Artemia Nauplii Research Articles

ИСПОЛЬЗОВАНИЕ НАУПЛИЙ РАЧКОВ ARTEMIA SALINA В КАЧЕСТВЕ НОСИТЕЛЯ ПРОБИОТИКОВ БАКТЕРИЙ РОДА BACILLUS В АКВАКУЛЬТУРЕ

This paper presents the results of the investigation of the effect of probiotic preparations based on Bacillus strains on Artemia salina nauplii. The use of live food is a necessary step in cultivation of many fish species, and Artemia nauplii are widely used for this purpose. It is crucial to use probiotics in aquaculture, as they can act as natural antagonists of aquatic pathogens, as well as stimulate fish growth and development. This work aims to study the immobilization of probiotic Bacillus strains on Artemia nauplii in order to develop highly effective feeds with probiotic properties for juvenile fish. Experiments on the introduction of various doses of preparations based on three probiotic strains of Bacillus into the water during the rearing of Artemia salina cysts were carried out. The number of bacteria in the water, as well as on the surface and inside the nauplii, was estimated by plating on nutrient media. It has been established that, despite the fact that brine shrimps do not feed at the orthonauplius stage, when probiotic strains are introduced into the water, bacteria are immobilized on the covers of the crustaceans; the concentration of the introduced Bacillus strains in the wipe samples taken from the nauplii surface is 1 order higher than it is for the planktonic form in the water. The introduction of bacilli at a dose of 0.0017 g/L activated the release of nauplii from cysts by 9-41 % of the control, while increasing the dose to 0.17 g/L led to a decrease in the proportion of hatched crustaceans. Thus, if the correct dosage were identified, it would make it possible to accomplish two important tasks at once: to obtain the live feed with probiotic properties for fish larvae and to increase the yield of nauplii.

Effect of live feed (Artemia Nauplii) and farm-made feed on growth and survival of Zebrafish, Danio rerio fry

Effect of live feed (Artemia Nauplii) and farm-made feed on growth and survival of Zebrafish, Danio rerio fry

The composition of monounsaturated fatty acids of artemia enriched with biologically active substances

The work is devoted to the study of monounsaturated fatty acids (MUFA) content in artemia enriched with biologically active substances at different stages of ontogenesis. Artemia cysts are used in the preparation of dietary supplements, highly effective feed additives for farm animals, fertilizers for crop production, chitosan for pharmaceutical industry and cosmetology, as raw materials in many other fields. When growing fish, crustaceans, shellfish in aquaculture, artemia nauplii are used as live starter feeds, which are obtained in situ when cultivating artemia cysts. Recently, the direction of enrichment of artemia nauplia used for feeding fish larvae and fry with biologically active substances has begun to develop: vitamins, essential amino acids, essential fatty acids, probiotics. In our work, we used a feed additive for the enrichment of artemia nauplia, including: vitamin-amino acid complex – «Chiktonic», probiotic – «Vetom-1», adaptogen – «Trekrezan», hemp oil. Enrichment was carried out through the skin at the stage of early nauplia. The aim of the work was to study the composition of MUFA at different stages of ontogenesis in intact artemia and artemia enriched with biologically active substances. The main function of MUFA is to activate metabolic processes and maintain homeostasis. When identifying monounsaturated fatty acids of artemia, the race we studied, the following were identified: oleic, palmitoleic, eicosenic, elaidic, erucic, nervonic, myristoleic acids. Oleic, palmitoleic and eicosenic fatty acids played a dominant role in the structure of MUFA. Two fatty acids, erucic and elaidic, can be distinguished in the composition of MUFA, the content of which was minimal.

Cría de larvas y canibalismo en la merluza europea (Merluccius merluccius Linnaeus, 1758) en España

The European hake, Merluccius merluccius, is considered a promising species for diversification in aquaculture. This work presents growth data for reared European hake larvae up to two months of life, and cannibalism within the cohort was evaluated. Larvae were fed a combination of rotifer (2 ind mL-1) and Artemia nauplii (0.2 ind. mL-1) at first feeding and later were grown with dry pellet until 105 days in a 500-L capacity circular tank. Rearing temperature and salinity were 14.5ºC and 34 psu, respectively, and a daily photoperiod of 12L:12D was used. Two-month-old larvae reached a total length of 17.66 ± 1.22 mm and a dry weight of 7.30 ± 1.65 mg, with a 12% survival rate. The final total length and wet weight (105 days old) were 52 ± 4.20 mm and 9.72 ± 2.32 mg, respectively. The length and dry weight growth equations and the length-weight relationship were estimated for the first two months of life. Larval survival at two and three months after hatching was 12% and 8%, respectively. Cannibalism was first observed from 35 days after hatching onwards..

