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The growth environment significantly influences the intestinal microbiota of aquatic organisms. We investigated the composition and functional differences in the intestinal microbiota of red claw crayfish (Cherax quadricarinatus) in rice fields (RB) and ponds (PB) by 16S rDNA high-throughput sequencing technology. The results indicate that the Shannon, Simpson, Sobs, Chao1, and ACE indices of PB are all higher than those of RB, demonstrating greater diversity and richness of intestinal microbiota. The dominant phyla in the intestinal microbiota of the Cherax quadricarinatus were Proteobacteria, Tenericutes, and Firmicutes. Tenericutes and Proteobacteria were significantly more abundant in the RB than in the PB, while Planctomycetes and Firmicutes were significantly more abundant in the PB than in the RB. The results of network correlation analysis indicate that Proteobacteria and Firmicutes exhibit strong connectivity with other microbial groups in the gut microbiota of Cherax quadricarinatus, showing significant centrality. They play an important role in the interactions within the gut microbiota community. The dominant bacterial genera in the Cherax quadricarinatus's gut were Citrobacter, Candidatus_Bacilloplasma, and Clostridium_sensu_stricto_1. The abundance of the genus Clostridium was significantly higher in the PB than in the RB, whereas the abundance of Candidatus_Hepatoplasma and Vibrio was significantly lower in the PB than in the RB. The prediction function of KEGG enrichment showed that the abundance of Amino acid metabolism, Biosynthesis of Other Secondary Metabolites, Transport and Catabolism, Cancers, and Nervous System, Substance Dependence were significantly higher in the PB, while the infectious diseases pathway was enriched in the RB. In summary, our results revealed significant differences in the composition and diversity of intestinal microbiota in the Cherax quadricarinatus between rice paddy and pond farming environments. The intestinal microbiota of the Cherax quadricarinatus grown in pond environments exhibit higher diversity and stability, manifested by an increase in beneficial bacteria abundance and a decrease in opportunistic pathogens. These findings significantly improve understanding of the complex relationship among Cherax quadricarinatus, intestinal microbiota, and the environment. [ABSTRACT FROM AUTHOR]

Understanding the eco‐evolutionary processes which drive phenotypic variability in non‐native species is crucial to predicting impact and informing spatially explicit management models. Invasive redclaw crayfish, Cherax quadricarinatus, are spreading rapidly through the ecologically and economically important Upper and Middle Zambezi system in south‐central Africa.We tested whether there was an invasion front effect in the Barotse floodplain and disentangle whether these effects were related to environmental filtering, spatial sorting, or density‐dependent processes along a nonlinear 200 km invasion gradient over seasonal hydrological periods.Crayfish spread up‐ and down‐stream indicated an expanding population compared to the former invasion front in 2019, facilitated by both sexes. Wet season detection probability and relative abundance were lower than in the dry season. No signals of environmental filtering were detected as a result of high connectivity of habitats in the wet season.The invasion front population was characterised by lower relative abundance, lower body condition, larger overall body and chelae size, and longer front leg length. There was no effect on sex ratio. This indicated that spatial sorting, density‐dependent processes and predation pressure are acting as selective forces on phenotypic variability across the invasion gradient.Better understanding of the effects of flood regime and trophic interactions on phenotypic variability and dispersal is urgently needed. Population suppression to reduce spatial sorting and conspecific competition could be a viable management option at the invasion front. [ABSTRACT FROM AUTHOR]

【Objective】This trial was conducted to investigate the protein nutrient demand of crayfish (Cherax quadricarinatus) in low salinity (1.5‰), which would provide a theoretical basis for the development of artificial compound feed of crayfish in low salinity.【Method】Six kinds of equal energy feeds with different protein levels of 26.83% (D1), 29.71% (D2), 32.59% (D3), 35.42% (D4), 38.37% (D5) and 41.09% (D6) were prepared, and the crayfish larvae with initial weight of (0.41±0.01) g were cultured for 56 d as research objectives. The influence of feed protein level on the growth performance, basic muscle nutrients and amino acid content of young crayfish in low salinity culture environment were analyzed.【Result】The results showed that dietary protein level significantly affected the weight gain rate, specific growth rate, crude protein and crude lipid contents, and amino acid content (P＜0.05, the same below), but did not show any significant influence on survival rate, moisture and ash content of the crayfish (P＞0.05, the same below) . The weight gain rate and specific growth rate of crayfish in each group first increased and then decreased with the increase of protein level in the dietary. The weight gain rate in D3 was the highest, which was significantly higher than that in other groups. There was no significant difference in specific growth ratio among D3-D6 groups, but it was significantly higher than that in D1 and D2 groups. The crude protein content in crayfish muscle was positively correlated with the dietary protein level, and the crude protein content in high protein level group (D5, D6) was significantly higher than that in other groups. On the contrary, the crude lipid content of crayfish muscle was negatively correlated with the dietary protein level, and the crude lipid content of crayfish muscle decreased significantly with the continuous increase of dietary protein level. Seventeen amino acids were detected in muscle, including 7 essential amino acids (EAA), 2 semi-essential amino acids (HEAA) and 8 non-essential amino acids (NEAA) . The total amount of amino acids with protein level of 29.71%-41.09% increased significantly with the increase of dietary protein level.【Conclusion】In the low salinity culture environment, considering specific growth rate, the optimum protein level of crayfish feed was 36.09%. And considering umami amino acid ratio(WDAA/WTAA), the optimum protein level of crayfish feed was 30.96%. [ABSTRACT FROM AUTHOR]

Abstract Background The introduction of non-native species is a primary driver of biodiversity loss in freshwater ecosystems. The redclaw crayfish (Cherax quadricarinatus) is a freshwater species that exhibits tolerance to hypoxic stresses, fluctuating temperatures, high ammonia concentration. These hardy physiological characteristics make C. quadricarinatus a popular aquaculture species and a potential invasive species that can negatively impact tropical and subtropical ecosystems. Investigating the genomic basis of environmental tolerances and immune adaptation in C. quadricarinatus will facilitate the development of management strategies of this potential invasive species. Results We constructed a chromosome-level genome of C. quadricarinatus by integrating Nanopore and PacBio techniques. Comparative genomic analysis suggested that transposable elements and tandem repeats drove genome size evolution in decapod crustaceans. The expansion of nine immune-related gene families contributed to the disease resistance of C. quadricarinatus. Three hypoxia-related genes (KDM3A, KDM5A, HMOX2) were identified as being subjected to positive selection in C. quadricarinatus. Additionally, in vivo analysis revealed that upregulating KDM5A was crucial for hypoxic response in C. quadricarinatus. Knockdown of KDM5A impaired hypoxia tolerance in this species. Conclusions Our results provide the genomic basis for hypoxic tolerance and immune adaptation in C. quadricarinatus, facilitating the management of this potential invasive species. Additionally, in vivo analysis in C. quadricarinatus suggests that the role of KDM5A in the hypoxic response of animals is complex.

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For the first time, the data on the feeding habits of the Australian red claw crayfish Cherax quadricarinatus in water bodies of Russia are presented. The studies were carried out during the cultivation of crayfish in three ponds of the scientific and experimental complex of aquaculture BIOS of the Volga-Caspian branch of the Russian Federal Research Institute of Fisheries and Oceanography (VNIRO) in Astrakhan oblast in 2022. The food spectrum of C. quadricarinatus was dominated by plant remains and detritus (mainly rotting parts of cane), they were noted in all stomachs with food, and their share in the virtual food bolus constituted 82.4% on average. The share of the animal component in the virtual food bolus was 12.8% on average, and it was represented mainly by macrobenthos. Planktonic crustaceans did not make up a significant proportion in the virtual food bolus. In total, 20 taxa of invertebrates were found in stomachs. Among the benthic species, larvae of Odonata, chironomids, and larvae and imagoes of Coleoptera predominated. A preliminary assessment of the possible impact of crayfish Cherax quadricarinatus on ecosystems when it penetrates into natural water bodies of the South of Russia has been carried out. [ABSTRACT FROM AUTHOR]

Fishing is part of human culture since ancient times to catch fish. The use of live bait by anglers is an important factor in the spread of invasive aquatic species. To analyze the habits of Indonesian anglers in using freshwater crayfish as live bait, an anonymous online questionnaire was spread via social media in Indonesia. The questionnaire included a series of closed and open-ended questions that investigated various socio-psychological parameters and types of bait used by Indonesian anglers. Redclaw crayfish Cherax quadricarinatus, which is non-indigenous in most of the Indonesian territory, was found to be used by 13% of anglers for this purpose there. These findings illustrate the need for focused management activities. Any potentially invasive non-native species imported into Indonesia, as well as those that are accidentally or deliberately released into the waters, should be regulated, so as not to cause environmental damage. [ABSTRACT FROM AUTHOR]

