Survival Of Postlarvae Research Articles

Effect of copepod Apocyclops dengizicus addition on growth, survival, and proximate composition of Macrobrachium rosenbergii postlarvae cultured in brackish‐water biofloc system

AbstractObjectiveThe effects of periodically adding the cyclopoid copepod Apocyclops dengizicus (every 4 days at a rate of 4 individuals/mL) with biofloc technology (BFT‐C) was compared with conventional biofloc technology (BFT; without copepod) or a clear‐water control for Macrobrachium rosenbergii postlarvae nursery culture.MethodsSurvival, growth, proximate composition, and economics of SMacrobrachium rosenbergii postlarvae was calculated. Water quality and biofloc proximate composition were also measured among treatments. For the BFT, maize starch was applied to achieve a C:N ratio of 20:1. Triplicate 125‐L polyethylene tanks containing 500 postlarvae each (9.40 ± 1.88 mg) were evaluated.ResultSpecific growth rate was significantly greater in the BFT‐C group (8.40 ± 0.24% per day) than BFT (7.23 ± 0.21% per day) and control (7.12 ± 0.42% per day) groups. Postlarvae survival was significantly increased with the BFT‐C (94.46%) treatment compared with the BFT (87.33%) and control (82.60%). A significantly lower food conversion ratio (1.08) was obtained in BFT‐C than both the BFT (1.73) and control (1.90), possibly due to significantly higher biofloc crude protein and lipid contents in the BFT‐C than BFT. Postlarvae whole‐body protein and lipid contents were significantly elevated in BFT‐C compared to the BFT and control treatments. Economics of gross return, net return, and cost‐benefit ratio were significantly better at BFT‐C than in either the BFT or control groups.ConclusionThis study indicates that copepod additions with BFT enhanced prawn postlarvae survival, growth, and whole body protein and lipid, as well as economics, which could augment productivity and sustainability in this industry.

Optimising abalone settlement and metamorphosis: a red macroalgae candidate as an alternative to existing algal substrates

ABSTRACT Settlement induction potential of two red algae, Sahlingia subintegra and Rhodosorus marinus, and one green macroalgae, Ulvella leptochaete was examined to identify potential alternative algal species to improve reliability and reproducibility of Haliotis tuberculata sp. settlement. CCA was used as a positive control. Settlement rates, post-larval survival and growth of Haliotis tuberculata sp. were evaluated for different algal species tested. Results showed that Sahlingia subintegra induced significantly higher settlement rates (58.17 ± 12.71%) compared to CCA, Ulvella leptochaete and Rhodosorus marinus. In all treatments, post-larvae were weekly fed a mix of diatoms (Amphora sp., and Navicula incerta). At four weeks post settlement, post-larval survival rates were significantly higher on CCA and Sahlingia subintegra substrates compared to the other two algal species tested. However, at four and five weeks post settlement there were no significant differences in post-larval shell length and growth rates between CCA and Sahlingia subintegra substrates. These findings suggest that Sahlingia subintegra could be a promising alternative red macroalgae providing settlement cue for abalone hatchery stages, particularly for Haliotis tuberculata sp. and could contribute to improve abalone breeding techniques through the selection of alternative settlement substrates that could be easily managed in abalone farms environments.

Залежність лінійного зростання та виживання личинок субтропiчної прiсноводної креветки (Мacrobrachium nipponense Dе Haan, 1849) від температури і солоності