Green synthesis of silver nanoparticles from Cassia Auriculata: Targeting antibacterial, antioxidant activity, and evaluation of their possible effects on saltwater microcrustacean, Artemia Nauplii (non-target organism)

Due to their huge surface area to volume ratio, metallic nanoparticles are becoming increasingly important in numerous spheres of life. Here, initially, we aimed to evaluate the potential use of Cassia auriculata (CA) extract to synthesize silver nanoparticles (AgNPs). Then, we evaluated its antimicrobial potential and antioxidant capacity, as well as performed in silico analysis, and investigated the possible non-toxic effect of AgNPs on Artemia nauplii. Fourier transform infrared (FTIR) spectroscopy, scanning and transmission electron microscopy (SEM/TEM), energy dispersive spectroscopy (EDX), X-ray diffraction (XRD), and dynamic light scattering (DLS) studies were used to characterize the biosynthesized AgNPs. Our data indicate that Bacillus cereus, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus bacteria were susceptible to the biosynthesized AgNPs, whose effect was concentration-response. With a ZOI of 10 mm, the AgNPs were most efficient against gram-positive B. cereus bacteria at the highest concentration (75 μg/mL). The biosynthesized AgNPs (at 25 to 125 μg/mL) showed good antioxidant activity in the DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) and FRAP (ferric reducing antioxidant power) assays. Oleanolic acid from CA exhibited strong binding affinity and high binding energy to E. coli and B. cereus (−9.66 and − 9.74 kcal/mol) on in silico research. According to the comparative non-toxicity analysis, AgNPs, AgNO3, and CA bark extract had the least toxic effects on A. nauplii, with respective mortality rates of 28.14, 32.26, and 38.42 %, respectively. In conclusion, the current work showed that AgNPs produced from CA bark could be a promising material for diverse applications.

Can Artemia franciscana produce essential fatty acids? Unveiling the capacity of brine shrimp to biosynthesise long-chain polyunsaturated fatty acids

Artemia nauplii are widely used as live preys for feeding early life-cycle stages of marine finfish and shrimp. However, a major drawback associated to using Artemia is their deficient nutritional value for marine larvae that is primarily linked to suboptimal levels of long-chain polyunsaturated fatty acids (LC-PUFA), essential nutrients that guarantee normal growth and development of animals. While common marine hatchery procedures involve enrichment processes to address such nutritional deficiencies, the specific drivers accounting for the naturally occurring variability in LC-PUFA of Artemia are largely unknown. Biosynthesis, along diet, is one of the main factors determining the LC-PUFA profiles in animals and it depends upon the repertoire and function of fatty acyl elongases and desaturases existing in a particular species. The aim of this study was the molecular and functional characterisation of all elongase and desaturase enzymes involved in the LC-PUFA biosynthesis from Artemia franciscana, arguably the most commonly used Artemia species. Seven out of eight elongases (termed “Elo1-8”) found in A. franciscana had distinctive features of LC-PUFA biosynthesising elongases. Consistently, functional assays showed these elongases were able to elongate multiple substrates and thus enabling A. franciscana to perform all elongation reactions of the LC-PUFA biosynthetic pathways. While all seven functionally characterised elongases from A. franciscana showed activity towards multiple substrates including C18 to C22 polyunsaturated fatty acids, particularly high activity was detected for the Elovl8 orthologue (termed herein as “Elo7”). Additionally, A. franciscana was found to have three genes of the so-called “first” desaturases (“Des1-3”), and lack other key LC-PUFA biosynthesising desaturases such as methyl-end and front-end desaturases. Two desaturases have the expected ∆9 desaturase activity, whereas a third one showed ∆12 activity. Neither methyl-end nor front-end desaturases were found in A. franciscana. In conclusion, this study demonstrated that A. franciscana has high elongation capacity but its overall LC-PUFA biosynthesis can be regarded as limited due to the lack of an adequate complement of fatty acyl desaturases in its genome.

Synthesis of Zinc Oxide Nanoparticles with Bioflavonoid Rutin: Characterisation, Antioxidant and Antimicrobial Activities and In Vivo Cytotoxic Effects on Artemia Nauplii.