Aim. The concentration of total protein in the hemolymph of the Australian red-clawed crayfish Cherax quadricarinatus, Von Martens 1868, contained in artificial conditions in closed water supply installations and an aquarium complex, was studied. Methodology. The object of the study was the Australian red-clawed crayfish, a total of 161 individuals were used in the experiment. Crayfish were kept in closed water supply installations. To study the protein concentration depending on the time of year, samples were taken and analyzed in the period 2021-2023: January – winter; April – spring; August – summer; September, October and November – autumn. To conduct an experiment to study the total protein content of cancer hemolymph, depending on the water temperature, three experimental groups of 15 cancers were formed in each. The experimental groups were seated in three aquariums, with a water temperature of 20, 25, 30 ° C. The duration of the crayfish exposure was 10 days. On the tenth day, hemolymph was collected. The total hemolymph protein was determined by the refractometric method. Results. It was found that the concentration of total protein in the hemolymph can be in the ranges from 10.8 to 108.8 g/l and average 50.5 ± 21.1 g/l. In crustaceans kept in unfavorable conditions, the concentration of total protein was 1.6 times lower. There were no differences in protein concentration at different seasons of the year. After molting, the concentration of total protein in the hemolymph decreases 2.7 times. It was found that short-term exposure of cancer in water with a temperature of 20, 25, 30 ° C does not lead to a change in the total protein content. Conclusion. A wide range of total protein concentrations may indicate a high adaptive potential of this organism. A decrease in the concentration of total protein may be due to the presence of a crustacean in unfavorable conditions and its defeat by a bacterial agent. It is noted that the change in protein concentration at different times of the year in a crustacean under artificial conditions cannot be interpreted as seasonal fluctuations.

The purpose of the experiment was to study the effects of Lactobacillus on the growth performance and intestinal microbial community structure of Cherax quadricarinatus. A total of 600 Cherax quadricarinatus seedlings with initial weight of (0.55±0.05) g were randomly divided into four groups with three replicates in each group and 50 shrimp seedlings in each replicate. CA group, TB group, TC group, and TD group were fed with 0, 1.8x105, 1.8x106, and 1.8x107 CFU/g of Lactobacillus, respectively. The trial period was 45 days. The results showed that compared with CA group, the final weight, weight gain rate, and specific growth rate of Cherax quadricarinatus in TB group and TC group increased significantly (P<0.05), the feed coefficient in TC group decreased significantly (P<0.05), while the growth performance of TD group did not increase further. The addition of Lactobacillus in feed obviously changed the intestinal microflora structure of Cherax quadricarinatus, improved the diversity and abundance of beneficial bacteria in intestinal tract, and inhibited the growth of conditional pathogenic bacteria, especially in the early stage. The results showed that adding 1.8x106 CFU/g Lactobacillus to the feed could obviously improve the growth performance of Cherax quadricarinatus, increase the diversity and abundance of beneficial bacteria in the intestinal tract of Cherax quadricarinatus, inhibit the growth of conditional pathogenic bacteria, and benefit the health of Cherax quadricarinatus. [ABSTRACT FROM AUTHOR]

Freshwater lobsters are one of the crustacean commodities that have started to be developed through cultivation. Besides having high nutritional value, freshwater lobsters have a stable sales value or price throughout the year. Freshwater lobster is a crustacean commodity that is not easily stressed or easily attacked by disease. The availability of calcium is essential for lobster growth, especially the formation of its shell. This research aims to determine the effectiveness of adding calcium carbonate at different time intervals by adding 150 mg/L CaCo3 lime. The study was conducted from June to July 2020 at the Aquaculture Environmental Laboratory, Bogor Agricultural Institute. The research used a Completely Randomized Design (CRD) with five treatments and three replications. The treatment used was K+ and K-, and the time interval for adding CaCo3 was once every five days, once every ten days, and once every 15 days. The aquarium measures 100 x 50 x 51 cm with a water height of 21 cm. The lobster used measures 1.5 cm. The research results after statistical testing showed that aquarium A1 (addition of CaCo3 every five days) experienced an increase in length of 0.67 cm. Weight of 0.67 g, B1 (addition of CaCo3 every ten days) experienced an increase in length of 0.87 cm and weight of 0.78 g, C1 (addition of CaCo3 every 15 days) experienced an increase in length of 0.97 cm and weight of 0.98 g, K+1 experienced an increase in length of 1.05 cm and weight of 1.06 gr, K-1 experienced an increase in length of 0.46 cm and weight of 0.45 g. [ABSTRACT FROM AUTHOR]

The purpose of this experiment is to explore the effect of different additives on the nursing effect of young Cherax quadricarinatus. A total of 10 800 Cherax quadricarinatus. were selected and randomly divided into six groups, with three repetitions in each group and 600 Cherax quadricarinatus. in each repetition. Group 1 (control group) was fed basic feed, Group 2 was fed 70% basic feed + 30% Spirulina powder, Group 3 was fed 80% basic feed + 20% Spirulina powder, Group 4 was fed 80% basic feed + 10% Spirulina powder + 3% astaxanthin +2% linseed oil + 3% Antarctic krill oil + 2% riboflavin, Group 5 was fed 70% basic feed + 10% Spirulina powder + 6% astaxanthin + 4% linseed oil + 6% Antarctic krill oil + 4% riboflavin, and Group 6 was fed 70% basic feed + 20% Spirulina powder + 3% astaxanthin + 2% linseed oil + 3% Antarctic krill oil + 2% riboflavin. The experiment lasted for 10 days. The results showed that the survival rates of juveniles in Group 4 and Group 5 were significantly higher than those in Group 1 and Group 2 (P<0.05), with the survival rates ranking as follows: Group 4 > Group 5 > Group 3 > Group 6 > Group 2 > Group 1. Juveniles in Group 4 exhibited higher weight gain and total length increase rates, with the weight gain rates ranking as follows: Group 4 > Group 3 > Group 5 = Group 6 = Group 2 > Group 1, and the total length increase rates ranking as follows: Group 4 > Group 5 > Group 3 > Group 2 > Group 6 > Group 1. The activity of TPS, SOD, ACP, and AKP in juveniles from Group 4 was significantly higher than those in Group 1 and Group 2 (P<0.05). The results showed that Group 4 had a higher survival rate, growth rate, and immune related enzyme activities, that was, 80% basic feed +10% Spirulina powder + 3% astaxanthin + 2% linseed oil + 3% Antarctic krill oil + 2% riboflavin had better effect. [ABSTRACT FROM AUTHOR]

Crayfish are known to effectively invade freshwater systems worldwide. Whilst no native crayfish species exist in Israel, three exotic species have been documented in recent years, and their introduction details are hereby discussed. Three of these introduction events, one of each species, were previously reported; one was established, one failed to establish, and the third was successfully eradicated. However, more recently, invasive crayfish have been independently detected multiple times, involving a variety of natural and artificial habitats. Altogether, three invasive crayfish species currently inhabit Israeli freshwaters: Cherax quadricarinatus, Procambarus clarkii, and Procambarus virginalis. They were found in fourteen independent cases, and at least five of them represent established populations. Similar to other crayfish invasions around the globe, we speculate that the invasive populations in Israel result from the intentional release of aquarium inhabitants, as well as from aquaculture escapees. The import and trade policy of aquatic organisms in Israel requires thorough revision to prevent future invasions. Thought should also be given to the prevention of the spread of the existing invasive populations as well as to their eradication, if possible. [ABSTRACT FROM AUTHOR]

Cutibacterium acnes is one of the bacteria that cause acne on the face. Freshwater crayfish (Cherax quadricarinatus) shells have been abandoned and are not used by the community; thus, their shells are processed into economically valuable compounds such as chitosan. Chitosan has antibacterial characteristics that can inhibit acne bacterial development. The purpose of this study is to see if chitosan derived from crayfish shells may be stable in the form of an anti-acne gel and has antibacterial action against Cutibacterium acnes. Anti-acne gel was made from crayfish shells at concentrations of 2, 4 and 6 %, then gel formulations were evaluated and antibacterial efficacy against Cutibacterium acnes germs was tested. Chitosan produced by freshwater lobster shells was 68.75 %. The results of the test of freshwater crayfish shells against Cutibacterium acnes revealed that the average diameter of the inhibition was 6.34 mm at a concentration of 2 %, 6.57 mm at a concentration of 4 % and 6.90 mm at a concentration of 6 %; thus, a concentration of 6 % has the best inhibition. According to the organoleptic test, there was no change in shape or color. According to the homogeneity test, there are no lumps or coarse grains. According to the spreadability test, all preparations were within a 56 cm range. The adhesion test shows a satisfactory adhesion time of more than 1 s. The pH test revealed that all preparations were within the normal skin pH range, indicating that the recipe satisfied the specifications. Anti-acne gel prepared from the shell of a freshwater crayfish displays antibacterial action against Cutibacterium acnes as a cause of acne, with an inhibitory diameter of 6.11 mm at 2 % concentration, 6.8 mm at 4 % concentration and 7.11 mm at 6 % concentration. The diameter of the inhibitory zone in the positive control was 11.9 mm. [ABSTRACT FROM AUTHOR]

