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Understanding how changes in the hydrological regime drive parasite loads and dynamics remains a challenging issue in ecological parasitology. Temporal changes in streamflow and rainfall are key hydrological factors that could alter interactions between the parasite and host and affect parasitism levels. However, to investigate the effect of streamflow, rainfall and its mechanisms, it is important to control host traits that can also influence parasitism levels in freshwater systems. Here, we used a cymothoid‐palaemonid prawn model to test the combined effects of streamflow and rainfall accounting for host traits to predict variations in parasite loads in stream ecosystems. We collected the palaemonid prawns monthly for 2 years and measured the variation of rainfall and streamflow (i.e. stream discharge) at the time of prawn sampling. Our best model showed that streamflow can predict parasitism levels in prawns better than host traits. We found a higher prevalence and abundance of parasites in reduced streamflow compared to increased ones. We also found higher ectoparasite loads in females rather than males and occurring in autumn and winter rather than in spring and summer. Our results also showed that ectoparasite loads also suffer an effect of host body size, sex and moult stage, but not host age. Our findings show that reduced streamflow can facilitate host finding that favours parasite transmission in dry seasons and increase parasitism levels in stream systems. Temporal variability in streamflow can have a strong influence on parasite loads and dynamics compared to host traits in stream ecosystems. Identifying how interactions between aquatic invertebrates and parasites respond to variability in the hydrological regime can help to better understand and predict disease outbreaks as habitat reduction and disturbance continue in stream ecosystems. [ABSTRACT FROM AUTHOR]

Determination of protein and lipid requirements is crucial in prawn species aquaculture. The present study investigated the impact of six diets with different protein and lipid levels (T1, 30/08; T2, 30/12; T3, 35/08; T4, 35/12; T5, 40/08; and T6, 40/12), in triplicate, on the zootechnical performance and body composition of juvenile Macrobrachium macrobrachion over 56 days. These protein and lipid levels were chosen based on the requirements of other freshwater prawn species. The stocking density was one individual per liter. Results show that prawn survival was lower in T6 (with 40% protein and 8% lipid) compared to all others. The treatment T3 (35% protein and 8% lipid) shows higher survival (with 40.0 ± 24.0%) but not significantly different from other diets. The specific growth rate obtained in the present study was not different between diets. Negative values were recorded for treatments T2, T3, and T4 (30%, 35%, and 35% proteins and 12%, 8%, and 12% lipids, respectively) and positive values for treatments T1, T5, and T6 (30%, 40%, and 40% proteins and 8%, 8%, and 12% lipids, respectively). The protein efficiency coefficient (PEC) and the lipid efficiency coefficient (LEC) did not differ between treatments; however, there was a trend for these coefficients to be lower in T4, T5, and T6 (35%, 40%, and 40% proteins and 12%, 8%, and 12% lipids, respectively) compared with the other diets. The highest protein efficiency rates were recorded with the T3 and T4 treatments (35% proteins and 8% and 12% lipids, respectively), while the best lipid level was obtained with T4 (35% proteins and 12% lipids). According to dose–response models, the optimal protein/lipid ratio requirements for M. macrobrachion juveniles can be estimated at 35/8. This study is the first to provide relevant information on the nutritional needs of juveniles of African native freshwater prawn M. Macrobrachion. Further research is needed to optimize nutritional requirements at early stages of development. [ABSTRACT FROM AUTHOR]

Freshwater macroinvertebrates can connect tropical forests and stream food webs by consuming both terrestrially and aquatically produced foods, but direct observations of nocturnal feeding behavior in these natural ecosystems are rare. Observational data on decapods feeding behavior are limited partly because they are cryptic and often forage at night to avoid predators and competitors. We hypothesized that freshwater decapods forage on riparian fruit fall based on its relatively high energy and nutrient content. We used underwater cameras to video record night-time foraging under dim red light. Palm fruits (Acrocomia aculeata (Jacq.) Lodd. ex Mart.) were added to determine rates of feeding responses among crabs (Silviocarcinus australis Magalhães and Turkay, 1996) and shrimp (Macrobrachium amazonicum Heller, 1862) in a spring-fed, clear-water stream in the state of Mato Grosso do Sul, Brazil. Within 30 min, shrimp located the fruit, and within 60 min, crabs began shredding the pulp of the palm fruit. Crabs fed on the palm fruits, on average five times longer than shrimp and produced pieces of palm fruit pulp that some shrimp consumed without aggressively interacting with the crab. Small fish also consumed some palm pulp particles. This interaction network is an example of fruit-fall processing based on indirect facilitation among different types of consumers. [ABSTRACT FROM AUTHOR]

A freshwater prawn M. sundaicum, is an obligate species to acidic peat swamp. Up to the present, M. sundaicum has only been reported in the West Kalimantan, the Riau Archipelago, and Jambi Provinces in Indonesia. The aim of this research is to determine the distribution and habitat preferences of peat swamp prawn in Selat Panjang Island, Riau Province, Indonesia. The samples were collected in seven peat swamp rivers by hand net. The study yielded one hundred specimens. The acidic peat swamp is a perfect habitat for M. sundaicum. This study provided the basic information about peat swamp prawn in Selat Panjang Island, especially their distribution and habitat preferences. [ABSTRACT FROM AUTHOR]

In prawn farming, the main protein source used in aquafeed formulations is fishmeal. Nevertheless, one estimates that in the coming years, this protein source will no longer be able to meet the demand for the activity. The search for new ingredients is important to meet the increasing demand and minimize environmental impacts, such as the reduction in fish stocks and the eutrophication of aquatic systems. The objective of this study was to determine the apparent digestibility coefficients of dry matter (DM), crude protein (CP), gross energy (GE), and ether extract (EE) of fishmeal, poultry co-products (viscera and hydrolysed feather), and insect meal (Gromphadorhina portentosa) for giant river prawn (Macrobrachium rosenbergii) juveniles. To determine the apparent digestibility coefficients (ADCs), 90 prawns (average weight, 15 g) were randomly distributed among three experimental units. The reference feed was formulated according to the requirements of the giant river prawn, with 35% crude protein and a gross energy of 3600 kcal kg−1. The test diets comprised 70% of the reference diet and 30% of the respective test ingredients. Prawns were fed three times a day until apparent satiety. Faeces were collected using the indirect siphoning method, twice a day at the same feeding site (at 7:30 a.m. and 6:30 p.m.). The water parameters were temperature (27 °C), dissolved oxygen (6.65 mg L−1) and pH (7.76). The ACDs of DM, CP, EE, and GE were, respectively, 61.48; 88.28; 99.89 and 88.25 for fishmeal; 76.48; 81.55; 97.29 and 85.13 for poultry viscera meal; 73.82; 75.21; 73.17 and 76.42 for hydrolysed feather meal; and 52.35; 59,48; 87.95 and 67.64 for G. portentosa meal. The values of protein (%) and digestible energy (kcal kg−1) were 55.20 and 3711 for fishmeal; 47.27 and 4285 for poultry viscera's meal; 65.03 and 4145 for hydrolysed feather meal; and 47.72 and 3616 for G. portentosa meal. These results showed the potential use of insect meals and poultry co-products as ingredients for the diets of M. rosenbergii juveniles, as they present digestible values close to those found for fishmeal, the main raw material used in aquaculture diets. [ABSTRACT FROM AUTHOR]

The use of aquaponic systems has grown in recent years, but few of these systems have integrated the production of prawns and short-cycle vegetables. This study evaluated the potential for producing microgreens (beet, amaranth, arugula, and red cabbage) integrated with Amazon River prawns (Macrobrachium amazonicum) in an aquaponic system. Four seeding densities (5, 10, 15, or 20 seeds/cell) were assessed in two treatments: one using prawn wastewater and the other using plain dechlorinated water (control). Water quality, prawn growth performance, and microgreen productivity were monitored over 13 days, revealing optimal conditions for both prawns and microgreens in the aquaponic system. Amaranthus paniculatus yielded 374.00 g/m2 in prawn wastewater compared to 231.34 g/m2 in the control, while Beta vulgaris produced 1734.39 g/m2 in wastewater versus 1127.69 g/m2 in the control. Similarly, Brassica oleracea (2180.69 g/m2) and Eruca sativa (2109.46 g/m2) had higher yields in the prawn aquaponics system. These findings demonstrate that integrating prawn cultivation in aquaponic systems significantly enhances microgreen production compared to traditional methods. This integrated approach not only improves yields but also offers a more sustainable production model. Significant variation in productivity and growth metrics among species treatments underscores the viability and need for more systematic aquaponic procedures. [ABSTRACT FROM AUTHOR]

