摘要: For mobile animals such as fish, different habitat types at various life stages are required to support a broad range of ecological requirements. However, in urban areas, access to suitable habitat may be impeded. Moreover, rehabilitation efforts focused on urban waterbodies are infrequent, small-scale, and inadequately monitored. We characterized the connectivity of the fish community between the Jock River in eastern Ontario and a rehabilitated stormwater management pond during late spring. Passive integrated transponder (PIT) tags were implanted into over 800 individual fish, representing sixteen species with a wide range of body sizes and life-histories. Summer residency and behavior were assessed using detections from an array of autonomous PIT receiver stations. This research revealed that there is ecological connectivity between an adjacent rehabilitated stormwater pond and the Jock River. Some species were resident in the pond during the entire summer monitoring period while others such as sunfish (Lepomis sp.) and rock bass (Ambloplites rupestris) made regular forays between the river and the pond. There was also evidence of significant movement within the pond for species such as golden shiner (Notemigonus crysoleucas) and northern pike (Esox lucius). This study demonstrates the potential for created habitats in floodplain areas initially intended for stormwater management to be rehabilitated to provide significant ecological value in urbanized watersheds.

摘要: This study investigated the effects of dietary supplementation with the probiotic Bacillus pumilus on coho salmon (Oncorhynchus kisutch). A total of 360 juvenile fish, with an average initial weight of 130.75 f 1.33 g, were randomly assigned to four treatment groups, each with three replicates of 30 fish. The fish were then fed for 70 days using formulated diets containing four concentrations of B. pumilus: 0 (control group), 2 x 106, 4 x 108, and 8 x 1010 CFU/g. We then evaluated growth, nutrient metabolism, immune-related serum biochemical markers, enzyme activity, gene expression, and muscle composition. Additionally, we assessed intestinal histology and microbiota composition. Our findings revealed that B. pumilus significantly improved growth, protein and fat metabolism, and immune function compared to the control group. It also had a positive effect on the structure and function of the intestinal microbiota. The group receiving 4 x 108 CFU/g showed the greatest improvements. Overall, B. pumilus appears to be a promising probiotic for enhancing the health and performance of coho salmon in aquaculture.

摘要: Few studies have reported obtaining grass carp resistant to hemorrhagic disease via gene editing in commercial fish. Here, we demonstrate that the expression and activity of grass carp PI4KB (gcPI4KB) are vital for GCRV-I and GCRV-II replication. Given the obvious cytopathic effect (CPE) in the present available cell lines is only caused by GCRV-I, but GCRV-II is the current popular and fatal strain in grass carp, GCRV-I and GCRV-II are used in cell lines and in grass carp, respectively. In vitro studies in CIK cells revealed that gcPI4KB interacted with NS80 and VP3 of GCRV-I, and that gcPI4KB was recruited by NS80 for promoting the generation of GCRV viral inclusion bodies (VIBs). Since the negative regulatory role of gcPI4KB in GCRV infection was confirmed by in vitro data, we performed gene editing of gcPI4KB in grass carp. We found that PI4KB F0 juvenile grass carp crispants have obvious advantages in promoting growth and in resisting GCRV-II infection. Compared with uninfected WT grass carp, the uninfected PI4KB F0 juvenile grass carp crispants exhibit a higher expression level of many genes involved in growth- and development-related metabolic pathways such as the FoxO signaling pathway and insulin signaling pathway. Compared with WT grass carp without infection, PI4KB F0 juvenile grass carp crispants without infection or WT grass carp infected with GCRV-II, higher expression levels for many genes involved in metabolic diseases and viral infections were observed in the liver from PI4KB F0 juvenile grass carp crispants infected with GCRV-II. Altogether, the present study suggests the mechanism of gcPI4KB in facilitating GCRV replication, the signaling pathways regulated by gcPI4KB, and the possibility to obtain grass carp resistant to hemorrhagic disease via gene editing of PI4KB.

