Biology and Life Sciences

Abstract: This work is an update and extension of the previously published article “Jellyfish in Hong Kong: a citizen science dataset”, by Terenzini et al. (2024). This Data Update consists of 516 jellyfish observations made by citizen scientists in Hong Kong during 2024 and 2025, who submitted photographs and videos to the Hong Kong Jellyfish Project website, iNaturalist project, and through social media. While citizen science is not new to China or, more specifically, Hong Kong, the Hong Kong Jellyfish Project is the first time citizen science has been used to investigate jellyfish in the region, filling the knowledge gap of a previously under-studied taxa in a biodiversity-rich region of the South China Sea. This Data Update has new species occurrence records for Hong Kong, including rarely seen species, taxonomically uncertain species, and updates previous records because of recent taxonomic revisions. This Data Update makes jellyfish data available for research into the roles and influences jellyfish have on Hong Kong’s highly impacted marine ecosystems. The potential usage of the Data Update extends to improving comprehensive marine management and tourism policies. This dataset is publicly available and discoverable in the Global Biodiversity Information Facility database.

Abstract: The specific habitat conditions in different parts of the species’ range may give rise to intraspecific polymorphism at various levels (morphological, biological, genetic, etc.), but this phenomenon has not been sufficiently studied. The results of research of the morphological, biological, genetic, karyological, and parasitological characteristics of the gray rockfish Sebastes glaucus (Sebastidae, Scorpaeniformes) in two water bodies differing in habitat conditions are presented, i.e. a desalinated lagoon and adjacent sea areas off the Zavyalov Island (the northern Sea of Okhotsk). It was found that individuals in both water bodies differ significantly in terms of some morphological characters (the number of the lateral line pores and the total number of vertebrae), size (the fish in the lagoon has smaller length and body weight), maximum age and growth rates (individuals in the sea reach a greater age and grow faster), chromosome morphology and the number of chromosome arms, and the degree of infection with metacercariae of trematodes (100% in the lagoon and their complete absence in the sea). Furthermore, samples from the lagoon and the sea are reliably differentiated from each other based on genetic analysis using mtDNA markers. The identified differences may be due to a combination of factors, including both abiotic (lower temperature and salinity in the lagoon and its isolation from the sea) and biotic (limited forage resources and high parasite load in the isolated lagoon) factors.

Abstract: Although water recirculates through fish tanks, plant beds and filters in an aquaponic unit, each compartment supports a microbial community shaped by its local conditions. This distinction is especially important for major carps, including rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala), because these major South Asian food fishes occupy contrasting feeding niches and provide a useful comparison of shared environmental exposure and host-associated selection. This focused narrative review examines major-carp gut microbiota, aquaponic water and biofilter communities, gut-water connectivity, and the strengths and limitations of 16S rRNA amplicon sequencing and shotgun metagenomics. Literature screening started with the reference collection assembled for the initial research synopsis. Titles, abstracts and available full texts were reviewed, targeted PubMed searches were used to check coverage, and bibliographic details were cross-checked against publisher, DOI and indexing records. Literature available up to 10 September 2026 was considered. Studies of aquaponic systems consistently show that water, biofilters, roots, biofilms and fish-associated habitats support distinct microbial assemblages despite continuous recirculation. Major-carp studies likewise report variation among host species, gut regions and culture conditions. Overlap between gut and environmental taxa should therefore be treated as evidence of ecological connectivity rather than direct proof of colonization or transmission. Common limitations include inconsistent sampling designs, insufficient tank replication, reliance on relative abundance, limited temporal sampling, low-biomass contamination in water samples and weak functional validation. Future studies would benefit from replicated carp culture, synchronized sampling of gut and aquaponic compartments, water-quality measurements, 16S profiling for community structure and selected shotgun metagenomics for functional resolution. Nitrogen cycling, carbohydrate metabolism, antimicrobial-resistance determinants, mobile genetic elements and source-selection relationships deserve particular attention. Future work should move beyond cataloguing taxa and determine how host identity, aquaponic habitat and microbial function interact over time in a controlled production system.

