A new species of pomatiopsid freshwater snail, Fenouilia undata Chen & He, sp. nov., is described from Guangxi, China, based on morphological and molecular evidence. The new species can be distinguished from its congeners by the following combination of characters: shell with low, prosocline, rounded axial ribs and fine spiral striae, broader than high; aperture broader than shell height; radula with lateral teeth have only two or three faint, wavy ridges on inner side. A molecular analysis of partial mitochondrial COI and 16S DNA sequences supports the systematic position of the new taxon.

Based on specimens collected from Lake Fuxian in Yuxi City, Yunnan Province, China, we describe a new species of the genus Sinomytilus, Sinomytilus liuliwanqing sp. nov., all type specimens are deposited at Nanjing Normal University in Jiangsu Province, China. We provide a detailed morphological description of the species and molecular analysis based on partial mitochondrial COI supports its systematic position as a new taxon.

This study investigated heavy metal bioaccumulation, pollution sources, and human health risks in the Wujiang and Zhenjiang rivers, the major headwaters of the Beijiang River in southern China. Concentrations of 11 heavy metals (Fe, Mn, Ba, Zn, As, Cu, Ni, Cr, Co, Cd, Pb) in surface water, sediments, and the soft tissues of four bivalve species (Corbicula fluminea, Limnoperna fortunei, Unio douglasiae, and Anodonta woodiana) were determined. Results showed that surface water remained below pollution thresholds, whereas sediments in the Wujiang River exhibited moderate-to-heavy Cd, As, Pb, and Zn contamination linked to historical Pb-Zn mining. Among the two better-represented species, C. fluminea showed relatively high As and Zn concentrations, whereas L. fortunei showed relatively high Cu accumulation. Data for U. douglasiae and A. woodiana were treated as preliminary observations because of their limited sample sizes. Biota-sediment accumulation factor (BSAF) values indicated that Mn, Cu, Cd, Zn, Ni, and Cr were actively accumulated beyond sediment concentrations, whereas As and Pb showed limited sediment-to-biota transfer. Multivariate analysis of the two better-represented species indicated species-related differences in tissue metal profiles, with patterns consistent with both natural geogenic inputs and historical Pb-Zn mining activities. All four species posed potential non-carcinogenic health risks to consumers, with As and Mn as the dominant risk contributors. These findings underscore the necessity of multi-species biomonitoring and consumption advisories in mining-impacted watersheds.

Life-history plasticity allows fishes to exploit heterogeneous freshwater networks, and proactive habitat selection enhances their capacity to cope with climatic and human-induced stressors. Coilia brachygnathus, long regarded as a freshwater resident, nevertheless has a poorly understood habitat use and selection. We reconstructed habitat use of C. brachygnathus across the middle-lower Yangtze by coupling water ⁸⁷Sr/⁸⁶Sr baselines with otolith ⁸⁷Sr/⁸⁶Sr transects. We used 60 water samples, compiled published datasets, and measured additional water samples from the mainstem, major tributaries, and connected lakes. In situ ⁸⁷Sr/⁸⁶Sr profiles were smoothed with generalized additive models, revealing significant within-profile variation for all fish. Two modes emerged: (i) residents, whose otolith values remained within local water ranges, consistent with limited movement; and (ii) migrants, whose profiles departed from local baselines, indicating exchanges among lakes, tributaries, and the mainstem. Several fish captured at Anqing and Zhenjiang possess Poyang-like core signatures that declined to mainstem values, while bidirectional shifts were common in the Dongting-Xiang system. These results overturn the residency paradigm, demonstrate flexible partial migration, and indicate proactive habitat selection in the face of environmental change, thereby supporting management that maintains river–lake connectivity and quantifies lake contributions to mainstem stocks.

To assess the applicability of environmental DNA (eDNA) technology in monitoring fish diversity in Dongting Lake, located in Hunan Province within the Yangtze River Basin, China, this study combined eDNA metabarcoding with traditional fishing gear to describe the diversity characteristics of the fish community in its habitat. Water samples were collected from 20 representative sites for eDNA analysis, followed by filtration, DNA extraction, and high-throughput sequencing targeting the 12S rDNA region. Concurrently, traditional fishing gear using gill nets and fish traps was conducted at the same locations. The results revealed 82 fish species detected by both methods combined, with eDNA alone identifying 21 species (including rare species encompassing Saurogobio gracilicaudatus and Glyptothorax sinense), while traditional fishing gear detected 27 species. Among the 82 fish species, a total of thirty-four species of fish could be observed in catches from both methods. In terms of α-diversity, eDNA showed higher Chao1, species richness, and ACE indices compared to traditional fishing gear, but lower Shannon and Simpson indices. eDNA was more sensitive to species richness, while traditional fishing gear was better at characterizing community evenness and diversity. β-Diversity analysis showed higher spatial similarity in the fish community structure detected by eDNA, while traditional fishing gear revealed significant differences between the upstream and downstream areas. In summary, eDNA technology has the advantages of non-invasiveness, high sensitivity and broad coverage, effectively serving as a valuable supplementary tool of traditional fishing gear, particularly in monitoring rare species. However, further improvements are needed in terms of species abundance quantification and database dependency. The combination of these two methods provides a more comprehensive scientific basis for fish resource conservation in Dongting Lake.

A new species of bivalve, Curvemysella bajie sp. nov. [八戒陷腹蛤] (Bivalvia, Galeommatoidea), is described, based on samples collected from Qingdao (Shandong, China). The intertidal zone of the China Yellow and Bohai Sea is home to a large number of Blepharipoda liberata (Shen, 1949), which often have clams attached to their bodies. Samples of B. liberata were collected from the intertidal zone of Golden Beach in Qingdao and examined for associated molluscs. In addition to description of the shell morphology of C. bajie sp. nov., molecular analysis based on four-gene combined dataset (18S + 28S + H3 + COI) also supports its phylogenetic position.