Purpose. Studies of the growth and survival of Oriental river prawn (Macrobrachium nipponense) larvae depending on water temperature and salinity during cultivation. Methodology. Experimental studies were carried out at the Aquatic Department of Aquatic Bioresources and Aquaculture of the Odesa State Ecological University in 2020-2021. Brood Oriental river prawns (Macrobrachium nipponense) were caught in the lower Dniester river and placed into a 0.8 m3 RAS. The larvae were stocked in separate aquariums with automatically maintained specified temperature regime. The first series of experiments in fresh water investigated the influence of water temperatures of 20–22, 22–24, 24–26, and 28–31°C on the growth of shrimp larvae (from the 1st stage to the Pl stage). Cultivation in water with a salinity of 5, 7, 12 ‰ was carried out at a temperature of 20–22, 22–24, 28–31 °C. Ten prawn larvae were measured daily under a binocular microscope (MBS-10) using an eyepiece-micrometer. The stage of larval development and the survival rate were determined. Water salinity was determined using an ATAGO-100 refractometer, and an Azha-101M thermal oximeter was used to determine the oxygen content in water. Statistical processing of data was carried out in Microsoft Excel. Findings. It was established that at a temperature of 24–26°C, the duration of the transition from one stage of larval development to another in Oriental river prawn (Macrobrachium nipponense) increased as the larvae grew and developed. It lasted 4–5 days in the first stages (1-3), then stages from 6 to 9 days in the later stages. High temperature stimulated the growth of larvae and accelerated their development. In fresh water at a temperature of 29–31°C, the length of postlarvae (Pl) reached 6.69±1.15 mm in 28 days of rearing. Cultivation at high temperature resulted in a significant variation in larval sizes (from 4.4 to 8.6 mm CV–25,27). At lower temperatures (25-27, 22-24 and 20-22°C), the average sizes of prawn postlarvae were smaller (5.83±0.78, 4.56±0.15, 4.43±0.15), and the survival rates increased (46, 49 and 54%, respectively). Survival of larvae was inversely dependent on temperature r = –0.89. It was minimal (32%) at a temperature of 29–31°C. The higher the growing temperature, the lower the output of postlarvae. Water salinity, like temperature, significantly affected the growth, survival and size uniformity of postlarvae. In water with a salinity of 5‰, postlarvae reached their maximum length (6.56±0.15 mm) at a temperature of 29-31 °C. At temperatures of 20-22 and 22-24 °C, the size of the postlarvae did not reliably differ among themselves. The maximum survival of postlarvae (52%) was noted at a temperature of 22-24°. Regardless of water temperature, salinity of 5‰ ensured high uniformity of larvae size (CV: 6.11–9.09). At a salinity of 7‰, the maximum length of postlarvae was reached at a temperature of 29-31oC, and the highest survival rate of prelarvae (34%) was noted at a temperature of 20-22oC. The size of the larvae and their survival at other growing temperature conditions did not differ significantly (Р<95). A salinity of 7‰ also ensured the uniformity of postlarvae sizes (CV: 6.12-8.97). At a salinity of 12‰, high water temperature stimulated the growth of larvae with relative uniformity of their linear sizes, but in all variants of the experiment the survival rate of postlarvae was very low (4–9%). Originality. Experimental data on the growth and survival of larvae of the Oriental river prawn (Macrobrachium nipponense) depending on temperature and salinity are presented for the first time. The influence of the salinity of the environment on the size uniformity of the larvae was established. Practical value. The obtained results can be used for the development and improvement of methods of artificial reproduction and cultivation of the Oriental river prawn (Macrobrachium nipponense) under controlled conditions in recirculation aquaculture systems (RAS).

Reproductive Performance and Larval quality of Freshwater Prawn Broodstock of different water resources