Abstract: Curcumin is a plant-derived polyphenol with antioxidant, immunomodulatory, and metabolic regulatory activities, but its integrated effects on edible-tissue quality and hepatopancreatic homeostasis in abalone remain unclear. We evaluated five dietary curcumin levels (0, 0.02%, 0.04%, 0.06%, and 0.08%) in 240 green–Pacific abalone hybrids (Haliotis discus hannai ♀ × H. fulgens ♂) for 8 weeks. The 0.04% treatment increased muscle crude protein, while 0.04–0.06% increased total amino acids; all supplemented diets reduced crude lipid and free fatty acids. Curcumin improved hepatopancreatic histology, reduced Oil Red O-positive lipid deposition, increased superoxide dismutase, glutathione peroxidase, and total antioxidant capacity, and decreased malondialdehyde. Acid phosphatase, alkaline phosphatase, and lysozyme increased in all supplemented groups, whereas polyphenol oxidase peaked at 0.04%. Transcriptomic comparison of the control and 0.04% groups identified 622 differentially expressed genes (336 upregulated and 286 downregulated), with enrichment involving lysosome, phagosome, Toll/Imd, MAPK, and FoxO-associated processes. RT-qPCR confirmed increased SOD2, CAT, and HSP70 expression. Overall, 0.04% dietary curcumin produced the most consistent benefits, improving muscle nutritional quality, redox status, and hepatopancreatic health in hybrid abalone.

Abstract: To characterize the growth performance and morphological traits of the Yunjin hybrid grouper (Epinephelus moara ♀ × E. tukula ♂) and its parental populations, this study investigated three 6-month-old grouper populations. Nineteen morphological traits were measured, and correlation analysis, path analysis, coefficient of determination, and gray correlation analysis were conducted to evaluate the relationships between morphological traits and body weight. The results showed that the body weight of 6-month-old Yunjin hybrid groupers reached 72.21 ± 15.10 g, representing a 20% increase compared to the maternal E. moara. The coefficient of variation for body weight was higher than that for measurable length-related traits. Path analysis revealed that total length, eye diameter, body width, and interorbital distance had significant direct effects on body weight in the Yunjin hybrid grouper. Multivariate linear regression equations were established for the three fish species based on the selected traits: Y_{E. tukula}= -208.010 + 10.669X₁ + 25.299X₅ + 14.869X₆; Y_{E. moara}= -105.1640 + 4.442X₁ + 26.629X₄ + 9.582X₆ + 10.352X₇; Y_Yunjin = -134.970 + 6.825X₁ + 27.775X₅ + 10.600X₇ + 31.518X₁₀. The gray correlation analysis showed that the five traits most closely associated with body weight were ranked as follows: total length > body length > head length > body height > body width, which was consistent with the results of the path analysis. This study identified the key morphological indicators affecting body weight in the three grouper populations, providing fundamental biological information and theoretical references for research on hybrid vigor and the selective breeding of the Yunjin hybrid grouper.

Abstract: Triploidization can rescue otherwise poorly viable interspecific salmonid crosses, but practical production of rainbow trout (Oncorhynchus mykiss) female × brook trout (Salvelinus fontinalis) male hybrids remains constrained by parental seasonality and access to functionally competent paternal gametes. In this study, we compared fresh and cryopreserved sperm from four brook trout males in a paired hatchery trial. For each male and semen state, duplicate 350-mL rainbow trout egg batches were fertilized at 600,000 spermatozoa per egg and subjected to hydrostatic-pressure triploidization (9500 psi for 5 min at 350 degree-minutes). Cryopreservation reduced total motility from 91.05 ± 1.39% to 49.67 ± 10.83% (p = 0.0033), yet eyed-egg recovery remained high: 83.07 ± 10.57% with fresh and 77.96 ± 6.62% with cryopreserved semen (p = 0.590). At this dose, mean post-thaw MOT corresponded to ~2.98 × 10^5 motile spermatozoa per egg. Pooled viable embryos showed only 12.5% mortality from eyeing to first feeding, providing functional developmental evidence supporting the effectiveness of the employed allotriploidization protocol. Among thawed samples, VCL showed the largest observed donor-level correlation with of eyed-egg recovery (r = 0.83). Overall, cryobanking of brook trout sperm may extend paternal-gamete availability beyond the natural autumn spawning season and facilitate transportable, on-demand production of this hybrid at partner hatcheries.