This study aims to synthesise zinc oxide nanoparticles with rutin (ZnO-R NPs) using a green synthesis approach and characterise the nanostructures for diverse biomedical applications. In this study, the optical and chemical properties of synthesised ZnO-R NPs were verified through Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV-Vis) spectroscopy. The FTIR spectroscopy revealed a symmetric bending vibration peak of 460 cm−1 for ZnO-R NPs, whereas UV-Vis spectroscopy showed a distinct absorption band at 395 nm. Moreover, the oval-shaped morphology of ZnO-R NPs was verified through scanning electron microscopy and transmission electron microscopy. The synthesised nanoformulation revealed a wurtzite structure with a crystallite size of 13.22 nm; however, the zeta potential value was recorded as −8.50 ± 0.46 mV for ZnO-R NPs. According to an antioxidant study, ZnO-R NPs demonstrated lower free-radical scavenging activity than pure rutin. The cytotoxicity study was conducted using a human breast cancer cell line (MCF-7). In vitro analysis verified that ZnO-R NPs exhibited significantly higher anticancer and microbial growth inhibition activities than standard ZnO NPs (ZnO Std NPs) and pure rutin. In addition, ZnO-R NPs revealed a significantly lower IC50 value than the commercial ZnO Std NPs and pure rutin in MCF-7 cells (16.39 ± 6.03 μg/mL, 27 ± 0.91 μg/mL and 350 ± 30.1 μg/mL, respectively) after 48 h. However, synthesised ZnO-R NPs demonstrated no significant toxicity towards Artemia nauplii. These results highlight the synthesis of rutin-mediated ZnO NPs and their possible chemotherapeutic potential.

Enrichment of livefeed with very low level of docosahexaenoic acid (DHA) is enough for yellowtail sea bream (Acanthopagrus latus) larvae

The marine fish larvae mostly rely on livefeed, with certain nutritional deficiencies such as poor long chain fatty acids, in spite of recent progress in developing artificial feed. Thus, the present experiment was conducted to evaluate a 30-day dietary effects of enriched rotifer (Brachionus rotundiformis) and Artemia nauplii (Artemia franciscana) with docosahexaenoic acid (DHA) on performance of yellowtail sea bream (Acanthopagrus latus) larvae. For this purpose, 60,000 larvae from wild broodstocks were stocked in 12 tanks (50 larvae/L) supplied with green water (0.5 ×106 cell/ml Nannochloropsis. sp). The rotifer and Artemia were enriched with four experimental emulsions contained four levels of DHA including very low (6 %, DHA-VL), low (12 %, DHA-L), medium (24 %, DHA-M) and high (37.8 %, DHA-H). Larvae were fed with rotifers from day 2–20 post hatch (DPH) and Artemia metanauplii (Instar-II, from 16 to 30 DPH). After the 30-day dietary trial, survival rate and growth performance of larvae were found not affected by different levels of DHA (P > 0.05). The activity of digestive enzymes including total proteases, lipase, amylase, alkaline phosphatase, and leucine-alanine peptidase showed some fluctuations among the experimental groups. However, in the most of the sampling intervals, except for protease activity, the activity of digestive enzymes did not change significantly among the experimental groups. The n–3 polyunsaturated fatty acids, particularly eicosapentaenoic acid (EPA) and DHA, were the highest in the whole body of larvae from DHA-M treatment. The DHA/EPA ratio in the whole body of larvae was significantly increased with increasing DHA level (P < 0.05). Based on our findings, very low levels of DHA is enough for supporting normal growth, survival and metamorphosis in developing A. latus larvae up to 30 days post hatching.

Orange Chromide, Pseudetroplus maculatus (Bloch., 1795): A Potential Euryhaline Fish Model to Evaluate Climate Change Adaptations in Fishes