Simple Summary: The giant freshwater prawn (GFP; Macrobrachium rosenbergii) is a tropical aquatic animal with high economic value. However, we found that GFP in the same environment will vary in individuals, growth differences will affect the development of the industry. There are three types of body size in male GFP, namely, large, medium and small, which lead to differences in their phenotypes. Since the gut is responsible for nutrient digestion and the hemolymph is responsible for immunity, we believe that there is a close relationship between the gut, hemolymph, and phenotype. Therefore, we used different research methods to understand the causes of their body size differences. This study can provide a certain reference value for the GFP aquaculture industry and help to improve the development of GFP aquaculture industry. The giant freshwater prawn (GFP; Macrobrachium rosenbergii), a tropical species cultured worldwide, has high market demand and economic value. Male GFP growth varies considerably; however, the mechanisms underlying these growth differences remain unclear. In this study, we collected gut and hemolymphatic samples of large (ML), medium (MM), and small (MS) male GFPs and used the 16S rRNA sequencing and liquid chromatography–mass spectrometry-based metabolomic methods to explore gut microbiota and metabolites associated with GFP growth. The dominant bacteria were Firmicutes and Proteobacteria; higher growth rates correlated with a higher Firmicutes/Bacteroides ratio. Serum metabolite levels significantly differed between the ML and MS groups. We also combined transcriptomics with integrative multiomic techniques to further elucidate systematic molecular mechanisms in the GFPs. The results revealed that Faecalibacterium and Roseburia may improve gut health in GFP through butyrate release, affecting physiological homeostasis and leading to metabolic variations related to GFP growth differences. Notably, our results provide novel, fundamental insights into the molecular networks connecting various genes, metabolites, microbes, and phenotypes in GFPs, facilitating the elucidation of differential growth mechanisms in GFPs. [ABSTRACT FROM AUTHOR]

Simple Summary: The oriental river prawn, Macrobrachium nipponense, is a widely distributed species in freshwater and low-salinity estuarine regions of China and other Asian countries. This species has become an important commercial commodity in China because of its high nutritional value and palatability. There are significant differences in growth between male and female M. nipponense. The aim of this study was to determine the hepatopancreas transcriptome differences between sex-related size differences in M. nipponense. We identified four genes associated with sex-related size differences, as well as six closely related metabolic pathways. The results indicated the molecular mechanism underlying the sex-related size differences and identified key genes and metabolic pathways. This data will be invaluable to support explanations of individual differences between male and female prawns. Macrobrachium nipponense, a commercially popular crustacean species within the Chinese context, is recognized for its exceptional nutritional composition and palatability. There are significant differences in growth between male and female M. nipponense. Herein, transcriptomics was used to determine the hepatopancreas transcriptome differences between sex-related size differences in M. nipponense. We identified 974 differentially expressed genes (DEGs) between the SHE (female) and BHE (male) groups, which were validated using RT-qPCR. The genes encoding matrix metalloproteinase-9 (MM9), Ribosome-binding protein 1 (RBP1), Aly/REF export factor 2, and hematological and neurological expressed 1 (HN1) may play a role in modulating the sex-related size differences observed in M. nipponense. Clusters of orthologous groups and gene ontology functional analysis demonstrated that the DEGs for sex-related size in M.nipponense were associated with various biological functions. The Kyoto Encyclopedia of Genes and Genomes pathways analysis demonstrated that upregulated DEGs were mainly enriched in lysine biosynthesis, tryptophan metabolism, and lysine degradation pathways, whereas the downregulated DEGs were mainly enriched in ascorbate and aldarate metabolism, retinol metabolism, and drug metabolism-cytochrome P450 pathways. The results indicated the molecular mechanism underlying the sex-related size differences and identified key genes. This data will be invaluable to support explanations of individual differences between male and female prawns. [ABSTRACT FROM AUTHOR]

The river prawn Macrobrachium vollenhovenii (Herklots, 1857) and the brackish river prawn M. macrobrachion (Herklots, 1851) are economically and ecologically significant West African species. Recent molecular studies suggest they might be different ecotypes of the same species, complicating taxonomy and sustainable aquaculture practices. Both species face significant threats from human exploitation, leading to high exploitation rates and smaller average sizes within populations. Seasonal variations affect their abundance, with M. macrobrachion more prevalent during the rainy season and M. vollenhovenii thriving in the dry season. Their omnivorous detritivorous feeding habits involve consuming detritus, diatoms, phytoplankton, and insect larvae during juvenile stages. Aquaculture of M. vollenhovenii and M. macrobrachion encounters difficulties such as limited hatchery technology and low larval survival rates. Efforts to cultivate juveniles or adults in captivity face obstacles like high mortality rates due to moulting stress, handling, feeding, and cannibalism. Reintroducing captive-bred prawns into the wild offers dual benefits: controlling snail populations that host parasite causing schistosomiasis and restoring ecological balance while enhancing local fisheries and providing socio-economic benefits. To achieve sustainable aquaculture, it is crucial to address taxonomic complexities, implement management measures to mitigate overexploitation, improve hatchery technology, optimise feeding strategies, reduce stress during moulting and handling, and engage local communities through capacity building and awareness programs. This review aims to contribute to a better understanding of these prawns, promoting informed decision-making for sustainable management, conservation, and socio-economic benefits in West Africa. [ABSTRACT FROM AUTHOR]

The fishery of the river prawn Cryphiops caementarius in semiarid basins of northern Chile constitutes a small‐scale artisanal activity, developed in fragmented habitats with extended periods of drought, which represents a severe threat for the conservation of its populations. Fishers filed an environmental complaint for massive prawn mortalities caused by river channellings in the Choapa River basin. The government promoted a participatory program with fishers to carry out a restocking initiative in this basin, releasing ~4000 hatchery reared juveniles. The aim of this study was to evaluate site selection criteria for the releases, which included ecological variables relevant to the life habits of juveniles. These criteria incorporated background of the natural history of the species, seasonal monitoring of habitat indicators (fluvial habitat index and hydraulic stress index) and recommendations of fishers (traditional ecological knowledge). This study demonstrated that the integration of these criteria and restocking sciences based on aquaculture is beneficial when selecting the release site, with a high coincidence of ecological characteristics for C. caementarius to thrive. The results of this experience are discussed, emphasizing the pioneering character of this type of measure in freshwater crustaceans in Chilean basins, the ecological framework used to responsibly assist these measures in basins with intense anthropogenic impacts and recommendations that allow the improvement of the releases and monitoring efforts of this species, considering the drought scenario that affects this region of Chile. [ABSTRACT FROM AUTHOR]

The giant river prawn (Macrobrachium rosenbergii) is one of the most widely cultured crustacean species. In recent years, its aquaculture has faced challenges, including the degradation of germplasm resources and the emergence of viral diseases. Genomic information can be a valuable resource for developing molecular breeding programs for this important aquaculture species. Here we constructed a high-quality reference genome for M. rosenbergii by integrating Nanopore, Illumina, and high-throughput chromosome conformation capture (Hi-C) technologies. The final genome assembly is 3.18 Gb in size, with scaffold N50 and contig N50 of 62.73 Mb and 8.92 Mb, respectively. Approximately 98.6% of the assembled sequences were anchored into 59 pseudo-chromosomes. Benchmarking Universal Single-Copy Orthologs (BUSCO) benchmark of the genome assembly reached 94.5%. Repetitive sequences comprise 43.77% of the assembled genome, and 17,436 protein-coding genes were annotated. The high-quality genome of M. rosenbergii will empower molecular breeding efforts and provide invaluable resources for comparative genomic analysis of decapod species. [ABSTRACT FROM AUTHOR]