Abstract: The Mekong Delta of Vietnam is one of Southeast Asia’s most important food-producing regions, supporting intensive rice cultivation, globally significant aquaculture, and diverse inland and rice-field fisheries that contribute to food security, rural livelihoods, and ecosystem functioning. However, hydraulic engineering, agricultural intensification, aquaculture expansion, urbanization, upstream river development, and climate-related pressures have progressively altered the hydrological and ecological processes sustaining these interconnected systems. This review synthe-sizes evidence on the transformation of rice-field fisheries and aquatic animal production in the Lower Mekong Basin, with particular emphasis on the Mekong Delta, and evaluates how effectively pollution governance addresses cumulative pressures on aquatic ecosystems. Peer-reviewed studies, official statistics, policy and legal documents, Mekong River Commission reports, and international institutional publications were assessed through a systematic critical review com-bining evidence mapping with structured narrative synthesis. The synthesis reveals a marked transition from hydrologically connected, multispecies production landscapes toward increasingly specialized rice and aquaculture systems. In the Mekong Delta region, recorded inland wild-fish catch declined from approximately 165,000 tonnes in 1995 to 30,000 tonnes in 2024, while aquaculture production increased more than eightfold, from ap-proximately 78,000 to 650,000 tonnes, and rice production more than doubled, from 3.5 to 7.6 million tonnes. These contrasting trends coincided with high-dyke development, reduced flood-plain connectivity, altered sediment and flow regimes, habitat modification, and greater agro-chemical dependence. Major pollution pressures include nutrient and organic enrichment, pesticides, antibiotics and pharmaceuticals, domestic and industrial wastewater, micro-plastics, and acid-sulfate-soil drainage. Nevertheless, fishery decline cannot be attributed to pollution alone, because hydropower development, migration barriers, fishing pressure, habitat fragmentation, altered flood pulses, sediment deficits, and changing fishing participation interact across spatial and temporal scales. Although Vietnam has established increasingly comprehensive fisheries, environment, water-resource, regional-planning, and climate-adaptation frameworks, implementation remains fragmented. Priority actions include integrated basin-to-field monitoring, cumula-tive-risk assessment, pollution prevention at source, stronger discharge controls, restoration of seasonal floodplain connectivity, protection of aquatic refuges, community co-management, and wider adoption of context-appropriate floating-rice, rice–fish, and rice–shrimp systems in this Delta region.

Abstract: The article represents scale elemental analysis of three commercially important fishes Cyprinus carpio, Lates calcarifer, and Chrysochir aureus. The concentrations of As, Be, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V, and Zn using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). It was revealed that fish scale microchemistry differed in connection with their natural environment, habitat, and feeding habits. Higher levels of Be, Co, and Zn in the scales of C. carpio, which is a freshwater fish, are perhaps due to increased bioavailability of the elements, aquatic pollution, and fish’s interaction with sediment. L. calcarifer, collected from the brackish water environment, derived more Cu from mixing-zone chemistry and anthropogenic inputs, as well as from their prey. Marine fish, C. aureus, displayed significantly higher levels of As, Mn, Ni, and Se in their scales, likely due to the complexation process and their inherent seawater abundance. Significantly elevated As, Be, Cd, Co, Mn, Se, and Zn in the scales of benthopelagic fish may stem from prolonged exposure to water column particulates and dietary uptake. Omnivorous fish accumulate significantly higher levels of Be, Co, and Zn than their carnivorous counterpart that which might be attributed to a combination of their broad spectrum diet pattern. Although these differences could be caused by other variables such as species-specific physiology or geographic distribution, the findings suggests that fish scale microchemistry may be linked to trophic ecology and environmental exposure. The study might contribute to the future development of noninvasive approaches utilizing fish scales for ecological and environmental assessment.