Orange chromide, Pseudetroplus maculatus is a euryhaline species with both ornamental and food value. The species has several attributes similar to other fish model organisms such as smaller size, repeated breeding, ease of maintenance, and higher fecundity. A salinity tolerance study was performed in different salinities (0, 15, and 35 ppt) in triplicate introducing 10 fishes each (5.4 ± 0.08 g) in 12 plastic tanks of 60 L water-holding capacity. Fish were fed with commercial feed (1.2 mm and 40% protein) at 5% of body weight twice daily for 45 days. No significant variation (p&amp;lt; 0.05) in growth and survival was observed during the study indicating the wide salinity tolerance for the species. Experimental breeding of the species in freshwater and seawater (35 ppt) revealed the ability of the species to breed in varying salinities. Lenience in captive broodstock development, pair formation, and year-round natural breeding makes the seed production of the species easier. Characteristics such as multiple spawnings, a prolonged incubation period (48 to 72 hours) useful for elaborative embryonic studies, shorter larval development cycle (25 to 30 days), and better acceptance of live feed (Artemia nauplii and flakes) and commercial feed by the larvae make the species a potential euryhaline ornamental fish model to assess the physiological changes at different salinities. Minimal input requirements and lower capital and operational investments for the seed production of the species make it an ideal model organism for studying the impact of climatic and environmental changes on fish farming in different habitats.

Effects of Thermocyclops decipiens and Artemia Nauplii for Larval Rearing of Macrobrachium rosenbergii (De Man, 1879)

This study examines the effects of the freshwater cyclopoid Thermocyclops decipiens and Artemia nauplii on the growth and survival of Macrobrachium rosenbergii (De Man, 1879) larvae during the rearing phase. M. rosenbergii larvae were divided into three groups and fed exclusively with either Artemia nauplii or T. decipiens, and a mixed diet (50% T. decipiens and 50% Artemia nauplii) in triplicate. The results indicated that M. rosenbergii larvae reached 90% post larvae (PL) on the 23rd day of the mixed diet feeding regime, followed by 88% and 82% PL on the 24th and 26th days when fed with Artemia nauplii and T. decipiens , respectively. The highest length and weight of M. rosenbergii PL were observed in the mixed diet treatment with 14.37±0.51mm and 0.76±0.04mg, respectively. The specific growth rate and percentage weight gain were significantly (p &amp;lt; 0.05) higher in the mixed feeding treatment. However, the survival of larvae was highest (69.89±4.55%) in the Artemia nauplii treatment. The larval stage index (LSI) of M. rosenbergii larvae fed on different feeding regimes was mixed diet &amp;gt; Artemia nauplii &amp;gt; T. decipiens. The biochemical constituents of M. rosenbergii PL showed that protein concentration was higher in the larvae fed with T. decipiens, while carbohydrate and lipid content were also high in mixed feeding regimes. Results indicated that the larval stage index and growth parameters of M. rosenbergii larvae were highest in the mixed diet treatment

The potential use of Artemia for larval rearing of mandarin fish (Siniperca chuatsi)

The purpose of this study is to compare the effects of three live feeds for the larvae of the domesticated strain of mandarin fish (Siniperca chuatsi). Larvae of this strain of mandarin fish with salinity activation ingested Artemia nauplii was firstly observed. The larvae at 3 days post hatch (dph) were reared from first feeding to 9 dph and fed on starving (no food supplied), zebrafish (Danio rerio) (newly hatched larvae), Artemia nauplii and Daphnia magna, respectively. The results showed that the highest survival was found in the newly hatched larvae group (41.7 ± 1.5 %), and the lowest growth was found in the Daphnia group, respectively. A high food intake was found in the Artemia nauplii group, and the npy expression between the Artemia nauplii and newly hatched larvae groups had no significant difference (p＞0.05), whereas they were significantly lower than that of the starving group (p＜0.05). At the first feeding day, the activities of amylase, lipase and trypsin and the target of rapamycin (tor) expression in the Artemia nauplii and newly hatched larvae groups were significantly higher than those of the starving group. These results suggested that larvae of this strain of mandarin fish could feed on the newly hatched larvae and Artemia nauplii, and both of them could be digested, but the digestion might be insufficient in the Artemia nauplii group. Together, this study indicates that larvae of this strain of mandarin fish can ingest and digest Artemia nauplii during first-feeding.

