Yongxu Cheng

Background/Objectives: Antibiotics are routinely used in crustacean larviculture to mitigate bacterial infections, yet their widespread application compromises larval ontogeny. Probiotics and microalgae offer sustainable alternatives, but their combined molecular effects in crustacean larvae remain poorly characterized. This study aimed to evaluate the physiological and transcriptomic impacts of a probiotics–microalgae consortium versus antibiotics in mud crab (Scylla paramamosain) zoea, with the goal of elucidating mechanisms underlying improved larval development and identifying potential antibiotic alternatives. Methods: Scylla paramamosain larvae were reared under five treatments: clear water control (CN), microalgae alone (MA), probiotics alone (PB), a probiotics–microalgae consortium (PB-MA), and the antibiotic (AB) florfenicol. Samples were collected at 6 h and 24 h post-treatment during the first (Z1) and third (Z3) zoeal stages. Growth performance was assessed via survival and larval stage index, and multi-time point transcriptomic sequencing was performed to analyze dynamic gene expression profiles. Results: The PB-MA consortium significantly enhanced stage-specific survival from Z3 to Z5 and accelerated developmental progression compared to control and antibiotic groups. Transcriptomic analysis revealed from 492 to 2854 differentially expressed genes across treatments. PB-MA treatment was associated with the sustained upregulation of immune-related pathways (lysosome and Toll/Imd signaling), oxidative stress responses (peroxisome and glutathione metabolism), and energy metabolism (TCA cycle and carbon metabolism), whereas antibiotics predominantly suppressed these pathways. Key candidate genes, including NPC1, NAGA, ACOX1, HAO1, MUT, and PK, were prominently induced in PB-MA-treated larvae. Conclusions: The probiotics–microalgae consortium enhances basal immunity, antioxidant capacity, and metabolic adaptability in mud crab larvae at the molecular level. These findings provide transcriptomic evidence supporting the replacement of antibiotics with synergistic microbial consortia in sustainable crustacean larviculture.

Smallholder rice farmers in sub-Saharan Africa face persistent livelihood challenges due to declining returns from monocropping, limited diversification opportunities, and vulnerability to climate and market shocks. This study integrated the Drivers–Pressures–State–Impact–Response (DPSIR) framework with the sustainable livelihood approach to evaluate how the transition from rice monocropping to integrated rice–fish farming influences productivity, profitability, and household welfare in Nigeria’s leading rice-producing region. Using a mixed-methods, three-year panel (2021–2023) of 228 households across three communities in Kebbi State, descriptive statistics, regression models, and thematic analyses were combined to assess changes in livelihood capitals, system pressures, and response mechanisms. Adoption of rice–fish systems was associated with substantial improvements: 96.1% of farmers reported increased income, 56.3% improved food security, and 30.6% greater dietary diversity. Regression analyses confirmed that access to more land (p < 0.001 for healthcare and education; p = 0.011 for social status), labor affordability (p < 0.001), and farm size (p < 0.05) were consistent predictors of gains in healthcare, education, and social status, while pesticide and herbicide use negatively affected food access and wellbeing (p < 0.05). The DPSIR assessment revealed that rice–fish integration altered the state of rice production systems through reductions in input-related pressures and generated positive livelihood impacts. The results align with Sustainable Development Goals (SDGs) related to poverty reduction, food and nutrition security, sustainable production, and biodiversity conservation, and provide the first large-scale, longitudinal evidence from West Africa that integrated rice–fish systems support food security, income diversification, and sustainable resource management.

To meet the growing market demand for high‐quality red swamp crayfish ( Procambarus clarkii ), nutritional strategies are needed to improve both health and visual traits. The microalga Dunaliella salina , renowned for its rich natural β‐carotene content, presents a promising solution. This study investigated the effects of dietary supplementation with D. salina powder at five graded levels (0%, 0.34%, 0.67%, 1.34%, and 2.00%) on juvenile crayfish over a 60‐day feeding trial. Results demonstrated that weight gain rate (WGR) and specific growth rate (SGR) were highest in the 2.00% supplementation group. Notably, a low inclusion level of 0.34% significantly promoted ovarian development, as evidenced by the highest gonadosomatic index (GSI) and digestive enzyme activities. Antioxidant capacity (AOC, total superoxide dismutase [T‐SOD], total AOC [T‐AOC]) and nonspecific immunity (alkaline phosphatase [AKP]) were maximally enhanced at 0.67% inclusion. Most importantly, dietary D. salina was efficiently converted to astaxanthin and deposited in tissues, with carapaces and ovaries coloration parameters showing a strong, dose‐dependent correlation with carotenoid accumulation. Regression analysis identified an optimal inclusion range of 1.23%–1.53% for maximizing carotenoid deposition, immune function, and AOC. Furthermore, the 2.00% supplementation group exhibited the highest tolerance to air exposure stress. Our findings provide definitive, data‐driven insights for the precise application of D. salina in functional crayfish feeds, facilitating the industry’s transition from quantity‐focused production to quality‐ and value‐driven aquaculture.

