination of a commercial, neutral lipid (NL)-based HUFA-rich emulsion and Soya lecithin, or HUFA-rich phospholipids. The present study aimed at exploring the molecular form under which dietary HUFA are actually deposited in the metanaupliar lipids. Thus, we analysed the fatty acid (FA) composition of the PL and NL fractions from enriched metanauplii, with special emphasis on the fate of docosahexaenoic acid (DHA) within Artemia lipids. The results show that on-grown Artemia actively translocated ingested FA contained from PL to NL classes including triacylglycerides.

LIFE-FEED ENRICHMENT FOR LARVAL REARING OF YELLOWBAND CLOWNFISH (Premnas biaculeatus)

The seeds of yellowband clownfish from hatchery has a pale skin colour and a yellow stripe became white colour. The purposes of this research were to know the effects of life-feed enrichment on the growth of larva and the appearance of colors yellowband clownfish. The treatments were the enrichment of rotifers and Artemia with commercial enrichment + Nannochloropsis (A), and without commercial enrichment as control, only Nannochloropsis (B). This research conducted for 15 days rearing. Larva rearings of yellowband clownfish fish with treatment A were resulted the total length at the end experiment was 7.72 ± 0.63 mm, dan survival rate 52.6 ± 19.1 %. The total length at treatment B was 7. 61 ± 0.43 mm and survival rate 47.7 ± 24.2%. Different enrichment of life-feed was not significant different effect for total length, survival rate and colour of seeds Keywords: life-feed, enrichment, growth, survival rate, colour, yellowband clownfish.

LIFE-FEED ENRICHMENT FOR LARVAL REARING OF YELLOWBAND CLOWNFISH (Premnas biaculeatus)

&lt;p&gt;The seeds of yellowband clownfish from hatchery has a pale skin colour and a yellow stripe became white colour. The purposes of this research were to know the effects of life-feed enrichment on the growth of larva and the appearance of colors yellowband clownfish. The treatments were the enrichment of rotifers and Artemia with commercial enrichment + Nannochloropsis (A), and without commercial enrichment as control, only Nannochloropsis (B). This research conducted for 15 days rearing. Larva rearings of yellowband clownfish fish with treatment A were resulted the total length at the end experiment was 7.72 ± 0.63 mm, dan survival rate 52.6 ± 19.1 %. The total length at treatment B was 7. 61 ± 0.43 mm and survival rate 47.7 ± 24.2%. Different enrichment of life-feed was not significant different effect for total length, survival rate and colour of seeds&lt;/p&gt; &lt;p&gt;Keywords: life-feed, enrichment, growth, survival rate, colour, yellowband clownfish.&lt;/p&gt;

쥐노래미(Hexagrammos otakii)자치어의 먹이와 수온에 따른 성장 및 에너지 수지

The growth, respiration, ingestion, and ecological efficiencies of Hexagrammos otakii larvae and juveniles reared on different diets and temperatures were estimated. A factorial experiment using two diets [non-enriched hatched Artemia nauplii (NEA) and enriched Artemia nauplii (EA)] crossed with two temperatures [natural seawater temperature (NT, ) and heated seawater (HT, )] was conducted to investigate growth and energy budgets of Hexagrammos otakii larvae and juveniles. The energy used by larvae and juveniles for 6 weeks was calculated using data on ingestion, growth, respiration, excretion, and egestion. In the NT trials, the energy used for growth by larvae and juveniles was 0.121 and 0.129 Kcal in the NEA and EA treatments, respectively. Assimilation efficiency at NT were 78.0% and 80.2% in the NEA and EA trials, respectively. Gross growth efficiency () were 60.5% and 62.3% and net growth efficiency () was 77.56% and 77.71% in the NEA and EA trials, respectively. In the HT trials, the energy used for growth by juveniles was 0.189 and 0.212 Kcal in the NEA and EA trials, respectively. Assimilation efficiency at HT was 86.4% and 95.1% in the NEA and EA trials, respectively. Values of and at HT were 69.5% and 80.43%, respectively, in the NEA trials, and 73.9% and 77.66%, respectively, in the EA trials. These results suggest that enriched Artemia nauplii and higher temperatures () are effective for rearing larvae and juveniles of H. otakii.