Capability of Artemia to digest Chlorella vulgaris and Nannochloropsis oculata under stagnant culture conditions

The microalgae genera Chlorella and Nannochloropsis are commonly used as foods for rotifer culture and its nutritional enrichment materials. However, Artemia nauplii and early metanauplii cannot easily digest these genera because of their thick cell walls, and the conditions under which Artemia can digest them remain unclear. We investigated the size at which Artemia is capable of digesting these microalgae and the effects of Chlorella supply on Artemia fatty acid composition. Decreased microalgae cell densities in culture water were observed after Artemia reached 1.6 mm in total length for Chlorella and 1.1 mm for Nannochloropsis, but the rate of decrease was slow and excrement from Artemia was filled with intact microalgae cells, suggesting that Artemia can ingest microalgae but cannot digest them. The density of residual microalgae decreased linearly after Artemia reached 3.2 mm for Chlorella and 2.0 mm for Nannochloropsis, and the excrement contained broken cells, indicating true digestive performance. The absorption of fatty acids of Chlorella by the Artemia was detected after Artemia reached 3.5 mm in total length. These results suggest that Artemia acquires the ability to consume microalgae in a stepwise manner depending on the growth and species of microalgae.

Role of plant (tulasi, neem and turmeric) extracts in defining the morphological, toxicity and catalytic properties of silver nanoparticles

Silver nanoparticles (SNPs) synthesized using tulasi, neem and turmeric aqueous extracts; both individually and in combination were characterized using various analytical techniques. None of the SNPs have shown bactericidal activity against the Coagulase-negative staphylococci (CoNS), Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. SNPs-2 (Neem) have shown highest toxic effect against HeLa (59.19 ± 2.60 µg/mL) and K-562 (60.26 ± 2.23 µg/mL) cancer cell lines, whereas SNPs-7 (Tulasi:Neem:Turmeric) has shown least toxicity (>100 µg/mL). SNPs-2 has also shown highest mortality against Artemia nauplii with LC50 value of 16.98 µg/mL after 48 h exposure, whereas SNPs-7 has shown lowest mortality (>100 µg/mL). Contrastingly, SNPs-2 has shown highest catalytic activity in the reduction of rhodamine-B (rh-B) and methyl orange (MO) dyes in the presence of sodium borohydride (SBH) as reducing agent. SNPs-2 has degraded 98.45 ± 1.35% rh-B dye under 45 min with 0.0954 min−1 (pseudo-first order rate constant), whereas 94.27 ± 1.74% reduction was observed for MO dye under 35 min with 0.0857 min−1. SNPs-7 has shown 68.93 ± 2.18% (0.0288 min−1 under 45 min) and 90.81 ± 1.87% (0.0730 min−1 under 35 min) reduction for rh-B and MO dyes, respectively.

Turnover Rates and Diet-Tissue Discrimination Factors of Nitrogen and Carbon Stable Isotopes in Seahorse Hippocampus reidi Juveniles Following a Laboratory Diet Shift.

Simple SummaryThe main aim of the present study was to ascertain the effect of two feeding schedules (including copepods and Artemia nauplii) on the early development and physiology of seahorse Hippocampus reidi juveniles. For that, we analyzed seahorse performance (growth and survival) and trophic patterns by means of stable isotopes. Our results highlight that the welfare and condition of juveniles were enhanced by extending the period of feeding on copepods up to day 10 after the male’s pouch release. The analysis of turnover rates for δ13C and δ15N revealed that switching copepods to Artemia nauplii at earlier developmental stages would reduce prey assimilation resulting in lower growth rates and survivals. The present study also provides for the diet–tissue discrimination factors for δ13C and δ15N in seahorse juveniles for the first time.The initial development of seahorse juveniles is characterized by low digestion capabilities. Stable isotope analysis is an effective tool in studies of trophic food webs and animal feeding patterns. The present study provides new insights for the understanding of growth and food assimilation in early developing seahorses following a laboratory diet switch. The study was performed in the early life stages of the seahorse Hippocampus reidi by assessing the influence of diet shift on changes and turnovers in carbon (δ13C) and nitrogen (δ15N) stable isotope in juveniles. Newborn seahorses were fed for 60 days following two feeding schedules (A6 and A11) based initially on copepods Acartia tonsa and subsequently on Artemia nauplii (since days 6 and 11, respectively). After the prey shift, we determined δ13C and δ15N turnover rates as functions of change in either body mass (fitting model G) and days of development (fitting model D), contributions of metabolism and growth to those turnover rates, and diet–tissue discrimination factors. Survival, final dry weight, and final standard length for diet A11 were higher compared to diet A6. The shift from copepods to Artemia led to fast initial enrichments in δ13C and δ15N. Afterwards, the enrichment was gradually reduced until the isotopic equilibrium with the diet was reached. In most cases, both fitting models performed similarly. The isotopic analysis revealed that 100% of tissue turnover was attributed to growth in diet A11, whereas 19–25% was linked to metabolism in diet A6. Diet–tissue discrimination factors were estimated for the first time in seahorse juveniles, resulting in higher estimates for diet A11 (2.9 ± 0.7‰ for δ13C; 2.5 ± 0.2‰ for δ15N) than in diet A6 (1.8 ± 0.1‰ for δ13C; 1.9 ± 0.1‰ for δ15N). This study highlights the relevance of feeding on copepods and their effect on isotopic patterns and discrimination factors in seahorse juveniles after a dietary shift. Regarding the application of the results achieved in relation to the feeding schedules in the rearing of H. reidi, a long period of feeding on copepods during the first days of development is highly recommended.

