Characterization of avian influenza A (H4N2) viruses isolated from wild birds in Shanghai during 2019 to 2021.

The H4 subtype of avian influenza viruses has been widely distributed among wild birds. During the surveillance of the avian influenza virus in Shanghai from 2019 to 2021, a total of 4,451 samples were collected from wild birds, among which 46 H4 subtypes of avian influenza viruses were identified, accounting for 7.40% of the total positive samples. The H4 subtype viruses have a wide range of hosts, including the spot-billed duck, common teal, and other wild birds in Anseriformes. Among all H4 subtypes, the most abundant are the H4N2 viruses. To clarify the genetic characteristics of H4N2 viruses, the whole genome sequences of 20 H4N2 viruses were analyzed. Phylogenetical analysis showed that all 8 genes of these viruses belonged to the Eurasian lineage and closely clustered with low pathogenic avian influenza viruses from countries along the East Asia-Australia migratory route. However, the PB1 gene of 1 H4N2 virus (NH21920) might provide its internal gene for highly pathogenic avian influenza H5N8 viruses in Korea and Japan. At least 10 genotypes were identified in these viruses, indicating that they underwent multiple complex recombination events. Our study has provided a better epidemiological understanding of the H4N2 viruses in wild birds. Considering the mutational potential, comprehensive surveillance of the H4N2 virus in both poultry and wild birds is imperative.

A solution for restoration of critical wetlands and waterbird habitats in coastal deltaic systems.

Loss of coastal wetland habitats has been directly linked to a decline in waterbird populations including migratory species, leading to calls to reverse this trend in part by restoring these habitats. However, distinct "sediment scarcity" has hindered coastal habitat restoration. Here, taking the Yangtze River Delta, China as an example, we put forward a feasible solution to solve the sediment shortage in habitat restoration so necessary to restore migratory waterbird numbers. Four biological indices including total wetland area, wetland vegetation area and waterbird species richness and abundance, were used to compare and assess the restorative efforts. Three solutions were adopted for the rehabilitation sites, including promoting sediment deposition and settlement through engineering intervention in Chongming Dongtan (CD) and Eastern Nanhui (EN), and using dredged sediments to nourish and create new habitats in Hengsha Eastern Shoal (HES). The mean wetland area increased 19.66 km2/yr in EN, 8.78 km2/yr in HES and 3.83 km2/yr in CD after rehabilitation. Along with the increase of wetlands and habitats, the abundance of waterbirds increased 1.3 times, 121 times and 1.5 times in EN, HES and CD, respectively. In contrast, in the site of Fengxian and Jinshan (FJ) where no any rehabilitation measure was taken after reclamation, the habitats were lost almost completely and the waterbird abundance dropped drastically. The comparison and assessment results demonstrate that proper coastal silting structures and ecological utilization of nearby dredged sediments are the feasible and effective solutions to retain sediments, restore coastal habitats and increase waterbird diversity and abundance.

Long-term urbanization impacts the eastern golden frog (Pelophylax plancyi) in Shanghai City: Demographic history, genetic structure, and implications for amphibian conservation in intensively urbanizing environments.

Understanding the mechanisms of how urbanization influences the evolution of native species is vital for urban wildlife ecology and conservation in the Anthropocene. With thousands of years of agriculture-dominated historical urbanization followed by 40 years of intensive and rapid urbanization, Shanghai provides an ideal environment to study how the two-stage urbanization process influences the evolution of indigenous wildlife, especially of anuran species. Therefore, in this study, we used mitochondrial Cyt-b gene, microsatellite (SSR), and single nucleotide polymorphism (SNP) data to evaluate the demographic history and genetic structure of the eastern golden frog (Pelophylax plancyi), by sampling 407 individuals from 15 local populations across Shanghai, China. All local populations experienced bottlenecks during historical urbanization, while the local populations in urban areas maintained comparable contemporary effective population sizes (N e) and genetic diversity with suburban and rural populations. Nevertheless, the rapid modern urbanization has already imposed significant negative effects to the integrity of populations. The 15 local populations were differentiated into eight genetic clusters, showing a spatial distribution pattern consistent with the current urbanization gradient and island-mainland geography. Although moderate gene flow still occurred from the rural peripheral cluster to urban and suburban clusters, population fragmentation was more serious in the urban and suburban populations, where higher urbanization levels within 2-km radius areas showed significant negative relationships to the N e and genetic diversity of local populations. Therefore, to protect urban wildlife with limited dispersal ability, improving conditions in fragmented habitat remnants might be most essential for local populations living in more urbanized areas. Meanwhile, we highlight the need to preserve large unfragmented rural habitats and to construct corridor networks to connect discrete urban habitat remnants for the long-term wildlife conservation in intensively urbanizing environments.