Macrobrachium nipponense is an important commercial freshwater species in China. However, the ability of alkali tolerance of M. nipponense is insufficient to culture in the major saline-alkali water source in China. Thus, it is urgently needed to perform the genetic improvement of alkali tolerance in this species. In the present study, we aimed to analyse the effects of alkali treatment on gills in this species after 96 h alkalinity exposure under the alkali concentrations of 0 mmol/L, 4 mmol/L, 8 mmol/L, and 12 mmol/L through performing the histological observations, measurement of antioxidant enzymes, metabolic profiling analysis, and transcriptome profiling analysis. The results of the present study revealed that alkali treatment stimulated the contents of malondialdehyde, glutathione, glutathione peroxidase in gills, indicating these antioxidant enzymes plays essential roles in the protection of body from the damage, caused by the alkali treatment. In addition, high concentration of alkali treatment (> 8 mmol/L) resulted in the damage of gill membrane and haemolymph vessel, affecting the normal respiratory function of gill. Metabolic profiling analysis revealed that Metabolic pathways, Biosynthesis of secondary metabolites, Biosynthesis of plant secondary metabolites, Microbial metabolism in diverse environments, Biosynthesis of amino acids were identified as the main enriched metabolic pathways of differentially expressed metabolites, which are consistent with the previous publications, treated by the various environmental factors. Transcriptome profiling analyses revealed that the alkali concentration of 12 mmol/L has more regulatory effects on the changes of gene expression than the other alkali concentrations. KEGG analysis revealed that Phagosome, Lysosome, Glycolysis/Gluconeogenesis, Purine Metabolism, Amino sugar and nucleotide sugar metabolism, and Endocytosis were identified as the main enriched metabolic pathways in the present study, predicting these metabolic pathways may be involved in the adaption of alkali treatment in M. nipponense. Phagosome, Lysosome, Purine Metabolism, and Endocytosis are immune-related metabolic pathways, while Glycolysis/Gluconeogenesis, and Amino sugar and nucleotide sugar metabolism are energy metabolism-related metabolic pathways. Quantitative PCR analyses of differentially expressed genes (DEGs) verified the accuracy of the RNA-Seq. Alkali treatment significantly stimulated the expressions of DEGs from the metabolic pathways of Phagosome and Lysosome, suggesting Phagosome and Lysosome play essential roles in the regulation of alkali tolerance in this species, as well as the genes from these metabolic pathways. The present study identified the effects of alkali treatment on gills, providing valuable evidences for the genetic improvement of alkali tolerance in M. nipponense. [ABSTRACT FROM AUTHOR]

Integrated rice–aquatic animal farming has become a vital strategy for enhancing food security. To assess the effects of integrated rice–giant river prawn (Macrobrachium rosenbergii) farming (IRPF) on agricultural ecosystems, we used 16S rRNA gene sequencing to analyze soil bacterial communities in comparison with traditional rice monoculture (RM). Our study revealed that the IRPF did not significantly affect the diversity of the soil bacterial community. However, during the initial culture stage, IRPF markedly increased the relative abundance of the phylum candidate division NC10 and the genus Candidatus Methylomirabilis, enhancing nitrogen-cycling-related functions within the bacterial community. Additionally, IRPF reduced the complexity and stability of these communities in the early to middle culture stages. While stochastic processes usually dominate the assembly of these communities, IRPF restricted bacterial migration and reduced the influence of these stochastic processes. Furthermore, IRPF had a significant impact on environmental factors within paddy soils, strongly correlating with shifts in bacterial communities, particularly through variations in soil nitrite concentration. In conclusion, the influence of IRPF on the bacterial community in paddy soils was primarily observed during the early and middle culture stages, and the impacts of IRPF on the soil bacterial community were primarily driven by environmental changes, especially soil nitrite concentration. These findings provide theoretical insights and a reference for understanding the microbiological impacts of different integrated rice–fish farming systems on agricultural ecosystems. [ABSTRACT FROM AUTHOR]

The study was conducted to determine the physico-chemical parameters and prawn species available in Ase River at Ndokwa East L.G.A. of Delta State, Nigeria. Water samples were collected for nine (9) months from January to September, 2023. Samples were collected with plastic bottles at the deepest part of the river, they were labelled and kept in ice-chest box and transported to the laboratory for further analysis. Analysis of the water parameters followed standard procedure. Dissolved oxygen, electrical conductivity, temperature and pH were measured in-situ while other variables: (total dissolved solid, nitrate, carbonate, biochemical oxygen demand, and hardness) were determined in the laboratory. Prawn samples were collected from artisanal fisherfolks who used traditional basket valve traps made of bamboo to harvest. All protocol followed standard procedure. Results showed the mean dry season water temperature (27.9 ± 0.22 mg/l), carbonate (1.02 ± 0.02 mg/l) and BOD (2.23 ± 0.05 mg/l) which were significantly different (p < 0.05) and higher than the mean results for the wet season which were 26.6 ± 0.03 mg/, 0.86 ± 0.05 mg/l and 1.79 ± 0.10mg/l for temperature, carbonate and BOD respectively. Prawn species obtained and their percentage prevalence were Macrobrachium vollenhovenii (41.8%), Macrobrachium macrobrachion (36.5%) and Macrobrachium potamalpheops (21.7%). Results from the study showed that the variation in physico-chemical parameters influenced the abundance of prawn species found in the environment. It is recommended that government agencies carry out fisheries extension education which could help the artisanal fisherfolks in sustainable harvest practices. [ABSTRACT FROM AUTHOR]

This study was set out to quantify biochemical parameters in freshwater prawns (M. nipponense) raised in four different salinity levels and temperature ranges (20, 25, 30, and 35°C) as well as stress enzymes (ALT and AST), ionic content (Cl, K, Na, and Ca), and osmotic pressure. The Shatt al-Arab River in the Al-Mashab region of southern Iraq was the site of the M. nipponense sample collection. This study used a recycling aquarium system (RAS) with sixty-liter plastic containers for each subject. In comparison with the control group, all metrics increased significantly (P< 0.05), although biochemical parameters decreased significantly (P< 0.05). In addition, a negative relationship was detected between temperature, salinity, total protein, glucose, K, Na, ALT, and AST and a positive relationship with urea, Cl, Ca, and cholestrol. [ABSTRACT FROM AUTHOR]

Methyl farnesoate epoxidase (MFE) is a gene encoding an enzyme related to the last step of juvenile hormone biosynthesis. Mn-MFE cDNA has a total length of 1695 bp and an open reading frame (ORF) length of 1482 bp, encoding 493 amino acids. Sequence analysis showed that its amino acid sequence has a PPGP hinge, an FGCG structural domain, and other structural domains specific to the P450 family of enzymes. Mn-MFE was most highly expressed in the hepatopancreas, followed by the ovary and gill, weakly expressed in heart and muscle tissue, and barely expressed in the eyestalk and cranial ganglion. Mn-MFE expression remained stable during the larval period, during which it mainly played a critical role in gonadal differentiation. Expression in the ovary was positively correlated and expression in the hepatopancreas was negatively correlated with ovarian development. In situ hybridization (ISH) showed that the signal was expressed in the oocyte, nucleus, cell membrane and follicular cells, and the intensity of expression was strongest at stage O-IV. The knockdown of Mn-MFE resulted in a significantly lower gonadosomatic index and percentage of ovaries past stage O-III compared to the control group. However, no differences were found in the cumulative frequency of molting between the experimental and control groups. Moreover, the analysis of ovarian tissue sections at the end of the experiment showed differences between groups in development speed but not in subcellular structure. These results demonstrate that Mn-MFE promotes the ovarian development of Macrobrachium nipponense adults but has no effect on molting. [ABSTRACT FROM AUTHOR]

This study examined the effect of various process factors on the drying of fresh water filleted prawns (Macrobrachium felicinum). The aim was to obtain data utilizing experimental and theoretical analysis that can be applied in equipment development and process optimization for drying seafood. Thus, pre‐treated prawns at different brine concentrations were dried at three isothermal conditions using a laboratory oven. The experimental moisture content data was changed to a moisture ratio and was employed to determine the drying attributes of the prawn. Drying condition optimality was explored more for model suitability using seven drying models in existence. Treatment of the prawns at a brine concentration of 2–6% affected the drying kinetics. The effective moisture diffusivity and activation energy for brine treatments ranged from 3.66 × 10−7 to 7.52 × 10−7 m2/s and 39.09 to 40.86 kJ/mol respectively while the specific energy required for the drying procedure varied from 44.52 to 76.34 kWh/kg after 9–14 h continuous drying at 50–70°C. Furthermore, the drying data's optimization demonstrated that the optimum temperature for drying filleted prawns in thin layers was 60.59°C with a brining concentration of 4.35%. The moisture ratio data fitted into semi‐theoretical and empirical model revealed that the Page model was the best model for samples pretreated by 0%, 4%, and 6% brine, whereas the Logarithmic model was the best‐fit for the samples brined with 2% solution. The study's data will be useful in developing and assessing drying techniques and systems for prawns and other related freshwater products. Practical Applications: Prawns (Macrobrachium felicinum) are a common dietary item in several countries, and demand for dried marine food delicacies is increasing as they are high in antioxidant poly‐unsaturated fatty acids, astaxanthin, and vitamin B12. However, because prawns are highly perishable and post‐harvest losses are predicted to make up 35% of daily catches, drying is required to minimize these losses. To guarantee that the drying process is both efficient and cost‐effective, optimum drying conditions must be established. As a result, this study was carried out to produce data that would be useful for drying pretreated prawn fillets. [ABSTRACT FROM AUTHOR]