Insecticidal Efficacy of Metarhizium anisopliae Derived Chemical Constituents against Disease-Vector Mosquitoes.

Insecticides can cause significant harm to both terrestrial and aquatic environments. The new insecticides derived from microbial sources are a good option with no environmental consequences. Metarhizium anisopliae (mycelia) ethyl acetate extracts were tested on larvae, pupae, and adult of Anopheles stephensi (Liston, 1901), Aedes aegypti (Meigen, 1818), and Culex quinquefasciatus (Say, 1823), as well as non-target species Eudrilus eugeniae (Kinberg, 1867) and Artemia nauplii (Linnaeus, 1758) at 24 h post treatment under laboratory condition. In bioassays, Metarhizium anisopliae extracts had remarkable toxicity on all mosquito species with LC50 values, 29.631 in Ae. aegypti, 32.578 in An. stephensi and 48.003 in Cx. quinquefasciatus disease-causing mosquitoes, in A. nauplii shows (5.33–18.33 %) mortality were produced by the M. anisopliae derived crude extract. The LC50 and LC90 values were, 620.481; 6893.990 μg/mL. No behavioral changes were observed. A low lethal effect was observed in E. eugeniae treated with the fungi metabolites shows a 14.0 % mortality. The earthworm E. eugeniae mid-gut histology revealed that M. anisopliae extracts had no more harmful effects on the epidermis, circular muscle, setae, mitochondrion, and intestinal lumen tissues than chemical pesticides. By Liquid chromatography mass spectrometry (LC-MS) analysis, camphor (25.4 %), caprolactam (20.68 %), and monobutyl phthalate (19.0 %) were identified as significant components of M. anisopliae metabolites. Fourier transform infrared (FT-IR) spectral investigations revealed the presence of carboxylic acid, amides, and phenol groups, all of which could be involved in mosquito toxicity. The M. anisopliae derived chemical constituents are effective on targeted pests, pollution-free, target-specific, and are an alternative chemical insecticide.

Optimization of 17α-Methyl Testosterone Dose in Artemia Nauplii and Rotifer using Enrichment Technique

Background: The present study explored the possibility of using live feed, as vector for supplementing the androgenic hormone in aquaculture seed production. Methods: The study consisted of five treatment doses of 17α-methyl testosterone namely; control (without hormone), T1 (20 mg L-1), T2 (40 mg L-1), T3 (60 mg L-1) and T4 (80 mg L-1) and each were triplicated. The doses were tested in the live feed of Artemia nauplii and rotifer by following completely randomized design. The Artemia nauplii (Artemia salina), collected by hatching the Artemia cyst and 5-8 days old rotifers, collected from mass culture unit of rotifer, were released in their respective treatment doses at 100 and 800 individuals/ml, respectively. Result: The study found significant difference in accumulation of hormone in the tissues of live feed at different time intervals. In Artemia, significantly higher amount of 17α-MT (15.33±0.09 mg L-1) was observed in 80 mg L-1 group at 24 h. In rotifer, significantly higher value of 17α-MT (17.42±0.06 mg L-1) was recorded in 60 mg L-1 group at 6 h. The level of 17α-MT in Artemia nauplii and rotifer started showing a decreasing trend in 24 h and 6 h, respectively. Overall the findings of the present study support that supplementation of hormone through live feed is possible as live feed accumulated 17α-MT in its tissue after enrichment which can be further explored for producing all-male population in a more sustainable way.