Cladophora-dominated filamentous algal blooms constitute a growing threat to aquatic ecosystem stability and aquaculture operations. This study systematically evaluated the algicidal efficacy of sodium hypochlorite (NaClO), both individually and in combination with an organosilicone adjuvant, against Cladophora sp., with particular focus on induced oxidative damage mechanisms. Results demonstrated that NaClO exhibited a dose- and time-dependent inhibitory effect, achieving ≥90% inhibition at 1.20 mmol L⁻¹ within 48 h and >99% by 120 h, significantly surpassing the efficacy of lower concentrations (0.40 mmol L⁻¹) (p < 0.05). Physiological assessment revealed that 1.20 mmol L⁻¹ NaClO significantly suppressed total antioxidant capacity (T-AOC) after 96 h (p < 0.05). Notably, synergistic enhancement was observed with adjuvant co-application: at 0.40 mmol L⁻¹ NaClO, superoxide dismutase (SOD) activity reached its minimum with 0.33 ppm organosilicone adjuvant, showing significant reduction compared to higher adjuvant concentrations (p < 0.05). Furthermore, combinations of 0.80 and 1.20 mmol L⁻¹ with organosilicone adjuvant consistently maintained inhibition rates ≥ 94% across all sampling intervals, achieving control efficacy equivalent to 2.00 and 2.40 mmol L⁻¹ NaClO alone within 48 h. These findings demonstrate that NaClO supplemented with low-dose organosilicone adjuvant constitutes a promising and efficient strategy for mitigating Cladophora blooms.

Freshwater ecosystems are increasingly degraded by Cladophora blooms, prompting a need to understand its reproductive characteristics for effective control. We combined continuous microscopical monitoring and single-factor and orthogonal experiments, to characterize the life history and reproductive and growth response to different nutrients, pH, temperature, and light conditions of a bloom-forming Cladophora sp. A novel mode was observed, in which mature sporangia and gametangia rupture to extrude a pyknotic cytoplasmic mass, inside which zoospores and gametes complete maturation and release. The peak zoospore production occurred in Aquatic No. 6 medium at pH 5, 35 °C, and 54 µmol m⁻² s⁻¹, whereas maximum gamete release was recorded in Knop medium at pH 4, 30 °C, and the same irradiance, with temperature being the principal driver for zoospores and nutrient regime for gametes. Growth trials further revealed that low-N and -P conditions sustain growth, whereas nutrient-rich conditions favor reproduction. In addition, pH 4–5, 35 °C, and 54 µmol m⁻² s⁻¹ conditions favored propagule formation, while pH 7–8, 25 °C, and 81 µmol m⁻² s⁻¹ maximized biomass. These findings provide a basis for predicting Cladophora bloom dynamics and offer references for sustainable management of Cladophora in freshwater ecosystems.

Agonistic behavior is common among crustaceans, but it presents risks such as energy loss, injury, and even death in aquaculture settings. Our previous study indicated that l-tryptophan (l-TRP) inhibits agonistic behavior in Eriocheir sinensis. However, supplementing l-TRP in diets increases costs and reduces nutritional quality. This study explores the role of tryptophan hydroxylase (TPH) in l-TRP metabolism and its regulation of agonistic behavior in E. sinensis. Our results show that l-TRP supplementation significantly increases the serotonin level and TPH expression. Subcellular localization confirmed the expression of the TPH in the cytoplasm of HEK293T cells. RNA interference of TPH significantly enhanced in the contact numbers of the crabs. While overexpression of the TPH significantly inhibited agonistic behavior in E. sinensis. Specifically, the fight duration was reduced from 6.67 ± 2.03 min in the control group to 1.81 ± 0.39 min, and the fight number decreased from 17 ± 2.47 to 8.0 ± 1.27. Moreover, the concentration of serotonin in E. sinensis was increased after TPH overexpression. Additionally, fluoxetine injection also significantly inhibited the agonistic behavior. In summary, our findings suggest that TPH regulates agonistic behavior in E. sinensis by mediating the conversion of l-TRP into 5-HT.

