A prototype pond water management system (dissolved oxygen, pH and temperature) for giant freshwater prawn farming in Pak Phanang, Southern Thailand.

Significant income was promised by giant freshwater prawn farming, which served as a key occupation for farmers. However, challenges were faced by traditional methods, including difficulties in selling prawns of incorrect sizes, limited market demand, low prices, and the risk of waterborne diseases. In pond-raised environments, these prawns were prone to diseases due to deteriorating environmental conditions, particularly poor pond bottoms, resulting in unsuitable water quality and vulnerability in prawn growth. Consequently, the application of water management technology in the prawn ponds becomes crucial to address these issues. This research aims to develop a prototype for a smart water management system, designed to regulate the water quality that significantly impacts the growth of Pak Phanang giant freshwater prawns within a pond. The equipment and tools utilized comprise ponds, water treatment systems, and smart water quality control systems. The investigation resulted in favorable findings, obtaining a total of 270 river prawns, each measuring an average length of 10-12 cm and weighing between 24 and 30 g. After a rearing period of 120 days in this system, 252 river prawns were successfully harvested, exhibiting a survival rate of 93.3 %. These prawns measured 20-25 cm in length and weighed between 190 and 268 g each, while remaining free from diseases. The results demonstrate that the developed system effectively manages water quality throughout the culture process, offering a valuable model to address the challenges faced by giant freshwater prawn farmers. The prawns obtained are of marketable size, and disease-free, enhancing the farmers' credibility with long-term benefits in the consumer market, in addition to their income generation potential.

Molecular insight into the hepatopancreas of oriental river prawn (Macrobrachium nipponense) in response to residual chlorine stimulus.

Chlorine or chloric disinfectants are cost-effective disinfectants, which are widely used to disinfect domestic and industrial water. The residual chlorine levels in some of these waters have been proven toxic to several aquatic organisms; however, the molecular mechanisms of toxicity of residual chlorine to aquatic crustaceans, including Macrobrachium nipponense, an economically important freshwater prawn native to Asian countries, have not been investigated to date. Here, M. nipponense was exposed to 0.53 mg/L of residual chlorine, and comparative transcriptomics analyses were performed to determine their response mechanisms at the molecular level. Residual chlorine caused lethal effects on prawns. Furthermore, a total of 940 differentially expressed genes (DEGs), including 501 up-regulated and 439 down-regulated genes, were identified after 48 h of residual chlorine exposure compared to the control group. After enrichment analysis of GO (Gene Ontology) functions and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, identified DEGs were demonstrated to be associated with a variety of functions including exerting "oxidoreductase activity", and participating in "oxidation-reduction process". In addition, cytochrome P450 family 1 subfamily A1 (CYP1A1), glutathione S-transferase (GST), and glucuronosyltransferase (UGT) were enriched in the pathway of metabolism of xenobiotics by cytochrome P450. Furthermore, protein-protein interaction (PPI) network analysis revealed interactions among actin beta/gamma 1 (ACTB_G1) gene encoding protein and a series of multiple functional DEGs (e.g., hexokinase (HK), fructose 1,6-biphosphate-aldolase A (ALDOA), cytochrome c (CYC), and elongation factor 1-alpha (EEF1A)) encoding proteins. This study laid a theoretical foundation for safety evaluation of chlorinated aquatic water and further investigation of the toxicity of chlorination to M. nipponense.

Efficacy of encapsulated biogenic silver nanoparticles and its disease resistance against Vibrio harveyi through oral administration in Macrobrachium rosenbergii.

Biological synthesis of silver nanoparticles (AgNPs) by Cheatomorpha antennia and its in vitro and in vivo antibacterial activity against Vibrio harveyi in Macrobrachium rosenbergii was demonstrated in the study. In vitro growth curve analysis, cell viability and bacterial inhibitory assays were performed to test the efficacy of synthesised AgNPs against bacteria. Sodium caseinate was used as an encapsulating agent to deliver the antibacterial drugs and the commercial process of microencapsulation comprises the antibacterial bioelements for oral administration to improve the disease resistance of AgNPs against V. harveyi due to the eco-friendly for non-toxic behaviour of nanoparticle and their treatment. Characterisation of antibacterial silver was performed by UV spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy and Scanning Electron Microscopy. The peak at 420 nm showed the presence of nanoparticles in the solution and the crystal nature of the particle was identified by the XRD. FTIR characterised the functional harveyi biomolecules and further SEM confirmed the size of the nanoparticles around 24 ± 2.4 nm. Experimental pathogenicity of V. harveyi showed 100% mortality at the 120th hour. Treatment of encapsulated AgNPs was administered orally for the relative percentage of survival which acquired almost 90% of survival till 30 days of exposure. In conclusion, the microencapsulation of AgNPs in the biopolymer matrices promotes the health, growth responses, immunity and disease resistance of encapsulated AgNPs with an improved relative percentage of survival.

A Novel RNA Virus, Macrobrachium rosenbergii Golda Virus (MrGV), Linked to Mass Mortalities of the Larval Giant Freshwater Prawn in Bangladesh.