PCR-DGGE METHOD FOR MICROFLORA ALTERATION IN SHRIMP DIGESTIVE ORGAN FOLLOWING Lactobacillus ADMINISTRATION

Recently, bacteria as probiotic usage in aquaculture are deeply investigated. Probiotic application in aquaculture leads to alteration in bacteria community within environment and inside digestive system of the host. However, the evidence of treated bacteria presence is very limit. This study was aimed to reveal the effectiveness of PCR-DGGE method to bring some evidence of the applied probiotic existence within aquatic organism. Two species of Lactobacillus were applied in this experiment. Litopenaeus vannamei was used as host for applied bacteria, L. vannamei was reared using natural sea water in the 45 cm x 15 cm x 25 cm aerated glass tank. Twice daily of enriched Artemia were gived as nutrition during experiment. The result showed that Lactobacillus represent higher in treatment group compare with control after 20 days treatment. In the other hand there was no different of bacteria number between two treated Lactobacillus. PCR-DGGE is a rapid and reliable method for bacteria detection within aquatic organism.

The Effects of Different Feed Enrichments on Survivorship and Growth of Early Juvenile Longsnout Seahorse, Hippocampus reidi

AbstractCulturing the longsnout seahorse, Hippocampus reidi, remains challenging because unlike most cultured seahorse species, Artemia is not an optimal first feed. Ideally, more nutritious live feeds such as wild plankton or copepods should be used, but are not always readily available. Therefore, facilities commonly utilize enriched rotifers. Numerous feed enrichment products exist, including Dan's Feed Artemia Enrichment®, (Dan's Feed) which is a blend of commercially available enrichment products. The aim of this study was to assess the survivorship, growth, and condition factor (CF) of 0–28 DPR (days post release) H. reidi fed with rotifers and Artemia enriched with Dan's Feed. This enrichment was evaluated against (1) rotifers and Artemia enriched with live alga (Isochrysis galbana), and (2) wild plankton and Artemia enriched with Dan's Feed. At 28 DPR, in terms of survivorship and growth, seahorses fed with rotifers and Artemia enriched with Dan's Feed had a lower CF and outperformed those fed rotifers and Artemia enriched with I. galbana. Seahorses fed with rotifers and Artemia enriched with Dan's Feed performed on par with those fed with wild plankton and Artemia with no significant difference in CF. These findings demonstrated that the culture of H. reidi may be feasible with rotifers and Artemia enriched with Dan's Feed.

Prey selection of juvenile seahorse Hippocampus reidi

The culture of ornamental organisms is seen as a possible alternative to capturing wild specimens. The low newborn survival in seahorse aquaculture may be related to the provision of ideal live food since seahorses do not accept dry food. In most cultures of seahorses, juveniles are fed Artemia sp. nauplii and rotifers however, the newborn survival is not always satisfactory. The use of wild pelagic or cultivated harpacticoid copepods in marine larval fish cultures can promote higher juvenile growth and survival. The objective of this study was to evaluate the ingestion rate and prey selection of juvenile seahorses, Hippocampus reidi, 1, 5 and 10days after release, for: copepod (Tisbe biminiensis) offspring, Artemia sp. nauplii, enriched Artemia sp. metanauplii and rotifers (Brachionus plicatilis) in relation to prey and mouth size. The experiments tested 4 treatments mixing two live preys at 50% proportion at 10mL−1, and were performed on 5 experimental units of 600mL glass beakers with 10 juveniles each at 26 to 28°C, 30 salinity. Five beakers with the same mix of food without juveniles were used as controls for each treatment. After 5h, 3 samples of 10mL per beaker were collected and fixed to estimate the final food concentration. The ingestion rate, the proportion of offered and ingested preys, Ivlev selectivity indexes (I), prey sizes and mouth sizes of the juveniles were estimated. T. biminiensis offspring and rotifer (B. plicatilis) were positively selected for the 1 DAR, and Artemia were negatively selected. At the fifth and tenth day the negative selection disappeared in treatments, except the treatments with rotifers. The width of most prey items on the first day were compatible with the hypothetical maximal size of the prey estimated from mouth size, thus prey size doesn't appear to be the cause of the prey selectivity of the newly released juveniles. These results indicated that copepods or rotifers were important food items for the feeding of 1 DAR H. reidi.