The present study was conducted to compare the reproductive performance and offspring quality of adults of the giant freshwater prawn, Macrobrachium rosenbergii broodstock from four different sites (1) Ganga riverine wild breeders (GW) (2) Ganga riverine pond-reared (GP) breeders (3) Gandak riverine wild breeders (gp); and (4) Gandak riverine pond-reared breeders (gw) were grown out in culture ponds and collected as broodstock at the end of grow-out culture period. M. rosenbergii females were individually stocked for 120 days in three 1500L freshwater recirculation system tanks and fed a commercial diet. Ovarian development, molting and spawning events were checked daily. In addition a number of egg and larval quality parameters were determined. The breeding frequency, fecundity, egg laying success rate, egg dimensions and egg hatchability were not significantly different between animals from the four different sources. However, there were significant differences in terms of offspring quality between the different broodstock sources. Individual dry weight, larval development rate, time to reach the post-larval stage, post-larval survival and tolerance to ammonia toxicity were all better in offspring originating from all broods did not significantly differ in terms of breeding frequency, fecundity and egg dimensions. However, larval quality of Ganga riverine wild and Ganga riverine pond-reared breeders was markedly better than that of Gandak riverine wild reared stock and Gandak riverine pond-reared stock in terms of larval development, survival and post larval production. These results indicate that broodstock sourcing deserves proper attention in hatchery operations of M. rosenbergii. It furthermore proves that domesticated (pond-reared) animals are not necessarily inferior as breeders as compared to wild-sourced animals. The results may also point out the potential to selectively breed stocks with improved characteristics adapted to the local culture environment.

Responses of early life stages of European abalone (Haliotis tuberculata) to ocean acidification after parental conditioning: Insights from a transgenerational experiment

CO2 absorption is leading to ocean acidification (OA), which is a matter of major concern for marine calcifying species. This study investigated the effects of simulated OA on the reproduction of European abalone Haliotis tuberculata and the survival of its offspring. Four-year-old abalone were exposed during reproductive season to two relevant OA scenarios, ambient pH (8.0) and low pH (7.7). After five months of exposure, abalone were induced to spawn. The gametes, larvae and juveniles were then exposed for five months to the same pH conditions as their parents. Several biological parameters involved in adult reproduction as well as in larval, post-larval and juvenile fitness were measured. No effects on gametes, fertilisation or larval oxidative stress response were detected. However, developmental abnormalities and significant decreases in shell length and calcification were observed at veliger stages. The expression profile of a GABA A receptor-like gene appeared to be regulated by pH, depending on larval stage. Larval and post-larval survival was not affected by low pH. However, a lower survival and a reduction of growth were recorded in juveniles at pH 7.7. Our results confirm that OA negatively impacts larval and juvenile fitness and suggest the absence of carry-over effects on abalone offspring. This may compromise the survival of abalone populations in the near future.

Effects of Temperature and Salinity on Incubation Time, Hatching Success, and Larvae Survival of the Giant Tiger Prawn Penaeus monodon under Experimental Conditions

Prawns are commercially one of the most important marine resources. However, in their early developmental stages, they face challenges related to physico-chemical and environmental changes. This study aimed at investigating the effects of temperature and salinity on egg incubation time, hatching success, larval and postlarval survival of the giant tiger prawn, Penaeus monodon (Fabricius 1798) obtained from the coastal waters of Tanzania. The adult females P. monodon collected off Rufiji delta were left to acclimatize and spawn at 28.5 ± 0.5 °C and 32 ppt in the hatchery. Spawned eggs were incubated at experimental temperatures of 27 °C, 31 °C and 35 °C with three subgroups of salinities of 30 ppt, 35 ppt and 40 ppt. The incubation time was longest (15.2 hours) at 27 °C and 30 ppt, and shortest (10.7 hours) at 35 °C and 40 ppt. Hatching success was highest (85.2%) at 31 °C temperature and 30 ppt salinity, and lowest (69.45%) at 35 °C and 40 ppt. Larval and postlarval survival was suitable at 27–31 °C and 30–35 ppt. These findings suggest that optimum rearing temperature and salinity for P. monodon range 27–31 °C and 30–35 ppt, respectively. Changes in temperature and salinity above the optimum range may jeopardize the hatching and subsequent survival of P. monodon especially at their early developmental stages which are more sensitive to environmental changes.
 Keywords: Penaeus monodon, Temperature, Salinity, Incubation time, Hatching success, Survival rate.

