Search Results (4)

Environmental DNA (eDNA) metabarcoding was utilized to compare the fish species composition, diversity, and their relationships with environmental factors in four medium-sized drinking water reservoirs (Tongjiqiao, Andi, Shafan, and Jinlan) within the Qiantang River Basin during both wet and dry seasons. A total of 44 fish species belonging to 6 orders, 15 families, and 40 genera were detected, with Cyprinidae being identified as the dominant family (68.2%). Silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) were identified as the most abundant species, representing 81.94% and 99.98% of the relative eDNA abundance, respectively. The fish communities were characterized by river-resident species (59.1%), pelagic species (43.2%), and omnivorous (43.2%) and carnivorous (43.2%) feeding habits. Significant influences of seasonal and reservoir-specific variations on physicochemical parameters, species composition, and ecological traits were observed. However, no significant differences in community diversity (Chao1, Pielou_e, Shannon, and Simpson indices) or distribution patterns were detected between wet and dry seasons. In contrast, Jinlan Reservoir was found to exhibit distinct diversity and distribution patterns compared to the other three reservoirs, which was consistent with the relative eDNA abundance of H. molitrix and H. nobilis. Through a Spearman correlation analysis, the relative abundance of H. molitrix was revealed to be negatively correlated with community diversity, while H. nobilis was shown to have positive correlations (except with Chao1). This suggests that the excessive stocking of H. molitrix may lead to reduced diversity, whereas moderate stocking of H. nobilis could promote diversity restoration. Among physicochemical factors, Chao1 richness was found to be negatively correlated with conductivity, pH, phosphate–phosphorus (PO₄-P), and the total nitrogen to total phosphorus ratio (TN/TP), while Shannon and Simpson diversity indices were negatively correlated with nitrate nitrogen (NO₃-N) concentrations. A redundancy analysis (RDA) identified NO₃-N and permanganate index (COD_Mn) as the primary physicochemical drivers of fish community structure, indicating that while physicochemical differences were found to influence species composition and diversity, their effects were considered relatively limited. These findings suggest that the overwhelming dominance of H. molitrix and H. nobilis in the reservoirs may reduce the influence of seasonal variations and cross-reservoir physicochemical disparities on fish community dynamics. Full article

The development of effective and innovative vaccination strategies is urgently needed to better control the spread and transmission of the low-pathogenic avian influenza H9N2 subtype (LPAI-H9N2) in poultry. In addition, the enhancement of innate immunity by some of these innovative inactivated vaccines has not yet been investigated. Here, an experiment was conducted in commercial broiler chickens to compare the immune response to two different inactivated H9N2 vaccines. For this, Group 1 (G1) broilers were vaccinated with vaccine 1 [Nobilis^® H9N2-P (pathogen-associated molecular patterns—PAMP) technology], broilers in G2 were vaccinated with vaccine 2 [an inactivated whole H9N2 virus (IWV) autogenous oil emulsion vaccine], while birds in G3 were not vaccinated. The study lasted 34 days. Innate immune parameters (phagocytic activity, nitric oxide, and lysozyme), cytokine signaling (IL-1β, IL-6, IL-8), humoral immunity using the hemagglutination inhibition (HI) test, and the gene expressions of IFN-γ and TLR-21 were assessed. The results showed a significant increase in innate immunity and modulatory cytokines at 24–48 h after the vaccination of G1 broilers, with a continuous increase until the end of the experiment. In addition, a significant increase in geometric mean HI titers was observed in G1 at 11 days post-vaccination (dpv), and a significant (p ˂ 0.05) upregulation of IFN-γ and TLR-21 was observed in the same group, G1, at 31 dpv compared to G2 and G3. Nobilis^® H9N2-P may induce faster and stronger innate and active humoral immunity compared to another IWV, which may contribute to the protection of broilers against early H9N2 infections. However, challenge protection studies for several IWV vaccines, including PAMP-H9N2 against LPAI-H9N2, should be further evaluated in both specific pathogen-free (SPF) and commercial broilers. Full article

We describe the characterization of a novel fish leech species found on the gills of bighead carp (Hypophthalmichthys nobilis) from lakes and reservoirs in China. This leech is morphologically similar to Limnotrachelobdella sinensis recorded on goldfish and common carp. However, there are 0–2 pairs of symmetrical or asymmetrical eyes and 10 pairs of pulsatile vesicles in the newly discovered leech, in remarkable contrast to L. sinensis. Except for bighead carp, where it demonstrated a higher than 90% prevalence, and silver carp (H. molitrix), where there was low infection, this leech was not detected on any other fish from the Qiandao reservoir in China that were examined during this investigation. Molecular analyses indicated 87.8% ITS sequence identity with L. sinensis and 85.0 and 86.1% COX1 sequence identity with L. sinensis and L. okae, respectively. The uncorrected p-distance based on the COX1 sequence was found to be 15.1 and 14.0% for L. sinensis and L. okae, respectively, suggesting interspecific variation. Phylogenetic analyses based on the combination of 18S and COX1 sequences showed that the newly discovered leech groups with Limnotrachelobdella species. Histopathological observation indicated that attachment of the leech on the gill rakers and gill arches causes a loss of connective tissue, hemorrhage, and ulceration. Based on the morphology, molecular analyses, and host specificity, we conclude that this leech is a new species of Limnotrachelobdella and named it Limnotrachelobdella hypophthalmichthysa n. sp. Full article

Traditional aquaculture can cause serious environmental pollution. Biofilm and biofloc technology have the potential to limit aquaculture pollution. An outdoor experiment was conducted to evaluate the combined effects of eco-substrates and carbon addition on water quality, fish performance and nutrient budgets in the pond polyculture system. In the treatment group, the total ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, and total nitrogen of the water were significantly lower compared to the control group (p < 0.05). The growth performance of H. molitrix and A. nobilis, including the final individual weight, specific growth rate, weight gain rate, total production and net production, was significantly higher in the treatment groups compared to the control (p < 0.05), while there was no significant difference in those of C. carpio between the two groups. Feed was the main N (>92%) and P (>95%) input during the experiment. Comprehensive accumulation was the main N (>58%) and P (>69%) output. The N and P feed input and comprehensive accumulation output declined in the treatment group. The N utilization efficiency in the experimental group increased slightly (p > 0.05), while the P utilization efficiency in the experimental group was significantly higher compared to the control (p < 0.05). Therefore, the application of eco-substrates and carbon addition can increase water quality, improve fish growth, and promote nutrient utilization efficiency in pond polyculture systems. Full article