摘要: Identifying precise egg attachment areas and tracking trends of spawning magnitude (total amount of spawned eggs) are critical for accurate habitat assessment and effective conservation efforts, especially for lithophilic spawning fishes. However, accurate measurement of spawning conditions across both spatial and temporal dimensions poses significant challenges. We conducted a fourteen-year field study below the Gezhouba Dam, the main spawning ground for the Chinese sturgeon, using Kernel Density Estimation (KDE) method and Catch per Unit of Effort (CPUE) to refine knowledge on egg attachment areas relative to previous assessments. In addition, our analysis documented shifts in spawning locations within these four areas over the past fourteen years, revealing a worrying trend of decreasing spawning magnitude. This approach not only enabled the incorporation of the density distribution of eggs into the assessment of spawning magnitude trends, but also underscored the potential of the KDE as a framework for identifying egg attachment areas and estimating spawning magnitude trends. Our results provide valuable insights into spawning degradation of Chinese sturgeon and inform conservation strategies to protect their fragile spawning grounds.

摘要: Hypoxia is one of the major environmental stressors, frequently resulting in serious yield losses for maricultured large yellow croaker (Larimichthys crocea). We know that pyroptosis contributes to tissue damage under hypoxic conditions. However, whether GSDMEs-mediated pyroptosis is involved in hypoxia-induced tissue damage in fish remains unclear. In the present study, two Lcgsdme genes, Lcgsdmea/b, were cloned and characterized from the large yellow croaker. Both genes contain a conserved N-terminal pore-forming domain, a C-terminal autoinhibitory domain, and a flexible hinge region. After hypoxia stress, the expression of Lcgsdmea/b transcripts and proteins in the liver were significantly higher than in unstressed fish. The proteins of LcGSDMEa/b could be cleaved under hypoxic conditions. Compared to LcGSDMEb, the expression of LcGSDMEa was higher in both mRNA and protein levels, thus exhibiting a stronger response during hypoxia stress. Furthermore, after 48 h of hypoxia stress, approximately 65% liver cells exhibited abnormalities, with pyroptosis being detected using a transmission electron microscope. TUNEL/LcGSDMEa double staining assay revealed a high expression of LcGSDMEa in the dead cells. We observed a significant up-regulation of pyroptosis pathway genes (asc, caspase-3) and pro-inflammatory cytokine genes (il-1 beta, il-18). After simultaneous knockdown of Lcgsdmea/b in vivo, the liver exhibited better health compared to the control group, with less cell swelling and vacuolation. Taken together, these findings demonstrate that hypoxia stress could activate LcGSDMEa/b and induce pyroptosis in the liver of large yellow croakers, thereby contributing to tissue damage. Our study improves the understanding of hypoxiainduced tissue damage in fish, and provides new clues for protecting fish against hypoxia-induced damage.

摘要: Seahorses are specialized teleosts due to their unique male pregnancy and reproductive physiology. In particular, they have distinct gonad structures and different patterns of gametogenesis development in both sexes. However, the molecular mechanism of germ cell development in seahorses remains unknown. Nanos, which encodes conserved zinc-finger RNA-binding proteins, play essential roles for germline development in both vertebrates and invertebrates. In this study, we characterized the nanos gene family members and their potential roles in germline development in the lined seahorse, Hippocampus erectus. We showed that the nanos family members in the seahorse are the nanos1a, nanos1b, and nanos3 genes, while nanos2, a key germline stem cell (GSC) maintenance factor, is intriguingly absent. More interestingly, nanos3, which is reported to be a female-specific gene, was also highly expressed in male gonads, as well as in the early developmental stages of testes and ovaries. Our results also showed that nanos3 was highly expressed in early meiotic germ cells, and that expression levels of nanos3 were lower in the gonad after TBT exposure. These findings suggest that nanos3 may function during male germ cell development, and in female initial germ cell production - processes which are regulated by nanos2 in other teleosts. This is the first research into how nanos governs germ cell development in an ovoviviparous fish. Our study provides insights into the regulatory mechanisms of germ cells development, as well as the early events during gametogenesis in the family Syngnathidae.