Abstract: Water hyssop (Bacopa monnieri (L.) Wettst.) is a water-demanding medicinal plant whose responses to declining soil moisture remain insufficiently characterized, particularly in relation to phenolic accumulation. This study investigated the morphological, physiolog-ical, and anatomical responses of water hyssop to water limitation and identified the soil moisture conditions associated with enhanced phenolic accumulation. Short-term water limitation (11 days at 9.06% soil moisture) maximized total phenolic content (TPC), which reached a peak of 195.69 µg mL−1. Physiological stress was initially detected at 21–22% soil moisture, evidenced by a decline in relative water content (RWC). Furthermore, 8–9% soil moisture marked a critical physiological threshold characterized by severe photosyn-thetic impairment, elevated oxidative stress, and cellular damage. Prolonged water limita-tion (4 weeks at 20–30% soil moisture) reduced leaf greenness, RWC, and photosynthetic performance. Concurrently, long-term stress resulted in anatomical adaptations in both stem and leaf, such as chloroplast depletion, starch accumulation in the stem cortex, and a reduction in stem xylem vessel diameter. These findings demonstrate that drought stress can serve as an effective elicitor to enhance bioactive compound accumulation in water hyssop, providing valuable insights for applications in controlled-stress cultivation and irrigation management.

Abstract: This study provides a comprehensive assessment of the amount of biomass and taxonomic-functional composition of stranded macroalgae and seagrasses on a highly productive shellfish bank of NW Iberia (Galicia) frequently affected by “green tides”, based on a year-long monitoring program and multivariate anal-ysis. Macroalgal biomass showed strong seasonal and spatial variability, peaking in spring and summer. Chlorophyta, especially Ulva lacinulata, dominated the community, accounting for over 63% of total biomass. This species, along with other foliose morphotypes, shaped both seasonal and spatial dynamics. Statis-tical analysis revealed significant effects of season, transect, and tidal level on stranded biomass, as well as significant interactions between transect and tidal level and between tidal level and sea-son, highlighting marked spatial and temporal heterogeneity in biomass deposition. The absence of a consistent vertical zonation pattern in stranded biomass and the accumulation of material in upper intertidal zones reveal the role of these areas as passive hydrodynamic filters, decoupling production from deposition. Incorporating functional approaches and hydrodynamic context into monitoring and management strategies will be essential to mitigate the ecological and socio-economic impacts of green tides under ongoing global change.

Abstract: Empirical evidence integrating multiple biological levels on freshwater biodiversity persistence in regulated river basins remains scarce for Neotropical systems. We evaluated fish assemblage structure, reproductive strategies, and life-cycle support for migratory species across lotic and lentic habitats in three tributaries of the Porto Primavera Reservoir, Upper Paraná basin, Brazil, over an 11-year monitoring period (2007–2018), encompassing 104 species and a Life-cycle Support Index (LSI) based on occurrence of eggs, larvae, juveniles, and adults. Marginal lagoons functioned as biodiversity hotspots, with higher richness and diversity than river channels; reproductive guilds were habitat-partitioned, with opportunistic and parental-care strategists in lentic environments and periodic/migratory strategists in lotic habitats. Tributary identity was the strongest predictor of assemblage composition: the Aguapeí River, partially protected, showed the highest LSI values, whereas the Verde River provided the strongest evidence of reproduction for conservation-priority taxa, including the critically endangered Brycon orbignyanus, whose adults occurred exclusively there, and the vulnerable Pseudoplatystoma corruscans, for which adults, eggs, and larvae co-occurred. Three proposed hydropower developments on the Verde River would fragment a 200-km free-flowing stretch, threatening these conditions. Undammed tributaries are irreplaceable for freshwater biodiversity and should be recognized as conservation priorities in hydro-power licensing and basin governance.