Yeast Meyerozyma guilliermondii inoculation in mature and heterotrophic biofloc systems for Litopenaeus vannamei nursery rearing exhibits bioremediation potential and improvement of shrimp survival

This study aimed to isolate a yeast strain and evaluate its potential to be inoculated in the biofloc technology culture of Pacific white shrimp employing in vitro and in vivo assays. A yeast strain identified as Meyerozyma guilliermondii (CPQBA 1459/17 DRM-01) was isolated from the soil of an estuary. Its growth kinetics under different salinities (0%, 1.0%, 2.0%, 3.0% NaCl) and Vibrio alginolyticus inhibition were evaluated in vitro. For the in vivo assay, a factorial design was employed to evaluate the effects of yeast addition and biofloc management strategy in the nursery culture of Litopenaeus vannamei as regards shrimp growth performance, water quality and water microbiology. The two factors evaluated were biofloc (mature and heterotrophic) and yeast (addition or no addition), totaling four treatments. In the in vitro trials, the yeast strain was capable of growing under all salinities evaluated, but no pathogen inhibition was observed. In the in vivo experiment, the addition of yeast significantly reduced the concentration of total suspended solids (p < 0.05), in addition to promoting a higher post-larvae survival when considering only the two mature biofloc treatments (p < 0.05). No significant effects on water Vibrio spp. and total heterotrophic bacteria counts were found (p ≥ 0.05). In conclusion, the inoculation of yeast in the biofloc culture of L. vannamei exhibited bioremediation potential and improvement in shrimp survival, the latter being modulated by the biofloc management strategy.

Enterococcus faecium are associated with the modification of gut microbiota and shrimp post-larvae survival

BackgroundProbiotics are widely used to promote host health. Compared to mammals and terrestrial invertebrates, little is known the role of probiotics in aquatic invertebrates. In this study, eighteen tanks with eight hundred of shrimp post-larvae individuals each were randomly grouped into three groups, one is shrimps administered with E. faecium as probiotic (Tre) and others are shrimps without probiotic-treatment (CK1: blank control, CK2: medium control). We investigated the correlations between a kind of commercial Enterococcus faecium (E. faecium) powder and microbiota composition with function potentials in shrimp post-larvae gut.ResultsWe sequenced the 16S rRNA gene (V4) of gut samples to assess diversity and composition of the shrimp gut microbiome and used differential abundance and Tax4Fun2 analyses to identify the differences of taxonomy and predicted function between different treatment groups. The ingested probiotic bacteria (E. faecium) were tracked in gut microbiota of Tre and the shrimps here showed the best growth performance especially in survival ratio (SR). The distribution of SR across samples was similar to that in PCoA plot based on Bray-Curits and two subgroups generated (SL: SR < 70%, SH: SR ≥ 70%). The gut microbiota structure and predicted function were correlated with both treatment and SR, and SR was a far more important factor driving taxonomic and functional differences than treatment. Both Tre and SH showed a low and uneven community species and shorted phylogenetic distance. We detected a shift in composition profile at phylum and genus level and further identified ten OTUs as relevant taxa that both closely associated with treatment and SR. The partial least squares path model further supported the important role of relevant taxa related to shrimp survival ratio.ConclusionsOverall, we found gut microbiota correlated to both shrimp survival and ingested probiotic bacteria (E. faecium). These correlations should not be dismissed without merit and will uncover a promising strategy for developing novel probiotics through certain consortium of gut microbiota.

Antimicrobial effect of Moringa oleifera seed powder against Vibrio cholerae isolated from the rearing water of shrimp (Penaeus vannamei) postlarvae.