Вирощування австралійського червоноклешневого раку Cherax quadricarinatus у багатьох країнах стало популярним через швидку інтенсивність росту, високу харчову та біологічну цінність м’яса та доволі значний попит серед споживачів. Метою нашого дослідження було визначити хімічний, амінокислотний та жирнокислотний склад м’яса раків Cherax quadricarinatus та його енергетичну цінність за годівлі різними видами кормів. Жирнокислотний склад у м’яса раків визначали хроматографічним методом, а амінокислотний - методом капілярного електрофорезу. Встановлено, що під час годівлі раків розробленим кормом Decapodafood енергетична цінність м’яса була на 4,3 ккал вищою, ніж за годівлі раків акваріумним кормом Ancistrus menu. Годівля кормом Decapodafood сприяє більшому вмісту незамінних амінокислот, порівняно з годівлею комерційним акваріумним кормом Ancistrus menu. Зокрема, статистично ймовірним був вищий вміст у м’ясі таких незамінних амінокислот, як треонін, валін, метіонін, лізин. Крім того, виявлено високу біологічну цінність та засвоюваність м’яса раків, оскільки сума ΣНAК/ΣЗАК у всіх пробах становила вище 80 %, що в середньому на 20 % більше, ніж стандартний показник, рекомендований ФАО/ВООЗ. Годівля раків кормом Decapodafood сприяє зменшенню у складі м’яса насичених жирних кислот та збільшенню ненасичених. Зокрема, виявлено в 1,9 раза менший вміст лауринової кислоти та в 1,5 раза – маргаринової кислоти у м’ясі раків, яким згодовували корм Decapodafood, порівняно з раками, яких годували акваріумним кормом Ancistrus menu, а міристинової й пентадеканової – був у середньому в 1,3 раза менший. Серед ненасичених жирних кислот ймовірне збільшення в 1,4 раза відзначали для пальмітолеїнової та докозагексаєнової кислот, порівняно з їх вмістом у контрольному м’ясі. Вміст інших поліненасичених жирних кислот (лінолевої й ейкозапентаєнової), хоч і був вищим, але несуттєво. Отже, годівля раків Cherax quadricarinatus кормом Decapodafood сприяє покращенню енергетичної та біологічної цінності отриманого м’яса, що робить його високозасвоюваним та делікатесним продуктом.

Freshwater crayfish farming is a promising area of production in the food market. This aquaculture industry is currently gaining popularity around the world, but given the high consumer demand, it requires modernisation. The efficiency of aquaculture production is based on the introduction of innovative methods into production processes, which are based on knowledge of biological characteristics, including reproductive capacity and the embryonic period of caviar development. The study aims to assess the reproductive quality of females and determine the incubation period of caviar, its quantity, weight, and survival rate. The study presents the results of research on the reproductive qualities and embryonic period of crayfish eggs of four species (Cherax quadricarinatus, Procambarus clarkii, Procambarus fallax forma virginalis, Cherax destructor) kept in separate closed water supply tanks at an optimal planting density of 4 individuals per 0.45 m2 . Studies have shown that the colour range of caviar and the duration of the incubation period for its maturation varies among different crayfish species. Thus, the first stage of incubation was the shortest and ranged from 2.80 (Florida crayfish) to 3.55 (destructor crayfish) days, while the second stage lasted the longest – from 13.17 to 15.80 days for Australian and broad-toed crayfish, respectively. Based on the analysis of the physiological characteristics of the female crayfish micropopulation, they were divided into quality categories, considering the following indicators: female weight, egg weight, total number of eggs, and number of eggs per 1 g of female. Females of the Australian red snapper of the excellent category was the best among all species in terms of live weight (63.0±0.67 g), egg weight (5.0±0.05 g) and total number of eggs (376.8±16.34 pcs.), the lowest similar indicators were in the marble species (16.8±0.15 g, 1.6±0.03 g, 124.5±2.66 pcs.), respectively. In terms of the number of eggs per 1 g of female weight, Florida crayfish prevailed (7.8±0.19). Instead, the destructor crayfish had intermediate results in these characteristics. The study results can be used in the economic activities of enterprises producing aquatic organisms

The growth environment significantly influences the intestinal microbiota of aquatic organisms. We investigated the composition and functional differences in the intestinal microbiota of red claw crayfish (Cherax quadricarinatus) in rice fields (RB) and ponds (PB) by 16S rDNA high-throughput sequencing technology. The results indicate that the Shannon, Simpson, Sobs, Chao1, and ACE indices of PB are all higher than those of RB, demonstrating greater diversity and richness of intestinal microbiota. The dominant phyla in the intestinal microbiota of the Cherax quadricarinatus were Proteobacteria, Tenericutes, and Firmicutes. Tenericutes and Proteobacteria were significantly more abundant in the RB than in the PB, while Planctomycetes and Firmicutes were significantly more abundant in the PB than in the RB. The results of network correlation analysis indicate that Proteobacteria and Firmicutes exhibit strong connectivity with other microbial groups in the gut microbiota of Cherax quadricarinatus, showing significant centrality. They play an important role in the interactions within the gut microbiota community. The dominant bacterial genera in the Cherax quadricarinatus’s gut were Citrobacter, Candidatus_Bacilloplasma, and Clostridium_sensu_stricto_1. The abundance of the genus Clostridium was significantly higher in the PB than in the RB, whereas the abundance of Candidatus_Hepatoplasma and Vibrio was significantly lower in the PB than in the RB. The prediction function of KEGG enrichment showed that the abundance of Amino acid metabolism, Biosynthesis of Other Secondary Metabolites, Transport and Catabolism, Cancers, and Nervous System, Substance Dependence were significantly higher in the PB, while the infectious diseases pathway was enriched in the RB. In summary, our results revealed significant differences in the composition and diversity of intestinal microbiota in the Cherax quadricarinatus between rice paddy and pond farming environments. The intestinal microbiota of the Cherax quadricarinatus grown in pond environments exhibit higher diversity and stability, manifested by an increase in beneficial bacteria abundance and a decrease in opportunistic pathogens. These findings significantly improve understanding of the complex relationship among Cherax quadricarinatus, intestinal microbiota, and the environment.

Nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs), classified as pattern recognition receptors (PRRs), play crucial roles in innate immune responses. However, research on this topic in crustaceans remains limited. In the present study, 27 NLR family members were identified and characterized based on the redclaw crayfish genome. Gene structure, conserved domain, and motif analyses revealed that these NLR genes were classified into four subfamilies with three major domains, and phylogenetic and structural analyses further confirmed their evolutionary conservation. qRT-PCR analysis showed that the relative expression levels of several NLR genes changed significantly under the DIV1 challenge. More importantly, in vivo silencing of NAWD1 gene in Cherax quadricarinatus promoted DIV1 replication . These findings, together with those of previous studies, suggest that NLR genes in crustaceans may play a key role in immune responses to viral infections.

Cherax quadricarinatus, also known as the redclaw crayfish, is native to northern Australia and southern Papua New Guinea and is an important freshwater aquaculture species in many countries. Studying the genetic structure of the current cultured population can improve the breeding plan for redclaw crayfish to better manage the hybridization and germplasm bank and promote their rational utilization; however, microsatellite resources for redclaw crayfish remain insufficient. The purpose of this study was to analyze the genetic diversity of different redclaw crayfish populations in China. After screening 18 pairs of microsatellite markers from redclaw crayfish transcriptome data, 240 samples from seven main breeding areas (Changsha, Guangzhou, Haikou, Huzhou, Jiangmen, Wuxi, and Zhanjiang) were evaluated and detected using these microsatellite markers. In total, 97 alleles were detected, of which the minimum number was two and the maximum number was twelve. The observed heterozygosity ranged from 0.258 to 0.807, with an average of 0.559, and the expected heterozygosity ranged from 0.288 to 0.815, with an average value of 0.558. The polymorphic information content values of seven populations ranged from 0.268 to 0.791, with an average of 0.511. Moreover, pairwise genetic differentiation within the population was between 0.007 and 0.031. The UPGMA clustering results showed that the Zhanjiang population stands alone on a branch, but the genetic variation between branches is very small. Meanwhile, STRUCTURE analysis further revealed that the genetic backgrounds of each population are essentially identical, with no noticeable genetic differentiation arising from geographic differences. These results provide a basic assessment of the genetic diversity of the main cultured populations of redclaw crayfish and a molecular foundation for future genetic monitoring and selective breeding research.