Phosphorus, calcium, and magnesium are pivotal elements in the exoskeleton of crustaceans, playing a crucial role in the moulting stages. As crustaceans cannot synthesize these nutrients, their acquisition relies on external sources, with tissues such as the hepatopancreas and gills actively participating in this process. Studying changes in phosphorus, calcium, and magnesium concentrations in these tissues is essential for a comprehensive understanding of their role in nutrient absorption during the moulting stages. The hepatopancreas, gills, muscles, and carapace of Macrobrachium nipponense (De Haan, 1849) were taken from the premoult, postmoult, and intermoult stages to study the changes in phosphorus, calcium and magnesium contents in the hepatopancreas, gills, muscles, and carapace during the moulting process of M. nipponense. Three parallel experiments were measured in each stage, and 10-20 prawns were mixed for each stage. Phosphorus content per tissue unit weight was measured using the vanadium-molybdenum yellow colorimetric method, and calcium and magnesium content per unit weight of tissue were measured using atomic absorption spectrophotometry. Phosphorus in the hepatopancreas and gills increased significantly from the premoult stage to the postmoult stage (P < 0.05), and magnesium also showed the same trend. Calcium in the hepatopancreas was significantly highest in the premoult phase, whereas phosphorus was significantly highest in the postmoult stage (P < 0.05). The hepatopancreas Ca/P ratio decreased significantly before and after moulting, while it increased significantly in the gills (P < 0.05). The results show that the hepatopancreas and gills are the main tissues that absorb phosphorus, calcium, and magnesium. The hepatopancreas absorbs and stores calcium earlier than phosphorus. The changes in the Ca/P ratio of the hepatopancreas and gills found that M. nipponense consumes more phosphorus than calcium during moulting and growth, and the gills have a better ability to absorb calcium than phosphorus. [ABSTRACT FROM AUTHOR]

The availability of resources for aquafeed production is one of the main constraints that could hinder the rapid expansion of aquaculture. Our aim was to investigate the inclusion of spent brewer's yeast as an ingredient in aquafeeds and evaluate the zootechnical performance, proximate and elemental body composition, amino acid profile, and egg development of the freshwater prawn Macrobrachium borellii. We fed juvenile prawns with three feeds: D18, D25, and D32, which represent 18%, 25%, and 32% inclusion of SBY as a partial substitute for FM, respectively, during a 75-day trial. Prawns cultivated with D18 exhibited higher growth increment (97.73 ± 7.30%), specific growth rate (0.39 ± 0.02%), and protein efficiency ratio (0.27 ± 0.04%) than other treatments. However, the total biomass produced, as well as the proximate and elemental body composition of prawns, was similar across treatments. The most abundant essential amino acids in the prawn's body were arginine, leucine, and lysine while feeds showed good quality despite the limitations of arginine and phenylalanine. We observed successful hatching when prawns were fed with feed containing more SBY, indicating a more successful reproductive stock. Farming prawns with feeds containing different inclusion percentages of SBY is feasible. The inclusion of this raw material in high replacement percentages (up to 50%) is viable and could promote the bioeconomy by utilizing discarded local raw material instead of wild-caught resources. [ABSTRACT FROM AUTHOR]

Dmrt (doublesex and mab-3 related transcription factor) is a protein family of transcription factors implicated in sexual regulation. Dmrt proteins are widely conserved and known for their involvement in sex determination and differentiation across species, from invertebrates to humans. In this study, we identified a novel gene with a DM (doublesex/Mab-3)-domain gene in the river prawn, Macrobrachium nipponense, which we named MniDmrt1B due to its similarities and close phylogenetic relationship with Dmrt1B in Macrobrachium rosenbergii. Through amino acid alignments and structural predictions, we observed conservation and identified putative active sites within the DM domain. qRT-PCR analysis revealed that MniDmrt1B exhibited high expression levels in the testis, with consistently higher expression in males compared to females during development. Additionally, similar to other sex-regulated genes, the MniDmrt1B gene exhibited high expression levels during the sex differentiation–sensitive periods in M. nipponense. These results strongly indicated that MniDmrt1B probably plays an important role in testis development and sex differentiation in M. nipponense. [ABSTRACT FROM AUTHOR]

NPC intracellular cholesterol transporter 1 (NPC1) plays an important role in sterol metabolism and transport processes and has been studied in many vertebrates and some insects, but rarely in crustaceans. In this study, we characterized NPC1 from Macrobrachium nipponense (Mn-NPC1) and evaluated its functions. Its total cDNA length was 4283 bp, encoding for 1344 amino acids. It contained three conserved domains typical of the NPC family (NPC1_N, SSD, and PTC). In contrast to its role in insects, Mn-NPC1 was mainly expressed in the adult female hepatopancreas, with moderate expression in the ovary and heart. No expression was found in the embryo (stages CS–ZS) and only weak expression in the larval stages from hatching to the post-larval stage (L1–PL15). Mn-NPC1 expression was positively correlated with ovarian maturation. In situ hybridization showed that it was mainly located in the cytoplasmic membrane and nucleus of oocytes. A 25-day RNA interference experiment was employed to illustrate the Mn-NPC1 function in ovary maturation. Experimental knockdown of Mn-NPC1 using dsRNA resulted in a marked reduction in the gonadosomatic index and ecdysone content of M. nipponense females. The experimental group showed a significant delay in ovarian maturation and a reduction in the frequency of molting. These results expand our understanding of NPC1 in crustaceans and of the regulatory mechanism of ovarian maturation in M. nipponense. [ABSTRACT FROM AUTHOR]

Objective: We sought to identify and characterize an immune deficiency (IMD) homolog from the giant freshwater prawn (also known as the giant river prawn) Macrobrachium rosenbergii. The IMD is a death‐domain‐containing protein that plays a crucial role as an adaptor protein in the IMD pathway—one of the most important response mechanisms to viral and bacterial invasion of invertebrates. Methods: An IMD homolog gene from M. rosenbergii (MrIMD) was isolated using rapid amplification of complementary DNA ends. The tissue distribution and response to immune challenge of MrIMD were analyzed by real‐time reverse transcription polymerase chain reaction to understand the regulatory mechanism of MrIMD messenger RNA (mRNA) expression in M. rosenbergii. Result: The open reading frame of MrIMD comprised 555 nucleotides encoding a protein consisting of 184 amino acids, with a conserved death domain at the C‐terminus. The MrIMD protein demonstrated 53–74% similarity with IMDs from other crustaceans; the highest similarity was with the IMD from the oriental river prawn M. nipponense. Gene expression analysis revealed that MrIMD mRNA levels were highest in gill tissues. After Aeromonas hydrophila stimulation, MrIMD was significantly upregulated in the muscle, gills, and intestine, whereas there was no significant difference in the hemocytes and hepatopancreas. In the case of Macrobrachium rosenbergii nodavirus stimulation, MrIMD was dramatically upregulated in the muscle and hepatopancreas, whereas downregulation was observed in the gills. Conclusion: These results suggest that the MrIMD gene may play different roles in response to gram‐negative bacteria and viral infection and plays a crucial role in innate immunity as an important key molecule in the defense against bacterial and viral infections. Impact statementThe study of the function and response of the MrIMD gene to bacterial and viral infections in freshwater prawns provided further understanding of the immune response in shrimp. This knowledge may lead to strategies for the management of prawn diseases. [ABSTRACT FROM AUTHOR]

Iriomote Island is a small continental island hosting approximately 40 rivers characterized by short, steep-gradient streams and small waterfalls. We examined the population genetic structure and diversity of the freshwater prawn Macrobrachium shokitai Fujino & Baba, 1973 (Palaemonidae) using the mitochondrial cytochrome c oxidase subunit I (COI) gene sequence. Specimens were collected from 19 sites along ten rivers on the island, covering the known geographic distribution of the species. Haplotype and nucleotide diversities were very low within each river on the island. Nearly all haplotypes were exclusive to a given river, confirming distinct population structures among rivers at a small geographical scale. Slight genetic differentiation was discerned between the upper and lower sites of waterfalls in only the Yuchin River. Phylogenetic tree reconstruction, haplotype network, and principle coordinate analysis classified five clades roughly correspond to geographical groups in the western, southern, central, and northern regions of the island. Extreme caution should therefore be taken when translocating individuals to other rivers to avoid introducing genetic disturbance, even during conservation and mitigation efforts. [ABSTRACT FROM AUTHOR]