Mass mortalities of the larval stage of the giant freshwater prawn, Macrobrachium rosenbergii, have been occurring in Bangladesh since 2011. Mortalities can reach 100% and have resulted in an 80% decline in the number of hatcheries actively producing M. rosenbergii. To investigate a causative agent for the mortalities, a disease challenge was carried out using infected material from a hatchery experiencing mortalities. Moribund larvae from the challenge were prepared for metatranscriptomic sequencing. De novo virus assembly revealed a 29 kb single­stranded positive-sense RNA virus with similarities in key protein motif sequences to yellow head virus (YHV), an RNA virus that causes mass mortalities in marine shrimp aquaculture, and other viruses in the Nidovirales order. Primers were designed against the novel virus and used to screen cDNA from larvae sampled from hatcheries in the South of Bangladesh from two consecutive years. Larvae from all hatcheries screened from both years were positive by PCR for the novel virus, including larvae from a hatchery that at the point of sampling appeared healthy, but later experienced mortalities. These screens suggest that the virus is widespread in M. rosenbergii hatchery culture in southern Bangladesh, and that early detection of the virus can be achieved by PCR. The hypothesised protein motifs of Macrobrachium rosenbergii golda virus (MrGV) suggest that it is likely to be a new species within the Nidovirales order. Biosecurity measures should be taken in order to mitigate global spread through the movement of post-larvae within and between countries, which has previously been linked to other virus outbreaks in crustacean aquaculture.

Population structure of the shrimp Palaemon pandaliformis (Stimpson, 1871) (Caridea: Palaemonidae) in the river Rio Itapemirim, in Southeastern Brazil / Estrutura populacional do camarão Palaemon pandaliformis (Stimpson, 1871) (Caridea: Palaemonidae) no Rio Itapemirim, sudeste do Brasil

Abstract The present study analyzes the population structure of Palaemon pandaliformis, based on sex ratio, the frequency distribution in defined size classes and the reproductive biology of samples captured in seasonal collections (winter 2011 to autumn 2012) with sieves under marginal vegetation. A total of 1,043 specimens were obtained, 222 juveniles, 465 males and 356 females, being that of this total of females, 58.42% were in the ovigerous condition. The average size of the carapace for both sexes varied between 4 and 6 mm (p> 0.05) only the ovigerous females had higher averages (p <0.0001). The sex ratio differed with 1:0.76 for males (p = 0.0001), although juvenile individuals and females were present in all sampled periods, except ovigerous females in autumn. Highest abundances were observed during the winter and spring period (p = 0.0001), decreasing in the periods with higher water temperature and salinity (summer and autumn). Was observed a continuous recruitment due to the presence of juveniles in all seasons, with greater abundance in winter and spring. Thus, based on the presence of ovigerous females in almost all seasons and juveniles in all, the reproduction for P. pandaliformis can be defined as seasonal-continuous with peak in winter period.

Resumo O presente estudo analisou a estrutura populacional de Palaemon pandaliformis, com base na razão sexual, distribuição de frequência em classe de tamanho e biologia reprodutiva de amostras capturadas em coletas sazonais (inverno/2011 a outono/2012), com peneiras sob a vegetação marginal. Um total de 1.043 exemplares foi obtido, sendo 222 juvenis, 465 machos e 356 fêmeas, sendo que deste total de fêmeas, 58.42 % estavam na condição ovígeras. O tamanho médio da carapaça, para ambos os sexos, variou entre 4 e 6 mm (p>0,05), apenas as fêmeas ovígeras apresentaram maiores médias (p<0,0001). A razão sexual diferiu em 1:0,76 para machos (p=0,0001), embora os indivíduos jovens e as fêmeas estiveram presentes em todos os períodos amostrados, exceto as fêmeas ovígeras no outono. As maiores abundâncias foram observadas durante o período de inverno e primavera (p=0,0001), diminuindo nos períodos de maior temperatura e salinidade da água (verão e outono). Foi observado um recrutamento contínuo devido a presença de juvenis em todas as estações, com maior abundância no inverno e primavera. Assim, com base na presença de fêmeas ovígeras em quase todas as estações e juvenis em todas, a reprodução de P. pandaliformis pode ser definida como sazonal-contínua, com pico no período do inverno.

Autophagy-Associated Shrinkage of the Hepatopancreas in Fasting Male Macrobrachium rosenbergii Is Rescued by Neuropeptide F.

Invertebrate neuropeptide F-I (NPF-I), much alike its mammalian homolog neuropeptide Y, influences several physiological processes, including circadian rhythms, cortical excitability, stress response, and food intake behavior. Given the role of autophagy in the metabolic stress response, we investigated the effect of NPF-1 on autophagy during fasting and feeding conditions in the hepatopancreas and muscle tissues of the male giant freshwater prawn Macrobrachium rosenbergii. Starvation up-regulated the expression of the autophagy marker LC3 in both tissues. Yet, based on the relative levels of the autophagosome-associated LC3-II isoform and of its precursor LC3-I, the hepatopancreas was more responsive than the muscle to starvation-induced autophagy. Injection of NPF-I inhibited the autophagosome formation in the hepatopancreas of fasting prawns. Relative to the body weight, the muscle weight was not affected, while that of the hepatopancreas decreased upon starvation and NPF-1 treatment could largely prevent such weight loss. Thus, the hepatopancreas is the reserve organ for the nutrient homeostasis during starvation and NPF-I plays a crucial role in the balancing of energy expenditure and energy intake during starvation by modulating autophagy.