Shrimp farming has experienced rising costs as a result of disease outbreaks associated with Vibrio spp. Suitable strategies for disease prevention and control are therefore urgently needed. This study aimed to evaluate the antimicrobial effect of Moringa oleifera seed powder against Vibrio cholerae in the rearing water of Pacific white shrimp (Penaeus vannamei) postlarvae. In vitro assays included the determination of minimum inhibitory concentration (MIC) of M. oleifera seed powder against V. cholerae, whereas in vivo assays included the effect of M. oleifera seed powder on bacterial load and water quality parameters in the rearing tanks, as well as its effect on shrimp postlarvae survival. M. oleifera seed powder inhibited the growth of V. cholerae with MIC values of 62·5µgml-1 . Moreover, seawater pH of treated tanks (8·66) was significantly lower (P<0·01) than pH of the control tanks (9·02), whereas the visibility of treated tanks (37·08cm) was significantly higher (P<0·01) as compared to control tanks (35·37cm). Likewise, V. cholerae load was significantly reduced (P<0·01) from 4·7×104 to 3·1×103 CFU per ml in tanks treated with M. oleifera seed powder. Altogether, this study demonstrates the antimicrobial activity of M. oleifera against V. cholerae in shrimp culture.

Nutritional profiling of microfungi and its effects on the growth performance, bacterial communities, and survival with Vibrio harveyi on white shrimp post-larvae (Litopenaeus vannamei)

We evaluated seven microfungi isolated from rivers or streams in Indonesia for a nutritional profile including protein, lipid, amino acids, fatty acids, and beta-glucan, i.e., Trichoderma harzianum, Macrophoma theicola, Trichoderma lentiforme, Trichoderma hamatum, Mucor circinelloides, Lasiodiplodia theobromae, and Fusarium oxysporum. All isolates had relatively high nutritional content, where the proteins ranging from 31.56–45.58%, lipids 2.22–6.54%, amino acids 11.023–18.881 g/100 g, fatty acids 1.094–5.253%, and beta-glucan 0.170–0.280 g/dry weight. The most amino acids were glutamic acid, lysine, and leucine, while fatty acids were oleic acid (C 18:1ω9C), linoleic acid (C18:2ω6), and linolenic acid (C 18:3ω3 and ω6). Moreover, we have conducted a 14-day feeding trial on white shrimp post-larvae (PL-10) with two isolates of microfungi and their combination, including M. circinelloides and T. harzianum. Finally, the results indicated that T. harzianum fed with 0.5% and 1.5% could improve white shrimp post-larvae survival and growth performance. It was found that two dominant bacteria were Gordonia polyisoprenivorans and Croceibacter atlanticus. The cumulative mortality rate was not significant from the challenge trial with Vibrio harveyi (p > 0.05). However, further in-depth investigation needs to be conducted, and some microfungi contain anti-nutrients that can affect growth.

Biofloc formation without occurrence of cultured organisms (P. vannamei post-larvae) to sustain high density of biofloc concentration - A preliminary study

Carbon-nitrogen ratio, micro-fauna abundance, water flow rate, water quality parameters were several factors studied by researchers. Unfortunately, main nutrient source and occurrence of organisms were as critically important to be investigated for biofloc formation. In this study, biofloc was formed without the occurrence of organisms (P. vannamei post-larvae) with the additional of an economical nutrient source and inoculum to speed-up and increase the concentration of biofloc formation. The triplicate experimental set-up was prepared under two condition - Treatment A (30% protein pellet feed and molasses) and Treatment B (30% protein pellet feed, molasses, wheat flour, urea, superphosphate and clay) where P. vannamei post-larvae was used as control of each treatment. Water quality parameters, biofloc volume and P. vannamei post-larvae survival rate were observed within 30 days. There was no significant difference (P < 0.05) between the water quality parameters, however, biofloc volume showed a significant difference with and without the occurrence of P. vannamei. Treatment B shows a progressive result where biofloc volume was indicated up to 90.0±4.58 mL/L at day 30. Formation of biofloc without the addition of P. vannamei post-larvae was successful within 5 days with the addition of inoculum and can be used as a starter stock in forming biofloc.