Abstract: Long non-coding RNAs (lncRNAs) have emerged as important regulators of gene expression acting through transcriptional, post-transcriptional, and epigenetic mechanisms. In teleosts, high-throughput sequencing has identified a growing number of lncRNAs associated with gonadal development and reproductive function, yet current knowledge remains fragmented across species and reproductive contexts. This review summarizes recent progress in understanding lncRNA-mediated regulation of fish reproduction, with emphasis on gametogenesis and germ cell development, gonadal maturation, steroidogenesis, sex determination and differentiation, sex reversal, sexual dimorphism, and fertility. Evidence from transcriptomic and functional studies indicates that lncRNAs are involved in complex regulatory networks through cis- and trans-acting effects, competing endogenous RNA (ceRNA) interactions, and hormone-responsive pathways. Several lncRNAs have been associated with key reproductive genes, including gsdf, dmrt1, amhr2, ccne1, and cyp19a1, underscoring their potential roles in gonadal development and reproductive performance. Despite these advances, most reported lncRNAs remain functionally uncharacterized, limiting a full understanding of their biological significance. Future studies that integrate transcriptomics, genome editing, and mechanistic validation will be essential to define the precise functions of those lncRNAs. Overall, current evidence supports lncRNAs as emerging regulatory components of teleost reproductive biology with potential relevance to aquaculture, reproductive biotechnology, and environmental research.

Abstract: Puntius sophore, a small indigenous fish species, has significance to the nutritional and livelihood security of rural communities in India. This study presents baseline data on the population dynamics, length-weight relationships (LWRs), and condition factors of P. sophore in two major rivers, the Ganga and Punpun in India, while assessing multi-decadal (1990-2023) land use and land cover (LULC) changes. Fish samples (506) were collected monthly from each of three landing sites from the river Ganga and Punpun. The results revealed that populations in both rivers have positive allometric growth, with length-weight relationship (LWR) equations of W = 0.0129 L^3.023 (Ganga) and W = 0.0079 L^3.169 (Punpun). The condition factors (Kc, Kn, Ka) were significantly higher (p < 0.05) than 1 in the Punpun River, indicating a favorable environment, while values < 1 in the Ganga showed higher ecological stress. The growth aspects (L∞ = 134.60 mm, K = 0.71 yr⁻¹ for Ganga; L∞ = 133.42 mm, K = 0.735 yr⁻¹ for Punpun) were analyzed by TropFish-R, showing a fast-growing species. Total mortality (Z) was higher in the Ganga (1.822 yr-1) in comparison to the Punpun (1.797 yr-1), though, exploitation rates (E < 0.5) confirmed under-exploitation. Length-based spawning potential ratio (LB-SPR) analysis revealed recruitment overfishing (SL < Lm), with a sustainable SPR of 0.40 in the Punpun and a depleting SPR of 0.32 in the Ganga. Although current fishing pressure is adequate, spatiotemporal LULC indicated that rapid urbanization and habitat fragmentation exhibit a substantial "squeeze" effect that adversely impacts aquatic ecosystems and poses a significant risk to spawning and feeding grounds of that ecosystem. Effective management approaches, including the execution of seasonal fishing bans during monsoon recruitment and the implementation of strict mesh-size standards, are essential for the conservation of wild populations and the protection of regional food supplies.