The introduction of the crayfish Cherax quadricarinatus into new areas of Malaysia resulted in the introduction of new parasites that harmed other aquatic organisms. A study was conducted to determine the prevalence and sites specificity of temnocephalids in wild and cultured Cherax quadricarinatus. In this study, 33 wild (Melaka) and 32 cultured (Johor) C. quadricarinatus were sampled in January 2020. The prevalence of the parasite was determined using dissecting microscopes and their sites specificity were compared. The prevalence (P) and mean intensity (MI) of temnocephalids in wild crayfish were 93.94% and 35.13%, whereas in the cultured crayfish were 100% and 18.31%, respectively. The temnocephalid species were identified as Diceratocephala sp., Craspedella sp., and Decadidymus sp. The prevalence of adults and eggs of Decadidymus sp. was found to be significant in cultured C. quadricarinatus (p

Microcystin-LR (MC-LR), the most prevalent cyanobacterial toxin, poses a serious threat to the survival of aquatic animals. Herein, crayfish (Cherax quadricarinatus) were treated with MC-LR at 33.06 μg kg−1 for 48 h, and the effects of MC-LR on behavior, histomorphology, oxidative stress, non-specific immunity, and gene expression were investigated to elucidate the molecular mechanisms underlying antioxidation and detoxification in crayfish. MC-LR caused vacuolation and disruption of crayfish hepatopancreatic cells, although no significant effect was observed on the structure of intestinal cells. Moreover, MC-LR increased the activity of antioxidant enzymes (SOD, CAT, GPx, GST) and up-regulated the expression of genes encoding antioxidant enzymes (ecCu,Zn-SOD, SOD, Se-GPx, GPx3P, GST). In addition, GSH was found depleted in the hepatopancreas and plasma. MC-LR activated the immune system, enhanced immunoenzyme activity (ACP, AKP) and induced the expression of immunity-related genes (C-LZM, proPO, hemocyanin). Furthermore, caspase and HSP70 genes were induced in the hepatopancreas of crayfish under MC-LR stress. Taken together, MC-LR was shown to cause a positive response in crayfish, and our findings suggested that the antioxidant activity and immune system play an important role in protecting crayfish from MC-LR stress by regulating gene expression and activities of antioxidant and immune enzymes.

We explored the effects of different conditions on the artificial incubation of redclaw crayfish eggs in an effort to improve this process. Samples at the egg and juvenile stages were selected. The samples at different stages were separated from the pleopods, then they were placed in incubator boxes and sterilized with different disinfectant solutions. The density was 300,400 and 500 eggs/incubator box, the vibration frequency was 11,16 and 26 vibrations/min, and the water circulation cycle was 2.1, 4.8 and 7.1 cycles/h. The results showed the eggs disinfected with 3000 ppm formaldehyde for 15 min had stronger antioxidant capacity. The hatching and survival rates of five pairs of appendage stage group were significantly lower than those of other groups. In the egg stage, acid phosphatase (ACP) level of compound eye pigmentation stage group was significantly higher than those of other groups. In the juvenile stage, malondialdehyde (MDA) content of five pairs of appendage stage group was significantly higher than those of other groups. The survival rate of 500 eggs/box group was significantly higher than that of other groups. In the egg stage, alkaline phosphatase (AKP) level of 400 eggs/box group was significantly higher than that of other groups. The survival rate of 11 vibrations/min group was significantly higher than that of other groups. In the egg stage, ACP and AKP levels of 11 vibrations/min group were significantly higher than those of 26 vibrations/min group. In the juvenile stage, superoxide dismutase (SOD), ACP and AKP levels of 11 vibrations/min group was significantly higher than those of 26 vibrations/min group. In the juvenile stage, AKP level of 4.8 cycles/h group was significantly lower than that of other groups. In conclusion, egg development at the stage after seven pairs of appendages, with a density of 400 eggs/box, vibration frequencies set at 11 vibrations/min achieved high hatching rates (93.58 %) and survival rates (75.67 %). Moreover, bronopol or hydrogen peroxide might have a better choice to replace formaldehyde if further exploration was conducted to reduce stimulation of the in vitro-grown egg. These conditions could be used on a large scale to optimize the production of redclaw crayfish.

Annexin (Anx) family protein is a highly conserved protein family that plays important roles in immune defense of vertebrates and invertebrates against invading pathogens. In this study, a novel Anx was cloned and characterized from the red claw crayfish, Cherax quadricarinatus. The Open Reading Frame of Cq AnxB9 consisted of 930 nucleotide bases pair and encoded 309 amino acids. The Cq AnxB9 protein contained three repeat Anx domains and a typical KGLGT sequence. Tissue expression analysis showed that the expression levels of Cq AnxB9 were mainly expressed in the intestine, hepatopancreas and hemocytes. After WSSV challenge, Cq AnxB9 expression was up-regulated in the hematopoietic tissue (Hpt) cells. Moreover, knockdown of Cq AnxB9 inhibited WSSV replication and VP28 expression, suggesting that Cq AnxB9 plays a positive role in WSSV infection. Further studies revealed that recombinant Cq AnxB9 protein was found to bind to the viral envelop protein VP28. All these findings indicate that new-found Cq AnxB9 is likely to promote WSSV infection in crustaceans, which provides a better understanding of the pathogenesis of WSSV. • A novel AnnexinB9 gene (Cq AnxB9) was firstly identified from Cherax quadricarinatus , which belongs to Annexin family. • Cq AnxB9 was widely expressed in various tissues with highest expression in Intestine but lowest in Nerve tissue. • Cq AnxB9 was located mainly in the cell membrane and cytoplasm. • Knockdown of Cq AnxB9 could inhibit the viral replication of WSSV. • Cq AnxB9 protein could bind to the viral envelope protein VP28. [ABSTRACT FROM AUTHOR]

The effect of exposure on the hematological parameters of the red claw crayfish Cherax quadricarinatus Von Martens 1868 has been studied. The hemolymph is taken immediately after extraction from the water after 2, 4, and 8 h of exposure on the shore and 24 and 72 h after returning to the water. The total hemocyte counts (THCs), hemogram, general protein, and hemocyanin disease are determined. The dynamics of the growth of hematological parameters in the temporal aspect is revealed: THC and the proportion of granulocytes increase to reveal the entire pattern of growth, the proportion of agranulocytes, and the total content of protein and hemocyanin. After exposure on the shore, the color of the hemolymph changes from bluish with a grayish tint to cloudy gray-green (deviation from the norm). The data indicate the development of compensatory factors and pathological properties in response to stress and the occurrence of symptoms in the air, which can be used in practice in assessing the state of the red claw crayfish in the process of transport. [ABSTRACT FROM AUTHOR]

Red claw crayfish Cherax quadricarinatus has emerged as a highly significant and suitable species to be raised in integrated rice–aquatic animal farming systems. To optimize an integrated aquaculture and agriculture (IAA) system and ensure sustainable utilization and development of land resources, an IAA system combining rice cultivation with red claw crayfish culture was implemented to assess the impacts of rice–red claw crayfish co-culturing on the dynamics and assembly of bacterial communities in paddy soils. We established two experimental groups, each with eight replicates. We utilized 16S rRNA Illumina high-throughput sequencing to access the bacterial community composition and assembly in paddy soils. Red claw crayfish C. quadricarinatus cultivation did not significantly affect the alpha diversity of the bacterial community in the paddy field, but it obviously increased the relative abundances of the phyla Acidobacteriota and Pseudomonadota involved in organic matter degradation and nitrogen, phosphorus, and carbon cycling. Red claw crayfish cultivation could lead to more complex bacterial communities, increased bacterial resistance to disturbances, the promotion of niche differentiation, and increased competition intensity between bacterial communities during the mid-cultivation period. Nitrogen emerged as a critical factor influencing the bacterial community composition in paddy soil during the culture period, and the red claw crayfish cultivation affected the bacterial community by altering the ammonia concentration in the paddy soil. As the culture progressed, the assembly of the bacterial community in the paddy soil was predominantly driven by stochastic processes, and red claw crayfish cultivation accelerated the evolution of the bacterial community assembly towards a stochastic process. Our study offers valuable insights into the dynamic changes occurring in the composition and assembly of bacterial communities in paddy soils in response to red claw crayfish cultivation. [ABSTRACT FROM AUTHOR]