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This study evaluated the level of selected heavy metals in the surface water and macrobrachium along Eagle Island, Bonny Estuary. Triplicate samples were collected from four locations for six months (May-October 2021). Samples were processed and analysed for heavy metals according to standards. The result showed that the concentration of heavy metals (chromium: Cr, lead: Pb, nickel: Ni and zinc: Zn) in water from the four studied locations had similar mean values of 0.001±0.00. Meanwhile, there was a significant variation in the level of heavy metals in macrobrachium in all the locations. The mean Cr value of 0.15±0.46 mg/kg, 0.001±0.00 mg/kg, 0.01±0.00 mg/kg and 0.03±0.05 mg/kg was observed. For Pb, 0.09±0.00 mg/kg, 2.15±0.03 mg/kg, 0.05±0.00 mg/kg and 0.003±0.00 mg/kg were recorded. For Ni, 0.23±0.01 mg/kg, 0.01±0.00 mg/kg, 0.08±0.00 mg/kg and 0.00±0.00 mg/kg were obtained. For Zn, 2.11±0.01 mg/kg, 2.06±0.00 mg/kg, 0.46±0.30 mg/kg and 0.00±0.00 mg/kg were recorded, respectively, from Eagle Island - UST Bar gate, Mgboshimili, Ogbogolo and Rumueme. The concentration of heavy metals in water fell below WHO and FEPA limits for drinking water. In contrast, some heavy metal levels in macrobrachium from Eagle Island exceeded the regulatory limits set by WHO. The observed increase in these heavy metals may be due to oil bunkering activities within the creeks. Thus, the level of some heavy metals in macrobrachium from water bodies (Station I and II) pose a concern as it may cause some health risks and implications for man, who is the final consumer. [ABSTRACT FROM AUTHOR]

The increasing concern for invertebrate welfare has led to improvements in management procedures and protective legislation; under discussion is the use of anaesthetic agents to improve the welfare of farmed prawns. In parallel, the aquatic environments present changes in their physical and chemical characteristics, like the acidification of waters. With this perspective, our study analysed the effectiveness of Ocimum gratissimum essential oil (EO-OG) as a natural anaesthetic for Macrobrachium rosenbergii at different concentrations and water pHs. Juvenile M. rosenbergii were exposed to five different EO-OG concentrations (0, 100, 200, 300, and 400 μL L−1) and vehicle control (ethanol), at two water pHs (8.08 ± 0.10 and 6.42 ± 0.15). Induction time was EO-OG concentration-dependent regardless of water pH; i.e. the time required for sedation and anaesthesia decreased with the increase of EO-OG concentration. No correlation was found between recovery time and EO-OG concentration. The most effective EO-OG concentration was 400 μL L−1, with prawn sedation in 2.0–2.5 min, anaesthesia in 3.5–4.1 min, and full recovery in 16 min, regardless of water pH. The different tested water pHs influenced sedation time; i.e. sedation time was higher in mild acidic water than in mild alkaline water. Anaesthesia induction and recovery times were similar at both water pHs. Survival rates were 100% in all experimental groups. In summary, EO-OG is effective as a sedative and anaesthetic for juvenile M. rosenbergii in routine procedures, at the recommended concentration of 400 μL L−1, with mild alkaline water. [ABSTRACT FROM AUTHOR]

One way to approach the nutritional requirements of native shrimp, necessary to consolidate their culture, is to know their biochemical composition. The effect of feeding two levels of lipids (4 and 12% L) and four levels of proteins (30, 35, 40 and 45% P) in M. tenellum females was evaluated with respect to the biochemical composition of their eggs (EG), larvae (LR), gonad (GO) and hepatopancreas (HP). Total protein (TP), total carbohydrate (TC) and total lipid (TL) were estimated. In EG, L and P levels influence TP and TL; TP increases in diets higher than P35. In LR, there are no differences (p > 0.05) in TP and in TL, only diets L4P40 and L12P30 were different (p < 0.05). In GO, there is no trend in TP differences; in TC there was variation in the range of the data and TL was higher in L4P30 and L4P35. In HP, the diets with L4 obtained the highest TP values (p < 0.05); the L12 diets were higher in TL (p < 0.05). In general, diets with an inclusion of L12 showed the highest TP, TC and TL means, within this lipid level the P30 diet stood out; therefore, it is recommended to use a diet with L12P30 in the formulation of balanced feed for the species. [ABSTRACT FROM AUTHOR]

In order to study the muscle quality of different crustaceans, we aim to provide a comprehensive assessment of their muscle quality characteristics as a theoretical reference. In this work, seven major species of farmed and consumer crustaceans were selected, including crayfish (Procambarus clarkii), freshwater prawns (Macrobrachium rosenbergii), pacific white shrimp (Litopenaeus vannamei), black tiger shrimp (Penaeus monodon), kuruma prawns (Penaeus japonicus), river prawns (Macrobranchium nipponense), and Chinese shrimp (Penaeus chinensis). Their morphometric parameters, nutritional composition, textural properties, and physical and chemical indexes were comparatively analyzed. The results showed that the meat content (MC, about 14.78%) of crayfish was significantly lower than that of the other six species. By contrast, pacific white shrimp had the highest MC, although the MCs of black tiger shrimp, kuruma prawns, and Chinese shrimp are greater than 40%. All seven crustacean species were high in protein and low in fat, while pacific white shrimp had the highest crude protein, crude lipid, and crude ash content compared to the other crustaceans. The content of threonine (Thr) was the highest in crayfish. The content of methionine (Met) and lysine (Lys) was the highest in freshwater prawns. The content of isoleucine (Ile), leucine (Leu), and non–essential amino acid (NEAA) was the highest in pacific white shrimp. C18:2n-6 (linoleic acid, LA) was the highest in freshwater prawns and pacific white shrimp; C18:3n-3 (linolenic acid, LNA), C20:4n-6 (arachidonic acid, AA), unsaturated fatty acids (UFA), and monounsaturated fatty acids (MUFA) were all the highest in crayfish; and polyunsaturated fatty acids (PUFA) was the highest in freshwater prawns, but the content was not significantly different from crayfish, pacific white shrimp, black tiger shrimp, and Chinese shrimp. Pacific white shrimp had the highest values for hardness, cohesiveness, gumminess, and chewiness. The redness values of crayfish, black tiger shrimp, and Chinese shrimp were significantly higher than those of the other three species except kuruma prawns. Compared to other crustaceans, river prawns had the highest drip loss and cooking loss. Black tiger shrimp and Chinese shrimp had the lowest cooking loss rates. The research shows that the tail muscle of the seven species of crustaceans is rich in protein, essential amino acids, unsaturated fatty acids and low in fat, representing a high-quality protein. Among these crustaceans, the main essential amino acids and essential fatty acids in the tail muscle of pacific white shrimp, freshwater prawns, and crayfish are higher in content and better in nutritional value. [ABSTRACT FROM AUTHOR]

River typology is determined by a set of hydrological and geomorphological characteristics, which can determine the structure of aquatic macroinvertebrate communities throughout a watershed. In this study we aim to address the gap of knowledge in the classification of the typology of Neotropical rivers and determine their association with macroinvertebrate assemblages. In total, 138 sites from 107 rivers were sampled in Costa Rica, between years 2015 and 2020. Rivers were classified into V, Tr and U typologies based on the shape of the riverbed, substrates, current velocity and contact with riparian forest. The affinity of aquatic macroinvertebrate taxa to each typology was determined. The results confirmed a clear separation of the aquatic macroinvertebrate assemblages between the typologies, and we observed that some genera showed affinity to a specific typology: Macrobrachium and Caenis are related to U-type; Simulium and Anacroneuria to V-type, while Americabaetis and Thraulodes to Tr-type. This separation was related to in-stream habitat supply and substrate characteristics, yet there was an overlap of shared taxa between the V and Tr-type, and between the Tr and U-type. Our study linked 238 taxa to three river typologies, highlighting the importance of river hydrogeomorphology as a robust factor structuring the macroinvertebrate assemblages in tropical streams. River channel typology should be considered a relevant explanatory variable when studying macroinvertebrate responses, not only within ecological studies, but also for biomonitoring and risk assessment related to land use changes, pollution, or watershed management. [ABSTRACT FROM AUTHOR]