Effects of carbon sources on the culture of giant river prawn in biofloc system during nursery phase

A six-week nursery culture of giant river prawn Macrobrachium rosenbergii was conducted in a zero-water exchange biofloc technology (BFT) system. Water quality, microorganisms, proximate composition and growth performance of prawn were compared by using five different carbon sources: wheat bran (WB), rice flour (RF), molasses (MO), maize starch (MS) and palm kernel expeller (PKE). These carbon sources were added at a carbon-nitrogen ratio of 15:1. Fifteen 125 L polyethylene tanks with water volume of 100 L were used for this experiment. Each tank was stocked with 100 postlarvae (average initial weight 21.9 ± 2.3 mg). Each treatment was randomly assigned in triplicate. The water quality parameters viz. temperature, pH, dissolved oxygen and ammonia-N did not differ (P > 0.05) among five different carbon treatments. MO based BFT system had significantly (P < 0.05) lowest nitrite-N and the highest biofloc volume than other treatments. The postlarval survival (88.6 %) was significantly higher (P < 0.05) in MS treatment and followed by RF (73.0 %), MO (68.3 %), WB (61.0 %) and PKE (56.3 %) treatments, respectively. Significantly (P < 0.05) better FCR (2.21) was obtained in MS treatment. The final weight, weight gain and specific growth were similar (P> 0.05) among the five treatments. Higher gross return, net return and benefit-cost ratio were obtained in MS group than WB, MO and PKE. Significantly (P < 0.05) the highest lipid (1.97 % dry weight) was obtained in MS bioflocs and followed by RF, WB, MO and PKE bioflocs, respectively. The present study indicated that MS carbon source for biofloc technology enhanced M. rosenbergii postlarval survival and growth.

Growth and Survival of &lt;i&gt;Macrobrachium rosenbergii&lt;/i&gt; Postlarvae (De Man, 1879) Fed with EPA and DHA Enriched Artemia

Nutritional quality of Artemia used in prawn hatchery determines the quality of seed output and its performance in the culture. The present study aimed at determining the effect of n-3 HUFA enriched Artemia feeding on growth and survival of postlarvae (PL) of M. rosenbergii. The Artemia were fed with n-3 HUFA emulsions at 2 ml L-1 and samples were taken at 0, 12, 24, 36, 48 h for analyzing fatty acid profile. Results exhibited that 24 h enriched Artemia had a significantly higher level of EPA (3.76±0.11%) and DHA (2.29±0.01%) and it declined after 24 h. The PL of M. rosenbergii were fed with freshly hatched (T1), 12 h enriched (T2), 12 h un-enriched (T3), 24 h enriched (T4) and 24 h un-enriched (T5) Artemia during initial 10 days and reared for 40 days with commercial diet. The highest SGR (3.21% day-1) and survival (83.33 ± 3.34 %) was observed in T4 compared to other treatments. Data of the present study suggest that 24 h is an optimum duration for the enrichment of Artemia and feeding it for short duration enhanced the growth and survival of M. rosenbergii.

Quality assessment of Litopenaeus vannamei postlarvae produced in some commercial shrimp hatcheries of Choubdeh Abadan, Iran

In the present study, the quality of Litopenaeus vannamei postlarvae (PL) produced in some commercial hatcheries evaluated in three different hatcheries with different management in Chouebdeh Abadan, Iran. For evaluating management effects on PL quality, 180 postlarvae (30 postlarvae for each quality index) sampled from three hatcheries during the two sampling periods. Then morphometric indices (including body weight, total length, carapace length, length of the intestine, diameter of the sixth abdominal segment), behavioral indices (swimming activity), stress test (salinities of 0%, and 50%, formalin 100 and 200 ppm), carcass biochemical compositions, microbial indices, and microscopic observations) were analyzed and recorded. Management features assessed using a questionnaire. Based on the results, the highest morphometric indices were attributed to hatcheries 2 & 3. Also, the hepatopancreas index in hatchery no. 3 was better than other hatcheries. Similarly, the highest survival rate in the stress test and behavioral index were observed in the PLs of hatchery no. 3. The results of carcass biochemical composition also showed that carcass lipid decreased by increasing carcass protein content. The highest bacterial load was observed in the PLs of hatchery no. 2. The results of microscopic observations indicated that the post-larvae in the third hatchery had a completely dilated intestine and contained more food. The hepatopancreatic tissue was larger and consisted of multiple B cells with large vesicles. Based on the questionnaire, all PL samples were in PL 12 stage. The main differences between hatchery no. 3 and other hatcheries were as follows: The broodstocks weight was higher than other hatcheries; fresh and formulated diet was used in hatchery no. 3; larval growth assay, nauplius, and postlarval survival assay was carried out on a regular basis, and no sludge accumulation at the bottom of the tanks was observed in hatchery no. 3. The results of this research show that appropriate management, in hatchery no. 3 in comparison to other hatcheries, is considered as the main factor resulting in better quality for postlarvae production.