For the omnivorous Cherax quadricarinatus crayfish, plant raw materials can be good alternatives to dietary fish meal (FM). A 56-d feeding trial was conducted in C. quadricarinatus (11·70 (se 0·13) g). Diet with 100 % FM as the protein source was the control. Seven experimental diets were formulated by replacing 75 or 100 % of FM with soyabean meal (SM75, SM100) or cottonseed meal (CM75 and CM100), and a mixture of SM and CM (protein content is 1:1) replacing 50, 75 or 100 % of FM (SC50, SC75 and SC100). Crayfish fed the CM100 and SC100 showed significantly lower weight gain (WG), specific growth rate, trypsin and pepsin activities compared with the control diet. Crayfish in CM100 group showed significantly higher GPx, alanine aminotransferase, aspartate aminotransferase activities and malondialdehyde content than the control. SM100 and CM100 diets can cause slight separation of the peritrophic membrane from the intestinal folds. The pepsin activity of crayfish in SC50 was significantly higher than those in other experimental diets. The highest WG and muscle arginine content were also found in crayfish fed SC50. The relative abundance of Proteobacteria , Unclassified Enterobacteriaceae and Candidatus Bacilloplasma was significantly higher, but Actinobacteriota was significantly lower in SM100, CM100 and SC100 than in control. Microbiota functional prediction indicated that the relative abundance of 'cell motility' pathway in crayfish fed CM100 was significantly decreased compared with the control. In conclusion, only half of the FM can be effectively substituted with a mixture of SM and CM (protein content is 1:1) for C. quadricarinatus. [ABSTRACT FROM AUTHOR]

The introduction of the crayfish Cherax quadricarinatus into new areas of Malaysia resulted in the introduction of new parasites that harmed other aquatic organisms. A study was conducted to determine the prevalence and sites specificity of temnocephalids in wild and cultured Cherax quadricarinatus. In this study, 33 wild (Melaka) and 32 cultured (Johor) C. quadricarinatus were sampled in January 2020. The prevalence of the parasite was determined using dissecting microscopes and their sites specificity were compared. The prevalence (P) and mean intensity (MI) of temnocephalids in wild crayfish were 93.94% and 35.13%, whereas in the cultured crayfish were 100% and 18.31%, respectively. The temnocephalid species were identified as Diceratocephala sp., Craspedella sp., and Decadidymus sp. The prevalence of adults and eggs of Decadidymus sp. was found to be significant in cultured C. quadricarinatus (p < 0.05). Significant differences were observed by adult Diceratocephala sp. and Craspedella sp. on the cephalothorax and walking legs, and in the gills and gill covers of wild C. quadricarinatus , respectively. These findings showed that the cultured C. quadricarinatus had a higher temnocephalid infestation compared to the wild C. quadricarinatus. These different temnocephalid species occupied different niche areas, but factors accounting for their distribution on C. quadricarinatus need further investigation. [ABSTRACT FROM AUTHOR]

Polyculture is an effective way to achieve efficient utilization of nutrient resources in high-density intensive aquaculture systems. In order to study the optimal culture mode of Oreochromis niloticu, Aristichthys nobilis, and Cherax quadricarinatus, the budget of nitrogen and phosphorus in various polyculture systems (CH, CHC1, CHC2, CHC3) was studied with land-based enclosures. The results showed that all the three polyculture systems had higher total yields of cultured animals than the control group (two polyculture systems) (p < 0.05). The co-cultured organisms absorbed artificial feed or organic matter (such as plankton and sediment) from the polyculture system to different degrees. Feed was the main input of nitrogen (98.22–98.33%) and phosphorus (99.43–99.56%) in all systems. Considering the N and P outputs, 46.64–64.58% and 81.60–84.79%, respectively, accumulated in the sediment, and 34.43–52.55% and 14.89–17.30% of the N and P outputs, respectively, were harvested by aquaculture organisms. The pollution production coefficients of TN and TP in the O. niloticus polyculture ponds were 5.35–6.26 g/m2 and 1.17–1.61 g/m2, respectively. The TN production coefficients of O. niloticus and the ternary polyculture groups (CHC1, CHC2, and CHC3) were lower than that of the control group (CH). The TP production coefficients showed the opposite pattern. The N and P utilization efficiencies in the group with the optimal ratio of O. niloticus, A. nobilis, and C. quadricarinatus (4, 0.15, and 3 ind/m2, respectively) were 2.56–12.82% and 6.62–11.03% higher, respectively, compared with those of the other groups. The N utilization efficiency was effectively improved in this group with the optimum stocking density for the polyculture systems, resulting in improved ecological efficiency and economic benefits. [ABSTRACT FROM AUTHOR]

Stocking density is a crucial factor affecting productivity in aquaculture, and high stocking density is a stressor for aquatic animals. In this study, we aimed to investigate the effects of stocking densities on oxidative stress and energy metabolism in the gills of Cherax quadricarinatus under rice-crayfish farming. The C. quadricarinatus were reared at low density (LD), medium density (MD), and high density (HD) for 90 days. The results showed that the superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and malondialdehyde (MDA) levels were higher in the HD group than those in the LD group. Transcriptomic analysis revealed 1944 upregulated and 1157 downregulated genes in the gills of the HD group compared to the LD group. Gene ontology (GO) enrichment analysis indicated that these differentially expressed genes (DEGs) were significantly associated with ATP metabolism. KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis also showed that high stocking density resulted in the dysregulation of oxidative phosphorylation. Furthermore, high stocking density upregulated six lipid metabolism-related pathways. Overall, our findings, despite the limited number of samples, suggested that high stocking density led to oxidative stress and dysregulation of energy metabolism in the gills of C. quadricarinatus under rice–crayfish co-culture. Alteration in energy metabolism may be an adaptive response to adverse farming conditions. [ABSTRACT FROM AUTHOR]

The threats posed by invasive freshwater crayfish species are one of the greatest concerns for freshwater ecologists, environmental managers, policy makers and local communities in the invaded regions. The invasive Australian redclaw crayfish Cherax quadricarinatus is rapidly spreading in southern Africa. Fishers in the Zambezi Basin have reported that crayfish affect their catch through partial consumption of fish caught on static gillnets. Owing to the immeasurable contributions of fishery to socioeconomic livelihoods in Africa, the catch losses that are due to crayfish are of concern. With this problem in Africa, it is imperative to continue researching on adaptive strategies to cope with the invasion. This study tested the effectiveness of "misdirection traps" to prevent fish spoilage and gear damage for gillnet catches by crayfish in Lake Kariba, Zimbabwe. The method involved placing baited traps along a gillnet to misdirect crayfish into the traps rather than fishing gear to prevent fish spoilage by scavenging. The misdirection traps significantly lowered the amount of catch spoilage. Gillnet damage by crayfish in general was minimal, although it was higher for gillnets without baited traps. The misdirection traps pose a pragmatic management initiative to reduce socioeconomic fishery costs from crayfish. We consider this method to be applicable in all the invaded regions where artisanal fishers are experiencing catch spoilage problems making a huge step towards preventing socioeconomic impacts associated with crayfish invasion. [ABSTRACT FROM AUTHOR]

The redclaw crayfish had been listed as an invasive species in Malaysia following the various negative impacts displayed on both environment and economy. The species are largely culture in Malaysia for food, but unluckily escaped and expands to several waterbodies across the country. For effective control management of redclaw crayfish species, a total of 52 wild samples were collected from six locations in Peninsular Malaysia and analyzed using a 16S mitochondrial DNA to assess their genetic diversity and introduction history. Five haplotypes were detected associated with an overall low genetic diversity (Hd = 0.385, p = 0.00133). A single genetic structure was detected with a phylogenetic relationship showing two clusters related to the haplotypes from Australia and Papua New Guinea. The finding of this study provides the basic data that will aid the appropriate Malaysian authorities for both monitoring and management strategies of redclaw crayfish in Peninsular Malaysia. [ABSTRACT FROM AUTHOR]