Based upon mixed linear model and incomplete diallel cross between different strains of Macrobrachium nipponense, the additive‐genetic correlations of growth and morphometrics with meat yield traits in M. nipponense were estimated using the minimum norm quadratic unbiased estimation procedure. Path analysis method was utilized to investigate the overall additive‐genetic determinations of growth and morphometric traits on the meat yield traits. Results indicated that growth and morphometrics were genetically positively correlated with abdominal meat weight (p < 0.01), but were not genetically correlated with abdominal meat percentage (p > 0.05) in both sexes. Growth and morphometrics were genetically positively correlated (p < 0.01). Abdominal meat weight was genetically positively correlated with abdominal meat percentage (p < 0.01). In terms of the overall additive‐genetic determination, body weight had the greatest impact on abdominal meat weight in both sexes. In contrast, abdominal meat weight, abdominal length, and body weight were most influential on abdominal meat percentage in both sexes. The genetic relationships of growth and morphometrics to meat yield traits were elucidated in M. nipponense for the first time, contributing to formulation of sound improvement plan for the meat yield traits in this commercially important prawn species. [ABSTRACT FROM AUTHOR]

The effects of the intensification on the performance of the Amazon River prawn hatchery carried out in a simple recirculation system were investigated. Newly hatched larvae were stocked in 120 L tanks at 80, 100, 120 and 140 larvae L−1 in a closed recirculating system. The experiment used a randomized block design with five replicates. An exponential equation was adjusted to express the relationship between the stocking density and productivity (postlarvae L−1). The development, larval quality, survival and postlarval (PL) dry weight did not significantly differ among the treatments (p > 0.05). When 80 larvae were stocked, the productivity (54 ± 11 PL L−1) was lower than those at higher densities (p < 0.05). Stocking 120 and 140 larvae L−1 resulted in higher productivities (75 ± 18 and 80 ± 17 PL L−1, respectively) with a lower use of Artemia nauplii to produce each postlarvae (~1200 Artemia nauplii PL−1). The maximum mean M. amazonicum postlarval production estimated by the exponential model was 93 PL L−1. This means that despite the increase in stocking density, productivity tends to stabilize. The results showed that M. amazonicum tolerates high intensification in recirculating hatchery systems based on a crushed shell bed biofilter, and the intensification optimizes Artemia use. [ABSTRACT FROM AUTHOR]

Macrobrachium nipponense, decapod crustaceans belonging to Palaemonidae family, is an important nutritionally economically species. Ammonia is a major pollutant in the aquatic environment, and adversely affect the health of M. nipponense and other associated commercial species. Here, the animal of interest was exposed to acute toxicity levels of ammonia at 3, 3.5, 4, 4.5, 5, and 6mg/L for a duration of 72 hours. DNA damage served as an indicator for ammonia toxicity in the current study. Fragmentation occurring in DNA of the animal as a result of ammonia toxicity was substantiated using the comet assay and expressed as a percentage of tail DNA. The results showed an increase in the DNA damage at ammonia concentrations of 4.5 and 5mg/L for a duration of 72 hours, with the tail DNA percentage reaching 14 and 19%, respectively. While the highest DNA damage occurred at ammonia concentration of 6mg/L for a duration of 72 hours, the tail DNA recorded 23%. These findings suggested that exposure to ammonia caused damage in the DNA of M nipponense which reflects its effect on the physiological functions and threaten this economically important animal. [ABSTRACT FROM AUTHOR]

Simple Summary: This study focused on investigating the genetic factors related to hypoxia tolerance and growth traits in Macrobrachium nipponense, a species of freshwater prawn. Specifically, a gene called glutathione S-transferase-2 (GST-2) and its single nucleotide polymorphism (SNP) in M. nipponense were studied. By analyzing samples from different populations, 38 SNP loci were identified in the GST-2 gene. The genetic diversity of these loci was assessed, and associations between specific SNP loci and hypoxia tolerance and growth traits were studied. The results showed that certain SNP loci were significantly correlated with hypoxia tolerance and growth traits in different populations of M. nipponense. Moreover, some SNP loci associated with growth traits exhibited a high degree of genetic linkage. These findings provide valuable insights into the genetic improvement of growth and hypoxia tolerance in M. nipponense, which can contribute to the cultivation of prawns with desirable characteristics. Investigating hypoxia tolerance and growth trait single nucleotide polymorphisms (SNPs) in Macrobrachium nipponense is conducive to cultivating prawns with hypoxia tolerance and good growth characteristics. The glutathione S-transferase-2 gene (GST-2) has been shown to regulate hypoxia responses in M. nipponense. In this study, we identified a single GST-2 SNP in M. nipponense, and analyzed its regulatory relationship with hypoxia tolerance and growth. The GST-2 sequence was amplified with a polymerase chain reaction from 197 "Taihu Lake No. 3", "Taihu Lake No. 2", and Pearl River population samples to identify SNP loci. The full-length Mn-GST2 sequence was 2317 bp, including three exons and two introns. In total, 38 candidate SNP loci were identified from GST-2 using Mega11.0 comparisons, with most loci moderately polymorphic in terms of genetic diversity. Locus genotypes were also analyzed, and basic genetic parameters for loci were calculated using Popgene32 and PIC_CALC. The expected heterozygosity of the 38 SNP loci ranged from 0.2334 to 0.4997, with an average of 0.4107, while observed heterozygosity ranged from 0.1929 to 0.4721, with an average of 0.3401. The polymorphic information content ranged from 0.21 to 0.37. From SPSS analyses, the G+256A locus was significantly correlated with hypoxia tolerance across all three M. nipponense populations, while the SNP loci A+261C, C+898T, A+1370C, and G+1373T were significantly associated with growth traits. Further analyses revealed that the T+2017C locus was significantly correlated with hypoxia tolerance in "Taihu Lake No. 2" populations, G+256A, A+808T, C+1032T, and A+1530G loci were significantly correlated with hypoxia tolerance in "Taihu Lake No. 3" populations, while no SNP loci were correlated with hypoxia tolerance in Pearl River populations. A+1370C and G+1373T loci, which were associated with growth traits, exhibited a high degree of linkage disequilibrium (r2 = 0.89 and r2 > 0.8), suggesting potential genetic linkage. Our data suggest associations between hypoxia tolerance and growth trait SNP loci in M. nipponense, and provide valuable evidence for the genetic improvement of growth and hypoxia tolerance in this prawn species. [ABSTRACT FROM AUTHOR]

The population of the freshwater prawn Macrobrachium tenellum (Smith, 1871) in four sites in the lower part of the coastal plain of the Ameca River, Mexico is analyzed before drastic anthropogenic modifications of the riverbed occurred. Of the 7,100 individuals of M. tenellum collected between February 2015 and January 2016, 45.7% of which were females (3,250), 4.3% ovigerous females (309), 39.3% males (2,79), and 10.6% undifferentiated (750). Males were significantly larger and heavier than females. In general, the largest individuals were collected at the most distant sites from the coastline (Colomo and San Juan), whereas the smallest ones were captured near the river mouth. The sex ratio (males:females 1:1.3) deviated from the expected 1:1. The length-weight relationship of females, males, and the population in general indicated a negative allometric growth for all three groups. The results of our research may serve as a reference point for future investigations assessing the impact of anthropogenic changes on M. tenellum populations. [ABSTRACT FROM AUTHOR]

We had previously revised the systematics of four species of Macrobrachium Spence Bate, 1868 from the Pacific coast of Mexico, including the Baja California Peninsula (BCP): M. americanum Spence Bate, 1868 , M. digueti (Bouvier, 1895), M. hobbsi Nates & Villalobos in Villalobos Hiriart & Nates Rodríguez, 1990 , and M. occidentale Holthuis, 1950. Genetic analyses of the mitochondrial markers 16S ribosomal RNA (16S) and cytochrome oxidase I (COI) of individuals of these morphological species from BCP have shown that, even facing the Gulf of California (Sea of Cortés) as an apparent marine ecological barrier, they are conspecific to their respective genetic lineages (species) found from the Pacific slope of mainland Mexico. We discuss the systematics of the fifth species of Macrobrachium from the Mexican Pacific slope, M. tenellum (Smith, 1871) to test the hypothesis that individuals of the putative M. tenellum from BCP belong to the same species from the Pacific slope of mainland Mexico. We revised the morphological characters of taxonomic importance using material obtained in the field and voucher material deposited in Mexican scientific collections, and performed molecular genetic analyses with newly generated fragments of the mitochondrial markers 16S and COI. We conclude, as in our previous studies on Macrobrachium species of the region, that the examined specimens of the putative M. tenellum from BCP belong to the same species found on the Pacific slope of mainland Mexico, and that oceanic dispersal is responsible for the distribution of the species of Macrobrachium in the peninsula rather than by vicariant events. [ABSTRACT FROM AUTHOR]