Obtaining high-quality larvae for mass production of glass eels: Can we refine our approach?

Because the post-larval (leptocephalus) survival rates of batches of Japanese eels vary widely, a useful indicator is needed to identify good-quality larval batches before the time of first feeding. This study therefore evaluated the effects on post-larval survival of early ontogenetic variables, including rates of fertilization, abnormal cleavage, hatching, survival during the larval stage until 5 days post hatching (dph), and deformities of individual larvae reared in wells of 48-well microplates. In addition, the survival rate of larvae reared in a 180-l mass rearing tank with flowing seawater was measured. Both simple and multiple linear regression analyses showed that none of the variables assessed by the microplate method correlated with post-larval survival, although the survival in the mass rearing tank at 5 dph was significantly associated with post-larval survival. These results suggest that early ontogenetic variables were likely strongly influenced by incubation methods, with the optimal method of identifying good-quality larvae being to measure the survival rate of mass reared rather than individually reared larvae. We suggest that larvae reared by the microplate method were likely subjected to excessively reduced environmental stress, due to the presence of antibiotics and the lack of interference between individuals, resulting in an overestimation of larval quality.

Ảnh hưởng của bổ sung probiotic trong ương ấu trùng tôm chân trắng (Litopenaeus vannamei Boone, 1931) theo công nghệ biofloc

The study was conducted to determine the appropriate probiotic content in white leg shrimp larvae applied biofloc technology on the growth, survival and productivity of postlarvae. The experiment consisted of 4 treatments, a control treatment without a probiotic supplement, and the remaining 3 treatments were added with probiotics with a content of 1, 2 and 3 g/m3/day. Sugar is used as an additional carbon source to create biofloc and to maintain C/N ratio of 15. The rearing tank has a volume of 500 liters, a density of 150 ind/L and a salinity of 30‰. After 20 days of rearing, the environmental factors in the treatments were in the suitable range for shrimp larvae to survive and develop. The mean length of shrimp postlarvae (PL-12) in the different treatments was not statistically significant (p> 0.05), ranging from 10.99 to 11.54 mm. The survival rate of PL-12 varied from 50.9 to 57.3% and yield from 76,407 to 85,977 ind/m3, in which the treatment of probiotic adding of 1 g/m3 was higher but the difference was not significant (p>0.05) compared to the remaining treatments, when PL-12 was shocked with 100 ppm formol and reduced 50% salinity, PL-12 of all treatments had a survival rate of 100%. Results showed that probiotic adding in rearing of white leg shrimp did not affect the growth and survival of postlarvae.

Periphyton and phytoplankton assessment in a shrimp nursery: signature pigments analysis

Understanding microalgae composition is key for an improved aquaculture system management. The primary objective of this research was to estimate microalgae community structure in a Marsupenaeus japonicus nursery. The secondary objective was to analyze the environmental parameters (salinity, pH, dissolved oxygen, total dissolved ammonia, nitrites, nitrates and phosphates) and shrimp density effect on abundance, composition and development of microalgae in a shrimp nursery. Periphyton and phytoplankton composition and abundance were determined using HPLC signature pigment analysis coupled with CHEMTAX software. Environmental parameters were measured in the tanks with probes or in the laboratory following standard procedures of water quality analysis. A nonparametric repeated-measures ANOVA statistical analysis was done to test differences between treatments. Spearman rank correlation analyses were performed on environmental and biological variables with phytoplankton or periphyton groups in order to examine significant relationship. The results showed diatoms were significantly higher than any other groups in both phytoplankton and periphyton communities. Shrimp density effect on periphyton, phytoplankton composition and environmental parameters was minor. Nutrients played a key role on phytoplankton development, but had a minor effect on periphyton, which was more affected by colonization processes and other environmental variables. The analysis of signature pigments allowed to report the presence of previously undetected groups on periphyton, prasinophytes and prymnesiophytes, which are characterized by high nutritional value. This is especially important in nurseries because shrimp grazing on periphyton can increase post-larvae survival.