Abstract: Research into molecular machinery of eukaryotic unicellular organisms (protists) gives a unique opportunity to unveil mechanisms of intricate cellular processes and complete life cycles at the level of a single cell as a whole organism. Knowledge of protistan molecular biology and life cycle shifts as adaptations to varying physical-chemical features of the environment helps resolve important issues like evaluation of the balance between external abiotic triggers and internal molecular drivers of cells development. Understanding molecular mechanisms of these processes is crucial for prognostic modeling of population growth of the ecologically and economically important protists like toxic species forming harmful algal blooms (HABs) that currently expand worldwide. Here, we review basic features of bloom-forming mixotrophic dinoflagellates as drivers of their excess proliferation and HABs. We unveil key components of molecular machinery involved in life cycle regulation of dinoflagellates and highlight the deficiency/redundancy of nitrogen- and phosphorus-containing substrates as modulators of life cycles, diversity and nutrition strategies, including mixotrophy and kleptoplasty. We discuss linkages between cellular and molecular biology, omics and ecological modeling, since merging research approaches of these disciplines is a promising perspective for future progress of molecular biology within the framework of translational aquatic ecology.

Abstract: This paper is a literature study supplemented with self-collected data on fish density, age and growth of smelt (Osmerus eperlanus) in Lake Mjøsa over the last 40 – 50 years. Smelt is an important prey fish for piscivorus brown trout, and the development of the brown trout population is illuminated by catch reports. The smelt abundance in Lake Mjøsa declined in the period 1980 to 1990 but increased sharply in 2018 and 2023. Re-cruitment to the smelt population is positively correlated with air temperature in May and July. Increased smelt abundance is a possible reason why the population of large grown brown trout also appears to have increased, while smelt has shown reduced in-dividual growth in recent years. The brown trout population does not appear to have a decisive effect on the smelt stock but may have contributed to increased mortality in smelt in the material from 2006 - 2022 as compared to 1980. The effect of brown trout stocking, conducted for the last time in 2021, is uncertain, but future catch reporting will provide a better answer to this.

Abstract: Environmental DNA (eDNA) metabarcoding is a valuable, non-invasive approach for assessing fish biodiversity in freshwater ecosystems. This study characterized fish-associated diversity across four freshwater locations in Indiana, including upstream and downstream sites of the White River, Shadyside Lake, and Trail Creek, and examined contemporary White River fish communities in the context of recovery following the historical 1999 chemical spill. Water samples were analyzed using high-throughput sequencing targeting the mitochondrial 12S rRNA gene, and fish-associated exact sequence variants (ESVs) were evaluated using richness, diversity, and community composition analyses. A total of 87 unique fish-associated ESVs were detected. White River downstream exhibited the highest ESV richness (60), followed by White River upstream (27), Shadyside Lake (22), and Trail Creek (7), and also had the highest Shannon diversity (H′ = 2.30). Community analyses revealed substantial overlap between the two White River sites and greater similarity between them than with Shadyside Lake or Trail Creek. The relatively high richness and diversity detected downstream are consistent with previous biological assessments documenting substantial recovery of White River fish communities following the 1999 spill. Overall, these findings support eDNA metabarcoding as a useful complement to conventional fish monitoring for assessing freshwater biodiversity and long-term ecological change.

Abstract: The cytochrome P450 (CYP) system is a superfamily of heme-containing monooxygenases essential for the metabolism of endogenous compounds and xenobiotics. In fish, CYP enzymes process diverse pollutants and contribute to adaptation to chemical stress. Their activity depends on NADPH-cytochrome P450 reductase (CYPOR), which provides electrons for CYP-mediated reactions. Two aspects remain insufficiently understood: the mechanisms underlying species-specific CYPOR reactivity in relation to ecological niche and the potential of CYPOR dynamics as a biomarker of bioremediation effectiveness. This review-hypothetical study aims to formulate and substantiate hypotheses linking CYPOR species specificity with ecological niche and to establish a conceptual framework for using CYPOR in bioremediation monitoring. Scientific literature published from 1980 to 2026 was searched in PubMed, Scopus, Web of Science, and Google Scholar. The proposed hypotheses form an integrated model in which species-specific CYPOR reactivity is considered an evolutionarily fixed trait reflecting ecological adaptation, while CYPOR dynamics may serve as an integrated indicator of pollution and remediation efficiency. The central concept is CYPOR as a common elec-tron donor system whose activity reflects the cumulative induction of CYP isoforms and responds to changes in toxicant exposure. This framework provides a basis for interpreting CYPOR variability in fish populations and developing future biomonitoring approaches.