In order to explore the changes of nutrients in the fertilized eggs of Australian freshwater lobster during development, the fertilized eggs in the egg-nauplius stage, the embryo with eye pigment forming stage, the prepare-hatchling stage and newly hatched shrimp were systematically analyzed in this study. The results showed that, moisture content in fertilized eggs increased significantly with the development of fertilized eggs to newly hatched shrimp, crude protein and lipid content decreased significantly with the development process, the ash content of newly hatched shrimp was the highest; Total amino acids, essential amino acids, and flavoring amino acids content of fertilized eggs decreased significantly with the development process; Based on the nutritional evaluation by amino acids score (AAS) and chemical score (CS), (Met+Cys) was the first limiting amino acids of fertilized eggs and newly hatched shrimp; EAAI of fertilized eggs and newly hatched shrimp decreased significantly with the development of fertilized eggs to newly hatched shrimp; 10 main fatty acids were detected in fertilized eggs and newly hatched shrimp of Australian freshwater lobster, and the contents of PUFA and DHA in newly hatched shrimp were significantly lower than those in fertilized eggs, but the content of EPA+DHA was significantly higher than that of fertilized eggs. In conclusion, the content of ash and EPA+DHA of newly hatched shrimp were significantly higher than those of fertilized eggs, so the addition of calcium dihydrogen phosphate and EPA+DHA can be appropriately increased in the preparation of open bait for Australian freshwater lobster larvae. [ABSTRACT FROM AUTHOR]

High mortalities of redclaw crayfish (Cherax quadricarinatus) were reported from northern Queensland farms, mainly attributed to two viruses, Chequa iflavirus and Athtab bunyavirus. From a research population of redclaw crayfish with these pre-existing viral infections, five individuals were found uninfected by Chequa iflavirus but infected with Athtab bunyavirus. A pilot study was designed to examine if progeny crayfish from this cohort were resistant to infections by Chequa iflavirus. Two experiments measured changes in viral load with RT-qPCR. Seven donors, four negative controls and six crayfish injected with a purified virus or saline were used. In Experiment 1, the purified viral inoculum was injected into the crayfish, and they were bled 14 days post-injection (dpi). In Experiment 2, haemolymph containing the viruses was injected into the same crayfish and they were bled at 24 hpi, 48 hpi, 7 dpi and 14 dpi. In Exp. 1, the crayfish cleared Chequa iflavirus infections within 14 dpi, while in Exp. 2, it was within 24 hpi. One mortality was observed, but that crayfish had cleared the virus before dying. The number of copies of Athtab bunyavirus and the weights of the crayfish did not differ significantly (p > 0.05) between the control and injected crayfish. Histology of crayfish all showed that the haemolymph vessels were clear of granulomas, suggesting no bacterial involvement. There was no melanisation in the gill tissue of control crayfish, but it was prominent in virus-injected crayfish. Neither group had haemocytic infiltration of the muscle fibres. Anti-viral immune mechanisms of RNA interference and Cherax quadricarinatus Down Syndrome Cell Adhesion Molecule (DSCAM) are hypothesised to be involved in viral clearance. We conclude that these crayfish were resistant to Chequa iflavirus infections and could be commercially exploited by aquaculturists as a nuclear breeding stock if numbers are increased over time. [ABSTRACT FROM AUTHOR]

Red claw crayfish (Cherax quadricarinatus) is a valuable aquatic species with fast growth, big size, delicious meat, and strong resistance to diseases worldwide. Microcystin-LR (MC-LR) is the most common and potently toxic and is known to infect aquatic animals. The present study was performed at the transcriptome level to investigate the mechanism of C. quadricarinatus in responses to MC-LR by RNA sequencing (RNA-seq) analysis. A total of 57,153,501, 51,955,723, and 56,316,927 clean reads were retrieved from the three libraries of C. quadricarinatus (0 h, 6 h, and 48 h). A total of 37,616 unigenes were identified and compared with NR, Swiss-Prot, Pfam, COG, GO, and KEGG databases. A total of 4980 and 4585 differentially expressed genes (DEGs) were obtained at 6 h and 48 h compared with control (0 h), respectively. Most of these DEGs were up-regulated in 6 h, but most were down-regulated in 48 h, indicating that gene expression levels were inhibited by MC-LR in 48 h. Based on the GO and KEGG pathways analyses of DEGs, we obtained various pathways related to apoptosis, immunity, and detoxification. A total of 234 DEGs were related to the immune system, including 19 immune metabolic pathways, such as the Toll-like receptor signaling pathway, Toll and Imd signaling pathway, interleukin-17 (IL-17) signaling pathway, etc. Besides, detoxification-associated and apoptosis-associated pathways were also identified, including drug metabolism-cytochrome P450 and glutathione metabolism, apoptosis and p53 signaling pathway, etc. Twelve DGEs involved in immune response and MC-LR detoxification were discovered and validated by quantitative real-time polymerase chain reaction (qRT-PCR). The results indicated that the C. quadricarinatus might counteract the toxicity of MC-LR at the transcriptomic level by increasing expression levels of immune- and detoxification-related genes. In summary, this study first reported the response mechanism of the C. quadricarinatus with injected MC-LR at the transcriptional level. The identification of differential expression genes and pathways can help us to understand further the response mechanism of C. quadricarinatus under MC-LR stress.

Vibrio parahaemolyticus (V. parahaemolyticus) is a primary pathogen in crustaceans and causes acute hepatopancreatic necrosis disease. Interferon regulatory factor-4 (IRF4) belongs to the regulatory factor family and plays a key role in the innate immunity of crustaceans. To better understand the IRF4 regulatory mechanism and its immunomodulatory role in response to challenge with Vibrio in crustaceans, the cDNA of Cherax quadricarinatus (C. quadricarinatus) IRF4 (CqIRF4) was isolated and the immune effect of this protein in the C. quadricarinatus response to V. parahaemolyticus was studied. The length of CqIRF4 was 2354 bp, with a 1251 bp open reading frame encoding 417 amino acids. After infection with V. parahaemolyticus, the expression levels of CqIRF4 in the hepatopancreas and hemolymph of C. quadricarinatus were significantly upregulated (P

The objective of the present study was to investigate the effects of different doses of dietary Eucommia ulmoides leaf extract (ELE) on juvenile red claw crayfish (Cherax quadricarinatus). A total number of 720 red claw crayfish (initial body weight of 0.24 ± 0.01 g) were randomly assigned to six groups and fed diets containing 0 (Diet 1), 0.5 (Diet 2), 1 (Diet 3), 2 (Diet 4), 4 (Diet 5) and 10 (Diet 6) g dry weight (dw) ELE kg (dw)−1 diets for eight weeks and challenged with microcystin-LR stress. The results indicated that dietary supplementation with 1–2 g dw ELE kg (dw)−1 diet could significantly improve the weight gain rate (WGR) and specific growth rate (SGR) of crayfish. Muscle crude protein contents of crayfish fed Diet 2, Diet 3, and Diet 4 were significantly higher than those of the control group. Compared with the control group, dietary ELE could increase total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GPx), acid phosphatase (ACP), alkaline phosphatase (AKP), and phenoloxidase (PO) activities and decrease malondialdehyde (MDA) level of crayfish. Dietary ELE significantly increased the relative expression levels of SOD, thioredoxin 1 (TRX1), GPx, selenium-dependent glutathione peroxidase (Se-GPx), cytochrome P450 (CYP450), anti-lipopolysaccharide factor (ALF) and C-type lysozyme (C-LZM) mRNA of crayfish compared with the control group during the feeding experiment. When subjected to MC-LR stress for 48 h, the mRNA expression levels of SOD, GPx, Se-GPx, glutathione-s-transferase 1 (GST1), ALF, hemocyanin (HEM), and C-LZM in the hepatopancreas could be improved to varying degrees compared with the Diet 1. Supplementation of 1–2 g dw ELE kg (dw)−1 diet could improve the survival rate (SR) of crayfish under MC-LR stress. These results indicated that dietary ELE (1–2 g dw ELE kg (dw)−1 diet) could improve the growth performance, muscle protein, and non-specific immune response and increase the SR of crayfish under MC-LR stress by regulating the mRNA expression levels of the immune- and antioxidant-related genes. [ABSTRACT FROM AUTHOR]