Hsp70 knockdown reduced the tolerance of Litopenaeus vannamei post larvae to low pH and salinity

To better understand stress tolerance of the White leg shrimp, Litopenaeus vannamei, RNA interference (RNAi) was used to assess the role of the molecular chaperone, Hsp70 in protecting post larvae against low pH and salinity. As revealed by SDS-polyacrylamide gel electrophoresis and immunoprobing of western blots, injection of L. vannamei post larvae with Hsp70 and Hsc70 dsRNA reduced Hsp70 but had no apparent effect on survival. However, the survival of post larvae lacking Hsp70, as compared to those containing the heat shock protein, was reduced more than two-fold 48 h after exposure to low salinity and pH, strongly indicating that Hsp70 is required for protection against these abiotic stressors. This is the first time to our knowledge that RNAi has been used to demonstrate a role for Hsp70 in protecting L. vannamei post larvae against salinity and pH stress, an effect undoubtedly due to the importance Hsp70 assumes in maintaining protein homeostasis within cells. Information generated in this work provides further understanding of Hsp70 function in the stress response of Penaeid shrimp and will assist in the development of strategies to mitigate abiotic stresses experienced by aquatic invertebrates during aquaculture.

Effects of temperature and tank color on post larvae release and survival of freshwater Prawn Macrobrachium nipponense

Berried females of Macrobrachium nipponense were incubated under four different temperatures (20,23,26 and 28 ºC) and two types of tanks with different background coloration (dark and transparent tanks) to determine the best larval release and the post larvae survival were observed. The results show best larval release were 124 ind./L achieved at 26 ºC at dark color tanks, while 68 ind. / L larvae were released at the transparent color tank at the same temperature, while only 16 ind./L were released from berried females incubated at 20 ºC at dark color tanks and 6 ind./L at the transparent tanks. The best survival of larvae was 80 % at 23 ºC at dark color tanks and 75 % at transparent color tanks. Four stages for eggs development were discriminated based on color, size and eyes.

Uji Tantang Bakteri Vibrio harveyi Pada Pasca Larva Udang Vaname (Litopenaeus vannamei)

This research aims to determine the survival of Litopenaeus vannamei post larvae when challenged with various density of pathogenic Vibrio harveyi. The L. vannamei post larvae used in this study was obtained from Vannamei Broodstock Center BPIUUK, Karangasem Bali. This research was conducted for two months, from April to May 2018 in fishery laboratory, Faculty of Marine Science and Fisheries, Udayana University by using complete randomized experimental design with four different V. harveyi density and three times repetitions. The study showed that the higher density of pathogenic V. harveyi resulted on the lower survival of L. vannamei post larvae. The highest density of V. harveyi 107 CFU/mL in treatment D resulted on 53±5.77% post larvae survival, while treatment A as control without addition of V. harveyi was still has survival of 100±0.00% at the end of experiment. The density 105 CFU/mL of V. harveyi (Treatment B) seems able to be tolerated by L. vannamei post larvae since the shrimp was still have high survival at this V. harveyi density. Further both V. harveyi density of 106 CFU/mL and 107 CFU/mL were not able to tolerated by the shrimp post larvae and lead to the high shrimp mortality. Although affected on shrimp survival, addition of V. harveyi have no significant effect to the weight of shrimp post larvae between treatments.