Larval rearing of the white leg shrimp Penaeus vannamei and the first culture laboratory in Basrah, Iraq

In the study we cultured the shrimp P. vannamei (initial weight 0.0004 g) under laboratory conditions in marine science center and using three types of food. These were life food (Artemia nauplii), artificial died and mixed food (Artemia nauplii and artificial died). The highest average weight were achieved when feeding on the mixed feed (1.210 g), while, lower values achieved when fed on artificial diets 0.220 g. There are significant differences (P&lt;0.05) between these three food types. A similar results were obtained for growth in terms of length, the highest average length of larvae after six weeks was achieved when fed on the mixed food (36.58 mm), comparing with these larvae fed on Artemia and artificial feed were 31.11 and 18.72 mm respectively, and there are difference significantly too (P &lt; 0.05) between the three food types. The highest average weight increment was recorded during the sixth week with mixed food it was 0.55 g, compared with 0.23g and 0.12 g for Artemia and artificial diets respectively. The higher survival rates after sixth week were calculated for the three treatments, the high survival in larvae fed on Artemia it was 90.58 %, while, these fed on mixed food and artificial diet it was 85.62% and 73.24 % respectively.

Larval rearing of the white leg shrimp Penaeus vannamei and the first culture laboratory in Iraq, Basrah

In the study we cultured the shrimp L. vannamei (initial weight 0.0004 g) under laboratory conditions in marine science center and using three types of food. These were life food (Artemia nauplii), artificial died and mixed food (Artemia nauplii and artificial died). The highest average weight were achieved when feeding on the mixed feed (1.210 g), while, lower values achieved when fed on artificial diets 0.220 g. There are significant differences (P&lt;0.05) between these three food types. A similar results were obtained for growth in terms of length, the highest average length of larvae after six weeks was achieved when fed on the mixed food (36.58 mm ), comparing with these larvae fed on Artemia and artificial feed were 31.11 and 18.72 mm respectively, and there are difference significantly too (P &lt; 0.05) between the three food types. The highest average weight increment was recorded during the sixth week with mixed food it was 0.55 g, compared with 0.23g and 0.12 g for Artemia and artificial diets respectively. The higher survival rates after sixth week were calculated for the three treatments, the high survival in larvae fed on Artemia it was 90.58 %, while, these fed on mixed food and artificial diet it was 85.62% and 73.24 % respectively.

Feeding Behavior, Shrinking, and the Role of Mucus in the Cannonball Jellyfish Stomolophus sp. 2 in Captivity

The importance of mucus produced by jellyfish species remains as understudied as their feeding behavior. Here, we study medusae under captivity, ascertain the role of mucus, and describe its feeding behavior. Between February and March 2019, live adult cannonball jellyfish, Stomolophus sp. 2, were collected in Las Guásimas Bay (Gulf of California, Mexico) and were offered fish eggs, mollusk “D” larvae, or Artemia nauplii in 4-day trials. Descriptions of feeding structures were provided for S. sp. 2. Digitata adhere food and scapulets fragment them, which, driven by water flow, pass via transport channels to the esophagus and the gastrovascular chamber where food is digested. Due to stress by handling, medusae produced mucus and water, lost feeding structures, and decreased in size. Based on our observations and a thorough literature review, we conclude that the production of mucus in S. sp. 2 plays several roles, facilitating capture and packing of prey, acting as a defense mechanism, and facilitating sexual reproduction; the latter improves the likelihood of a population persisting in the long run, because fertilized oocytes in mucus transform to planulae, settle, and transform into asexually reproducing polyps. Polyps live longer than the other life stages and are more resistant to adverse environmental conditions than the medusoid sexual stage.

Effect of the varying inclusion levels of the egg yolk powder on growth, stress tolerance, and pigmentation of Guppy (Poecilia reticulata)

ABSTRACT The newly hatched nauplii of Artemia is extensively used as a live feed for ornamental fish hatchlings; however, its high cost and unbalanced nutrients necessitate exploring sustainable alternatives. An experiment was conducted to evaluate the effects of four formulated diets of 0%,5%, 10%, and 20% inclusion levels of egg yolk powder and other ingredients (fish meal, soybean meal, rice polish, corn) during the nursery stage of Guppy (Poecilia reticulata) compared to Artemia salina as a control. Results showed that survival did not differ (P > 0.05) among the diets. Weight gain, daily weight gain, and specific growth rate of the fry fed with 10% egg yolk-included diet containing 49.6% fish meal and 18.8% soybean meal were significantly higher (P < 0.05) than those of the other test diets and the A. salina. All the diets showed higher stress indexes (P < 0.05) than the control; the test diets did not affect pigmentation.