The effects of dietary vitamin A in rotifers on the performance and skeletal abnormality of striped trumpeter Latris lineata larvae and post larvae

Several nutritional studies have linked dietary vitamin A (VA) to skeletogenesis in marine fish larvae. In our study, rotifers were enriched with eight levels of retinyl palmitate. Striped trumpeter (Latris lineata) larvae were fed rotifers twice daily, VA-enriched rotifers (morning feed) and Algamac−3050 enriched rotifers (afternoon feed), in greenwater systems from 6 to 18days post-hatch (dph). The VA-enriched rotifers had incorporated 0, 6, 14, 26, 57, 109, 215 and 388ng retinyl palmitatemg−1 dry weight (DW) following 2h enrichment with emulsions containing 0 (control), 68, 187, 532, 1402, 2670, 4808 and 9523ng retinyl palmitatemg−1 emulsion. After the rotifer feeding phase (6 to 18dph), the larvae were fed Algamac−3050 enriched Artemia until 43dph. The pattern of increasing VA in the enriched rotifers was not reflected in the larvae. Larvae incorporated 11.08±0.27ng total retinolmg−1 DW (mean±SD) when fed rotifers containing 0.93 to 2.32ng total retinolmg−1 DW (6 to 14ng retinyl palmitatemg−1 DW) and incorporated a lower level of 5.57±0.30ng total retinolmg−1 DW when fed rotifers with 0.52 (control) or ≥16.31ng total retinolmg−1 DW (0 and ≥57ng retinyl palmitatemg−1 DW). By 43dph, neither larval growth in length (16.0±0.1mm) or dry weight (4.57±0.20mg), nor survival (34.8±10.6%), were significantly affected by increasing dietary levels of retinyl palmitate. The prevalence of vertebral column malformations in 43dph post larvae was positively correlated with total retinol content of larvae at 16dph (R2=0.55, P<0.001). Unlike other studies on a range of marine fish species, retinyl palmitate enrichment in rotifers did not affect the type or severity of jaw malformations. By 43dph, 81±9% of post larvae displayed severe jaw malformations. Vitamin A daily inclusion of more than 123ng total VAmg−1 DW rotifer, equivalent to more than 35ng total retinol mg−1 DW rotifer (109ng retinyl palmitatemg−1 DW rotifers), is recommended to reduce vertebral column malformations when L. lineata larvae are reared in greenwater.

Effect of light, temperature and diet on the fatty acid profile of the tropical sea anemoneAiptasia pallida

Sea anemones of the genus Aiptasia are used as biological models for research and as a prey for the culture of the highly priced ornamental nudibranch Aeolidiella stephanieae. Symbiotic Aiptasia display a remarkable trophic plasticity, being able to fulfil their energetic demands heterotrophically and autotrophically. Consequently, they display a highly variable fatty acid (FA) profile. The objective of the present study was to analyse how light regime (12 h light : 12 h dark versus 24 h darkness), water temperature (22 versus 26 °C) and diet (Artemia nauplii versus enriched Artemia metanauplii) affect the FA composition of A. pallida. The FA profile of wild specimens was also analysed. The dominant FAs of cultured A. pallida were 16:0, 18:1n-9 and 22:6n-3. Higher FA levels were recorded when anemones were exposed to light, with this factor explaining the largest amount of variation in the composition of FA profiles. Cultured A. pallida that best mimicked wild anemones were obtained when using a regular light regime, Artemia metanauplii and 22 °C water temperature. Higher FA levels were obtained at a higher temperature and by providing nauplii to cultured anemones. The present study also indicated that A. pallida has the potential to recycle nutrients in marine aquacultures.