An optimal diet is an important factor for the proper growth and health of crustaceans. However, the regulation of antioxidant activity and non‐specific immunity related to the consumption of feed additives has not been studied in RC‐crayfish. Triplicate groups of 20 crayfish/tank (36.72 ± 0.70 g) fed with a basal diet and sixteen experimental diets that contained five feed additives with four grade levels (40, 160, 240 and 320 mg/kg vitamin E, 2, 4, 6 and 8 g/kg nucleotides, 2, 4, 6 and 8 g/kg Haematococcus pluvialis, 5, 10, 15 and 20 g/kg arachidonic acid and 2.5, 5, 10 and 15 g/kg yeast extract) on physiological parameters, fatty acids profile and growth of Cherax quadricarinatus for a period of 70 days by using orthogonal array method (L16 45). The results showed that the antioxidants activity in the haemolymph and hepatopancreas were both higher in crayfish fed with diets NO. 9 to 12 than others. Also, all the diets except diets NO. 13 to 16 showed lower free radicals contents than the control group. Similarly, significantly higher non‐specific immune parameters were observed in the hepatopancreas of crayfish supplementations than those fed a control diet. Biochemical parameters related to protein profile in haemolymph increased in diets NO. 9 to 12 and then decreased in control and diets NO. 13 to 16, while the highest biochemical parameters related to lipid profile except HDL‐c contents in haemolymph were observed in crayfish fed the control diet. Fatty acid composition in the hepatopancreas, muscle and ovary of RC‐crayfish was significantly influenced by using the combination of Vit E, NT, H. pluvialis and YP compared to the control group. Compared to all treatments, RC‐crayfish fed with diets NO. 2 and 12 had significantly stimulated higher growth performance and feed utilisation. Overall, our results suggest that diets supplemented with Vit E level of 240 mg/kg, in combination with 8 g/kg NT, 4 g/kg, H. pluvialis, 5 g/kg ARA and 10 g/kg YP are the promising treatments to increase antioxidants activity, non‐specific immune response, fatty acids composition and growth of RC‐crayfish. However, high dietary supplementations level can reduce antioxidants activity, immunity and inhibit growth. [ABSTRACT FROM AUTHOR]

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To study the effect of light intensity on red claw crayfish juveniles, experiments were carried out in this study. The results showed the following. (1) The 20 lux group had the highest survival rate. (2) The growth rates of the 20 lux, 200 lux and 0 lux groups were faster. (3) The juveniles in the 1000 lux and natural light groups were always clustered, while other groups were dispersed within 2–3 days. The 0 lux and 20 lux groups had higher dispersion. (4) Antioxidant capacities in the 0 lux and 20 lux groups were higher, and immune capacity in the 20 lux group was higher. (5) Monoamine contents were lower in the 0 lux and 20 lux groups. (6) α‐AMY or EcR expression in the 20 lux or 0 lux group was higher. We concluded that (1) juveniles under 20 lux light intensity had higher survival and growth rates. (2) The dispersion of juveniles at 0 lux and 20 lux light intensity was higher. (3) The physiological metabolism and immune abilities of juveniles at 0 lux and 20 lux light intensity were higher. (4) 0 lux and 20 lux was helpful in inhibiting cannibalism. (5) A 20 lux light intensity was helpful to in the expression of α‐AMY to improve digestion and absorption capacity. Low‐intensity light enhanced the expression of EcR, which contributed to the moulting of juveniles. We considered in actual production, it could be necessary to control 20 lux light intensity during the intermediate cultivation period of juveniles. [ABSTRACT FROM AUTHOR]

Glycerol monolaurate (GML), one of the medium-chain fatty acid esters, is often used as an emulsifier or preservative. Its biological functions include antibacterial and antiviral activities. In this study, we examined the effects of dietary GML on the resistance of the red claw crayfish to WSSV infection. Crayfish fed with 4 g/kg GML showed higher survival rate and lower WSSV copy numbers than the control after WSSV infection. A RT–qPCR analysis showed that GML supplementation enhanced the expression of immune-related genes, especially JAK and caspase. Our data indicate that GML affects the immune parameters of crayfish, including the total hemocyte counts and phenoloxidase, acid phosphatase, superoxide dismutase, lysozyme, and peroxidase activities. After treatment with GML, the apoptosis of hemocytes increased significantly in both WSSV-infected and uninfected crayfish. In summary, GML reduced the mortality of WSSV-infected crayfish, perhaps by modulating the innate immunity of the crayfish. Our study shows that GML can be used to induce the innate immunity and enhance the immune protection of the red claw crayfish against WSSV infection, either therapeutically or as a preventive measure. • Glycerol monolaurate supplement significantly reduced the mortality caused by WSSV infection. • Glycerol monolaurate significantly reduced the rate of hemocyte apoptosis in crayfish. • The WSSV copy numbers were reduced by glycerol monolaurate supplement. [ABSTRACT FROM AUTHOR]

In the Redclaw Crayfish, Cherax quadricarinatus, males grow larger and faster than females, and interest has focused on monosex breeding techniques for the production of males only. The adult male and female sexual characteristics of Cherax quadricarinatus are easily distinguished but cannot be determined in the embryo and juvenile stages. Because there is no DNA marker for the identification of sex in Cherax quadricarinatus, we sequenced its juvenile transcriptome in order to produce a reliable transcript to determine sex and to investigate its sex differentiation mechanisms at the molecular level. In this study, a female sex‐linked expression gene CqLRPPRC (Leucine‐rich PPR‐motif‐containing) of Cherax quadricarinatus was found in the transcriptome. Using semi‐quantitative RT‐PCR analysis, we found that the expression of the LRPPRC (leucine‐rich pentatricopeptide repeat cassette) gene was greater in the ovaries of females than in the testes of males, from the early juvenile stages onwards. Furthermore, in situ hybridization showed that the expression of its sexual dimorphism may be focused in the gonads. The results of an RNA interference treatment showed that a knockdown of CqLRPPRC up‐regulated the expression of vitellogenin (Vtg). The LRPPRC gene, and characteristic of shrimp, are reported here for the first time, and an assay of this gene can provide a molecular test to determine the sex of Cherax quadricarinatus in its different developmental stages, especially those during which no obvious sexual differences are visible. [ABSTRACT FROM AUTHOR]

Red claw crayfish (Cherax quadricarinatus) is an economic freshwater shrimp with great commercial potential. However, the suitable stocking density of C. quadricarinatus is still unclear in integrated rice–crayfish farming system. Thus, this study aimed to investigate the effects of stocking density on growth performance, mitophagy, endocytosis and metabolism of C. quadricarinatus. The C. quadricarinatus was reared at low density (LD, 35.73 g/m² ), middle density (MD, 71.46 g/m² ) and high density (HD, 107.19 g/m² ) in an integrated rice–crayfish farming system. After 90 days of farming, the growth performance of C. quadricarinatus significantly decreased in the MD and HD groups relative to that in the LD group. The HD treatment caused oxidative stress and lipid peroxidation at the end of the experiment in hepatopancreas. Transcriptome analysis showed that there were 1,531 DEGs (differently expressed genes) between the LD group and HD group, including 1,028 upregulated genes and 503 downregulated genes. KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis indicated that the DEGs were significantly enriched in endocytosis and mitophagy pathways. Meanwhile, four lipid metabolism pathways, including biosynthesis of unsaturated fatty acids, fatty acid biosynthesis, glycerolipid metabolism and glycerophospholipid metabolism, exhibited an upregulated tendency in the HD group. In conclusion, our data showed that when the stocking density reached up to 207.15 g/m² in HD group, the growth performance of C. quadricarinatus was significantly inhibited in this system. Meanwhile, the data indicated that C. quadricarinatus may respond to the stressful condition via activating antioxidant defense system, endocytosis, mitophagy and metabolism-related pathways in hepatopancreas. [ABSTRACT FROM AUTHOR]

Freshwater lobster (Cherax quadricarinatus) is a freshwater fishery commodity that has a very promising selling price. The price of live freshwater lobster can be sold up to Rp. 250,000/kg and frozen to death at a price of Rp. 100,000 in Pekanbaru. The export value of lobster commodities in Indonesia grows by an average of 3.54% per year. One way to maintain the life of the lobster during the lobster export process is by means of a dry system of live transportation. Giving natural anesthetics can use green betel leaf extract. The purpose of this study was to determine the storage time of freshwater crayfish (Cherax quadricarinatus) given natural anesthesia with green betel leaf extract (Piper betle L). This study used a laboratory experimental method with a non-factorial completely randomized design (CRD) as the treatment was storage time consisting of 4 levels of treatment, namely 6, 12, 18, and 24 hours and repeated 3 times. The test parameters of this study were the length of time awake, survival, and body weight loss of lobster during storage. The best treatment in this study was K2 a storage time of 12 hours getting survival rates of up to 90% and body weight loss during storage of 3%. [ABSTRACT FROM AUTHOR]

