The interaction between urbanization and the eco-environment is usually viewed as an effect–feedback framework. Its coupling system is composed of urbanization and eco-environment subsystems. In this paper, the coupling degree (CD) and the coupling coordinated degree (CCD) are used to reflect the coupling interaction and coupling coordination between the urbanization subsystem and the eco-environment subsystem. Based on the dynamic relative quantities of urbanization and eco-environment data in the Pearl River Delta, CD and CCD values were calculated, and the spatiotemporal evolution trend of coordination was analyzed. The results show that (1) from 2000 to 2015, the nine cities in the Pearl River Delta had high CD values and CCD values. Though they had different performances in different periods, they were all in a coordinated class, including good coordination (GC), moderate coordination (MC), and bare coordination (BC). (2) In terms of temporal evolution, the coupling coordination between urbanization and the eco-environment in the entire Pearl River Delta greatly improved. (3) From the perspective of spatial distribution, the coupling coordination of the central region was higher than that of the peripheral regions, and that of the west bank of the Pearl River was higher than that of the east bank of the Pearl River. These results can help local policy makers enact appropriate measures for sustainable development.

Chlamydophila psittaci (C. psittaci) is an avian pathogen associated with systemic wasting disease in birds, as well as a public health risk. Although duck‐related cases of psittacosis have been reported, the pathogenicity and shedding status of C. psittaci in ducks are unclear. In this study, we reported that C. psittaci (genotype A) is responsible for a disease outbreak characterized by poor laying performance and severe lesions in multiple organs of ducks. Oral administration of antibiotic, doxycycline, was found to effectively control the C. psittaci infection in laying ducks. Collectively, our new findings provide evidence that C. psittaci was the major pathogen responsible for the outbreak of this disease in ducks. In order to reduce economic losses incurred by this disease, effective control measures must be taken to prevent infection in laying duck farms.

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