Phospholipids Effect on Survival and Molting Synchronicity of Larvae Mud Crab Scylla serrata

Effect of phospholipids on survival and molting synchronicity of mud crab larvae Scylla serrata were examined using Artemia enriched with five treatments of emulsion oil i.e. treatment with different level of soybean lecithin (SL) together with a level of DHA70G (referred to as DHA-SL0, 20 and 40) and treatment with SL and cuttle fish phospholipids (CPL) at 40 uL/L without DHA70G (referred to as WDHA-SL and WDHA-CPL). Survival rate, intermolt period, carapace width, and molting synchronicity were evaluated. Additionally, lipid classes and fatty acid composition of enriched Artemia were analyzed. Survival rate, intermolt period, and carapace width at the first crab (FC) stage of mud crab larvae fed DHA-SL0 to 40 were similar to that of WDHA-CPL but higher than that of WDHA-SL (P < 0.05). Moreover, mud crab larvae fed DHA-SL20, DHA-SL40, and WDHA-CPL had a significantly higher molting synchronicity index compared to that of larvae fed WDHA-SL and DHA-SL0. It can be concluded that combination of phospholipids and essential fatty acids exhibited an additive effect in improving molting synchronicity of mud crab larvae.

Use of essential trace elements enriched Artemia in the larval rearing of barramundi (Lates calcarifer)

Artemia is a vital nutriment in the rearing of barramundi (Lates carcarifer), however it’s mineral trace element content does not cover the requirements of the larvae. In our experiment the assumption was wether the cobalt, zinc and manganese concentration of Artemia could be increased during a 24 hours of enrichment period, as well as we wanted to investigate the resulted interactions between the elements. For this purpose 50, 100 and 1000 mg l-1 cobalt-chloride treatements (Co50, Co100, Co1000) were applied while in the case of 50 and 100 mg l-1 treatments the enrichment was also complemented with zink-sulphate and manganese-chloride in the same concentrations. According to the results the zooplankton were able to accumulate cobalt in higher amount, and yet zinc and manganese had no significant effect on each other, a strong synergistic effect occurred between cobalt and manganese. After the enrichment period the impact of essential trace element supplemented live feed on the survival and growth of barramundi larvae was also studied. The experiment was carried out by using 15 days-old larvae applying a total of 9 treatments for two weeks (Control, Co50, Co100, Mn50, Mn100, CoZn50, CoZn100, CoMn50, CoMn100), in duplicates. Considering the per cent of survivals, no significant difference was observed between the treatements (P&gt;0.05). In the case of CoMn50 and CoMn100, the loss statistically increased (P&lt;0.05) compared to the Control (80.5±4.95%) group. Our results show, that the Mn100 and CoMn100 treatements resulted in ignificantly higher (P&lt;0.05 ) in divid ual bod y w eight s, how ever taki ng the survival also into consideration the Mn100 treatements proved to be the mosteffective.

AreAcartia tonsacold-stored eggs a suitable food source for the marine ornamental speciesAmphiprion polymnus? A feeding study

Copepods are the natural food items for marine fish larvae but are still difficult to be cultured on a continuous basis. Therefore, suitable storage techniques for copepod subitaneous eggs are of great interest. Cold-stored copepod embryos still develop and retain a physiological activity during the cold storage period. As a consequence, their nutritional quality may change over the time of storage with these changes possibly affecting both eggs viability and larval fish survival and development. In this study, the clownfish, Amphiprion polymnus, was used as an experimental model to compare, for the first time, the effects of diets based on enriched rotifers and Artemia (control), Acartia tonsa copepods of a continuous culture and A. tonsa originated from 6 months cold-stored eggs. The effects of the different diets were tested through morphometric, molecular and biochemical approach. This study demonstrated that after a 6 months cold storage period, the quality of copepods obtained from those eggs was suboptimal for A. polymnus larval rearing. In fact, larvae fed those copepods showed lower growth and survival performances respect to the other experimental groups.