The aim of this work was to conduct a morphological analysis of hemocytes of the Australian red claw crayfish (Cherax quadricarinatus). Hemocytes were studied in the native and anticoagulant-treated hemolymph and stained with May–Grünwald and Romanowsky stains. Hemolymph was collected with a syringe from the ventral sinus. Microscopy was carried out using 40× or 100× objective lenses. Hemocyte count and the percentage of each of their types were determined in the Goryaev chamber. In the hemolymph of C. quadricarinatus, among the already known types of hemocytes (agranulocytes or hyalinocytes, semigranulocytes, and granulocytes), we found the cells morphologically different from the previously described, transparent cells. Hyalinocytes are oval or fusiform cells, about 26.6 µm long and 9.2 µm wide. As a rule, they lack granules, but sometimes a small number of tiny granules, sized less than 0.5 µm, can be found. Cells of this type are able to outlive other cells on a slide after isolation. Semigranulocytes are also oval or fusiform cells, 26.7 µm long and 9.3 µm wide, with a moderate number of small-sized granules (<0.5 µm) and sparse medium-sized granules ranging from 0.77 to 1.69 µm. Granulocytes are oval-shaped cells, the largest of all types, having a length and width of 28.7 and 11.1 µm, respectively. They contain large (0.8–2.48 µm) numerous granules and show a high refraction, due to which this cell type is well recognizable under a microscope. These cells have a lowest nuclear–cytoplasmic ratio compared to the former two types. Transparent cells are specifically characterized by abundant well-developed pseudopodia. After cell rounding, its diameter averages 10.7 ± 1.11 µm. This cell type begins to show up 10 min after their isolation in the anticoagulant-untreated hemolymph. Hyalinocytes are the dominant type of cells in the hemolymph, their proportion is 48.3 ± 11.4%, while semigranulocytes and granulocytes account for 26.3 ± 7.8 and 25.2 ± 6.9%, respectively. The total number of hemocytes varies in a wide range from 820 to 5510 cell/µL, with the average number of cells being 2707 ± 1096 cell/µL. The proportion of transparent cells averages 18.2 ± 3.8%. [ABSTRACT FROM AUTHOR]

Red claw crayfish Cherax quadricarinatus has emerged as a highly significant and suitable species to be raised in integrated rice–aquatic animal farming systems. To optimize an integrated aquaculture and agriculture (IAA) system and ensure sustainable utilization and development of land resources, an IAA system combining rice cultivation with red claw crayfish culture was implemented to assess the impacts of rice–red claw crayfish co-culturing on the dynamics and assembly of bacterial communities in paddy soils. We established two experimental groups, each with eight replicates. We utilized 16S rRNA Illumina high-throughput sequencing to access the bacterial community composition and assembly in paddy soils. Red claw crayfish C. quadricarinatus cultivation did not significantly affect the alpha diversity of the bacterial community in the paddy field, but it obviously increased the relative abundances of the phyla Acidobacteriota and Pseudomonadota involved in organic matter degradation and nitrogen, phosphorus, and carbon cycling. Red claw crayfish cultivation could lead to more complex bacterial communities, increased bacterial resistance to disturbances, the promotion of niche differentiation, and increased competition intensity between bacterial communities during the mid-cultivation period. Nitrogen emerged as a critical factor influencing the bacterial community composition in paddy soil during the culture period, and the red claw crayfish cultivation affected the bacterial community by altering the ammonia concentration in the paddy soil. As the culture progressed, the assembly of the bacterial community in the paddy soil was predominantly driven by stochastic processes, and red claw crayfish cultivation accelerated the evolution of the bacterial community assembly towards a stochastic process. Our study offers valuable insights into the dynamic changes occurring in the composition and assembly of bacterial communities in paddy soils in response to red claw crayfish cultivation.

Ftz‐f1 was a member of the NR5A‐family nuclear receptors, and previously predicted to be participated in the complex ovarian processes. In this study, we characterized the full‐length cDNA of Ftz‐f1 with an open reading frame of 1746 bp encoding 581 amino acids in the redclaw crayfish, Cherax quadricarinatus (CqFtz‐f1). Amino acid alignments and structural prediction uncovered that two highly conserved domain, DBD (DNA binding domain) and LBD (ligand binding domain) were identified, which shared with other members of nuclear receptors family. Tissues distribution showed that CqFtz‐f1 exhibited sexually dimorphic expression pattern with a higher transcript level in ovary. Staging of ovarian development was conducted, which to be divided into four different stages by external feature and histology analysis. The changes of GSI (Gonadosomatic index) were in accordance with the mRNA expression of CqFtz‐f1 during the reproductive cycle. In addition, both eyestalk ablation and β‐oestradiol (E2) injection significantly increased the expression levels of Ftz‐f1 and vg (vitellogenin). Furthermore, treatment with CqFtz‐f1 dsRNA injection generated distinct effects on the expression of vg, suggesting that CqFtz‐f1 might have positive effects on ovarian development by regulating vg expression in the redclaw crayfish. [ABSTRACT FROM AUTHOR]

Intestinal microbiota communities participate in several metabolic processes in the host, and are highly correlated to digestion, nutrition, growth, and immunity. However, the intestinal microbiota of aquatic invertebrates is poorly understood, especially in freshwater crayfish. In this study, the intestinal microbiota of two important freshwater economic aquaculture species, the invasive species, the red swamp crayfish (Procambarus clarkii, Pc), and the introduced species, the red claw crayfish (Cherax quadricarinatus, Cq), were investigated. The results showed that the community richness and diversity of Pc were higher than those of Cq, which might be one of the reasons that Pc have stronger environmental adaptability than Cq. Five core phyla were identified in the Pc group, including Proteobacteria (26.92%), Tenericutes (25.73%), Bacteroidetes (25.12%), Firmicutes (14.03%), and RsaHF231 (8.02%), and three phyla were detected in the Cq group, including Tenericutes (67.35%), Proteobacteria (25.98%), and Firmicutes (4.69%). In Pc and Cq groups, Proteobacteria exhibited significant differential abundance between males and females. In addition, Vibrio coralliilyticus were found particularly in the intestine of Cq. This study provides information on intestinal microbiota differences of Pc and Cq, contributing to the development of new dietary formulations and providing significance to future aquaculture. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the effects of different mineral inclusion in anchovy by-product (ABP) based feeds on the growth performance of red claw crayfish juveniles, Cherax quadricarinatus. A total of five experimental feeds with the inclusion of different mineral levels from 0-2.0% of the diet (M0, M0.5, M1.0, M1.5, & M2.0%) were fed to triplicate groups of 12 juvenile red claw crayfish with an average initial body weight of 2.20±0.10 g. There was no significant difference in terms of final body weight (g), final length (cm), weight gain (%), length gain (%), specific growth rate (%/d), and survival rate (%) of the juvenile red claw crayfish at the end of the feeding trial. Feed conversion ratio ranged from 1.60 (M0.5) to 1.76 (M1.0). Similar to the growth performance, the molting frequency was not affected by the different mineral inclusions in the feeds. Mineral inclusion in the feeds based on ABP can be reduced up to 0%, at least in a short culture period, and higher possibility of including minerals less than 2% in the feeds for juvenile red claw crayfish in a long-term culture period. Considering the good growth and survival of juvenile red claw crayfish in all treatments, the use of ABP as a source of protein and mineral in feeds for juvenile red claw crayfish is highly recommended as this will reduce the feed cost due to the much lower price of ABP. It can be concluded that the anchovy by-product meal used in the present study is a high potential ingredient to supply dietary protein and minerals in the formulated feeds for juvenile red claw crayfish. [ABSTRACT FROM AUTHOR]

Cherax quadricarinatus has been widely introduced and cultured around the world and has been seriously affected by pathogens, including viruses and bacteria. Small heat shock proteins (sHsps) have been shown to have a positive effect on immune responses in animals. In this study, three subunits of sHsps (CqsHsps, named CqHsp24.06, CqHsp41.97 and CqHsp40.17) from C. quadricarinatus were cloned. The coding sequence lengths of the CqHsp24.06, CqHsp41.97 and CqHsp40.17 genes were 654 bp, 1128 bp and 1074 bp, with a molecular weight of 24.06, 41.97 and 40.17 kDa, respectively. In normal tissues, the expression level of CqHsp24.06 was the highest in the intestinal tract and was 12 times higher than that in the hepatopancreas, while CqHsp41.97 was mostly expressed in the gills which was 8 times higher than that in the nerves. However, CqHsp40.17 was highest in the nerves and was 12 times higher than its expression level in the gonads. In gills of C. quadricarinatus stressed by Vibrio Alginolyticus, the relative expression levels of CqHsp24.06, CqHsp41.97 and CqHsp40.17 in gill first increased and then decreased, and the maximum expression increased by 25 times. Under Aeromonas hydrophila stress, the expression of CqHsp24.06 and CqHsp41.97 reached the highest level at the 3‐h time point and at the 12‐h time point for CqHsp40.17, and the maximum expression increased by 3.5 times. These results indicated that CqsHsps could induce the activation of the immune system, and they were more sensitive to Vibrio Alginolyticus than to Aeromonas hydrophila. [ABSTRACT FROM AUTHOR]