Eriocheir sinensis is an important and popular crustacean species in China, producing huge economic benefits. Large individuals of E. sinensis are preferred due to market demand. The long-term goal of our research group is to produce a new variety of E. sinensis with better growth performance and stronger abilities to resist environmental changes through mass selection. The present study aimed to evaluate the progress of the genetic breeding of E. sinensis by analyzing the genetic diversity and genetic distance between the basic breeding population (pooled population of Suqian and Yixing, G0) and generation 1 (G1) using whole-genome sequencing (WGS). The growth traits, including body weight, shell length, shell width, and third appendage length, in the G1 generation increased by 8.3%, 7.9%, 9.6%, and 9.3%, respectively, compared with those of the G0 generation, indicating that the G1 generation showed better growth performance. A total of 372,448,393 high-quality single nucleotide polymorphisms (SNPs) were detected in 40 E. sinensis individuals, with an average of 9,331,209.83 SNPs. The fixation index values were 0.007 between the Yixing and Suqian populations and 0.015 between the G0 generation and G1 generation, indicating a close genetic background between these groups, especially when considered in combination with the phylogenetic tree and principal component analysis. All of these data suggest that genetic information was stably inherited by the G1 generation, with no introduction of foreign genetic information during the genetic breeding process. In addition, the genetic diversity analysis revealed that the G0 and G1 generations showed a high level of genetic diversity and a relatively stable genetic structure. The present study evaluated the recent progress of the genetic improvement of E. sinensis by our research group, providing valuable evidence for further genetic improvement in this species. Future studies will be performed to select growth-related SNPs and genes through genome-wide association studies.

In animals, growth and development are strongly correlated with the gut microbiota. The gut of the economically important marine crab (Scylla paramamosain) harbors a diverse microbial community, yet its associations with the surrounding environment, growth performance, and developmental stages remain obscure. In this study, we first characterized stage-specific microbiomes and shifts in the contributions of live feed and water via SourceTracker. We observed decreased microbial diversity and increased priority effects along zoea stages. Psychobacter was identified as the core genus, whereas Lactobacillus was the hub genus connecting different stages. Second, microbial correlations with various stage-specific growth traits were observed under interventions generating enhanced (probiotic mixture enrichment), normal (control), and reduced (antibiotic treatment) microbiomes. By combining machine learning regression and bioinformatics analysis, we identified four candidate growth performance-associated probiotics belonging to Rhodobacterales, Sulfitobacter, Confluentimicrobium, and Lactobacillus, respectively. Our study interpreted the dynamics and origins of the Scylla paramamosain zoea microbiome and underscored the importance of optimizing potential probiotics to increase growth performance during early life stages in marine invertebrates for effective larviculture.

Background: The development of genetic markers is crucial for aquaculture and population genetics. Polyallelic microsatellite markers are widely used for breeding and family management of Eriocheir sinensis (E. sinensis), contributing to the sustainable development of the industry. Methods: Through transcriptome analysis, 100 highly polymorphic SSR markers were identified and developed. From these, four multiplex PCR panels, each containing 16 markers, were constructed and applied to parentage assignment in six E. sinensis families. Results: The number of alleles (N_a) ranged from 7 to 21, the observed heterozygosity (H_o) varied from 0.356 to 0.951, and the expected heterozygosity (H_e) varied from 0.656 to 0.909. The polymorphism information content (PIC) ranged from 0.633 to 0.900. The CERVUS analysis showed that using only the two most informative multiplex PCR panels, assignment success rates exceeded 90.34%, with 100% accuracy in assigning offspring to parents when three or four panels were used. Conclusions: This method significantly enhances the efficiency of microsatellite marker analysis, which provides a convenient and cost-effective method for breeding programs and family management of E. sinensis.