The caridean shrimps comprise one of the largest groups of amphidromous species, sharing their life cycle between freshwater habitats and the ocean. Key species of tropical ecosystems, some of which are also targets for local or international markets without any regulations being implemented, make carideans particularly vulnerable to the threats facing natural populations. We present an inventory of amphidromous carideans and an overview of their habitats, the interests they arouse, because of their ecological role as well as for their commercial importance and the threats they face. We suggest directions for future research following an experimental-biology approach, that may help to assess risks and impacts on natural habitats and ultimately prioritize conservation and management projects. [ABSTRACT FROM AUTHOR]

The previous publication identified that pyruvate dehydrogenase E1 (PDHE1) positively regulated the process of male reproduction in M. nipponense through affecting the expressions of insulin-like androgenic gland hormone. The present study aimed to identify the potential male-reproduction-related genes that were regulated by PDHE1 through performing the transcriptome profiling analysis in the testis and androgenic gland after the knockdown of the expressions of PDHE1 by the injection of dsPDHE1. Both RNA-Seq and qPCR analysis identified the significant decreases in PDHE1 expressions in the testis and androgenic gland in dsPDHE1-injected prawns compared to those in dsGFP-injected prawns, indicating the efficiency of dsPDHE1 in the present study. Transcriptome profiling analysis identified 56 and 127 differentially expressed genes (DEGs) in the testis and androgenic gland, respectively. KEGG analysis revealed that the energy-metabolism-related pathways represented the main enriched metabolic pathways of DEGs in both the testis and androgenic gland, including pyruvate metabolism, the Citrate cycle (TCA cycle), Glycolysis/Gluconeogenesis, and the Glucagon signaling pathway. Thus, it is predicted that these metabolic pathways and the DEGs from these metabolic pathways regulated by PDHE1 may be involved in the regulation of male reproduction in M. nipponense. Furthermore, four genes were found to be differentially expressed in both the testis and androgenic gland, of which ribosomal protein S3 was down-regulated and uncharacterized protein LOC113829596 was up-regulated in both the testis and androgenic gland in dsPDHE1-injected prawns. The present study provided valuable evidence for the establishment of an artificial technique to regulate the process of male reproduction in M. nipponense. [ABSTRACT FROM AUTHOR]

This study investigates the role of lysosomal acid lipase (LIPA) in sex hormone regulation and gonadal development in Macrobrachium nipponense. The full-length Mn-LIPA cDNA was cloned, and its expression patterns were analyzed using quantitative real-time PCR (qPCR) in various tissues and developmental stages. Higher expression levels were observed in the hepatopancreas, cerebral ganglion, and testes, indicating the potential involvement of Mn-LIPA in sex differentiation and gonadal development. In situ hybridization experiments revealed strong Mn-LIPA signaling in the spermatheca and hepatopancreas, suggesting their potential role in steroid synthesis (such as cholesterol, fatty acids, cholesteryl ester, and triglycerides) and sperm maturation. Increased expression levels of male-specific genes, such as insulin-like androgenic gland hormone (IAG), sperm gelatinase (SG), and mab-3-related transcription factor (Dmrt11E), were observed after dsMn-LIPA (double-stranded LIPA) injection, and significant inhibition of sperm development and maturation was observed histologically. Additionally, the relationship between Mn-LIPA and sex-related genes (IAG, SG, and Dmrt11E) and hormones (17β-estradiol and 17α-methyltestosterone) was explored by administering sex hormones to male prawns, indicating that Mn-LIPA does not directly control the production of sex hormones but rather utilizes the property of hydrolyzing triglycerides and cholesterol to provide energy while influencing the synthesis and secretion of self-sex hormones. These findings provide valuable insights into the function of Mn-LIPA in M. nipponense and its potential implications for understanding sex differentiation and gonadal development in crustaceans. It provides an important theoretical basis for the realization of a monosex culture of M. nipponense. [ABSTRACT FROM AUTHOR]

Zoogeography and ecology of 3 widespread anguillid species (Anguilla marmorata, A. megastoma, A. obscura) in the western South Pacific are reviewed in relation to the freshwater habitats and communities of the many islands of Oceania (island geological ages, from > 40 Ma to < 1 Ma. Anguillid eels show habitat segregation among A. obscura (lower reaches-brackish water), A. marmorata (habitat generalist) and A. megastoma (upper reaches), where they feed on amphidromous snails, Macrobrachium shrimp and gobies, and freshwater insect larvae. Some information has been obtained about possible anguillid spawning areas in the region near New Caledonia and Fiji from larval surveys and satellite transmitting tagging studies. Larval drift simulations suggest separate spawning areas occur in the eastern region of French Polynesia. Little is known about how geography might influence the spawning ecologies and population structures of South Pacific anguillid eels that live on the many tropical islands that are spread across a wide region of ocean in the western Indo-Pacific. [ABSTRACT FROM AUTHOR]

Macrobrachium lanchesteri (De Man, 1911), a translucent freshwater prawn has a wide distribution range throughout mainland Southeast Asia. A high morphological variation and genetic divergence between different geographical M. lanchesteri populations in Thailand have peculiarly extended the uncertainty of species boundaries and blended confusingly with several Macrobrachium species. To clarify these circumstances, broad sample examinations of the morphological variation, including topotype specimens, and phylogenetic reconstruction based on the concatenated mitochondrial dataset (16s rRNA and COI genes) were performed. Broad morphological examination of M. lanchesteri has shown congruency with phylogenetic analyses by revealing prominent lineages of M. lanchesteri sensu stricto and two new sibling lineages with interspecific variation between 6.48–8.76% for COI and 3.06–4.23% for 16S. Descriptions of two new species, named herein as M. panhai Chaowvieng & Siriwut, sp. nov. and M. rostrolevatus Chaowvieng & Siriwut, sp. nov. are provided. Morphological investigation of rostral form suggested plasticity in M. rostrolevatus populations showing the morphological trait associated with their habitat preferences. Furthermore, phylogenetic positions of the three taxa affirmed the hidden diversity of Thai freshwater Macrobrachium fauna correlated with the river network in the Mekong and Chao Phraya basins, Thailand. The genetic data and distribution records obtained in this study may also assist future river conservation plans as well as the sustainable management of freshwater prawn diversity. [ABSTRACT FROM AUTHOR]

Macrobrachium nipponense is gonochoristic and sexually dimorphic. The male prawn grows faster and usually has a larger size than the female. Therefore, a higher male proportion in stock usually results in higher yield. To investigate the impact of temperature on sexual differentiation in M. nipponense, two temperature treatments (26 °C and 31 °C) were conducted. The results showed that compared to the 31 °C treatment (3.20 ± 0.12), the 26 °C treatment displayed a lower female/male ratio (2.20 ± 0.11), which implied that a lower temperature could induce masculinization in M. nipponense. The temperature-sensitive sex differentiation phase was 25–35 days post hatching (DPH) at 26 °C while 15–20 DPH at 31 °C. Transcriptome and qPCR analysis revealed that a lower temperature up-regulated the expression of genes related to androgen secretion, and down-regulated the expressions of genes related to oogonia differentiation. Thirty-one temperature-regulated sex-differentiation genes were identified and the molecular mechanism of temperature-regulated sex differentiation was suggested. The finding of this study indicates that temperature regulation can be proposed as an innovative strategy for improving the culture yield of M. nipponense. [ABSTRACT FROM AUTHOR]

Background: Macrobrachium nipponense is a freshwater prawn of economic importance in China. Its reproductive molt is crucial for seedling rearing and directly impacts the industry's economic efficiency. 20-hydroxyecdysone (20E) controls various physiological behaviors in crustaceans, among which is the initiation of molt. Previous studies have shown that 20E plays a vital role in regulating molt and oviposition in M. nipponense. However, research on the molecular mechanisms underlying the reproductive molt and role of 20E in M. nipponense is still limited. Results: A total of 240.24 Gb of data was obtained from 18 tissue samples by transcriptome sequencing, with > 6 Gb of clean reads per sample. The efficiency of comparison with the reference transcriptome ranged from 87.05 to 92.48%. A total of 2532 differentially expressed genes (DEGs) were identified. Eighty-seven DEGs associated with molt or 20E were screened in the transcriptomes of the different tissues sampled in both the experimental and control groups. The reliability of the RNA sequencing data was confirmed using Quantitative Real-Time PCR. The expression levels of the eight strong candidate genes showed significant variation at the different stages of molt. Conclusion: This study established the first transcriptome library for the different tissues of M. nipponense in response to 20E and demonstrated the dominant role of 20E in the molting process of this species. The discovery of a large number of 20E-regulated strong candidate DEGs further confirms the extensive regulatory role of 20E and provides a foundation for the deeper understanding of its molecular regulatory mechanisms. [ABSTRACT FROM AUTHOR]

