青蟹陆基高密度循环水养殖技术的建立与应用

拟穴青蟹俗称青蟹,属甲壳纲、十足目、梭子蟹科、青蟹属,广泛分布于我国长江口及以南沿海海域,是我国具有重要经济价值的海洋渔业资源和海水养殖品种之一。该品种具有生长速度快、肉质鲜美、营养价值高等特点,素有"海中人参"之美誉,在国内外市场中供不应求,深受消费者欢迎。青蟹在我国已有100多年的养殖历史,在市场价值驱动下,渔民的养殖热情非常高涨,养殖规模居高不下。据《2018中国渔业统计年鉴》记录,我国的青蟹养殖面积接近35万亩,年养殖产量超过15万吨,而广东省的养殖产量占全国1/3以上。

Growth and survival of blue swimming crab (<i>Portunus pelagicus</i>) reared on frozen and artificial foods

Experiments were conducted to evaluate the efficacy of two frozen organism (with and without instant Nannochloropsis oculata and with and without instant encapsulated Spirulina) and artificial diet (with and without artificial encapsulated shrimp larvae feed) with live food as continues feed in the larval rearing of blue swimming crab, Portunus pelagicus. The larvae were conducted with six treatments and each treatment with three replications on newly one day hatched larvae in each replication. Results showed that these larvae fed with a combination diet of instant frozen N. oculata, Artemia nauplii and rotifer give a higher survival rate till 1st day juvenile crab compared to the treatment with instant encapsulated Spirulina and artificial diet (with artificial encapsulated shrimp larvae feed). One of experiments treated with encapsulated Spirulina recorded only 16 days for the zoea to reach the C1, one day earlier as compared to previous trials treated with and without instant frozen N. oculata. One of the experiments treated with artificial encapsulated shrimp larvae feed recorded 18 days for the zoea to reach the C1, 1 to 2 days longer as compared to all the previous trials earlier. Food type influenced survival, development, and metamorphosis to megalopa and 1st day juvenile crab of P. pelagicus zoea larvae. Our findings illustrate that the best survival, the most rapid development and the highest number of 1st day juvenile crabs were obtained from larvae fed with a combination diet of frozen N. oculata, Artemia nauplii and rotifer from hatching till the 1st day juvenile crab.

Myo-inositol accelerates the metamorphosis from megalopa to crablet of Scylla paramamosain by modulating cuticle decomposition and reconstruction

The mud crab Scylla paramamosain is a key species in China due to its high nutritional value and great economic worth and has grown in popularity.Myo-inositol can modulate versatile physiological functions in aquatic animals.In the present study,S.paramamosain megalopa were given graded concentrations of myo-inositol(0,1,2,4,and 8 ppm)by water immersion to explore how their metamorphosis would be affected.The results showed that supplementing with myo-inositol remarkably increased transformation and survival rate from megalopa to crablet by at least 1.16 and 1.26 times,respectively.To decipher the molecular mechanism of how myo-inositol increases metamorphosis and survival rate,we further performed transcriptome-based gene expression profiling of both megalopa and crablet treated with myo-inositol.The integrative transcriptome analyses predicted that the differentially expressed genes(DEGs)were significantly enriched in chitinase activity,structural constituent of cuticle,and chitin binding,which are associated with the decomposition and reconstruction of cuticle.qPCR results confirmed that myo-inositol mediated gene expression levels of the above cuticle-related pathways.Considering the importance of the cuticle in exoskeleton formation and molting,it can be concluded that myo-inositol-induced changes in the cuticle decomposition and reconstruction might have accelerated the transformation from megalopa to crablet of S.paramamosain.Besides,numerous DEGs were significantly enriched in protein digestion and absorption,amino sugar and nucleotide sugar metabolism.It implies that myo-inositol may improve survival by regulating energy or nutrient absorption.Additionally,the accelerated metamorphosis by myo-inositol may improve survival from megalopa to crablet of S.paramamosain.Overall,this study will provide the first insights into the underlying molecular mechanisms by which myo-inositol increases metamorphosis and survival.

Amino acid compounds released by the giant freshwater prawn Macrobrachium rosenbergii during ecdysis:a factor attracting cannibalistic behaviour?

Ecdysis is a comm on phe nomenon that happe ns throughout the life phase of the giant freshwater prawn Macrobrachium rosenbergii.It is vital to better understand the correlation between cannibalism and biochemical compound that exists during the moulting process.The objective of the present study was to determine the amino acid profile released by M.rosenbergii during the ecdysis process that promotes cannibalism.To accomplish this,changes in amino acid levels(total amino acid(TAA)and free amino acid(FAA))of tissue muscle,exoskeleton,and sample water of culture medium from the moulting(E-stage)and non-moulting(C-stage)prawns were analysed using highperformanee liquid chromatography(HPLC).Comparison study revealed that among the TAA compounds,proline and sarcosine of tissues from moulting prawn were found at the highest levels.The level of FAA from water that contains moulting prawns(E-stage)was dominated by tryptophan and proline.Significant values obtained in the present study suggested that these amino acid compounds act as a chemical cue to promote cannibalism in M.rosenbergii during ecdysis.The knowledge of compositions and compounds that were released during the moulting process should be helpful for better understanding of the mechanism and chemical cues that play roles on triggering cannibalism,and also for future dietary man ipulati on to improve feeding efficie ncies and feeding man agement,which in directly impacts productivity and profitability.

A review of gynogenesis manipulation in aquatic animals

Gynogenesis is an established technique to generate all female type offspring and this technique has been successfully induced diploid gynogens progeny in aquatic animals of fishes and crustaceans.Monosex culture of all female shrimp and fishes were selected attribute to all female type offspring which have better size than male and help increase the market size and profitable.This article discusses on the protocol applied to produce gynogens progeny and the successful rate of gynogenesis production in fishes,molluscs and aquatic crustaceans of shrimps in general.Overall most of the UV length applied for irradiated the sperm were around 254-365 nm for(20-40 s),(20-80 s)and(5-8 s)for shrimps,254 nm,30 s for molluscs species and for fishes were around 254 nm for(1.5min)and(2-12 min)time of exposure respectively.For gynogenesis induction,the fertilized eggs were treated with cold shock,heat shock or cytochalasin-B for both shrimp and fishes gynogens technique.Fertilization rate was identified around 4.33%-19.67%in shrimp.Successful hatching rate was identified around 3.0%,14.9%-37.2%of gynogens offspring in shrimp and various percentages of hatching rates were identified from each species of fish gynogens.Overall,there is still low survival rate of gynogens produced using gynogenesis technique and further study should be carried out to improve the gynogens production.The discussed protocols serve as a guide lines for the gynogenesis technique application of all female monosex culture in the future.