摘要: Water level variations (WLVs) substantially affect the spatial distribution of riparian vegetation. Accurately quantifying the water level fluctuation requirements (WLFRs) of aquatic macrophytes is essential for effective ecological water level management. Nevertheless, studies on the WLFRs of herbaceous plants in large river floodplains, such as Phragmites australis (common reed) and Phalaris arundinacea (reed canarygrass), are limited. Herein, we investigated the WLFRs of the two plants across water bodies with different WLVs in the Yangtze River Basin. We focused on the effects of sub-monthly and sub-daily WLVs on their average monthly water depth requirements (WDRs) during critical growth periods. Our findings indicated: (1) For Phragmites, during the emergence period, the upper limits of WDRs decreased with increased amplitudes of sub-monthly WLVs and with greater frequency and amplitude of sub-daily WLVs, in which sub-daily variations had a more pronounced effect. Conversely, during the rapid growth period, the upper limits increased with larger sub-monthly WLVs amplitudes, but decreased with higher frequency and amplitude of sub-daily WLVs. (2) For Phalaris, during both the emergence and rapid growth periods, intensified sub-daily WLVs led to decreased upper limits of WDRs. In summary, although distinct disparities existed in the WLFRs of Phragmites and Phalaris across various water bodies, the trends in WDRs during the emergence and rapid growth periods were consistent for both species. These findings provide essential quantitative data to restore aquatic vegetation and carry out effective ecological water level management in large-scale riparian ecosystems.

摘要: Atlantic cod, Gadus morhua, is a marine fish, but there are several Arctic lakes, where it also occurs. Mogilnoye Lake on Kildin Island in the Barents Sea is especially famous for them. It is a salinity stratified meromictic lake. The surface layer is fresh with saline water saturated with hydrogen sulfide underneath. Kildin cod have been studied over the last 100 years with emphasis on taxonomy, physiology, genetics and growth. However, the conservation of this species has been overlooked. Recent sonar surveys showed that the cod are quite abundant, but in danger from hydrogen sulfide accumulation within the lower lake levels. Therefore, the habitat of this species is shrinking. Conservation studies must be a priority in the situations like this.

摘要: Climate change has had an unprecedented impact on lake ecosystems around the globe and has both direct and indirect consequences on lake structure and mineralization. These changes are threatening the unique biodiversity that lake ecosystems currently support. Siberia is experiencing one of the greatest impacts of climate change in the world, with exceptional warming in the north and increasing aridity in the south. Lakes in southern West Siberia, including saline and hypersaline waterbodies within endorheic basins, remain unexplored in terms of the biodiversity of the microbial eukaryotes inhabiting them. In this study, we investigated the taxonomic and functional diversity of planktonic protist communities in saline and hypersaline lakes (22-220 parts per thousand) in southern Western Siberia through Illumina 18S rDNA amplicon sequencing. Taxonomic diversity was represented by the Amoebozoa, Archaeplastida, Cryptista, Excavata, Haptista, Obazoa, Provora, and TSAR supergroups, and varied significantly among lakes of different salinities. Salinity has been shown to be an important determinant that directly influences the composition and uniqueness of protist communities. The co-occurrence network analysis revealed a decrease in the complexity of the network of protist communities with increasing salinity. The taxonomic diversity of protists in lakes determines functional diversity, which is expressed as the relative abundance of free-living heterotrophs, phototrophs, and parasites. Phototrophs dominated the delta-hypersaline waters, and free-living heterotrophs dominated the alpha- and beta-hypersaline lakes. The parasite amplicon sequence variants (ASVs) were affiliated mainly with mixohaline and beta-hypersaline lakes.

摘要: Micro-eukaryotic communities are highly sensitive to environmental changes, and their structure offers crucial insights into the impact of human activities on aquatic habitats. Despite their significance, the assembly mechanisms of micro-eukaryotic communities in lake ecosystems heavily influenced by human activities are not well understood. In this study, we utilized 18S rDNA amplicon sequencing to examine the biodiversity of microeukaryotes over a one-year period in Lake Weishan, one of the largest freshwater lakes in northern China. We analyzed the ecological processes governing community assembly among key ecological groups, specifically habitat generalists and specialists. Our findings revealed substantial temporal variation in microbial diversity and community composition, likely driven by water temperature, dissolved oxygen, and the concentrations of several ions (e.g., Ca2+ and F-). Notably, community assembly in this canal-disturbed lake was predominantly influenced by stochastic processes (58.18%) rather than deterministic processes (20.46%). Habitat specialists (425 operational taxonomic units, OTUs) exhibited significantly greater diversity compared to habitat generalists (189 OTUs) and were predominantly shaped by stochastic processes (52.47%). In contrast, habitat generalists were less influenced by these processes (17.69%). Altogether, these results suggest that the ecological processes governing micro-eukaryotic community assembly differ markedly between habitat generalists and specialists, primarily due to their varied adaptability to environmental changes.