Jian Su

The leucistic northern snakehead ( Channa argus ), a leucistic morph of the species, maintains the high-quality meat and nutrient density characteristic of the wild-type populations, while its unique coloration may further enhance its market appeal. However, the genetic basis and molecular mechanism of its rapid growth rate are still unclear. In this study, transcriptome sequencing was performed on the brain, liver, and muscle tissues of leucistic northern snakehead individuals with significantly different growth rates using high-throughput sequencing technology. Through in-depth bioinformatics analysis, a series of differential pathways closely related to growth rate were identified, among which pathways such as TGF-beta signaling pathway were activated in the big group. Further functional analysis suggests that these pathways may have an important impact on the rapid growth characteristics of the leucistic northern snakehead by regulating key biological processes such as muscle growth and metabolism. This study not only provides valuable clues for revealing the molecular mechanism of the growth traits of the leucistic northern snakehead, but also lays a solid theoretical foundation for the molecular breeding of the leucistic northern snakehead and the sustainable development of the aquaculture industry.

Schizothoracinae represent an endemic and dominant teleost group in the Qinghai–Xizang Plateau and adjacent regions. Despite their rich species diversity, closely related Schizothoracinae species exhibit remarkable external morphological similarity, which hinders traditional morphological discrimination. In this study, lapillus otoliths from 360 individuals representing 12 Schizothoracinae species collected across major Tibetan water systems were systematically examined. We evaluated and compared the performance of traditional scalar-based shape indices and Elliptic Fourier Analysis (EFA, 60 normalized harmonic coefficients following size-allometry correction) in otolith contour quantification and species identification. Statistical analyses including one-way ANOVA, principal component analysis (PCA), non-linear manifold learning (t-SNE and UMAP), and linear discriminant analysis (LDA) were executed. One-way ANOVA revealed highly significant differences among all 12 species across all shape indices and Fourier coefficients. The overall LDA classification accuracy was 35.3% for the shape index method, whereas EFA achieved a higher overall accuracy of 68.3%, representing a 33.0 percentage point improvement. Under EFA, Schizothorax lhasaensis (93.3%) and Schizothorax nukiangensis (90.0%) demonstrated the highest single-species discrimination success. Interspecific otolith morphological divergence was substantially higher in the riverine genus Schizothorax than in lacustrine genera (Gymnocypris and Schizopygopsis), the latter two of which show extensive morphological overlap consistent with their low genomic differentiation. Fishes of Gymnocypris displayed significantly higher otolith roundness (p < 0.05), which correlates with their adaptation to lacustrine or sluggish water habitats. Our findings demonstrate that EFA effectively captures multi-scale otolith contour harmonics, serving as a valuable morphometric approach for Schizothoracinae species identification and morphological discrimination, although challenges remain for species with incomplete lineage sorting. The morphometric database established herein provides valuable morphological baselines for the conservation and management of endemic QXP fish resources.

The river ecosystems of the Qinghai–Tibet Plateau, recognized as a vital component of the “Asian Water Tower,” possess unique hydrological conditions and extreme environments that have shaped key indicator groups, most notably zooplankton. The community dynamics and structural characteristics of these zooplankton exhibit regular spatio-temporal distribution patterns across elevational gradients and seasonal successions. However, the intrinsic mechanisms underlying community succession and their correlations with environmental factors remain poorly understood, and the primary environmental drivers influencing community structure require further elucidation. Based on systematic zooplankton surveys and environmental data collection conducted across the Lhasa River basin from 2019 to 2021, this study established a comprehensive species inventory comprising 113 taxa across four major groups, alongside a multi-dimensional environmental dataset. We analyzed the spatio-temporal heterogeneities of zooplankton community structures—including abundance, biomass, and diversity indices—across different seasons and river reaches. The results revealed the composition and seasonal turnover of dominant taxa, with rotifers accounting for 39.82% of the total taxonomic richness. Mean zooplankton abundance and biomass across the basin were 1.18 ind./L and 343.60 × 10⁻⁵ mg/L, respectively, with peak values observed during autumn and within the Chabalang Wetland. The zooplankton community structure in the upstream, midstream, and downstream reaches, as well as associated wetlands, was significantly correlated with specific environmental factors (p < 0.05), including ammoniacal nitrogen (NH₄⁺-N), magnesium (Mg²⁺), total hardness (TH), potassium (K⁺), iron (Fe²⁺), sodium (Na⁺), sulfite (SO₃²⁻), nitrate ion (NO₃⁻), chloride ion (Cl⁻), total phosphorus (TP), and sulfide (S²⁻). Cl⁻, TH, Mg²⁺, SO₃²⁻, and elevation (Ele) were the key environmental drivers significantly influencing zooplankton abundance across seasons (p < 0.05). Furthermore, zooplankton abundance decreased significantly with increasing elevation during the winter. This research deepens our understanding of community assembly mechanisms in plateau river ecosystems and provides a scientific foundation for aquatic biodiversity conservation and ecological management in the Lhasa River basin.

The dynamic changes in plateau river ecosystems and the driving mechanisms of environmental factors have garnered significant attention. Phytoplankton, a core component of aquatic ecosystems, can directly reflect changes in the aquatic environment. This study focuses on the phytoplankton in the Lhasa River Basin, including the riverbed from the source to the river mouth, five largest tributaries, and two adjacent wetlands. We analyzed the spatial and temporal variation characteristics of phytoplankton and explored the environmental driving mechanisms based on four field surveys conducted between September 2019 and March 2021. Results showed that a total of 127 species of phytoplankton from six algal phyla were identified, including Cyanobacteria. Among these, Bacillariophyta was the dominant group, accounting for 41.7% of the identified species. Spatially, phytoplankton diversity showed a decreasing trend from upstream to downstream while temporally peaking in spring and autumn. Redundancy analysis revealed that upstream phytoplankton were driven by total hardness and altitude, midstream by pH and potassium ions, and downstream by nitrate and ammonium nitrogen. Classification and regression tree analysis showed total hardness, magnesium ions, and nitrite were key factors influencing phytoplankton abundance, diversity, and evenness. This study highlights the ecological dynamics and driving mechanisms of phytoplankton communities in the Lhasa River, demonstrating their high sensitivity to environmental factors. These findings could help to establish phytoplankton as critical indicators of aquatic ecosystem health and provide scientific guidance for the conservation and management of the plateau river ecosystems.