Abstract: Microplastics (MPs) (1 μm - 5 mm-) are now ubiquitous in the environment. They exhibit a variety of different shapes and compositions and accumulate in organs of virtually every organism. Recently, biomedical researchers have focused on nanoplastics (NP) (1 nm -1 μm ) because of their potential to enter organisms, cross cell barriers, and impact biological processes. Taken together, micro- and nano-plastics (MNP) are increasingly considered a contaminant of concern in freshwater systems such as the Laurentian Great Lakes in North America, which provide drinking water for 40 million people in the United States and Canada. We review here the current knowledge and challenges to overcome for evaluating the long-term consequences of MNP exposure in freshwater ecosystems and their aquatic vertebrates. We demonstrate how the use of a novel animal model in the amphibian Xenopus within the context of a transdisciplinary research center has the potential to rapidly advance knowledge about key biological mechanisms and potential health impacts of environmentally-relevant MNPs.

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Probiotics, especially Bacillus species, have gained attention for their potential to improve growth and strengthen disease resistance in cultured shrimp. This study evaluated the effects of native Bacillus strains on growth performance, disease resistance and gut microbiota of Penaeus vannamei through the rearing water. The shrimp were reared in water supplemented with different treatments: (a) a negative control (no bacterial addition), (b) a commercial Bacillus spp.® product (positive control), (c) B. subtilis and (d) B. cereus, every 7 days over a period of 21 days. Shrimp reared with B. cereus showed significantly increased specific growth rate (SGR) and average daily gain (ADG) among treatments as compared to the control group (p < 0.05). There was no significant difference in final body weight and feed conversion ratio among groups (p > 0.05). After Vibrio parahaemolyticus challenge, the cumulative mortality was lowest in the B. cereus treated group, showing the highest disease resistance. Alpha diversity of gut microbiota was not significantly different among groups, but beta diversity analyses showed significant differences of gut microbial community structure and LEfSe identified the genus Bacillus as a significant biomarker of the B. cereus-treated group, confirming its colonization in shrimp gut. The results suggest that supplementation of water with a native B. cereus strain enhances growth efficiency and disease resistance and leads to a stable colonization of Bacillus in shrimp gut, offering a practical probiotic approach for intensive shrimp aquaculture.

Abstract: River–lake confluence zones are shaped by inflow hydrology, evaporative concentration, and water mixing, providing natural systems for examining phytoplankton responses to environmental gradients. Here, we investigated Siling Co and adjacent river–lake confluence zones at elevations above 4,500 m. We integrated genus-level phytoplankton cell-density and biomass data with 22 environmental variables from 14 sampling events at 10 sites, including seven Lake and seven River samples. Community diversity, composition, and community–environment associations were evaluated using ordination, permutation tests, correlation analyses, distance-based redundancy analysis, Mantel tests, and multi-method evidence integration. In total, 54 genera were recorded, with Bacillariophyta representing the dominant phylum. Lake and River samples overlapped in community composition, whereas sampling period explained more genus-level variation than water-body type. Major-ion and mineralization gradients were consistently associated with community turnover. pH and SiO₂ were associated with cell-density composition, whereas Cl⁻ was associated with biomass composition. Cyanobacterial relative biomass was positively correlated with total nitrogen and negatively correlated with SO₄²⁻. These findings indicate that phytoplankton community structure in the Siling Co river–lake confluence zone cannot be attributed simply to two discrete habitat types, namely lakes and rivers, and provide a new perspective on community assembly in extremely high-altitude river–lake confluence zones.