Contamination by polycyclic aromatic hydrocarbons (PAH) in freshwater ecosystems represents a serious environmental problem. When they enter the water, either by oil spills or industrial discharges, they adhere to suspended particles, accumulating in sediments and causing them to be absorbed by aquatic organisms, such as decapods and amphipods. Therefore, to evaluate the effects of PAHs on Macrobrachium borelli and Hyalella azteca, a bibliographic compilation was made considering the axes of hydrocarbon toxicity and adaptation mechanisms for these pollutants. The results for decapods indicate a high toxicity for the water-soluble fraction with diesel, although this does not prevent normal hatching of eggs. For amphipods, it was found that, according to their mortality, it is a more sensitive species than other organisms, such as chironomids. In addition, the sublethal effects due to PAH exposure vary in the affectation in the size and behavior of the organism, as well as DNA damage. Finally, the adaptive mechanisms it possesses are not considered effective for the survival of the species. [ABSTRACT FROM AUTHOR]

The aim of this work was to characterize the growth and reproduction dynamics of shrimp in the Lac Nokoué-Chenal de Cotonou complex. The results of one year's sampling from five stations (North, South, East, Central and West) of the lagoon complex revealed that linear growth in size in Lake Nokoué is decreasing over time in Macrobrachium macrobrachion (the most representative species of the genus Macrobrachium), but positive in Penaeus notialis (the most representative species of the genus Penaeus). Size-weight relationships indicate that the lowest growth coefficient (b = 1.56) is obtained in immature males of Macrobrachium felicinum , while the highest growth coefficient (b = 3.39) is obtained in mature females of Macrobrachium vollenhovenii , with an average of 2.84 for all shrimp species over both sexes considered. The χ 2 test indicated that only the species Macrobrachium vollenhovenii has a significant sexual imbalance in favour of females in Lake Nokoué. Fisher's Least Significant Difference test indicated that the estimated first sexual maturity sizes in Macrobrachium vollenhovenii and M. macrobrachion are significantly different from those estimated in M. felicinum at the α = 0.05 threshold. However, the same test indicates that there is not enough evidence to differentiate the sizes of first sexual maturation in M. vollenhovenii and M. macrobrachion. This work revealed that Penaeus monodon was the only species to show better positive growth within all its groups in Lake Nokoué while exposed to anthropogenic effects. A gradual average increase in the size of Penaeus notialis in Lake Nokoué is found between the beginning and end of the saline intrusion (which confirms the life cycle of the species presented). Species of the genus Macrobrachium showed good reproductive capacity, with the absence of sexually mature Penaeus in this lagoon. [ABSTRACT FROM AUTHOR]

An experiment was conducted to evaluate the reproductive performance and offspring quality of Macrobrachium vollenhovenii broodstock fed four diets: commercial maturation feed (control, T0), maggot (T1), fresh mackerel (T2) and locally formulated feed (T3). Spent broodstock of M. vollenhovenii fed experimental diets and their reproductive performances were evaluated in phase one experimentation. In phase two their offspring quality in a recirculation system with three replicates per treatment (TL0, TL1, TL2 and TL3) were evaluated for 30 days. The duration of gonadal development was significantly different among all the treatments, 28.67 ± 0.58 days and 16.33 ± 1.15 days for T0 and T1, respectively. T1 recorded the best GSI (16.08 ± 0.2%). Larval development in TL1 and TL3 were significantly faster than TL0 and TL2. However, survival rate was the best in TL3 (32.17 ± 0.57%) followed by TL0 (29.63 ± 0.33%). The results of this study are evidence of the possibility of successfully re-maturing and breeding this prawn in captivity. [ABSTRACT FROM AUTHOR]

Diadromous macrocrustaceans need connectivity between the ocean, estuary and river to complete their life cycle. Instream barriers in lower reaches of rivers threaten upstream migrations of diadromous macrocrustaceans. Varuna Utterata migrate upstream after a spawning event out at sea. These migration events have been poorly documented. We documented the presence V.litterata and Macrobrachium spp. at a vertical slot fishway and a rock ramp on the Lower Thukela River Bulk Water Supply Scheme Weir, KwaZulu-Natal, South Africa, during 2021-2022. We found Macrobrachium spp. and V.litterata made use of the rock ramp. However, the vertical slot fishway did hinder the migration of V. litterata significantly, as found in other studies. [ABSTRACT FROM AUTHOR]

A description of the smaller freshwater prawn, M. lamarrei is presented. It was initially reported by H. Milne Edwards in 1837 from Gujarat, India. In the present study, the species has been described based on the basis of morphometric characteristics and reported for the first time from river Gomti (U.P.), India, with the comments at subspecies level i.e. M. lamarrei lamarrei. [ABSTRACT FROM AUTHOR]

The oriental river prawn Macrobrachium nipponense is an important freshwater economic species in China, producing huge economic benefits. However, M. nipponense shows lower alkali tolerance than fish species, thus genetic selection is urgently needed in order to improve alkali tolerance in this species. In the present study, the effects of alkalinity exposure on the hepatopancreas of M. nipponense were measured under the alkali concentrations of 0 (control), 4, 8, and 12 mmol/L with the exposure time of 96 h through histological observations, measurement of antioxidant enzymes, metabolic profiling analysis, and transcriptome profiling analysis. The present study identified that the low concentration of alkali treatment (<4 mmol/L) did not result in morphological changes in the hepatopancreas and activity changes in antioxidant enzymes, while high-alkali treatment (>8 mmol/L) damaged the normal structures of the lumen and vacuoles and significantly stimulated the levels of superoxide dismutase, catalase, and total antioxidant capacity, indicating these antioxidant enzymes play essential roles in the protection of the body from the damage caused by the alkali treatment. Metabolic profiling analysis revealed that the main enriched metabolic pathways of differentially expressed metabolites in the present study were consistent with the metabolic pathways caused by environmental stress in plants and other aquatic animals. Transcriptome profiling analysis revealed that the alkali concentration of <8 mmol/L did not lead to significant changes in gene expression. The main enriched metabolic pathways were selected from the comparison between 0 mmol/L vs. 12 mmol/L, and some significantly up-regulated genes were selected from these metabolic pathways, predicting these selected metabolic pathways and genes are involved in the adaptation to alkali treatment in M. nipponense. The expressions of Ras-like GTP-binding protein, Doublesex and mab-3 related transcription factor 1a, and Hypothetical protein JAY84 are sensitive to changes in alkali concentrations, suggesting these three genes participated in the process of alkali adaptation in M. nipponense. The present study identified the effects of alkalinity exposure on the hepatopancreas of M. nipponense, including the changes in antioxidant status and the expressions of metabolites and genes, contributing to further studies of alkali tolerance in this species. [ABSTRACT FROM AUTHOR]

Adaptation to different salinity environments can enhance morphological and genomic divergence between related aquatic taxa. Species of prawns in the genus Macrobrachium naturally inhabit different osmotic niches and possess distinctive lifecycle traits associated with salinity tolerance. This study was conducted to investigate the patterns of adaptive genomic divergence during freshwater colonization in 34 Macrobrachium species collected from four continents; Australia, Asia, North and South America. Genotyping-by-sequencing (GBS) technique identified 5018 loci containing 82,636 single nucleotide polymorphisms (SNPs) that were used to reconstruct a phylogenomic tree. An additional phylogeny was reconstructed based on 43 candidate genes, previously identified as being potentially associated with freshwater adaptation. Comparison of the two phylogenetic trees revealed contrasting topologies. The GBS tree indicated multiple independent continent-specific invasions into freshwater by Macrobrachium lineages following common marine ancestry, as species with abbreviated larval development (ALD), i.e., species having a full freshwater life history, appeared reciprocally monophyletic within each continent. In contrast, the candidate gene tree showed convergent evolution for all ALD species worldwide, forming a single, well-supported clade. This latter pattern is likely the result of common evolutionary pressures selecting key mutations favored in continental freshwater habitats Results suggest that following multiple independent invasions into continental freshwaters at different evolutionary timescales, Macrobrachium taxa experienced adaptive genomic divergence, and in particular, convergence in the same genomic regions with parallel shifts in specific conserved phenotypic traits, such as evolution of larger eggs with abbreviated larval developmental. [ABSTRACT FROM AUTHOR]